WorldWideScience

Sample records for andes promotes diversification

  1. Diversification of clearwing butterflies with the rise of the Andes

    OpenAIRE

    De‐Silva, Donna Lisa; Elias, Marianne; Willmott, Keith; Mallet, James; Day, Julia J.

    2015-01-01

    Abstract Aim Despite the greatest butterfly diversity on Earth occurring in the Neotropical Andes and Amazonia, there is still keen debate about the origins of this exceptional biota. A densely sampled calibrated phylogeny for a widespread butterfly subtribe, Oleriina (Nymphalidae: Ithomiini) was used to estimate the origin, colonization history and diversification of this species‐rich group. Location Neotropics. Methods Ancestral elevation and biogeographical ranges were reconstructed using ...

  2. Diversification of clearwing butterflies with the rise of the Andes

    OpenAIRE

    De‐Silva, Donna Lisa; Elias, Marianne; Willmott, Keith; Mallet, James; Day, Julia J.

    2015-01-01

    Abstract Aim Despite the greatest butterfly diversity on Earth occurring in the Neotropical Andes and Amazonia, there is still keen debate about the origins of this exceptional biota. A densely sampled calibrated phylogeny for a widespread butterfly subtribe, Oleriina (Nymphalidae: Ithomiini) was used to estimate the origin, colonization history and diversification of this species‐rich group. Location Neotropics. Methods: Ancestral elevation and biogeographical ranges were reconstructed using...

  3. Out of the Andes: patterns of diversification in clearwing butterflies.

    Science.gov (United States)

    Elias, M; Joron, M; Willmott, K; Silva-Brandão, K L; Kaiser, V; Arias, C F; Gomez Piñerez, L M; Uribe, S; Brower, A V Z; Freitas, A V L; Jiggins, C D

    2009-04-01

    Global biodiversity peaks in the tropical forests of the Andes, a striking geological feature that has likely been instrumental in generating biodiversity by providing opportunities for both vicariant and ecological speciation. However, the role of these mountains in the diversification of insects, which dominate biodiversity, has been poorly explored using phylogenetic methods. Here we study the role of the Andes in the evolution of a diverse Neotropical insect group, the clearwing butterflies. We used dated species-level phylogenies to investigate the time course of speciation and to infer ancestral elevation ranges for two diverse genera. We show that both genera likely originated at middle elevations in the Andes in the Middle Miocene, contrasting with most published results in vertebrates that point to a lowland origin. Although we detected a signature of vicariance caused by the uplift of the Andes at the Miocene-Pliocene boundary, most sister species were parapatric without any obvious vicariant barrier. Combined with an overall decelerating speciation rate, these results suggest an important role for ecological speciation and adaptive radiation, rather than simple vicariance.

  4. Phylogeny and biogeography of the New World siskins and goldfinches: rapid, recent diversification in the Central Andes.

    Science.gov (United States)

    Beckman, Elizabeth J; Witt, Christopher C

    2015-06-01

    Time-calibrated molecular phylogenies can help us to understand the origins of the diverse and unique Andean avifauna. Previous studies have shown that the tempo of diversification differed between the Andes and adjacent lowland regions of South America. Andean taxa were found to have speciated more recently and to have avoided the decelerated diversification that is typical of Neotropical lowland clades. The South American siskins, a Pleistocene finch radiation, may typify this Andean pattern. We investigated the phylogenetic biogeography of all the New World siskins and goldfinches in new detail. To understand the specific role of the Andes in siskin diversification, we asked: (1) Was diversification faster in Andean siskin lineages relative to non-Andean ones? (2) Did siskin lineages move into and out of the Andes at different rates? We found that siskin lineages in the Andes had higher diversification rates and higher outward dispersal rates than siskin lineages outside the Andes. We conclude that páramo expansion and contraction in response to Pleistocene climatic cycles caused accelerated diversification and outward dispersal in Andean siskins. The younger average age of bird species in the Andes compared to lowland South America may be attributable to bursts of recent diversification in siskins and several other vagile, open-habitat clades.

  5. Research on Habitat Shift Promoting Species Diversification

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    PNAS published on August 15,2011 the article "Eocene habitat shift from saline to freshwater promoted Tethyan amphipod diversification" by Professor Shuqiang Li of Institute of Zoology,CAS,together with Slovenian cooperators. Current theory predicts that a shift to a new habitat would increase the rate of diversification;while as lineages evolve into multiple species,intensified competition would decrease the rate of diversification.

  6. The impact of rise of the Andes and Amazon landscape evolution on diversification of lowland terra-firme forest birds

    Science.gov (United States)

    Aleixo, A.; Wilkinson, M. J.

    2011-12-01

    Since the 19th Century, the unmatched biological diversity of Amazonia has stimulated a diverse set of hypotheses accounting for patterns of species diversity and distribution in mega-diverse tropical environments. Unfortunately, the evidence supporting particular hypotheses to date is at best described as ambiguous, and no generalizations have emerged yet, mostly due to the lack of comprehensive comparative phylogeographic studies with thorough trans-Amazonian sampling of lineages. Here we report on spatial and temporal patterns of diversification estimated from mitochondrial gene trees for 31 lineages of birds associated with upland terra-firme forest, the dominant habitat in modern lowland Amazonia. The results confirm the pervasive role of Amazonian rivers as primary barriers separating sister lineages of birds, and a protracted spatio-temporal pattern of diversification, with a gradual reduction of earlier (1st and 2nd) and older (> 2 mya) splits associated with each lineage in an eastward direction (the easternmost tributaries of the Amazon, the Xingu and Tocantins Rivers, are not associated with any splits older than > 2 mya). This "younging-eastward" pattern may have an abiotic explanation related to landscape evolution. Triggered by a new pulse of Andean uplift, it has been proposed that modern Amazon basin landscapes may have evolved successively eastward, away from the mountain chain, starting ~10 mya. This process was likely based on the deposition of vast fluvial sediment masses, known as megafans, which apparently extended in series progressively eastward from Andean sources. The effects on drainage patterns are apparent from the location of axial rivers such as the Negro / Orinoco and Madeira which lie at the distal ends of major megafan ramparts at cratonic margins furthest from the Andes. Megafan extension plausibly explains the progressive extinction of the original Pebas wetland of west-central Amazonia by the present fluvial landsurfaces where

  7. Independent evolution of the sexes promotes amphibian diversification.

    Science.gov (United States)

    De Lisle, Stephen P; Rowe, Locke

    2015-03-22

    Classic ecological theory predicts that the evolution of sexual dimorphism constrains diversification by limiting morphospace available for speciation. Alternatively, sexual selection may lead to the evolution of reproductive isolation and increased diversification. We test contrasting predictions of these hypotheses by examining the relationship between sexual dimorphism and diversification in amphibians. Our analysis shows that the evolution of sexual size dimorphism (SSD) is associated with increased diversification and speciation, contrary to the ecological theory. Further, this result is unlikely to be explained by traditional sexual selection models because variation in amphibian SSD is unlikely to be driven entirely by sexual selection. We suggest that relaxing a central assumption of classic ecological models-that the sexes share a common adaptive landscape-leads to the alternative hypothesis that independent evolution of the sexes may promote diversification. Once the constraints of sexual conflict are relaxed, the sexes can explore morphospace that would otherwise be inaccessible. Consistent with this novel hypothesis, the evolution of SSD in amphibians is associated with reduced current extinction threat status, and an historical reduction in extinction rate. Our work reconciles conflicting predictions from ecological and evolutionary theory and illustrates that the ability of the sexes to evolve independently is associated with a spectacular vertebrate radiation.

  8. The Impact of Rise of the Andes and Amazon Landscape Evolution on Diversification of Lowland terra-firme Forest Birds

    Science.gov (United States)

    Aleixo, Alexandre; Wilkinson, M. Justin

    2011-01-01

    . The youngest landsurfaces thus lie furthest from the mountains. In this scenario major drainages were also reoriented in wholesale fashion away from a northerly orientation generally towards the east and an Atlantic Ocean outlet. The advance of megafans is best seen by the location of axial rivers such as the Orinoco and Mamore which lie against the cratonic margins furthest from the Andes, at the distal ends of major megafan ramparts. More importantly, other major river courses in western-central Amazonia will have been established at progressively younger dates with distance eastward. If this landscape-sequence scenario is accurate, it parallels the progressive younging of the passerine lineages. The bird DNA data appears to confirm strongly the pervasive role of Amazonian rivers--as primary barriers separating sister lineages of birds, and thus probably as facilitaters of bird speciation. We show for the first time that a general spatio-temporal pattern of diversification for terra-firme lineages in the Amazon is associated with rivers ("younging-eastward"), and furthermore parallels a specific scenario of regional drainage evolution.

  9. Niche shifts and range expansions along cordilleras drove diversification in a high-elevation endemic plant genus in the tropical Andes.

    Science.gov (United States)

    Kolář, Filip; Dušková, Eva; Sklenář, Petr

    2016-09-01

    The tropical Andes represent one of the world's biodiversity hot spots, but the evolutionary drivers generating their striking species diversity still remain poorly understood. In the treeless high-elevation Andean environments, Pleistocene glacial oscillations and niche differentiation are frequently hypothesized diversification mechanisms; however, sufficiently densely sampled population genetic data supporting this are still lacking. Here, we reconstruct the evolutionary history of Loricaria (Asteraceae), a plant genus endemic to the Andean treeless alpine zone, based on comprehensive population-level sampling of 289 individuals from 67 populations across the entire distribution ranges of its northern Andean species. Partly incongruent AFLP and plastid DNA markers reveal that the distinct genetic structure was shaped by a complex interplay of biogeography (spread along and across the cordilleras), history (Pleistocene glacial oscillations) and local ecological conditions. While plastid variation documents an early split or colonization of the northern Andes by at least two lineages, one of which further diversified, a major split in the AFLP data correlate with altitudinal ecological differentiation. This suggests that niche shifts may be important drivers of Andean diversification not only in forest-alpine transitions, but also within the treeless alpine zone itself. The patterns of genetic differentiation at the intraspecific level reject the hypothesized separation in spatially isolated cordilleras and instead suggest extensive gene flow among populations from distinct mountain chains. Our study highlights that leveraging highly variable markers against extensive population-level sampling is a promising approach to address mechanisms of rapid species diversifications.

  10. Oceanic barriers promote language diversification in the Japanese Islands.

    Science.gov (United States)

    Lee, S; Hasegawa, T

    2014-09-01

    Good barriers make good languages. Scholars have long speculated that geographical barriers impede linguistic contact between speech communities and promote language diversification in a manner similar to the process of allopatric speciation. This hypothesis, however, has seldom been tested systematically and quantitatively. Here, we adopt methods from evolutionary biology and attempt to quantify the influence of oceanic barriers on the degree of lexical diversity in the Japanese Islands. Measuring the degree of beta diversity from basic vocabularies, we find that geographical proximity and, more importantly, isolation by surrounding ocean, independently explains a significant proportion of lexical variation across Japonic languages. Further analyses indicate that our results are neither a by-product of using a distance matrix derived from a Bayesian language phylogeny nor an epiphenomenon of accelerated evolutionary rates in languages spoken by small communities. Moreover, we find that the effect of oceanic barriers is reproducible with the Ainu languages, indicating that our analytic approach as well as the results can be generalized beyond Japonic language family. The findings we report here are the first quantitative evidence that physical barriers formed by ocean can influence language diversification and points to an intriguing common mechanism between linguistic and biological evolution.

  11. 75 FR 3871 - Promoting Diversification of Ownership in Broadcast Services; Suspension of Filing Date

    Science.gov (United States)

    2010-01-25

    ... published at 74 FR 56135 on October 30, 2009, which amended the requirement that Form 323 must be...-244; DA 09-2618] Promoting Diversification of Ownership in Broadcast Services; Suspension of Filing... Ownership Report Form (Form 323), DA 09-2457 (rel. Nov. 23, 2009); Promoting Diversification in...

  12. Diversification in the Andes

    DEFF Research Database (Denmark)

    Sánchez-González, Luis A.; Navarro-Sigüenza, Adolfo G.; Krabbe, Niels Kaare;

    2015-01-01

    With nearly 30 species, the Atlapetes brush-finches are one of the most species-rich genera in the New World sparrows (Passerellidae). Atlapetes is mainly distributed in highland forests from Mexico to north-western Argentina, with a few taxa in the foothills (......With nearly 30 species, the Atlapetes brush-finches are one of the most species-rich genera in the New World sparrows (Passerellidae). Atlapetes is mainly distributed in highland forests from Mexico to north-western Argentina, with a few taxa in the foothills (...

  13. Fast demographic traits promote high diversification rates of Amazonian trees

    OpenAIRE

    Baker, Timothy R.; Pennington, R. Toby; Magallon, Susana; Gloor, Emanuel; Laurance, William F.; Alexiades, Miguel; Alvarez, Esteban; Araujo, Alejandro; Arets, Eric J. M. M.; Aymard, Gerardo; de Oliveira, Atila Alves; Amaral, Iêda; Arroyo, Luzmila; Bonal, Damien; Roel J.W. Brienen

    2014-01-01

    The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show that fast demographic traits - short turnover times - are associated with high diversification rates across 51 clades of canopy trees. This relationship is robust to assuming that diversification rat...

  14. Fast demographic traits promote high diversification rates of Amazonian trees

    Science.gov (United States)

    Baker, Timothy R; Pennington, R Toby; Magallon, Susana; Gloor, Emanuel; Laurance, William F; Alexiades, Miguel; Alvarez, Esteban; Araujo, Alejandro; Arets, Eric J M M; Aymard, Gerardo; de Oliveira, Atila Alves; Amaral, Iêda; Arroyo, Luzmila; Bonal, Damien; Brienen, Roel J W; Chave, Jerome; Dexter, Kyle G; Di Fiore, Anthony; Eler, Eduardo; Feldpausch, Ted R; Ferreira, Leandro; Lopez-Gonzalez, Gabriela; van der Heijden, Geertje; Higuchi, Niro; Honorio, Eurídice; Huamantupa, Isau; Killeen, Tim J; Laurance, Susan; Leaño, Claudio; Lewis, Simon L; Malhi, Yadvinder; Marimon, Beatriz Schwantes; Marimon Junior, Ben Hur; Monteagudo Mendoza, Abel; Neill, David; Peñuela-Mora, Maria Cristina; Pitman, Nigel; Prieto, Adriana; Quesada, Carlos A; Ramírez, Fredy; Ramírez Angulo, Hirma; Rudas, Agustin; Ruschel, Ademir R; Salomão, Rafael P; de Andrade, Ana Segalin; Silva, J Natalino M; Silveira, Marcos; Simon, Marcelo F; Spironello, Wilson; ter Steege, Hans; Terborgh, John; Toledo, Marisol; Torres-Lezama, Armando; Vasquez, Rodolfo; Vieira, Ima Célia Guimarães; Vilanova, Emilio; Vos, Vincent A; Phillips, Oliver L; Wiens, John

    2014-01-01

    The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show that fast demographic traits – short turnover times – are associated with high diversification rates across 51 clades of canopy trees. This relationship is robust to assuming that diversification rates are either constant or decline over time, and occurs in a wide range of Neotropical tree lineages. This finding reveals the crucial role of intrinsic, ecological variation among clades for understanding the origin of the remarkable diversity of Amazonian trees and forests. PMID:24589190

  15. 78 FR 2925 - Promoting Diversification of Ownership in the Broadcasting Services

    Science.gov (United States)

    2013-01-15

    ... to the 323 Order, 74 FR 25163 (2009), and the 323 MO&O, 74 FR 56131 (2009) in this proceeding... Documents in Rulemaking Proceedings, 63 FR 24121 (1998). Electronic Filers: Comments may be filed... COMMISSION Promoting Diversification of Ownership in the Broadcasting Services AGENCY: Federal...

  16. Bacteriophage predation promotes serovar diversification in Listeria monocytogenes.

    Science.gov (United States)

    Eugster, Marcel R; Morax, Laurent S; Hüls, Vanessa J; Huwiler, Simona G; Leclercq, Alexandre; Lecuit, Marc; Loessner, Martin J

    2015-07-01

    Listeria monocytogenes is a bacterial pathogen classified into distinct serovars (SVs) based on somatic and flagellar antigens. To correlate phenotype with genetic variation, we analyzed the wall teichoic acid (WTA) glycosylation genes of SV 1/2, 3 and 7 strains, which differ in decoration of the ribitol-phosphate backbone with N-acetylglucosamine (GlcNAc) and/or rhamnose. Inactivation of lmo1080 or the dTDP-l-rhamnose biosynthesis genes rmlACBD (lmo1081-1084) resulted in loss of rhamnose, whereas disruption of lmo1079 led to GlcNAc deficiency. We found that all SV 3 and 7 strains actually originate from a SV 1/2 background, as a result of small mutations in WTA rhamnosylation and/or GlcNAcylation genes. Genetic complementation of different SV 3 and 7 isolates using intact alleles fully restored a characteristic SV 1/2 WTA carbohydrate pattern, including antisera reactions and phage adsorption. Intriguingly, phage-resistant L. monocytogenes EGDe (SV 1/2a) isolates featured the same glycosylation gene mutations and were serotyped as SV 3 or 7 respectively. Again, genetic complementation restored both carbohydrate antigens and phage susceptibility. Taken together, our data demonstrate that L. monocytogenes SV 3 and 7 originate from point mutations in glycosylation genes, and we show that phage predation represents a major driving force for serovar diversification and evolution of L. monocytogenes.

  17. C4 photosynthesis promoted species diversification during the Miocene grassland expansion.

    Directory of Open Access Journals (Sweden)

    Elizabeth L Spriggs

    Full Text Available Identifying how organismal attributes and environmental change affect lineage diversification is essential to our understanding of biodiversity. With the largest phylogeny yet compiled for grasses, we present an example of a key physiological innovation that promoted high diversification rates. C4 photosynthesis, a complex suite of traits that improves photosynthetic efficiency under conditions of drought, high temperatures, and low atmospheric CO2, has evolved repeatedly in one lineage of grasses and was consistently associated with elevated diversification rates. In most cases there was a significant lag time between the origin of the pathway and subsequent radiations, suggesting that the 'C4 effect' is complex and derives from the interplay of the C4 syndrome with other factors. We also identified comparable radiations occurring during the same time period in C3 Pooid grasses, a diverse, cold-adapted grassland lineage that has never evolved C4 photosynthesis. The mid to late Miocene was an especially important period of both C3 and C4 grass diversification, coincident with the global development of extensive, open biomes in both warm and cool climates. As is likely true for most "key innovations", the C4 effect is context dependent and only relevant within a particular organismal background and when particular ecological opportunities became available.

  18. Disentangling adaptive evolutionary radiations and the role of diet in promoting diversification on islands

    Science.gov (United States)

    Demiguel, Daniel

    2016-07-01

    Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil data, rigorous attempts to identify this phenomenon in the fossil record are largely uncommon. Here I focus on direct evidence of the diet (through tooth-wear patterns) and ecologically-relevant traits of one of the most renowned fossil vertebrates-the Miocene ruminant Hoplitomeryx from the island of Gargano-to deepen our understanding of the most likely causal forces under which adaptive radiations emerge on islands. Results show how accelerated accumulation of species and early-bursts of ecological diversification occur after invading an island, and provide insights on the interplay between diet and demographic (population-density), ecological (competition/food requirements) and abiotic (climate-instability) factors, identified as drivers of adaptive diversification. A pronounced event of overpopulation and a phase of aridity determined most of the rate and magnitude of radiation, and pushed species to expand diets from soft-leafy foods to tougher-harder items. Unexpectedly, results show that herbivorous mammals are restricted to browsing habits on small-islands, even if bursts of ecological diversification and dietary divergence occur. This study deepens our understanding of the mechanisms promoting adaptive radiations, and forces us to reevaluate the role of diet in the origins and evolution of islands mammals.

  19. The Neogene rise of the tropical Andes facilitated diversification of wax palms (Ceroxylon: Arecaceae) through geographical colonization and climatic niche separation

    DEFF Research Database (Denmark)

    Sanín, María José; Kissling, W. Daniel; Bacon, Christine D.;

    2016-01-01

    out in the palm family (Arecaceae) due to its adaptation to cold, mountainous environments. Here, we reconstruct the biogeography and climatic preference of this lineage to test the hypothesis that Andean uplift allowed diversification by providing suitable habitats along climatic and elevational...

  20. Diversification of an organisational field: how Europe promotes and hampers domestic change

    Energy Technology Data Exchange (ETDEWEB)

    Boasson, Elin Lerum

    2008-11-15

    Better understanding of Europeanization requires research on national, societal change. This paper presents a theoretical framework that enables assessment of Europeanised change processes within national industries. Empirically it explores how European Union (EU) state aid regulations and European renewable energy trends in conjunction led to diversification among Norwegian stationary energy producers. Key theoretical implications are as follows: (1) The pattern of interaction between change impulses from the European environment, governmental hierarchical steering and institutional logics within the national organisational field was crucial to the output of the change process. (2) Misfit between institutional logics at the European level and the organisational field hampers change, rather than promoting it. (3) The carriers / the actors that bring the European impulses into the organisational field / matter because they translate change impulses in line with their institutional logic. (4) National politicians are unable to control the process of translating these impulses, and that reduces their political clout. (5) Europeanization brings greater challenges to national democratic governance of liberalised industries. (author). refs., tabs

  1. Multi-country evidence that crop diversification promotes ecological intensification of agriculture.

    Science.gov (United States)

    Gurr, Geoff M; Lu, Zhongxian; Zheng, Xusong; Xu, Hongxing; Zhu, Pingyang; Chen, Guihua; Yao, Xiaoming; Cheng, Jiaan; Zhu, Zengrong; Catindig, Josie Lynn; Villareal, Sylvia; Van Chien, Ho; Cuong, Le Quoc; Channoo, Chairat; Chengwattana, Nalinee; Lan, La Pham; Hai, Le Huu; Chaiwong, Jintana; Nicol, Helen I; Perovic, David J; Wratten, Steve D; Heong, Kong Luen

    2016-02-22

    Global food security requires increased crop productivity to meet escalating demand(1-3). Current food production systems are heavily dependent on synthetic inputs that threaten the environment and human well-being(2,4,5). Biodiversity, for instance, is key to the provision of ecosystem services such as pest control(6,7), but is eroded in conventional agricultural systems. Yet the conservation and reinstatement of biodiversity is challenging(5,8,9), and it remains unclear whether the promotion of biodiversity can reduce reliance on inputs without penalizing yields on a regional scale. Here we present results from multi-site field studies replicated in Thailand, China and Vietnam over a period of four years, in which we grew nectar-producing plants around rice fields, and monitored levels of pest infestation, insecticide use and yields. Compiling the data from all sites, we report that this inexpensive intervention significantly reduced populations of two key pests, reduced insecticide applications by 70%, increased grain yields by 5% and delivered an economic advantage of 7.5%. Additional field studies showed that predators and parasitoids of the main rice pests, together with detritivores, were more abundant in the presence of nectar-producing plants. We conclude that a simple diversification approach, in this case the growth of nectar-producing plants, can contribute to the ecological intensification of agricultural systems.

  2. Mixed infections may promote diversification of mutualistic symbionts: why are there ineffective rhizobia?

    Science.gov (United States)

    Friesen, M L; Mathias, A

    2010-02-01

    While strategy variation is a key feature of symbiotic mutualisms, little work focuses on the origin of this diversity. Rhizobia strategies range from mutualistic nitrogen fixers to parasitic nonfixers that hoard plant resources to increase their own survival in soil. Host plants reward beneficial rhizobia with higher nodule growth rates, generating a trade-off between reproduction in nodules and subsequent survival in soil. However, hosts might not discriminate between strains in mixed infections, allowing nonfixing strains to escape sanctions. We construct an adaptive dynamics model of symbiotic nitrogen-fixation and find general situations where symbionts undergo adaptive diversification, but in most situations complete nonfixers do not evolve. Social conflict in mixed infections when symbionts face a survival-reproduction trade-off can drive the origin of some coexisting symbiont strategies, where less mutualistic strains exploit benefits generated by better mutualists.

  3. Phylogenetic insights into Andean plant diversification

    Directory of Open Access Journals (Sweden)

    Federico eLuebert

    2014-06-01

    Full Text Available Andean orogeny is considered as one of the most important events for the developmentof current plant diversity in South America. We compare available phylogenetic studies anddivergence time estimates for plant lineages that may have diversified in response to Andeanorogeny. The influence of the Andes on plant diversification is separated into four major groups:The Andes as source of new high-elevation habitats, as a vicariant barrier, as a North-Southcorridor and as generator of new environmental conditions outside the Andes. Biogeographicalrelationships between the Andes and other regions are also considered. Divergence timeestimates indicate that high-elevation lineages originated and diversified during or after the majorphases of Andean uplift (Mid-Miocene to Pliocene, although there are some exceptions. Asexpected, Andean mid-elevation lineages tend to be older than high-elevation groups. Mostclades with disjunct distribution on both sides of the Andes diverged during Andean uplift.Inner-Andean clades also tend to have divergence time during or after Andean uplift. This isinterpreted as evidence of vicariance. Dispersal along the Andes has been shown to occur ineither direction, mostly dated after the Andean uplift. Divergence time estimates of plant groupsoutside the Andes encompass a wider range of ages, indicating that the Andes may not benecessarily the cause of these diversifications. The Andes are biogeographically related to allneighbouring areas, especially Central America, with floristic interchanges in both directionssince Early Miocene times. Direct biogeographical relationships between the Andes and otherdisjunct regions have also been shown in phylogenetic studies, especially with the easternBrazilian highlands and North America. The history of the Andean flora is complex and plantdiversification has been driven by a variety of processes, including environmental change,adaptation, and biotic interactions

  4. Cultural diversification promotes rapid phenotypic evolution in Xavánte Indians.

    Science.gov (United States)

    Hünemeier, Tábita; Gómez-Valdés, Jorge; Ballesteros-Romero, Mónica; de Azevedo, Soledad; Martínez-Abadías, Neus; Esparza, Mireia; Sjøvold, Torstein; Bonatto, Sandro L; Salzano, Francisco Mauro; Bortolini, Maria Cátira; González-José, Rolando

    2012-01-03

    Shifts in social structure and cultural practices can potentially promote unusual combinations of allele frequencies that drive the evolution of genetic and phenotypic novelties during human evolution. These cultural practices act in combination with geographical and linguistic barriers and can promote faster evolutionary changes shaped by gene-culture interactions. However, specific cases indicative of this interaction are scarce. Here we show that quantitative genetic parameters obtained from cephalometric data taken on 1,203 individuals analyzed in combination with genetic, climatic, social, and life-history data belonging to six South Amerindian populations are compatible with a scenario of rapid genetic and phenotypic evolution, probably mediated by cultural shifts. We found that the Xavánte experienced a remarkable pace of evolution: the rate of morphological change is far greater than expected for its time of split from their sister group, the Kayapó, which occurred around 1,500 y ago. We also suggest that this rapid differentiation was possible because of strong social-organization differences. Our results demonstrate how human groups deriving from a recent common ancestor can experience variable paces of phenotypic divergence, probably as a response to different cultural or social determinants. We suggest that assembling composite databases involving cultural and biological data will be of key importance to unravel cases of evolution modulated by the cultural environment.

  5. APOBEC3D and APOBEC3F potently promote HIV-1 diversification and evolution in humanized mouse model.

    Directory of Open Access Journals (Sweden)

    Kei Sato

    2014-10-01

    Full Text Available Several APOBEC3 proteins, particularly APOBEC3D, APOBEC3F, and APOBEC3G, induce G-to-A hypermutations in HIV-1 genome, and abrogate viral replication in experimental systems, but their relative contributions to controlling viral replication and viral genetic variation in vivo have not been elucidated. On the other hand, an HIV-1-encoded protein, Vif, can degrade these APOBEC3 proteins via a ubiquitin/proteasome pathway. Although APOBEC3 proteins have been widely considered as potent restriction factors against HIV-1, it remains unclear which endogenous APOBEC3 protein(s affect HIV-1 propagation in vivo. Here we use a humanized mouse model and HIV-1 with mutations in Vif motifs that are responsible for specific APOBEC3 interactions, DRMR/AAAA (4A or YRHHY/AAAAA (5A, and demonstrate that endogenous APOBEC3D/F and APOBEC3G exert strong anti-HIV-1 activity in vivo. We also show that the growth kinetics of 4A HIV-1 negatively correlated with the expression level of APOBEC3F. Moreover, single genome sequencing analyses of viral RNA in plasma of infected mice reveal that 4A HIV-1 is specifically and significantly diversified. Furthermore, a mutated virus that is capable of using both CCR5 and CXCR4 as entry coreceptor is specifically detected in 4A HIV-1-infected mice. Taken together, our results demonstrate that APOBEC3D/F and APOBEC3G fundamentally work as restriction factors against HIV-1 in vivo, but at the same time, that APOBEC3D and APOBEC3F are capable of promoting viral diversification and evolution in vivo.

  6. History of Lake Andes

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Information about the history and management of Lake Andes is compiled in this report. It is intended to help future refuge managers become acquainted with the...

  7. Into the Andes: multiple independent colonizations drive montane diversity in the Neotropical clearwing butterflies Godyridina.

    Science.gov (United States)

    Chazot, Nicolas; Willmott, Keith R; Condamine, Fabien L; De-Silva, Donna Lisa; Freitas, André V L; Lamas, Gerardo; Morlon, Hélène; Giraldo, Carlos E; Jiggins, Chris D; Joron, Mathieu; Mallet, James; Uribe, Sandra; Elias, Marianne

    2016-11-01

    Understanding why species richness peaks along the Andes is a fundamental question in the study of Neotropical biodiversity. Several biogeographic and diversification scenarios have been proposed in the literature, but there is confusion about the processes underlying each scenario, and assessing their relative contribution is not straightforward. Here, we propose to refine these scenarios into a framework which evaluates four evolutionary mechanisms: higher speciation rate in the Andes, lower extinction rates in the Andes, older colonization times and higher colonization rates of the Andes from adjacent areas. We apply this framework to a species-rich subtribe of Neotropical butterflies whose diversity peaks in the Andes, the Godyridina (Nymphalidae: Ithomiini). We generated a time-calibrated phylogeny of the Godyridina and fitted time-dependent diversification models. Using trait-dependent diversification models and ancestral state reconstruction methods we then compared different biogeographic scenarios. We found strong evidence that the rates of colonization into the Andes were higher than the other way round. Those colonizations and the subsequent local diversification at equal rates in the Andes and in non-Andean regions mechanically increased the species richness of Andean regions compared to that of non-Andean regions ('species-attractor' hypothesis). We also found support for increasing speciation rates associated with Andean lineages. Our work highlights the importance of the Andean slopes in repeatedly attracting non-Andean lineages, most likely as a result of the diversity of habitats and/or host plants. Applying this analytical framework to other clades will bring important insights into the evolutionary mechanisms underlying the most species-rich biodiversity hotspot on the planet.

  8. Diversification: Far term (2000 - )

    Science.gov (United States)

    1975-01-01

    Diversification, intended to underly the far term of the energy conservation program, was defined to imply conservation through substitution for scarce energy resources by maximizing the total number of viable energy system types in every sector. The following requirements or aspects of diversification that must be studied were given: fuel mix and end use patterns for various alternative diversification plans, current status of diversification, advantages and disadvantages of diversification, constraints and criteria, diversification actions and their controls, and means for implementing the chosen diversification strategy. The following advantages resulting from diversification were described: competition, crisis-related situations, local energy production, decentralized plant locations, long range energy policy, and environmental overloads. The major criteria by which a diversification program should be judged, the major constraints affecting the approaches, and the road to diversification, were elaborated.

  9. Diversification and Corporate Governance

    NARCIS (Netherlands)

    G.W.J. Hendrikse (George); A.A.C.J. van Oijen

    2002-01-01

    textabstractThis article addresses the impact of governance structure on diversification behavior. Hypotheses are developed regarding the differences in diversification strategy of cooperatives and stock listed companies. The analysis shows that stock listed companies are more diversified than coope

  10. Diversification of energy sources

    Science.gov (United States)

    1975-01-01

    The concept of energy source diversification was introduced as a substitution conservation action. The current status and philosophy behind a diversification program is presented in the context of a national energy policy. Advantages, disadvantages (constraints), and methods of implementation for diversification are discussed. The energy source systems for diversification are listed and an example impact assessment is outlined which deals with the water requirements of the specific energy systems.

  11. From specialization to diversification

    OpenAIRE

    Shuran, Iryna

    2012-01-01

    The main types of corporate diversification strategy were considered. Strategic opportunities to diversify the company's were given. The main advantages and disadvantages of diversification strategies in related and unrelated fields of activity were identified. The examples of companies that have implemented the strategic approaches to diversification were given. The most common approach of this strategy in the domestic industrial market was identified.

  12. DIVERSIFICATION IN SOFTWARE ENGINEERING

    Directory of Open Access Journals (Sweden)

    Er.Kirtesh Jailia,

    2010-06-01

    Full Text Available In this paper we examine the factors that have promoted the iversification of software process models. The intention is to understand more clearly the problem-solving process in software engineering & try to find out the efficient way to manage the risk. A review of software process modeling is given first, followed by a discussion of process evaluation techniques. A taxonomy for categorizing process models, based on establishing decision criteria,is identified that can guide selecting the appropriate model from a set of alternatives on the basis of model characteristics and software project needs. We are proposing a model in this paper, for dealing with the diversification in software engineering.

  13. Phenotypic plasticity's impacts on diversification and speciation.

    Science.gov (United States)

    Pfennig, David W; Wund, Matthew A; Snell-Rood, Emilie C; Cruickshank, Tami; Schlichting, Carl D; Moczek, Armin P

    2010-08-01

    Phenotypic plasticity (the ability of a single genotype to produce multiple phenotypes in response to variation in the environment) is commonplace. Yet its evolutionary significance remains controversial, especially in regard to whether and how it impacts diversification and speciation. Here, we review recent theory on how plasticity promotes: (i) the origin of novel phenotypes, (ii) divergence among populations and species, (iii) the formation of new species and (iv) adaptive radiation. We also discuss the latest empirical support for each of these evolutionary pathways to diversification and identify potentially profitable areas for future research. Generally, phenotypic plasticity can play a largely underappreciated role in driving diversification and speciation.

  14. Trees in the Andes:

    OpenAIRE

    Jost, François Paul

    2017-01-01

    High mountain regions including the Andean region are very sensitive to climate change. Farmers in the central Andes of Peru are increasingly being exposed to the impacts of climate variability. This transdisciplinary research uses field laboratories, combining the farming system and the sustainable livelihood approaches, to carry out social, ecological, and financial assessments so as to identify sustainable and resilient livelihood strategies for small-scale Andean farmers. The first r...

  15. The mechanism of technological diversification promoting corporate performance%技术多元化促进企业绩效的机理研究

    Institute of Scientific and Technical Information of China (English)

    何郁冰

    2011-01-01

    技术多元化影响着企业产品创新战略的选择与绩效,但是既有文献并未对技术多元化影响企业绩效的机制进行研究,也较缺乏基于中国企业的实证分析.基于最新理论研究并结合实地调研结果,本研究从产品创新战略角度探讨了技术多元化对企业绩效的中介机制问题.研究结果发现,产品创新战略在技术多元化影响企业经营绩效过程中起完全中介作用,在技术多元化影响企业创新绩效过程中起部分中介作用.%Technological diversification has a impact on the choice of company' s product innovation strategy and its performance, however the existing literatures have not analyzed on how the mechanism of technological diversification impacts corporate performance; in the meantime, the relative empirical analysis based on Chinese companies are also lack.Based on the latest theoretical research and the results of on site research, the mediative mechanism betwee corporate technological diversification and its performance is studied from a angle of product innovation strategy.The empirical results suggest that poruct innovation strategy has completely played a mediative role in the impact of corporate technological diversification on its business performance, but only has played a partially mediative role in the impact of corporate technological diversification on its innovation performance.

  16. From specialization to diversification

    Directory of Open Access Journals (Sweden)

    Shuran, Iryna

    2012-05-01

    Full Text Available The main types of corporate diversification strategy were considered. Strategic opportunities to diversify the company's were given. The main advantages and disadvantages of diversification strategies in related and unrelated fields of activity were identified. The examples of companies that have implemented the strategic approaches to diversification were given. The most common approach of this strategy in the domestic industrial market was identified.

  17. Histone H3.3 promotes IgV gene diversification by enhancing formation of AID-accessible single-stranded DNA.

    Science.gov (United States)

    Romanello, Marina; Schiavone, Davide; Frey, Alexander; Sale, Julian E

    2016-07-01

    Immunoglobulin diversification is driven by activation-induced deaminase (AID), which converts cytidine to uracil within the Ig variable (IgV) regions. Central to the recruitment of AID to the IgV genes are factors that regulate the generation of single-stranded DNA (ssDNA), the enzymatic substrate of AID Here, we report that chicken DT40 cells lacking variant histone H3.3 exhibit reduced IgV sequence diversification. We show that this results from impairment of the ability of AID to access the IgV genes due to reduced formation of ssDNA during IgV transcription. Loss of H3.3 also diminishes IgV R-loop formation. However, reducing IgV R-loops by RNase HI overexpression in wild-type cells does not affect IgV diversification, showing that these structures are not necessary intermediates for AID access. Importantly, the reduction in the formation of AID-accessible ssDNA in cells lacking H3.3 is independent of any effect on the level of transcription or the kinetics of RNAPII elongation, suggesting the presence of H3.3 in the nucleosomes of the IgV genes increases the chances of the IgV DNA becoming single-stranded, thereby creating an effective AID substrate.

  18. Hospital diversification: evaluating alternatives.

    Science.gov (United States)

    Hammer, L

    1987-05-01

    The appropriateness of diversification as a growth strategy for hospitals is discussed, and planning for diversification is described. Because new forms of health-care delivery are now in direct competition with hospitals, many hospitals are confronting environmental pressures and preparing for future survival through diversification. To explore the potential risks and benefits of diversification, the hospital must identify opportunities for new business ventures. Diversification can be "related," through an expansion of the primary product line (health care), or "unrelated," into areas not directly associated with health care. The hospital must establish specific criteria for evaluating each diversification alternative, and the two or three most attractive options should be analyzed further through a financial feasibility study. The hospital should also seek legal advice to determine the implications of diversification for maintenance of tax status, antitrust limitations, and applicability of certificate of need. Although diversification may not be appropriate for every institution, hospitals should consider it as a strategy for increasing their revenue base, confronting environmental pressures, and securing future survival.

  19. Diversification and Corporate Governance

    OpenAIRE

    Hendrikse, George; van Oijen, A.A.C.J.

    2002-01-01

    textabstractThis article addresses the impact of governance structure on diversification behavior. Hypotheses are developed regarding the differences in diversification strategy of cooperatives and stock listed companies. The analysis shows that stock listed companies are more diversified than cooperatives, related as well as unrelated.

  20. Andean uplift promotes lowland speciation through vicariance and dispersal in Dendrocincla woodcreepers.

    Science.gov (United States)

    Weir, Jason T; Price, Momoko

    2011-11-01

    Andean uplift contributed importantly to the build-up of high Neotropical diversity. Final uplift of the Eastern Cordillera of Colombia separated once-contiguous lowland faunas east and west of the Andes between 5 and 3.5 million years ago (Ma hereafter). We used DNA sequences from several moderate- to fast-evolving mitochondrial and two slow-evolving nuclear genes to generate a well-supported phylogeny of Dendrocincla woodcreepers, a genus with multiple species endemic to lowland regions both east and west of the Andes. A time-calibrated phylogeny and dispersal-vicariance analysis indicated that uplift of the Eastern Cordillera of Colombia resulted in the initial vicariant separation of a widespread lowland form east and west of the Andes at c. 3.6 Ma. This was followed by two separate east-to-west dispersal events over or around the completed Andes, each producing a genetically distinct lineage. Our analysis suggests that Andean uplift promoted the build-up of biodiversity in lowland Neotropical faunas both through vicariance-based speciation during uplift and through dispersal-based speciation following uplift. In contrast to the multiple colonizations of the trans-Andean region by Dendrocincla, the Atlantic Forest was colonized from the Amazon only once, followed by in situ diversification.

  1. International diversification and Microfinance

    NARCIS (Netherlands)

    Galema, Rients; Lensink, Robert; Spierdijk, Laura

    2011-01-01

    International commercial banks, institutional investors, and private investors have become increasingly interested in financing microfinance institutions (MFIs). This paper investigates whether adding microfinance funds to a portfolio of risky international assets yields diversification gains. By us

  2. Explosive ice age diversification of kiwi.

    Science.gov (United States)

    Weir, Jason T; Haddrath, Oliver; Robertson, Hugh A; Colbourne, Rogan M; Baker, Allan J

    2016-09-20

    Molecular dating largely overturned the paradigm that global cooling during recent Pleistocene glacial cycles resulted in a burst of species diversification although some evidence exists that speciation was commonly promoted in habitats near the expanding and retracting ice sheets. Here, we used a genome-wide dataset of more than half a million base pairs of DNA to test for a glacially induced burst of diversification in kiwi, an avian family distributed within several hundred kilometers of the expanding and retracting glaciers of the Southern Alps of New Zealand. By sampling across the geographic range of the five kiwi species, we discovered many cryptic lineages, bringing the total number of kiwi taxa that currently exist to 11 and the number that existed just before human arrival to 16 or 17. We found that 80% of kiwi diversification events date to the major glacial advances of the Middle and Late Pleistocene. During this period, New Zealand was repeatedly fragmented by glaciers into a series of refugia, with the tiny geographic ranges of many kiwi lineages currently distributed in areas adjacent to these refugia. Estimates of effective population size through time show a dramatic bottleneck during the last glacial cycle in all but one kiwi lineage, as expected if kiwi were isolated in glacially induced refugia. Our results support a fivefold increase in diversification rates during key glacial periods, comparable with levels observed in classic adaptive radiations, and confirm that at least some lineages distributed near glaciated regions underwent rapid ice age diversification.

  3. Fusion helps diversification

    NARCIS (Netherlands)

    S. Liang; Z. Ren; M. de Rijke

    2014-01-01

    A popular strategy for search result diversification is to first retrieve a set of documents utilizing a standard retrieval method and then rerank the results. We adopt a different perspective on the problem, based on data fusion. Starting from the hypothesis that data fusion can improve performance

  4. Charles Darwin in the Andes

    Science.gov (United States)

    Bizzo, Nelio; Bizzo, Luis Eduardo Maestrelli

    2006-01-01

    Considering geological time as an important epistemological obstacle to the construction of ideas on biological evolution, a study was carried out on the so-called "Darwin Papers". The conclusion was that Charles Darwin's excursion in the Andes during March-April 1835 was a crucial step in this regard. An expedition was carried out in…

  5. The Andes: A Geographical Portrait

    Directory of Open Access Journals (Sweden)

    Anthony Bebbington

    2016-05-01

    Full Text Available Reviewed: The Andes: A Geographical Portrait. By Axel Borsdorf and Christoph Stadel. Translated by Brigitte Scott and Christoph Stadel. Cham, Switzerland: Springer International Publishing, 2015. xiv + 368 pp. US$ 139.00. Also available as an e-book. ISBN 978-3-319-03529-1.

  6. 78 FR 24228 - Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Final Comprehensive Conservation Plan

    Science.gov (United States)

    2013-04-24

    ... Fish and Wildlife Service Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Final Comprehensive Conservation Plan AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of availability... conservation plan and finding of no significant impact (FONSI) for the Lake Andes National Wildlife...

  7. Natural Constraints to Species Diversification.

    Science.gov (United States)

    Lewitus, Eric; Morlon, Hélène

    2016-08-01

    Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades) within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the deep-time evolution of

  8. Viviparity stimulates diversification in an order of fish.

    Science.gov (United States)

    Helmstetter, Andrew J; Papadopulos, Alexander S T; Igea, Javier; Van Dooren, Tom J M; Leroi, Armand M; Savolainen, Vincent

    2016-04-12

    Species richness is distributed unevenly across the tree of life and this may be influenced by the evolution of novel phenotypes that promote diversification. Viviparity has originated ∼150 times in vertebrates and is considered to be an adaptation to highly variable environments. Likewise, possessing an annual life cycle is common in plants and insects, where it enables the colonization of seasonal environments, but rare in vertebrates. The extent to which these reproductive life-history traits have enhanced diversification and their relative importance in the process remains unknown. We show that convergent evolution of viviparity causes bursts of diversification in fish. We built a phylogenetic tree for Cyprinodontiformes, an order in which both annualism and viviparity have arisen, and reveal that while both traits have evolved multiple times, only viviparity played a major role in shaping the patterns of diversity. These results demonstrate that changes in reproductive life-history strategy can stimulate diversification.

  9. Corporate diversification: expectations and outcomes.

    Science.gov (United States)

    Clement, J P

    1988-01-01

    A review of the research concerning the diversification experience of firms in other industries shows that expectations of higher profit rates and lower risk are not entirely realistic. However, there are many ways in which the probability of financially successful diversification may be increased.

  10. The ANDES Deep Underground Laboratory

    CERN Document Server

    Bertou, X

    2013-01-01

    ANDES (Agua Negra Deep Experiment Site) is a unique opportunity to build a deep underground laboratory in the southern hemisphere. It will be built in the Agua Negra tunnel planned between Argentina and Chile, and operated by the CLES, a Latin American consortium. With 1750m of rock overburden, and no close- by nuclear power plant, it will provide an extremely radiation quiet environment for neutrino and dark matter experiments. In particular, its location in the southern hemisphere should play a major role in understanding dark matter modulation signals.

  11. To Orientate the Purpose of Higher Education--From popularization to diversification

    Institute of Scientific and Technical Information of China (English)

    薛波波

    2014-01-01

    In a new and developing period of higher education, it needs to develop the higher education in China from popularization to diversification. It is necessary to reform the existed modes to achieve the diversification of higher education, and explore new ways to promote the development of higher education further.

  12. Defense mutualisms enhance plant diversification.

    Science.gov (United States)

    Weber, Marjorie G; Agrawal, Anurag A

    2014-11-18

    The ability of plants to form mutualistic relationships with animal defenders has long been suspected to influence their evolutionary success, both by decreasing extinction risk and by increasing opportunity for speciation through an expanded realized niche. Nonetheless, the hypothesis that defense mutualisms consistently enhance plant diversification across lineages has not been well tested due to a lack of phenotypic and phylogenetic information. Using a global analysis, we show that the >100 vascular plant families in which species have evolved extrafloral nectaries (EFNs), sugar-secreting organs that recruit arthropod mutualists, have twofold higher diversification rates than families that lack species with EFNs. Zooming in on six distantly related plant clades, trait-dependent diversification models confirmed the tendency for lineages with EFNs to display increased rates of diversification. These results were consistent across methodological approaches. Inference using reversible-jump Markov chain Monte Carlo (MCMC) to model the placement and number of rate shifts revealed that high net diversification rates in EFN clades were driven by an increased number of positive rate shifts following EFN evolution compared with sister clades, suggesting that EFNs may be indirect facilitators of diversification. Our replicated analysis indicates that defense mutualisms put lineages on a path toward increased diversification rates within and between clades, and is concordant with the hypothesis that mutualistic interactions with animals can have an impact on deep macroevolutionary patterns and enhance plant diversity.

  13. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1995 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1995 calendar year. The report begins...

  14. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : Updated- 2003 annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 2003 calendar year. The report begins...

  15. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1994 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1994 calendar year. The report begins...

  16. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1997 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1997 calendar year. The report begins...

  17. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 2002 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 2002 calendar year. The report begins...

  18. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1998 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1998 calendar year. The report begins...

  19. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1999 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1999 calendar year. The report begins...

  20. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 2001 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 2001 calendar year. The report begins...

  1. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1996 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1996 calendar year. The report begins...

  2. Lake Andes NWR Water Use Report- 1979

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1979. General water uses are discussed for 1979 for each unit, impoundment data is tabulated...

  3. Lake Andes NWR Water Use Report- 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1987. General water uses are discussed for 1987 for each unit, impoundment data is tabulated...

  4. Lake Andes NWR Water Use Report- 1984

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1984. General water uses are discussed for 1984 for each unit, impoundment data is tabulated...

  5. Lake Andes NWR Water Use Report- 1985

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1985. General water uses are discussed for 1985 for each unit, impoundment data is tabulated...

  6. Lake Andes NWR Water Use Report- 1983

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1983. General water uses are discussed for 1983 for each unit, impoundment data is tabulated...

  7. Lake Andes NWR Water Use Report- 1986

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1986. General water uses are discussed for 1986 for each unit, impoundment data is tabulated...

  8. Lake Andes NWR Water Use Report- 1958

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1958. The report highlights the weather, water, habitat, and wildlife conditions for the year of...

  9. Lake Andes NWR Water Use Report- 1982

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1982. General water uses are discussed for 1982 for each unit, impoundment data is tabulated...

  10. Lake Andes NWR Water Use Report- 1971

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1971. General water uses are discussed for 1971 for each unit, impoundment data is tabulated...

  11. Business Choice of Enterprises' Diversification

    Institute of Scientific and Technical Information of China (English)

    QinZheng; ZouJianjun; ChenShou

    2005-01-01

    The strategy of diversification has become an important approach to enterprise development A successful diversification strategy depends mainly on the correct business choice. Before choosing a new business, we must identify the core competeneies of the enterprise and research the attraction and criticai success factors of the target business. Then we should make sure whether the core competencies match the critical success factors or not.The new business should be useful for cuitivating sustainable competitive advantage.

  12. Climate change adaptation in Ethiopia: to what extent does social protection influence livelihood diversification?

    DEFF Research Database (Denmark)

    Weldegebriel, Zerihun; Prowse, Martin Philip

    2013-01-01

    Social-protection programmes like the Productive Safety-Net Programme (PSNP) in Ethiopia can play a positive role in promoting livelihoods and enhancing risk management. This article uses propensity score matching to estimate its effect on income diversification. The results suggest that receivin...... in a positive manner for climate adaptation. The article concludes by arguing for the promotion of positive forms of income diversification and the further investigation of the PSNP’s influence on autonomous adaptation strategies....

  13. Inducible competitors and adaptive diversification

    Institute of Scientific and Technical Information of China (English)

    Beren W.ROBINSON; David W.PFENNIG

    2013-01-01

    Identifying the causes of diversification is central to evolutionary biology.The ecological theory of adaptive diversification holds that the evolution of phenotypic differences between populations and species-and the formation of new species-stems from divergent natural selection,often arising from competitive interactions.Although increasing evidence suggests that phenotypic plasticity can facilitate this process,it is not generally appreciated that competitively mediated selection often also provides ideal conditions for phenotypic plasticity to evolve in the first place.Here,we discuss how competition plays at least two key roles in adaptive diversification depending on its pattern.First,heterogenous competition initially generates heterogeneity in resource use that favors adaptive plasticity in the form of"inducible competitors".Second,once such competitively induced plasticity evolves,its capacity to rapidly generate phenotypic variation and expose phenotypes to alternate selective regimes allows populations to respond readily to selection favoring diversification,as may occur when competition generates steady diversifying selection that permanently drives the evolutionary divergence of populations that use different resources.Thus,competition plays two important roles in adaptive diversification--one well-known and the other only now emerging-mediated through its effect on the evolution of phenotypic plasticity.

  14. Formalized morphostructural zoning of the mountain zone of the Andes

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielov, A.M.; Gvishiani, A.D.; Zhidkov, M.P.

    1982-01-01

    A plan is presented for morphostructural zoning of the Andes compiled according to formalized signs for purposes of seismic forecasting. Characteristics are presented for the basic morphostructural subdivisions of the Andes.

  15. Fish Population Investigation: Lake Andes, Charles Mix County

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Brief background on Lake Andes fishing history, and data on current fish populations. Lake Andes was a much larger body of water prior to the construction of an...

  16. Recreational Fishery Management Plan for Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Current condition of lake Andes (1996) and highlights potential problems and recommendations for improving the lake as a hatchery. Lake Andes was a much larger body...

  17. Fishery Management Plan for Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Lake Andes was a much larger body of water prior to the construction of an artificial outlet structure that lowered the water level by 13 feet. Since Lake Andes is...

  18. Determinants of Export Diversification in Nigeria: Any Special Role for Foreign Direct Investment (FDI?

    Directory of Open Access Journals (Sweden)

    Damilola Felix Arawomo

    2014-12-01

    Full Text Available The importance of export diversification is presently taking a center stage in trade literature. This paper contributed to the evolving literature by examining the extent of export diversification in Nigeria and also analyzed the impact of foreign direct investment on it. Two major methods of export diversification: export count (horizontal and Herfindahl Index were used. Nigeria’s exports flows based on 4-digit SICT product classification were used. The Generalized Moment Methods (GMM was used to analyze our specified model. Empirical analysis showed that foreign direct investment discourages export diversification in Nigeria, while domestic investment promotes it. Exchange rate and democratic accountability are other factors that discourage export diversification in Nigeria. No evidence was found on the impact of per capita GDP, trade openness and natural resource.

  19. Impacts of the Cretaceous Terrestrial Revolution and KPg extinction on mammal diversification.

    Science.gov (United States)

    Meredith, Robert W; Janečka, Jan E; Gatesy, John; Ryder, Oliver A; Fisher, Colleen A; Teeling, Emma C; Goodbla, Alisha; Eizirik, Eduardo; Simão, Taiz L L; Stadler, Tanja; Rabosky, Daniel L; Honeycutt, Rodney L; Flynn, John J; Ingram, Colleen M; Steiner, Cynthia; Williams, Tiffani L; Robinson, Terence J; Burk-Herrick, Angela; Westerman, Michael; Ayoub, Nadia A; Springer, Mark S; Murphy, William J

    2011-10-28

    Previous analyses of relations, divergence times, and diversification patterns among extant mammalian families have relied on supertree methods and local molecular clocks. We constructed a molecular supermatrix for mammalian families and analyzed these data with likelihood-based methods and relaxed molecular clocks. Phylogenetic analyses resulted in a robust phylogeny with better resolution than phylogenies from supertree methods. Relaxed clock analyses support the long-fuse model of diversification and highlight the importance of including multiple fossil calibrations that are spread across the tree. Molecular time trees and diversification analyses suggest important roles for the Cretaceous Terrestrial Revolution and Cretaceous-Paleogene (KPg) mass extinction in opening up ecospace that promoted interordinal and intraordinal diversification, respectively. By contrast, diversification analyses provide no support for the hypothesis concerning the delayed rise of present-day mammals during the Eocene Period.

  20. Governance Structure, Product Diversification, and Performance

    NARCIS (Netherlands)

    A.A.C.J. van Oijen; G.W.J. Hendrikse (George)

    2002-01-01

    textabstractProduct diversification and its financial outcomes have been studied exhaustively. However, previous literature has focused on corporations, ignoring other important legal organizations or governance structures. In this paper, we study the diversification strategies of cooperatives and c

  1. Herbivory increases diversification across insect clades.

    Science.gov (United States)

    Wiens, John J; Lapoint, Richard T; Whiteman, Noah K

    2015-09-24

    Insects contain more than half of all living species, but the causes of their remarkable diversity remain poorly understood. Many authors have suggested that herbivory has accelerated diversification in many insect clades. However, others have questioned the role of herbivory in insect diversification. Here, we test the relationships between herbivory and insect diversification across multiple scales. We find a strong, positive relationship between herbivory and diversification among insect orders. However, herbivory explains less variation in diversification within some orders (Diptera, Hemiptera) or shows no significant relationship with diversification in others (Coleoptera, Hymenoptera, Orthoptera). Thus, we support the overall importance of herbivory for insect diversification, but also show that its impacts can vary across scales and clades. In summary, our results illuminate the causes of species richness patterns in a group containing most living species, and show the importance of ecological impacts on diversification in explaining the diversity of life.

  2. Diversification patterns and survival as firms mature

    DEFF Research Database (Denmark)

    Coad, Alexander Jean-Luc; Guenther, C.

    2013-01-01

    into new submarkets). Our analysis reveals four main insights. First, we observe that firms have lower diversification rates as they grow older, and that eventually diversification rates even turn negative for old firms on average (where negative diversification corresponds to exit from certain product...

  3. Diversification at Financial Institutions and Systemic Crises

    NARCIS (Netherlands)

    Wagner, W.B.

    2006-01-01

    We show that the diversification of risks at financial institutions has unwelcome effects by increasing the likelihood of systems crises.As a result, complete diversification is not warranted adn the optimal degree of diversification is arbitrarily low.We also identify externalities that cause finan

  4. Global patterns of insect diversification: towards a reconciliation of fossil and molecular evidence?

    Science.gov (United States)

    Condamine, Fabien L; Clapham, Matthew E; Kergoat, Gael J

    2016-01-18

    Macroevolutionary studies of insects at diverse taxonomic scales often reveal dynamic evolutionary patterns, with multiple inferred diversification rate shifts. Responses to major past environmental changes, such as the Cretaceous Terrestrial Revolution, or the development of major key innovations, such as wings or complete metamorphosis are usually invoked as potential evolutionary triggers. However this view is partially contradicted by studies on the family-level fossil record showing that insect diversification was relatively constant through time. In an attempt to reconcile both views, we investigate large-scale insect diversification dynamics at family level using two distinct types of diversification analyses on a molecular timetree representing ca. 82% of the extant families, and reassess the insect fossil diversity using up-to-date records. Analyses focusing on the fossil record recovered an early burst of diversification, declining to low and steady rates through time, interrupted by extinction events. Phylogenetic analyses showed that major shifts of diversification rates only occurred in the four richest holometabolous orders. Both suggest that neither the development of flight or complete metamorphosis nor the Cretaceous Terrestrial Revolution environmental changes induced immediate changes in diversification regimes; instead clade-specific innovations likely promoted the diversification of major insect orders.

  5. Hospital diversification and financial management.

    Science.gov (United States)

    Eastaugh, S R

    1984-08-01

    Hospital diversification and its impact on the operating ratio are studied for 62 New York hospitals during the period 1974-1979. Diversification and operating ratio are modeled in a two-stage least squares (TSLS) framework as being jointly dependent. Institutional diversification is found to yield better financial position, and the better operating ratio allows the institution the wherewithal to diversify. The impact of external government planning and hospital competition are also measured. An institution life cycle hypothesis is advanced to explain hospital behavior: boom and bust, diversification and divestiture, occasionally leading to closure or merger. These results should not be generalized beyond the New York State context. Restructuring of the organization, unrelated business ventures, and transactions with related organizations were not a problem in this sample. However, in 1983, many a new corporation is set up whose revenues do not become part of the hospital's and whose complex transactions conceal unallowable costs and maximize reimbursement. A number of hypotheses are advanced concerning hospital administrator's attitude toward risk.

  6. Inducible competitors and adaptive diversification

    Directory of Open Access Journals (Sweden)

    Beren W. ROBINSON, David W. PFENNIG

    2013-08-01

    Full Text Available Identifying the causes of diversification is central to evolutionary biology. The ecological theory of adaptive diversification holds that the evolution of phenotypic differences between populations and species––and the formation of new species––stems from divergent natural selection, often arising from competitive interactions. Although increasing evidence suggests that phenotypic plasticity can facilitate this process, it is not generally appreciated that competitively mediated selection often also provides ideal conditions for phenotypic plasticity to evolve in the first place. Here, we discuss how competition plays at least two key roles in adaptive diversification depending on its pattern. First, heterogenous competition initially generates heterogeneity in resource use that favors adaptive plasticity in the form of “inducible competitors”. Second, once such competitively induced plasticity evolves, its capacity to rapidly generate phenotypic variation and expose phenotypes to alternate selective regimes allows populations to respond readily to selection favoring diversification, as may occur when competition generates steady diversifying selection that permanently drives the evolutionary divergence of populations that use different resources. Thus, competition plays two important roles in adaptive diversification––one well-known and the other only now emerging––mediated through its effect on the evolution of phenotypic plasticity [Current Zoology 59 (4: 537–552, 2013].

  7. Distinguishing Between Related and Unrelated International Geographic Diversification: A Comprehensive Measure of Global Diversification

    OpenAIRE

    Sushil Vachani

    1991-01-01

    This paper argues that it is important to distinguish between related and unrelated international geographic diversification when measuring impact of diversification on performance. It then extends the Jacquemin-Berry entropy measure to propose a comprehensive measure of global diversification that comprises related and unrelated product diversification. It suggests a classification of firms based on diversification strategies and proposes hypotheses for future research.© 1991 JIBS. Journal o...

  8. Diversity of the genus Polylepis (Rosaceae, Sanguisorbeae in the Peruvian Andes

    Directory of Open Access Journals (Sweden)

    Wilfredo Mendoza

    2011-08-01

    Full Text Available This study provides information on the diversity of Peruvian species of Polylepis. Nineteen (19 species are reported here (more than 70% of the 27 species registered for the whole Andean region. As a result, Peru could be considered as the country with the largest diversity of Polylepis species, in comparison with Bolivia (13, Ecuador (7, Argentina (4, Colombia (3, Chile (2, and Venezuela (1. The species occur in 19 departments of Peru, with the majority of them in Cusco (10 and Ayacucho (8. Species diversity is mostly concentrated in the Peruvian southern Andes (15 species, with the region becoming the potential center of diversification of the genus Polylepis. Regarding their altitudinal distribution, the greatest diversity (18 is found between 3000 and 4000 m.

  9. Multiple continental radiations and correlates of diversification in Lupinus (Leguminosae): testing for key innovation with incomplete taxon sampling.

    Science.gov (United States)

    Drummond, Christopher S; Eastwood, Ruth J; Miotto, Silvia T S; Hughes, Colin E

    2012-05-01

    Replicate radiations provide powerful comparative systems to address questions about the interplay between opportunity and innovation in driving episodes of diversification and the factors limiting their subsequent progression. However, such systems have been rarely documented at intercontinental scales. Here, we evaluate the hypothesis of multiple radiations in the genus Lupinus (Leguminosae), which exhibits some of the highest known rates of net diversification in plants. Given that incomplete taxon sampling, background extinction, and lineage-specific variation in diversification rates can confound macroevolutionary inferences regarding the timing and mechanisms of cladogenesis, we used Bayesian relaxed clock phylogenetic analyses as well as MEDUSA and BiSSE birth-death likelihood models of diversification, to evaluate the evolutionary patterns of lineage accumulation in Lupinus. We identified 3 significant shifts to increased rates of net diversification (r) relative to background levels in the genus (r = 0.18-0.48 lineages/myr). The primary shift occurred approximately 4.6 Ma (r = 0.48-1.76) in the montane regions of western North America, followed by a secondary shift approximately 2.7 Ma (r = 0.89-3.33) associated with range expansion and diversification of allopatrically distributed sister clades in the Mexican highlands and Andes. We also recovered evidence for a third independent shift approximately 6.5 Ma at the base of a lower elevation eastern South American grassland and campo rupestre clade (r = 0.36-1.33). Bayesian ancestral state reconstructions and BiSSE likelihood analyses of correlated diversification indicated that increased rates of speciation are strongly associated with the derived evolution of perennial life history and invasion of montane ecosystems. Although we currently lack hard evidence for "replicate adaptive radiations" in the sense of convergent morphological and ecological trajectories among species in different clades, these

  10. Phylogeography in the northern Andes: complex history and cryptic diversity in a cloud forest frog, Pristimantis w-nigrum (Craugastoridae).

    Science.gov (United States)

    Kieswetter, Charles M; Schneider, Christopher J

    2013-12-01

    We investigated the pattern of genetic and morphological variation and the timing of diversification in a Neotropical direct developing frog, Pristimantis w-nigrum (Craugastoridae) to gain insight into the historical biogeography of the northern Andes. Phylogenetic inference and analyses of genetic differentiation at mitochondrial and nuclear markers reveal eight mitochondrial clades that display concordant and highly structured nuclear genetic variation along both eastern and western slopes of the Ecuadorian Andes. These eight phylogroups are deeply divergent and show little evidence of change in effective size over substantial periods of time. Consistent with other phylogenetic studies of vertebrates in the Andes, the timing of genetic divergence among lineages coincides with sequential bouts of Andean orogenesis during the late Miocene and early Pliocene. Morphometric analyses recover little morphological variation among populations in spite of considerable genetic divergence. The deep genetic differentiation among populations of P. w-nigrum suggests that this species harbors unrecognized diversity and may represent a complex of cryptic species. These results illuminate the evolutionary processes that generate diversity in tropical montane biomes and underscore the fact that cryptic diversity may be an important component of Neotropical montane biodiversity.

  11. Patterns and processes of diversification in a widespread and ecologically diverse avian group, the buteonine hawks (Aves, Accipitridae).

    Science.gov (United States)

    do Amaral, Fábio Raposo; Sheldon, Frederick H; Gamauf, Anita; Haring, Elisabeth; Riesing, Martin; Silveira, Luís F; Wajntal, Anita

    2009-12-01

    Buteonine hawks represent one of the most diverse groups in the Accipitridae, with 58 species distributed in a variety of habitats on almost all continents. Variations in migratory behavior, remarkable dispersal capability, and unusual diversity in Central and South America make buteonine hawks an excellent model for studies in avian evolution. To evaluate the history of their global radiation, we used an integrative approach that coupled estimation of the phylogeny using a large sequence database (based on 6411 bp of mitochondrial markers and one nuclear intron from 54 species), divergence time estimates, and ancestral state reconstructions. Our findings suggest that Neotropical buteonines resulted from a long evolutionary process that began in the Miocene and extended to the Pleistocene. Colonization of the Nearctic, and eventually the Old World, occurred from South America, promoted by the evolution of seasonal movements and development of land bridges. Migratory behavior evolved several times and may have contributed not only to colonization of the Holarctic, but also derivation of insular species. In the Neotropics, diversification of the buteonines included four disjunction events across the Andes. Adaptation of monophyletic taxa to wet environments occurred more than once, and some relationships indicate an evolutionary connection among mangroves, coastal and várzea environments. On the other hand, groups occupying the same biome, forest, or open vegetation habitats are not monophyletic. Refuges or sea-level changes or a combination of both was responsible for recent speciation in Amazonian taxa. In view of the lack of concordance between phylogeny and classification, we propose numerous taxonomic changes.

  12. Dynamic Diversification in Corporate Credit

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Jin, Xisong;

    We characterize diversification in corporate credit using a new class of dynamic copula models which can capture dynamic dependence and asymmetry in large samples of firms. We also document important differences between credit spread and equity return dependence dynamics. Modeling a decade...... the crisis and remain high as well. The most important shocks to credit dependence occur in August of 2007 and in August of 2011, but interestingly these dates are not associated with significant changes to median credit spreads....

  13. Andes Altiplano, Northwest Argentina, South America

    Science.gov (United States)

    1993-01-01

    This view of the Andes Altiplano in northwest Argentina (25.5S, 68.0W) is dominated by heavily eroded older and inactive volcano peaks. The altiplano is a high altitude cold desert like the Tibetan Plateau but smaller in area. It is an inland extension of the hyperarid Atacama Desert of the west coast of South America and includes hundreds of volcanic edifices (peaks, cinder cones, lava flows, debris fields, lakes and dry lake beds (salars).

  14. DETERMINANTS OF ON-FARM DIVERSIFICATION AMONG RURAL HOUSEHOLDS: EMPIRICAL EVIDENCE FROM NORTHERN ALGERIA

    Directory of Open Access Journals (Sweden)

    Benmehaia Mohamed Amine

    2016-04-01

    Full Text Available This study aims to analyze the determinants and patterns of the on-farm diversification among the agricultural producers in Algeria. The study uses a sample of agricultural producers randomly and proportionally selected from Northern Algeria and the data obtained was analyzed using three adequate regression models. Results indicate that, on the technical aspects, the farmers who have larger farm size, access to market information, more full land employment and an irrigation system, those who own machinery and livestock holdings are more likely to diversify, whereas those with off-farm income are likely to specialize. In order to promote crop diversification, providing farm machinery through easy loans and improving access to market information and irrigation technologies should be given attention. Farmer’s experience and his age are the major socio-economic determinants of farm diversification. The implication is drawn for provision of enabling socio-economic environment for the establishment of more diversification.

  15. DIVERSIFICATION

    Institute of Scientific and Technical Information of China (English)

    徐嬿

    2010-01-01

    说来惭愧.DIVERSIFICATION,当美亚娱乐资讯集团有限公司资深顾问邓思田(Stanley)先生脱口而出这一词汇时,笔者一时没能反应过来。2小时的长谈结束后,已然发现,自己对这个词的印象如此深刻。

  16. Diversification strategies for hospital pharmacies.

    Science.gov (United States)

    Smith, J E; Phillips, D J; Meyer, G E

    1984-09-01

    Several ways used by the pharmacy department of a large university hospital to generate revenue through diversification are described. The department offers its facilities and staff as a resource in training medical service representatives for several pharmaceutical manufacturers, which is projected to provide $85,000 in net income for fiscal year (FY) 1983-84. The pharmacy department also conducts a six-month program for training pharmacy technicians, which yields a small net profit. The pharmacy department actively participates in educational programs such as college courses and clerkships earning extra income. An apothecary-style outpatient pharmacy was set up under a for-profit corporation. Services have been expanded to include the preparation of i.v. solutions that support home care. A durable medical equipment (DME) business is planned. The ambulatory and home-care programs are expected to generate approximately $165,000 in net profit next year. Contract pharmaceutical services are provided to another hospital. The net income generated through diversification in this pharmacy department will exceed $250,000 in FY 1983-84.

  17. Constant diversification rates of endemic gastropods in ancient Lake Ohrid: ecosystem resilience likely buffers environmental fluctuations

    Science.gov (United States)

    Föller, K.; Stelbrink, B.; Hauffe, T.; Albrecht, C.; Wilke, T.

    2015-12-01

    contributes to one of the overall goals of the SCOPSCO deep-drilling program - inferring the driving forces for biotic evolution in Lake Ohrid. It might also enhance our understanding of how ecosystem resilience, in general, may promote relatively constant diversification rates in isolated ecosystems. However, we encourage future studies testing hypotheses about the lack of catastrophic events in Lake Ohrid. These studies should be based on high-resolution data for the entire geological history of the lake, and they should potentially involve information from the sediment fossil record, not only for gastropods but also for other groups with a high share of endemic taxa.

  18. Rapid and recent world-wide diversification of bluegrasses (Poa, Poaceae and related genera.

    Directory of Open Access Journals (Sweden)

    Matthias H Hoffmann

    Full Text Available Rapid species diversifications provide fascinating insight into the development of biodiversity in time and space. Most biological radiations studied to date, for example that of cichlid fishes or Andean lupines, are confined to isolated geographical areas like lakes, islands or island-like regions. Using DNA sequence data of the ribosomal internal transcribed spacer (ITS for many species of the Poa alliance, a group comprising about 775 C3 grass species, revealed rapid and parallel diversifications in various parts of the world. Some of these radiations are restricted to isolated areas like the Andes, whereas others are typical of the lowlands of mainly the northern hemisphere. These radiations thus are not restricted to island-like areas and are seemingly actively ongoing. The ages of the diversifying clades are estimated to be 2.5-0.23 million years (Myr. Conservative diversification rates in the Poa alliance amount to 0.89-3.14 species per Myr, thus are in the order of, or even exceeding, other instances of well-known radiations. The grass radiations of the mainly cold-adapted Poa alliance coincide with the Late Tertiary global cooling, which resulted in the retreat of forests and the subsequent formation of cold-adapted grasslands especially in the northern, but also in parts of the southern hemisphere. The cold tolerance, suggested to be one of the ecological key innovations, may have been acquired during the early diversification of the subfamily Pooideae, but became significant millions of years later during the Pliocene/Pleistocene radiation of the Poa alliance.

  19. Search Result Diversification Based on Query Facets

    Institute of Scientific and Technical Information of China (English)

    胡莎; 窦志成; 王晓捷; 继荣

    2015-01-01

    In search engines, different users may search for different information by issuing the same query. To satisfy more users with limited search results, search result diversification re-ranks the results to cover as many user intents as possible. Most existing intent-aware diversification algorithms recognize user intents as subtopics, each of which is usually a word, a phrase, or a piece of description. In this paper, we leverage query facets to understand user intents in diversification, where each facet contains a group of words or phrases that explain an underlying intent of a query. We generate subtopics based on query facets and propose faceted diversification approaches. Experimental results on the public TREC 2009 dataset show that our faceted approaches outperform state-of-the-art diversification models.

  20. Efficient Diversification of Web Search Results

    CERN Document Server

    Capannini, Gabriele; Perego, Raffaele; Silvestri, Fabrizio

    2011-01-01

    In this paper we analyze the efficiency of various search results diversification methods. While efficacy of diversification approaches has been deeply investigated in the past, response time and scalability issues have been rarely addressed. A unified framework for studying performance and feasibility of result diversification solutions is thus proposed. First we define a new methodology for detecting when, and how, query results need to be diversified. To this purpose, we rely on the concept of "query refinement" to estimate the probability of a query to be ambiguous. Then, relying on this novel ambiguity detection method, we deploy and compare on a standard test set, three different diversification methods: IASelect, xQuAD, and OptSelect. While the first two are recent state-of-the-art proposals, the latter is an original algorithm introduced in this paper. We evaluate both the efficiency and the effectiveness of our approach against its competitors by using the standard TREC Web diversification track test...

  1. Changing Student Attitudes using Andes, An Intelligent Homework System

    Science.gov (United States)

    van de Sande, Brett; Vanlehn, Kurt; Treacy, Don; Shelby, Bob; Wintersgill, Mary

    2007-03-01

    The size of introductory physics lectures often inhibits personal homework assistance and timely corrective feedback. Andes, an intelligent homework help system designed for two semesters of introductory physics, can fill this need by encouraging students to use sound problem solving techniques and providing immediate feedback on each step of a solution. On request, Andes provides principles-based hints based on previous student actions. A multi-year study at the U.S. Naval Academy demonstrates that students using Andes perform better than students working the same problems as graded pencil and paper homeworks. In addition, student attitude surveys show that Andes is preferred over other homework systems. These findings have implications for student attitudes toward, and mastery of, physics. See http://www.andes.pitt.edu for more information.

  2. Diversification of the silverspot butterflies (Nymphalidae) in the Neotropics inferred from multi-locus DNA sequences.

    Science.gov (United States)

    Massardo, Darli; Fornel, Rodrigo; Kronforst, Marcus; Gonçalves, Gislene Lopes; Moreira, Gilson Rudinei Pires

    2015-01-01

    The tribe Heliconiini (Lepidoptera: Nymphalidae) is a diverse group of butterflies distributed throughout the Neotropics, which has been studied extensively, in particular the genus Heliconius. However, most of the other lineages, such as Dione, which are less diverse and considered basal within the group, have received little attention. Basic information, such as species limits and geographical distributions remain uncertain for this genus. Here we used multilocus DNA sequence data and the geographical distribution analysis across the entire range of Dione in the Neotropical region in order to make inferences on the evolutionary history of this poorly explored lineage. Bayesian time-tree reconstruction allows inferring two major diversification events in this tribe around 25mya. Lineages thought to be ancient, such as Dione and Agraulis, are as recent as Heliconius. Dione formed a monophyletic clade, sister to the genus Agraulis. Dione juno, D. glycera and D. moneta were reciprocally monophyletic and formed genetic clusters, with the first two more close related than each other in relation to the third. Divergence time estimates support the hypothesis that speciation in Dione coincided with both the rise of Passifloraceae (the host plants) and the uplift of the Andes. Since the sister species D. glycera and D. moneta are specialized feeders on passion-vine lineages that are endemic to areas located either within or adjacent to the Andes, we inferred that they co-speciated with their host plants during this vicariant event.

  3. Temporal diversification of Central American cichlids

    Directory of Open Access Journals (Sweden)

    Hulsey C Darrin

    2010-09-01

    Full Text Available Abstract Background Cichlid fishes are classic examples of adaptive radiation because of their putative tendency to explosively diversify after invading novel environments. To examine whether ecological opportunity increased diversification (speciation minus extinction early in a species-rich cichlid radiation, we determined if Heroine cichlids experienced a burst of diversification following their invasion of Central America. Results We first reconstructed the Heroine phylogeny and determined the basal node to use as the root of Central American Heroine diversification. We then examined the influence of incomplete taxon sampling on this group's diversification patterns. First, we added missing species randomly to the phylogeny and assessed deviations from a constant rate of lineage accumulation. Using a range of species numbers, we failed to recover significant deviations from a pure-birth process and found little support for an early burst of diversification. Then, we examined patterns of lineage accumulation as nodes were increasingly truncated. We assumed that as we removed more recently diverged lineages that sampling would become more complete thereby increasing the power to detect deviations from a pure-birth model. However, truncation of nodes provided even less support for an early burst of diversification. Conclusions Contrary to expectations, our analyses suggest Heroine cichlids did not undergo a burst of diversification when they invaded from South America. Throughout their history in Central America, Heroine cichlids appear to have diversified at a constant rate.

  4. The latitudinal gradient in dispersal constraints: ecological specialisation drives diversification in tropical birds.

    Science.gov (United States)

    Salisbury, Claire L; Seddon, Nathalie; Cooney, Christopher R; Tobias, Joseph A

    2012-08-01

    Physiological and behavioural constraints arising from ecological specialisation are proposed to limit gene flow and promote diversification in tropical lineages. In this study, we use phylogenetic analyses to test this idea in 739 Amazonian bird species. We show that patterns of species and subspecies richness are best predicted by a suite of avian specialisms common in tropical avifaunas but rare in the temperate zone. However, this only applied to niche traits associated with dispersal limitation rather than vagility. These findings are consistent with the view that diversity is promoted by more finely partitioned niches, although not simply by coevolutionary adaptation and niche packing as is often assumed. Instead, they suggest that diversification is driven by dispersal constraints, and that niches characterised by these constraints are biased towards tropical systems. We conclude that specialised tropical niches reduce the likelihood of dispersal across barriers, thereby increasing allopatric diversification and contributing to the latitudinal diversity gradient.

  5. Constant diversification rates of endemic gastropods in ancient Lake Ohrid: ecosystem resilience likely buffers environmental fluctuations

    Directory of Open Access Journals (Sweden)

    K. Föller

    2015-08-01

    the driving forces for biotic evolution in Lake Ohrid. It might also enhance our understanding of how ecosystem resilience, in general, may promote relative constant diversification rates in isolated ecosystems. However, we encourage future studies testing hypotheses about the lack of catastrophic events in Lake Ohrid. These studies should be based on high-resolution data for the entire geological history of the lake, and potentially involving information from the sediment fossil record, not only for gastropods but also for other groups with a high share of endemic taxa.

  6. Widespread correlations between climatic niche evolution and species diversification in birds.

    Science.gov (United States)

    Cooney, Christopher R; Seddon, Nathalie; Tobias, Joseph A

    2016-07-01

    The adaptability of species' climatic niches can influence the dynamics of colonization and gene flow across climatic gradients, potentially increasing the likelihood of speciation or reducing extinction in the face of environmental change. However, previous comparative studies have tested these ideas using geographically, taxonomically and ecologically restricted samples, yielding mixed results, and thus the processes linking climatic niche evolution with diversification remain poorly understood. Focusing on birds, the largest and most widespread class of terrestrial vertebrates, we test whether variation in species diversification among clades is correlated with rates of climatic niche evolution and the extent to which these patterns are modified by underlying gradients in biogeography and species' ecology. We quantified climatic niches, latitudinal distribution and ecological traits for 7657 (˜75%) bird species based on geographical range polygons and then used Bayesian phylogenetic analyses to test whether niche evolution was related to species richness and rates of diversification across genus- and family-level clades. We found that the rate of climatic niche evolution has a positive linear relationship with both species richness and diversification rate at two different taxonomic levels (genus and family). Furthermore, this positive association between labile climatic niches and diversification was detected regardless of variation in clade latitude or key ecological traits. Our findings suggest either that rapid adaptation to unoccupied areas of climatic niche space promotes avian diversification, or that diversification promotes adaptation. Either way, we propose that climatic niche evolution is a fundamental process regulating the link between climate and biodiversity at global scales, irrespective of the geographical and ecological context of speciation and extinction.

  7. Institutions and Diversification: Related versus Unrelated Diversification in a Varieties of Capitalism framework

    OpenAIRE

    Boschma, Ron; Capone , Gianluca

    2014-01-01

    The Varieties of Capitalism literature has drawn little attention to industrial renewal and diversification, while the related diversification literature has neglected the institutional dimension of industrial change. Bringing together both literatures, the paper proposes that institutions have an impact on the direction of the diversification process, in particular on whether countries gain a comparative advantage in new sectors that are close or far from what is already part of their existi...

  8. Diversification as the strategic direction of foreign economic activity

    Directory of Open Access Journals (Sweden)

    Yu.I. Dozorova

    2015-12-01

    Full Text Available The issue of diversification, diversification of exports and imports, diversification of foreign trade. Determined the importance of diversification strategy to improve economic performance and proved that diversification allows the flexibility to respond to changing market opportunities and reduce the risks that may occur during production specialization. With the diversification of the company reinforce its competitive position in the market. The concept of diversification is used in the formulation of portfolio strategy as one of the four components, namely a vector or direction of future growth areas of the company. The proposed provisions, by which we can achieve a positive result. Proved that by diversifying, the company improves its economic performance.

  9. Reasons for an outstanding plant diversity in the tropical Andes of Southern Ecuador

    Directory of Open Access Journals (Sweden)

    Michael Richter

    2009-06-01

    Full Text Available Long-term field studies in the scope of a multidisciplinary project in southern Ecuador revealed extraordinary high species numbers of many organismic groups. This article discusses reasons for the outstanding vascular plant diversity using a hierarchical scale-oriented top-down approach (Grüninger 2005, from the global scale to the local microscale. The global scale explains general (paleo- ecological factors valid for most parts of the humid tropics, addressing various hypotheses and theories, such as the “greater effective evolutionary time”, constant input of “accidentals”, the “seasonal variability hypothesis”, the “intermediate disturbance hypothesis”, and the impact of soil fertility. The macroscale focuses on the Andes in northwestern South America. The tropical Andes are characterised by many taxa of restricted range which is particularly true for the Amotape-Huancabamba region, i.e. the so called Andean Depression, which is effective as discrete phytogeographic transition as well as barrier zone. Interdigitation of northern and southern flora elements, habitat fragmentation, geological and landscape history, and a high speciation rate due to rapid genetic radiation of some taxa contribute to a high degree of diversification. The mesoscale deals with the special environmental features of the eastern mountain range, the Cordillera Real and surrounding areas in southern Ecuador. Various climatic characteristics, the orographic heterogeneity, the geologic and edaphic conditions as well as human impact are the most prominent factors augmenting plant species diversity. On microscale, prevailing regimes of disturbance and environmental stresses, the orographic basement, as well as the general role on the various mountain chains are considered. Here, micro-habitats e.g. niches for epiphytes, effects of micro-relief patterns, and successions after small-sized disturbance events are screened. Direct effects of human impact are

  10. Nested radiations and the pulse of angiosperm diversification: increased diversification rates often follow whole genome duplications.

    Science.gov (United States)

    Tank, David C; Eastman, Jonathan M; Pennell, Matthew W; Soltis, Pamela S; Soltis, Douglas E; Hinchliff, Cody E; Brown, Joseph W; Sessa, Emily B; Harmon, Luke J

    2015-07-01

    Our growing understanding of the plant tree of life provides a novel opportunity to uncover the major drivers of angiosperm diversity. Using a time-calibrated phylogeny, we characterized hot and cold spots of lineage diversification across the angiosperm tree of life by modeling evolutionary diversification using stepwise AIC (MEDUSA). We also tested the whole-genome duplication (WGD) radiation lag-time model, which postulates that increases in diversification tend to lag behind established WGD events. Diversification rates have been incredibly heterogeneous throughout the evolutionary history of angiosperms and reveal a pattern of 'nested radiations' - increases in net diversification nested within other radiations. This pattern in turn generates a negative relationship between clade age and diversity across both families and orders. We suggest that stochastically changing diversification rates across the phylogeny explain these patterns. Finally, we demonstrate significant statistical support for the WGD radiation lag-time model. Across angiosperms, nested shifts in diversification led to an overall increasing rate of net diversification and declining relative extinction rates through time. These diversification shifts are only rarely perfectly associated with WGD events, but commonly follow them after a lag period.

  11. Social Capital and Diversification of Cooperatives

    NARCIS (Netherlands)

    W. Deng (Wendong)

    2015-01-01

    markdownabstract__Abstract__ This thesis contributes to two research streams of the literature regarding agricultural cooperatives, namely, social capital and product diversification of cooperatives. First, the thesis examines the nature of a marketing cooperative by considering both its economic a

  12. Testing for Stochastic Dominance with Diversification Possibilities

    NARCIS (Netherlands)

    G.T. Post (Thierry)

    2001-01-01

    textabstractWe derive empirical tests for stochastic dominance that allow for diversification between choice alternatives. The tests can be computed using straightforward linear programming. Bootstrapping techniques and asymptotic distribution theory can approximate the sampling properties of the te

  13. Diversification and firm performance: A study of Indian manufacturing firms

    OpenAIRE

    Ravichandran, Archana; Bhaduri, Saumitra

    2015-01-01

    The advantages and disadvantages of diversification and its impact on productivity or performance of a firm have been debated upon by academics and business professionals all over, although views on the topic still differ widely. While popular views are that related diversification increases value and unrelated diversification decreases value, the results of research conducted on the effects of overall diversification (without distinguishing between related and unrelated diversification) on p...

  14. Is the Potential for International Diversification Disappering?

    DEFF Research Database (Denmark)

    Christoffersen, Peter F.; Errunza, Vihang; Jacobs, Kris;

    2012-01-01

    International equity markets are characterized by nonlinear dependence and asymmetries. We propose a new dynamic asymmetric copula model to capture long-run and short-run dependence, multivariate nonnormality, and asymmetries in large cross-sections. We find that correlations have increased...... and nonlinear dependence. The benefits from international diversification have reduced over time, drastically so for DMs. EMs still offer significant diversification benefits, especially during large market downturns....

  15. Global Portfolio Diversification with Emerging Stock Markets

    Directory of Open Access Journals (Sweden)

    İlhan Meriç

    2016-02-01

    Full Text Available Because of their low correlation with each other and with developed stock markets, emerging stock markets are generally mentioned as attractive portfolio diversification prospects for global investors. In this paper, we use the Principal Components Analysis (PCA method to study the global portfolio diversification opportunities for the investors of seven developed stock markets in twenty emerging stock markets with data for the January 1, 2003-January 1, 2014 period.

  16. Annual narrative report: Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, and Lake Andes Wetland Management District: Calendar year 1975

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This collection of monthly activity reports summarizes activities on Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR during the 1975 calendar year. Resource...

  17. The abiotic and biotic drivers of rapid diversification in Andean bellflowers (Campanulaceae).

    Science.gov (United States)

    Lagomarsino, Laura P; Condamine, Fabien L; Antonelli, Alexandre; Mulch, Andreas; Davis, Charles C

    2016-06-01

    The tropical Andes of South America, the world's richest biodiversity hotspot, are home to many rapid radiations. While geological, climatic, and ecological processes collectively explain such radiations, their relative contributions are seldom examined within a single clade. We explore the contribution of these factors by applying a series of diversification models that incorporate mountain building, climate change, and trait evolution to the first dated phylogeny of Andean bellflowers (Campanulaceae: Lobelioideae). Our framework is novel for its direct incorporation of geological data on Andean uplift into a macroevolutionary model. We show that speciation and extinction are differentially influenced by abiotic factors: speciation rates rose concurrently with Andean elevation, while extinction rates decreased during global cooling. Pollination syndrome and fruit type, both biotic traits known to facilitate mutualisms, played an additional role in driving diversification. These abiotic and biotic factors resulted in one of the fastest radiations reported to date: the centropogonids, whose 550 species arose in the last 5 million yr. Our study represents a significant advance in our understanding of plant evolution in Andean cloud forests. It further highlights the power of combining phylogenetic and Earth science models to explore the interplay of geology, climate, and ecology in generating the world's biodiversity.

  18. How Damage Diversification Can Reduce Systemic Risk

    CERN Document Server

    Burkholz, Rebekka; Schweitzer, Frank

    2015-01-01

    We consider the problem of risk diversification in complex networks. Nodes represent e.g. financial actors, whereas weighted links represent e.g. financial obligations (credits/debts). Each node has a risk to fail because of losses resulting from defaulting neighbors, which may lead to large failure cascades. Classical risk diversification strategies usually neglect network effects and therefore suggest that risk can be reduced if possible losses (i.e., exposures) are split among many neighbors (exposure diversification, ED). But from a complex networks perspective diversification implies higher connectivity of the system as a whole which can also lead to increasing failure risk of a node. To cope with this, we propose a different strategy (damage diversification, DD), i.e. the diversification of losses that are imposed on neighboring nodes as opposed to losses incurred by the node itself. Here, we quantify the potential of DD to reduce systemic risk in comparison to ED. For this, we develop a branching proce...

  19. Comprehensive Conservation Plan: Lake Andes National Wildlife Refuge Complex

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Lake Andes NWR Complex for the next 15 years. This plan outlines the Refuge vision and...

  20. The Glaciation of the Ecuadorian Andes

    Science.gov (United States)

    Schubert, Carlos

    This pleasing book fills the gap in the knowledge about Pleistocene and recent glaciation between Colombia and Peru. A significant amount of data exists already for Colombia and Venezuela and for Peru, Bolivia, and, particularly, Chile. Hastenrath has now given us a description of glaciers and glaciation underneath the equator in the Andes.The book begins with brief summaries of the physiography and the atmospheric circulation, which give the general setting of Ecuador. Then follow detailed descriptions of the glaciers and glacial morphology of all the important mountains of the Western and Eastern Cordilleras. These are well illustrated, and a particularly useful feature is the comparison of old photographs and paintings of glaciers with modern photographs, many taken by the author. All illustrate the spectacular retreat of the glaciers in the Ecuadorian Andes during the last century and correlate quite well with observations elsewhere. This retreat is snown quantitatively in Table 4, in terms of decrease in glacier-covered area since the glacial advance of moraine stage III. The area of present-day glaciers is about 10% of the area during that stage (compared with about 1.5% in the Sierra Nevada de Mérida, Venezuela). A series of maps show the glacial morphology of the mountains (unfortunately, some of the maps have been included within the binding, thus losing some information; they could have been reduced somewhat to fit a single page or, if too large, could have been included in the pocket, together with the map of Chimborazo-Carihuairazo).

  1. Diversification and Corporate Performance: Evidence from China’s Listed Energy Companies

    Directory of Open Access Journals (Sweden)

    Qiming Li

    2016-09-01

    Full Text Available Recently, China’s energy industry has been continuously depressed due to a slowdown in its economic development. China’s energy companies have made considerable efforts to promote their corporate performance to mitigate this performance decline and to ensure the sustainable development of China’s energy industry, macro economy, society and environment. In this paper, the effects of two business strategies—industrial diversification and international diversification—on the performance of listed energy firms are empirically investigated. The empirical results show the following: (1 industrial diversification hinders corporate performance; (2 for industrially-diversified energy companies, related diversified strategies are more effective than unrelated diversified strategies; and (3 international diversification improves the performance of renewable energy firms, but hinders the performance of conventional energy firms. These results suggest that as economic conditions are not currently optimal, China’s energy companies should pay more attention to their main businesses and generate more products to satisfy market demand.

  2. Extinction probabilities and stationary distributions of mobile genetic elements in prokaryotes: The birth-death-diversification model.

    Science.gov (United States)

    Drakos, Nicole E; Wahl, Lindi M

    2015-12-01

    Theoretical approaches are essential to our understanding of the complex dynamics of mobile genetic elements (MGEs) within genomes. Recently, the birth-death-diversification model was developed to describe the dynamics of mobile promoters (MPs), a particular class of MGEs in prokaryotes. A unique feature of this model is that genetic diversification of elements was included. To explore the implications of diversification on the longterm fate of MGE lineages, in this contribution we analyze the extinction probabilities, extinction times and equilibrium solutions of the birth-death-diversification model. We find that diversification increases both the survival and growth rate of MGE families, but the strength of this effect depends on the rate of horizontal gene transfer (HGT). We also find that the distribution of MGE families per genome is not necessarily monotonically decreasing, as observed for MPs, but may have a peak in the distribution that is related to the HGT rate. For MPs specifically, we find that new families have a high extinction probability, and predict that the number of MPs is increasing, albeit at a very slow rate. Additionally, we develop an extension of the birth-death-diversification model which allows MGEs in different regions of the genome, for example coding and non-coding, to be described by different rates. This extension may offer a potential explanation as to why the majority of MPs are located in non-promoter regions of the genome.

  3. Income diversification and risk for fishermen.

    Science.gov (United States)

    Kasperski, Stephen; Holland, Daniel S

    2013-02-01

    Catches and prices from many fisheries exhibit high interannual variability, leading to variability in the income derived by fishery participants. The economic risk posed by this may be mitigated in some cases if individuals participate in several different fisheries, particularly if revenues from those fisheries are uncorrelated or vary asynchronously. We construct indices of gross income diversification from fisheries at the level of individual vessels and find that the income of the current fleet of vessels on the US West Coast and in Alaska is less diverse than at any point in the past 30 y. We also find a dome-shaped relationship between the variability of individuals' income and income diversification, which implies that a small amount of diversification does not reduce income risk but that higher levels of diversification can substantially reduce the variability of income from fishing. Moving from a single fishery strategy to a 50-25-25 split in revenues reduces the expected coefficient of variation of gross revenues between 24% and 65% for the vessels included in this study. The increasing access restrictions in many marine fisheries through license reductions and moratoriums have the potential to limit fishermen's ability to diversify their income risk across multiple fisheries. Catch share programs often result in consolidation initially and may reduce diversification. However, catch share programs also make it feasible for fishermen to build a portfolio of harvest privileges and potentially reduce their income risk. Therefore, catch share programs create both threats and opportunities for fishermen wishing to maintain diversified fishing strategies.

  4. Hospital diversification: how to involve the pharmacy.

    Science.gov (United States)

    Smith, J E; Black, B L

    1987-05-01

    Participation by hospital pharmacy departments in planning and development of diversified services is described. Diversification requires market planning. Seven basic marketing steps are identification of mission, goals, and objectives; identification of growth strategies (market penetration, market development, product development, and diversification); market analysis of external factors (size, growth, and logistics; reimbursement and financial considerations; competition; regulatory issues; and legal issues); market analysis of internal factors (departmental organization and reporting lines, demographics of the institution, and costs and productivity associated with the new service); program development and design; implementation; and evaluation. Hospitals can diversify by expanding acute-care services through management contracts and mergers; developing new services to include long-term-care, ambulatory-care, occupational-health, and wellness programs; starting other health-care ventures, such as consulting, continuing medical education, and continuing education for nurses; and expanding into non-health-care businesses. Vertical diversification is finding new markets for existing services; horizontal diversification is development of new services for new markets. To diversify, an institution may need to change its corporate structure; it may form a family of corporations that includes a university, nonprofit hospitals, holding companies, for-profit corporations, joint ventures, and service organizations. Through diversification, institutions and pharmacy departments can create alternative sources of funding and offer more comprehensive services to patients.

  5. Epigenetic Regulation of Adaptive NK Cell Diversification.

    Science.gov (United States)

    Tesi, Bianca; Schlums, Heinrich; Cichocki, Frank; Bryceson, Yenan T

    2016-07-01

    Natural killer (NK) cells were previously considered to represent short-lived, innate lymphocytes. However, mouse models have revealed expansion and persistence of differentiated NK cell subsets in response to cytomegalovirus (CMV) infection, paralleling antigen-specific T cell differentiation. Congruently, analyses of humans have uncovered CMV-associated NK cell subsets characterized by epigenetic diversification processes that lead to altered target cell specificities and functional capacities. Here, focusing on responses to viruses, we review similarities and differences between mouse and human adaptive NK cells, identifying molecular analogies that may be key to transcriptional reprogramming and functional alterations. We discuss possible molecular mechanisms underlying epigenetic diversification and hypothesize that processes driving epigenetic diversification may represent a more widespread mechanism for fine-tuning and optimization of cellular immunity.

  6. Seismological Parameters in the Northern Andes, Venezuela

    Science.gov (United States)

    Sobiesiak, M.; Palme de Osechas, C.; Choy, J. E.; Morandi S., M. T.; Campo, M.; Granado Ruiz, C.

    2001-12-01

    Venezuelas tectonic setting as part of the plate boundary between the Caribbean and the South American plate causes two major seismologically active fault systems: the roughly west - east trending strike slip fault system along the coast with numerous sub-parallel faults and the Bocono fault system, which dominates the Venezuelan southwest - northeast striking Andes. The main Bocono fault reaches a total length of about 500 km and has a width of approximately 100 km between the southern and northern baseline of the mountain slopes which are marked by inverse faults. This is believed to be due to strain partitioning, a concept which seems to apply as well to the Bocono fault system. The whole fault system is characterized by a high seismicity rate of small scale and intermediate event magnitudes ranging from 1.5 to 6.3 in the last fifty years. In this study we would like to present an investigation on 39 focal mechanism solutions and a b-value mapping of the Andean region with the main goal to throw light on the stess and strain situation. For recompiling the focal memchanisms calculated from first motion polarities, various sources had to been used: seismograms from stations of the local and regional networks of the Seismological Center of ULA, the national seismic network operated by FUNVISIS, the seismic network Lago Maracaibo of PDVSA and the local seismic network of DESURCA. For the b-value mapping we used the two catalogues of ULA and DESURCA of which the last one registered more than 6500 events from 1994 to 1999. The set of focal mechanism solutions studied showed normal, strike slip, and reverse faulting mechanisms concentrated in distinct areas of the Bocono fault system and thus resulting in a zonation also supported by the determinations of the azimuths of the maximum horizontal stress SHmax. This hypothesis of the zonation of the Andes region is strongly supported by the results of the b-value mapping. The zonation as seen in the varying major stress

  7. Does hospital diversification improve financial outcomes?

    Science.gov (United States)

    Clement, J P

    1987-10-01

    Service or product diversification is a popular recommendation made to hospitals to increase profitability and reduce financial risk as they face a more hostile environment. This paper presents results from an empirical study of these claims. Using data from all California nonprofit hospitals, the study finds that diversification, regardless of whether it is related or unrelated to preexisting services, is not associated with either increased profitability or reduced financial risk. However, other variables that do have these effects are identified in the research. Future research should evaluate the effect of both the size of and the length of time since the initial diversifying investment on financial variables.

  8. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1986

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1986 calendar year. The report...

  9. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1985

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1985 calendar year. The report...

  10. Lake Andes National Wildlife Refuge Complex : Annual narrative report : Calendar year 1991

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1991 calendar year. The report begins...

  11. Lake Andes National Wildlife Refuge : Annual narrative report : Calendar year 1992

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1992 calendar year. The report begins...

  12. Lake Andes National Wildlife Refuge Complex : Annual narrative report : Calendar year 1993

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1993 calendar year. The report begins...

  13. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1987 calendar year. The report...

  14. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1981

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1981 calendar year. The report...

  15. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1982

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1982 calendar year. The report...

  16. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1990

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1990 calendar year. The report...

  17. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1983

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1983 calendar year. The report...

  18. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1989

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1989 calendar year. The report...

  19. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1984

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1984 calendar year. The report...

  20. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1988

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1988 calendar year. The report...

  1. A palaeobiogeographic model for biotic diversification within Amazonia over the past three million years.

    Science.gov (United States)

    Ribas, Camila C; Aleixo, Alexandre; Nogueira, Afonso C R; Miyaki, Cristina Y; Cracraft, Joel

    2012-02-22

    Many hypotheses have been proposed to explain high species diversity in Amazonia, but few generalizations have emerged. In part, this has arisen from the scarcity of rigorous tests for mechanisms promoting speciation, and from major uncertainties about palaeogeographic events and their spatial and temporal associations with diversification. Here, we investigate the environmental history of Amazonia using a phylogenetic and biogeographic analysis of trumpeters (Aves: Psophia), which are represented by species in each of the vertebrate areas of endemism. Their relationships reveal an unforeseen 'complete' time-slice of Amazonian diversification over the past 3.0 Myr. We employ this temporally calibrated phylogeny to test competing palaeogeographic hypotheses. Our results are consistent with the establishment of the current Amazonian drainage system at approximately 3.0-2.0 Ma and predict the temporal pattern of major river formation over Plio-Pleistocene times. We propose a palaeobiogeographic model for the last 3.0 Myr of Amazonian history that has implications for understanding patterns of endemism, the temporal history of Amazonian diversification and mechanisms promoting speciation. The history of Psophia, in combination with new geological evidence, provides the strongest direct evidence supporting a role for river dynamics in Amazonian diversification, and the absence of such a role for glacial climate cycles and refugia.

  2. The first ANDES elements: 9-DOF plate bending triangles

    Science.gov (United States)

    Militello, Carmelo; Felippa, Carlos A.

    1991-01-01

    New elements are derived to validate and assess the assumed natural deviatoric strain (ANDES) formulation. This is a brand new variant of the assumed natural strain (ANS) formulation of finite elements, which has recently attracted attention as an effective method for constructing high-performance elements for linear and nonlinear analysis. The ANDES formulation is based on an extended parametrized variational principle developed in recent publications. The key concept is that only the deviatoric part of the strains is assumed over the element whereas the mean strain part is discarded in favor of a constant stress assumption. Unlike conventional ANS elements, ANDES elements satisfy the individual element test (a stringent form of the patch test) a priori while retaining the favorable distortion-insensitivity properties of ANS elements. The first application of this formulation is the development of several Kirchhoff plate bending triangular elements with the standard nine degrees of freedom. Linear curvature variations are sampled along the three sides with the corners as gage reading points. These sample values are interpolated over the triangle using three schemes. Two schemes merge back to conventional ANS elements, one being identical to the Discrete Kirchhoff Triangle (DKT), whereas the third one produces two new ANDES elements. Numerical experiments indicate that one of the ANDES element is relatively insensitive to distortion compared to previously derived high-performance plate-bending elements, while retaining accuracy for nondistorted elements.

  3. Result diversification based on query-specific cluster ranking

    NARCIS (Netherlands)

    He, J.; Meij, E.; de Rijke, M.

    2011-01-01

    Result diversification is a retrieval strategy for dealing with ambiguous or multi-faceted queries by providing documents that cover as many facets of the query as possible. We propose a result diversification framework based on query-specific clustering and cluster ranking, in which diversification

  4. Diversification Business of Petroleum Industry Set for Rapid Development

    Institute of Scientific and Technical Information of China (English)

    Wang Huangjin

    1994-01-01

    @@ The diversification of China's petroleum industry can be dated back to the late 1950s.After more than 30 years of development, CNPC now lists diversification as one of its three strategies for the development of petroleum industry. This has brought an increasing momentum to the development of the diversification sector-an important integral part of the petroleum economy.

  5. International Diversification Versus Domestic Diversification: Mean-Variance Portfolio Optimization and Stochastic Dominance Approaches

    Directory of Open Access Journals (Sweden)

    Fathi Abid

    2014-05-01

    Full Text Available This paper applies the mean-variance portfolio optimization (PO approach and the stochastic dominance (SD test to examine preferences for international diversification versus domestic diversification from American investors’ viewpoints. Our PO results imply that the domestic diversification strategy dominates the international diversification strategy at a lower risk level and the reverse is true at a higher risk level. Our SD analysis shows that there is no arbitrage opportunity between international and domestic stock markets; domestically diversified portfolios with smaller risk dominate internationally diversified portfolios with larger risk and vice versa; and at the same risk level, there is no difference between the domestically and internationally diversified portfolios. Nonetheless, we cannot find any domestically diversified portfolios that stochastically dominate all internationally diversified portfolios, but we find some internationally diversified portfolios with small risk that dominate all the domestically diversified portfolios.

  6. Geographic Diversification, Competition and Bank Survival

    NARCIS (Netherlands)

    T. Jochem

    2013-01-01

    This article analyzes the effects from portfolio diversification and banking competition on the stability of U.S. banks during the 2008-2011 banking crisis. To do so, it uses exogenous cross-sectional and time-series variation in states' branching restrictions between 1997-2005, the degree of local

  7. Home Care Service Diversification: A Pilot Investigation.

    Science.gov (United States)

    Jette, Alan M.; And Others

    1981-01-01

    Describes a diversified approach to delivering home care to vulnerable older people. This pilot program, funded by the Massachusetts Department of Elder Affairs, attempted to reduce the demand for scarce homemaker services. Results suggest homecare diversification did not alter consumer satisfaction but increased manager time. (Author/JAC)

  8. Global Biogeography and Diversification History of Palms

    DEFF Research Database (Denmark)

    Baker, William J.; Eiserhardt, Wolf L.; Kissling, W. Daniel

    and habitat heterogeneity variables. Incorporation of phylogenetic evidence reveals strong imprints of in situ diversification in the Neotropics and on islands, of biotic interchange, and of forest loss in Africa. We inferred an origin for palms in the mid-Cretaceous of Laurasia, which is significant for our...

  9. Portfolio Diversification Effects of Downside Risk

    NARCIS (Netherlands)

    N. Hyung (Namwon); C.G. de Vries (Casper)

    2004-01-01

    textabstractRisk managers use portfolios to diversify away the un-priced risk of individual securities. In this paper we compare the benefits of portfolio diversification for downside risk in case returns are normally distributed with the case fat tailed distributed returns. The downside risk of a s

  10. CNPC's Diversification Business Boosted by Advanced Technology

    Institute of Scientific and Technical Information of China (English)

    Yao Xuemin

    1996-01-01

    @@ The Eighth Five-Year Plan period witnessed rapid the development in the diversification business of China's onshore petroleum industry for five consecutive years mainly as a result of intensified efforts to develop new products and foreign- exchange- earning products by making full use of science and technology. In particular, great achievements were recorded in the following aspects.

  11. DNA Diversification in Two Sinorhizobium Species▿ †

    OpenAIRE

    Guo, Xianwu; Flores, Margarita; Morales, Lucía; García, Delfino; Bustos, Patricia; González, Víctor; Palacios, Rafael; Dávila, Guillermo

    2007-01-01

    The comparative analysis of genomic characteristics and single-nucleotide polymorphism patterns from large fragments borne on different replicons of Sinorhizobium spp. genomes clearly demonstrate that DNA recombination among closely related bacteria is a major event in the diversification of this genome, especially in pSymA, resulting in mosaic structure.

  12. How damage diversification can reduce systemic risk.

    Science.gov (United States)

    Burkholz, Rebekka; Garas, Antonios; Schweitzer, Frank

    2016-04-01

    We study the influence of risk diversification on cascading failures in weighted complex networks, where weighted directed links represent exposures between nodes. These weights result from different diversification strategies and their adjustment allows us to reduce systemic risk significantly by topological means. As an example, we contrast a classical exposure diversification (ED) approach with a damage diversification (DD) variant. The latter reduces the loss that the failure of high degree nodes generally inflict to their network neighbors and thus hampers the cascade amplification. To quantify the final cascade size and obtain our results, we develop a branching process approximation taking into account that inflicted losses cannot only depend on properties of the exposed, but also of the failing node. This analytic extension is a natural consequence of the paradigm shift from individual to system safety. To deepen our understanding of the cascade process, we complement this systemic perspective by a mesoscopic one: an analysis of the failure risk of nodes dependent on their degree. Additionally, we ask for the role of these failures in the cascade amplification.

  13. Risk Diversification by European Financial Conglomerates

    NARCIS (Netherlands)

    J.F. Slijkerman; D. Schoenmaker (Dirk); C.G. de Vries (Casper)

    2005-01-01

    textabstractWe study the dependence between the downside risk of European banks and insurers. Since the downside risk of banks and insurers differs, an interesting question from a supervisory point of view is the risk reduction that derives from diversification within large banks and financial congl

  14. Diversification of housing sources for military

    Directory of Open Access Journals (Sweden)

    Chimyshenko S.

    2013-06-01

    Full Text Available The article analyzes current mechanism of serviceman housing support, and highlights new possible ways of improving it through diversification of proper tools and methods in the context of so-called “monetization” of some methods of servicemen social protection.

  15. Ecological Factors and Diversification among Neotropical Characiforms

    Directory of Open Access Journals (Sweden)

    Cástor Guisande

    2012-01-01

    Full Text Available Morphological and DNA sequence data has been used to propose hypotheses of relationships within the Characiformes with minimal comparative discussion of causes underpinning the major intraordinal diversification patterns. We explore potential primary morphological factors controlling the early diversification process in some Neotropical characiforms as the first step to identifying factors contributing to the pronounced intraordinal morphological and species diversity. A phylogenetic reconstruction based on 16S rDNA (mitochondrial and 18S rDNA (nuclear genes provided the framework for the identification of the main morphological differences among the Acestrorhynchidae, Anostomidae, Characidae, Ctenoluciidae, Curimatidae, Cynodontidae, Gasteropelecidae, Prochilodontidae and Serrasalmidae. Results indicate an initial split into two major groupings: (i species with long dorsal-fin bases relative to the size of other fins (Curimatidae, Prochilodontidae, Anostomidae, Serrasalmidae which primarily inhabit lakes, swamps, and rivers (lineage I; and (ii species with short dorsal-fin bases (Acestrorhynchidae, Gasteropelecidae, Characidae which primarily inhabit creeks and streams (lineage II. The second diversification stage in lineage I involved substantial morphological diversification associated with trophic niche differences among the monophyletic families which range from detritivores to large item predators. Nonmonophyly of the Characidae complicated within lineage II analyzes but yielded groupings based on differences in pectoral and anal fin sizes correlated with life style differences.

  16. Diversification: Midland/Odessa Health & Retirement Endeavor.

    Science.gov (United States)

    Skipper, P. K.

    In reaction to the economic risks associated with an over reliance on oil and gas exports, residents of the Midland/Odessa area of Texas began seeking diversification options for the local economy and, in 1986, formed the Midland/Odessa Health and Retirement Endeavor (MOHRE). This non-profit corporation was formed to examine the feasibility of…

  17. Entrepreneurship in the Community College: Revenue Diversification.

    Science.gov (United States)

    Brightman, Richard W.

    1989-01-01

    Offers guidelines for community colleges wishing to become involved in for-profit ventures as a means of revenue diversification. Explains the differences between for-profit activities related to the college's non-profit mission and those that are not; alternative organizational structures; and common operations (e.g., catering, retail sales, and…

  18. Diversification Develops Rapidly in Henan Oilfields

    Institute of Scientific and Technical Information of China (English)

    Sun Qiao

    1997-01-01

    @@ During the 12 years ( 1985-1996 ),diversification in Henan oilfields produced altogether 3.25 billion yuan of output value,including over 2.9 billion yuan of sales income, more than 400 million yuan of fixed assets, over 230 million yuan of profit tax, and over 400 million yuan born as wages for the oilfields.

  19. Evolution of a climbing habit promotes diversification in flowering plants.

    Science.gov (United States)

    Gianoli, Ernesto

    2004-10-07

    Key innovations are traits that are associated with the particular evolutionary 'success' of some taxonomic groups. Climbing plants depend on the availability of physical support to reach the canopy and thereby prevent shading by neighbouring plants. The present article shows that the evolution of a climbing habit in flowering plants constitutes a key innovation. A literature survey identified 48 pairs of sister groups from 45 families of flowering plants for which information on phylogenetic relationships, growth habit and species richness was available. In 38 cases, the climbing taxa were more diverse than their non-climbing sister groups. This pattern was highly significant. The same result was found when separate analyses were carried out for herbaceous and woody climbing plants, which differ in their constraints for successfully reaching a support.

  20. Fast demographic traits promote high diversification rates of Amazonian trees

    NARCIS (Netherlands)

    Baker, Timothy R; Pennington, R Toby; Magallon, Susana; Gloor, Emanuel; Laurance, William F; Alexiades, Miguel; Alvarez, Esteban; Araujo, Alejandro; Arets, Eric J M M; Aymard, Gerardo; de Oliveira, Atila Alves; Amaral, Iêda; Arroyo, Luzmila; Bonal, Damien; Brienen, Roel J W; Chave, Jerome; Dexter, Kyle G; Di Fiore, Anthony; Eler, Eduardo; Feldpausch, Ted R; Ferreira, Leandro; Lopez-Gonzalez, Gabriela; van der Heijden, Geertje; Higuchi, Niro; Honorio, Eurídice; Huamantupa, Isau; Killeen, Tim J; Laurance, Susan; Leaño, Claudio; Lewis, Simon L; Malhi, Yadvinder; Marimon, Beatriz Schwantes; Marimon Junior, Ben Hur; Monteagudo Mendoza, Abel; Neill, David; Peñuela-Mora, Maria Cristina; Pitman, Nigel; Prieto, Adriana; Quesada, Carlos A; Ramírez, Fredy; Ramírez Angulo, Hirma; Rudas, Agustin; Ruschel, Ademir R; Salomão, Rafael P; de Andrade, Ana Segalin; Silva, J Natalino M; Silveira, Marcos; Simon, Marcelo F; Spironello, Wilson; ter Steege, Hans; Terborgh, John; Toledo, Marisol; Torres-Lezama, Armando; Vasquez, Rodolfo; Vieira, Ima Célia Guimarães; Vilanova, Emilio; Vos, Vincent A; Phillips, Oliver L; Santos, F.

    2014-01-01

    The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show th

  1. Analysis on the Land Use Behavior of Diversification Peasant Household Based on Allocation, Diversification and Investment Effects

    Directory of Open Access Journals (Sweden)

    Fang Luo

    2013-06-01

    Full Text Available In the process of traditional economy transforming into modern economy in china, farmer’s diversification phenomena has arisen and developed and will continue a long time in the future. Accordingly, the general economic type of farmer diversification will effect on the rural source allocation. The land use behavior characteristics of diversification farmer are the aims of the study. Theoretic analyzing and empiristical testing methods are used for the allocation, diversification and investment effects introduced by farmer diversification. It concluded that the allocation effect of land transfer and diversification effect of agricultural labor decreasing are mostly proved, but the investment effect of diversification income which will improve agricultural production capital is not significant.

  2. Functional Diversification within a Predatory Species Flock

    Science.gov (United States)

    Burress, Edward D.; Duarte, Alejandro; Serra, Wilson S.; Loueiro, Marcelo; Gangloff, Michael M.; Siefferman, Lynn

    2013-01-01

    Ecological speciation is well-known from adaptive radiations in cichlid fishes inhabiting lentic ecosystems throughout the African rift valley and Central America. Here, we investigate the ecological and morphological diversification of a recently discovered lotic predatory Neotropical cichlid species flock in subtropical South America. We document morphological and functional diversification using geometric morphometrics, stable C and N isotopes, stomach contents and character evolution. This species flock displays species-specific diets and skull and pharyngeal jaw morphology. Moreover, this lineage appears to have independently evolved away from piscivory multiple times and derived forms are highly specialized morphologically and functionally relative to ancestral states. Ecological speciation played a fundamental role in this radiation and our data reveal novel conditions of ecological speciation including a species flock that evolved: 1) in a piscivorous lineage, 2) under lotic conditions and 3) with pronounced morphological novelties, including hypertrophied lips that appear to have evolved rapidly. PMID:24278349

  3. Optimising investment performance through international diversification

    Directory of Open Access Journals (Sweden)

    J. Swart

    2014-01-01

    Full Text Available International portfolio diversification is often advocated as a way of enhancing portfolio performance particularly through the reduction of portfolio risk. Portfolio managers in Europe have for decades routinely invested a substantial portion of their portfolios in securities that were issued in other countries. During the last decade US investors have held a significant amount of foreign securities with over a trillion dollars invested in foreign assets by 1994. South African institutions have been allowed some freedom to diversify internationally since mid 1995 and individual investors since July 1997. In this paper the potential diversification benefits for South African investors are considered. The stability over time of the correlation structure is investigated and simple ex-ante investment strategies are formulated and evaluated.

  4. Diversification versus specialization in complex ecosystems.

    Directory of Open Access Journals (Sweden)

    Riccardo Di Clemente

    Full Text Available By analyzing the distribution of revenues across the production sectors of quoted firms we suggest a novel dimension that drives the firms diversification process at country level. Data show a non trivial macro regional clustering of the diversification process, which underlines the relevance of geopolitical environments in determining the microscopic dynamics of economic entities. These findings demonstrate the possibility of singling out in complex ecosystems those micro-features that emerge at macro-levels, which could be of particular relevance for decision-makers in selecting the appropriate parameters to be acted upon in order to achieve desirable results. The understanding of this micro-macro information exchange is further deepened through the introduction of a simplified dynamic model.

  5. Climate change adaptation in Ethiopia: to what extent does social protection influence livelihood diversification?

    DEFF Research Database (Denmark)

    Weldegebriel, Zerihun; Prowse, Martin Philip

    2013-01-01

    Social-protection programmes like the Productive Safety-Net Programme (PSNP) in Ethiopia can play a positive role in promoting livelihoods and enhancing risk management. This article uses propensity score matching to estimate its effect on income diversification. The results suggest that receivin...... in a positive manner for climate adaptation. The article concludes by arguing for the promotion of positive forms of income diversification and the further investigation of the PSNP’s influence on autonomous adaptation strategies.......Social-protection programmes like the Productive Safety-Net Programme (PSNP) in Ethiopia can play a positive role in promoting livelihoods and enhancing risk management. This article uses propensity score matching to estimate its effect on income diversification. The results suggest that receiving...... transfers from the PSNP, on average, did not increase farm or non-farm income but significantly increases natural-resource extraction (one component of off-farm income). While these results should be treated with caution, they suggest that the PSNP may not be helping smallholders diversify income sources...

  6. Organizational diversification in the American hospital.

    Science.gov (United States)

    Snail, T S; Robinson, J C

    1998-01-01

    This paper outlines a conceptual framework of organizational diversification and assesses the state of empirical research on hospital organizational change. The literature on economic organization of hospitals, one of the most developed branches of health services research, still has only weak ties to economic theory. Evolving physician-hospital organizations do not fit into existing frameworks based on horizontal integration, vertical integration, or diversification. Empirical research has primarily focused on horizontal integration, and cause-effect relationships are often obscured by models that depart from economic theory and lack controls for self-selection bias. Recent empirical studies indicate that hospital mergers had moderate, rather than dramatic, effects on the rate of change in operating costs, staffing, and scale. Mergers rarely resulted in hospital closure, but were as likely to result in acute care consolidation and restructuring as in conversion to non-acute inpatient uses. While administrative costs were higher in for-profit than non-profit system hospitals, total costs were similar. System hospitals had lower marginal and average costs per stay than independent hospitals. Hospital vertical integration into subacute care was largely an artifact of the governmental uniform pricing system, which encouraged vertical integration. Hospitals that shared governance or financial risks with physicians outperformed those with high levels of physician governance and financial integration (e.g. stock ownership). Formal physician-hospital organizational arrangements often served to coordinate managed care contracting or to forge links with primary care group practices. Hospital diversification into related services improved short-term financial performance over unrelated diversification, although long-term performance was similar.

  7. Historical biogeography of the catfish genus Hypostomus (Siluriformes: Loricariidae), with implications on the diversification of Neotropical ichthyofauna.

    Science.gov (United States)

    Montoya-Burgos, J I

    2003-07-01

    Tropical South America possesses the largest ichthyofauna of any continental region. To test whether palaeohydrological changes may have been the causes of such diversification, the 'hydrogeological' hypothesis, the phylogenetic relationships of 51 representatives of the catfish genus Hypostomus (Siluriformes: Loricariidae) were inferred using mitochondrial D-loop haplotype sequences. Specimens were collected in all main tropical South American rivers systems east to the Andes. The major interrelationships found with the D-loop data were confirmed with a subset of 21 species using complete internal transcribed spacer (ITS) region sequences. The phylogenetic analysis indicate that the genus Hypostomus can be divided into four monophyletic clades. The historical biogeographical analysis of each of these clades allows the identification of seven major cladogenetic events. Using calibrated D-loop and ITS molecular clocks, date estimations were attributed to each of these cladogenetic events allowing a linkage between four of them with documented hydrogeological changes. Comparisons with published distribution patterns of unrelated fish groups indicate that several of the reconstructed and dated hydrogeological-cladogenetic events may have acted at a large scale on the diversification of Neotropical freshwater fish fauna during late Tertiary.

  8. Andes hantavirus variant in rodents, southern Amazon Basin, Peru.

    Science.gov (United States)

    Razuri, Hugo; Tokarz, Rafal; Ghersi, Bruno M; Salmon-Mulanovich, Gabriela; Guezala, M Claudia; Albujar, Christian; Mendoza, A Patricia; Tinoco, Yeny O; Cruz, Christopher; Silva, Maria; Vasquez, Alicia; Pacheco, Víctor; Ströher, Ute; Guerrero, Lisa Wiggleton; Cannon, Deborah; Nichol, Stuart T; Hirschberg, David L; Lipkin, W Ian; Bausch, Daniel G; Montgomery, Joel M

    2014-02-01

    We investigated hantaviruses in rodents in the southern Amazon Basin of Peru and identified an Andes virus variant from Neacomys spinosus mice. This finding extends the known range of this virus in South America and the range of recognized hantaviruses in Peru. Further studies of the epizoology of hantaviruses in this region are warranted.

  9. Diversification of two lineages of symbiotic Photobacterium.

    Directory of Open Access Journals (Sweden)

    Henryk Urbanczyk

    Full Text Available Understanding of processes driving bacterial speciation requires examination of closely related, recently diversified lineages. To gain an insight into diversification of bacteria, we conducted comparative genomic analysis of two lineages of bioluminescent symbionts, Photobacterium leiognathi and 'P. mandapamensis'. The two lineages are evolutionary and ecologically closely related. Based on the methods used in bacterial taxonomy for classification of new species (DNA-DNA hybridization and ANI, genetic relatedness of the two lineages is at a cut-off point for species delineation. In this study, we obtained the whole genome sequence of a representative P. leiognathi strain lrivu.4.1, and compared it to the whole genome sequence of 'P. mandapamensis' svers.1.1. Results of the comparative genomic analysis suggest that P. leiognathi has a more plastic genome and acquired genes horizontally more frequently than 'P. mandapamensis'. We predict that different rates of recombination and gene acquisition contributed to diversification of the two lineages. Analysis of lineage-specific sequences in 25 strains of P. leiognathi and 'P. mandapamensis' found no evidence that bioluminescent symbioses with specific host animals have played a role in diversification of the two lineages.

  10. Diversification of two lineages of symbiotic Photobacterium.

    Science.gov (United States)

    Urbanczyk, Henryk; Urbanczyk, Yoshiko; Hayashi, Tetsuya; Ogura, Yoshitoshi

    2013-01-01

    Understanding of processes driving bacterial speciation requires examination of closely related, recently diversified lineages. To gain an insight into diversification of bacteria, we conducted comparative genomic analysis of two lineages of bioluminescent symbionts, Photobacterium leiognathi and 'P. mandapamensis'. The two lineages are evolutionary and ecologically closely related. Based on the methods used in bacterial taxonomy for classification of new species (DNA-DNA hybridization and ANI), genetic relatedness of the two lineages is at a cut-off point for species delineation. In this study, we obtained the whole genome sequence of a representative P. leiognathi strain lrivu.4.1, and compared it to the whole genome sequence of 'P. mandapamensis' svers.1.1. Results of the comparative genomic analysis suggest that P. leiognathi has a more plastic genome and acquired genes horizontally more frequently than 'P. mandapamensis'. We predict that different rates of recombination and gene acquisition contributed to diversification of the two lineages. Analysis of lineage-specific sequences in 25 strains of P. leiognathi and 'P. mandapamensis' found no evidence that bioluminescent symbioses with specific host animals have played a role in diversification of the two lineages.

  11. Lithospheric scale model of Merida Andes, Venezuela (GIAME Project)

    Science.gov (United States)

    Schmitz, M.; Orihuela, N. D.; Klarica, S.; Gil, E.; Levander, A.; Audemard, F. A.; Mazuera, F.; Avila, J.

    2013-05-01

    Merida Andes (MA) is one of the most important orogenic belt in Venezuela and represents the northern culmination of South America Andes. During the last 60 years, several models have been proposed to explain the shallow and deep structure, using different geological, geophysical, seismological, geochemical and petrologic concepts; nevertheless, most of them have applied local observation windows, and do not represent the major structure of MA. Therefore, a multidisciplinary research group, coordinated by FUNVISIS, in close cooperation with UCV, ULA and PDVSA, is proposed in order to get the outlined goals in the project entitled GIAME ("Geociencia Integral de los Andes de MErida") was established, which aims to generate a lithospheric scale model and the development of a temporal dynamic model for the MA. As a base for lithospheric investigations of the Merida Andes, we are proposing three wide angle seismic profiles across the orogen on three representative sites, in order to determine the inner structure and its relation with the orogen's gravimetric root. To the date, there are no seismic studies at lithospheric scale which cross MA. The wide angle seismic will be complemented with the re-processing and re-interpretation of existing reflection seismic data, which will allow to establish a relationship between MA and its associated flexural basins (Maracaibo and Barinas-Apure basins). Depending on the results of the VENCORP Project (VENezuelan COntinental Reflection Profiling), which might show some reliable results about crustal features and Moho reflectors along three long seismic profiles at Caribbean Moutain system, a reflection seismic profile across the central portion of MA is proposed. Additional tasks, consisting in MA quaternary deformation studies, using research methods like neotectonics and paleoseismology, georadar, numerical modeling, cinematic GPS, SAR interferometry, thermocronology, detailed studies on regional geology, flexural modeling

  12. Diversification of the rainfrog Pristimantis ornatissimus in the lowlands and Andean foothills of Ecuador

    Science.gov (United States)

    Hutter, Carl R.; Tapia, Elicio E.; Culebras, Jaime; Peñafiel, Nicolás; Pyron, R. Alexander; Morochz, Carlos; Funk, W. Chris; Arteaga, Alejandro

    2017-01-01

    Geographic barriers and elevational gradients have long been recognized as important in species diversification. Here, we illustrate an example where both mechanisms have shaped the genetic structure of the Neotropical rainfrog, Pristimantis ornatissimus, which has also resulted in speciation. This species was thought to be a single evolutionary lineage distributed throughout the Ecuadorian Chocó and the adjacent foothills of the Andes. Based on recent sampling of P. ornatissimus sensu lato, we provide molecular and morphological evidence that support the validity of a new species, which we name Pristimantis ecuadorensis sp. nov. The sister species are elevational replacements of each other; the distribution of Pristimantis ornatissimus sensu stricto is limited to the Ecuadorian Chocó ecoregion (< 1100 m), whereas the new species has only been found at Andean localities between 1450–1480 m. Given the results of the Multiple Matrix Regression with Randomization analysis, the genetic difference between P. ecuadorensis and P. ornatissimus is not explained by geographic distance nor environment, although environmental variables at a finer scale need to be tested. Therefore this speciation event might be the byproduct of stochastic historic extinction of connected populations or biogeographic events caused by barriers to dispersal such as rivers. Within P. ornatissimus sensu stricto, morphological patterns and genetic structure seem to be related to geographic isolation (e.g., rivers). Finally, we provide an updated phylogeny for the genus, including the new species, as well as other Ecuadorian Pristimantis. PMID:28329011

  13. Diversification of the rainfrog Pristimantis ornatissimus in the lowlands and Andean foothills of Ecuador.

    Science.gov (United States)

    Guayasamin, Juan M; Hutter, Carl R; Tapia, Elicio E; Culebras, Jaime; Peñafiel, Nicolás; Pyron, R Alexander; Morochz, Carlos; Funk, W Chris; Arteaga, Alejandro

    2017-01-01

    Geographic barriers and elevational gradients have long been recognized as important in species diversification. Here, we illustrate an example where both mechanisms have shaped the genetic structure of the Neotropical rainfrog, Pristimantis ornatissimus, which has also resulted in speciation. This species was thought to be a single evolutionary lineage distributed throughout the Ecuadorian Chocó and the adjacent foothills of the Andes. Based on recent sampling of P. ornatissimus sensu lato, we provide molecular and morphological evidence that support the validity of a new species, which we name Pristimantis ecuadorensis sp. nov. The sister species are elevational replacements of each other; the distribution of Pristimantis ornatissimus sensu stricto is limited to the Ecuadorian Chocó ecoregion (< 1100 m), whereas the new species has only been found at Andean localities between 1450-1480 m. Given the results of the Multiple Matrix Regression with Randomization analysis, the genetic difference between P. ecuadorensis and P. ornatissimus is not explained by geographic distance nor environment, although environmental variables at a finer scale need to be tested. Therefore this speciation event might be the byproduct of stochastic historic extinction of connected populations or biogeographic events caused by barriers to dispersal such as rivers. Within P. ornatissimus sensu stricto, morphological patterns and genetic structure seem to be related to geographic isolation (e.g., rivers). Finally, we provide an updated phylogeny for the genus, including the new species, as well as other Ecuadorian Pristimantis.

  14. Molecular method for the detection of Andes hantavirus infection: validation for clinical diagnostics

    Science.gov (United States)

    Vial, Cecilia; Martinez-Valdebenito, Constanza; Rios, Susana; Martinez, Jessica; Vial, Pablo; Ferres, Marcela; Rivera, Juan Carlos; Perez, Ruth; Valdivieso, Francisca

    2016-01-01

    Hantavirus Cardiopulmonary Syndrome is a severe disease caused by exposure to New World hantaviruses. Early diagnosis is difficult due to the lack of specific initial symptoms. Anti-hantavirus antibodies are usually negative until late in the febrile prodrome or the beginning of cardiopulmonary phase while Andes hantavirus (ANDV) RNA genome can be detected before symptoms onset. We analyzed the effectiveness of RTqPCR as a diagnostic tool detecting ANDV-Sout genome in peripheral blood cells from 78 confirmed hantavirus patients and 166 negative controls. Our results indicate that RTqPCR had a low detection limit (~10 copies), with a specificity of 100% and a sensitivity of 94.9%. This suggests the potential for establishing RT-qPCR as the assay of choice for early diagnosis, promoting early effective care of patients and improve other important aspects of ANDV infection management, such as compliance of biosafety recommendations for health personnel in order to avoid nosocomial transmission. PMID:26508102

  15. Unveiling the diversification dynamics of Australasian predaceous diving beetles in the Cenozoic.

    Science.gov (United States)

    Toussaint, Emmanuel F A; Condamine, Fabien L; Hawlitschek, Oliver; Watts, Chris H; Porch, Nick; Hendrich, Lars; Balke, Michael

    2015-01-01

    During the Cenozoic, Australia experienced major climatic shifts that have had dramatic ecological consequences for the modern biota. Mesic tropical ecosystems were progressively restricted to the coasts and replaced by arid-adapted floral and faunal communities. Whilst the role of aridification has been investigated in a wide range of terrestrial lineages, the response of freshwater clades remains poorly investigated. To gain insights into the diversification processes underlying a freshwater radiation, we studied the evolutionary history of the Australasian predaceous diving beetles of the tribe Hydroporini (147 described species). We used an integrative approach including the latest methods in phylogenetics, divergence time estimation, ancestral character state reconstruction, and likelihood-based methods of diversification rate estimation. Phylogenies and dating analyses were reconstructed with molecular data from seven genes (mitochondrial and nuclear) for 117 species (plus 12 outgroups). Robust and well-resolved phylogenies indicate a late Oligocene origin of Australasian Hydroporini. Biogeographic analyses suggest an origin in the East Coast region of Australia, and a dynamic biogeographic scenario implying dispersal events. The group successfully colonized the tropical coastal regions carved by a rampant desertification, and also colonized groundwater ecosystems in Central Australia. Diversification rate analyses suggest that the ongoing aridification of Australia initiated in the Miocene contributed to a major wave of extinctions since the late Pliocene probably attributable to an increasing aridity, range contractions and seasonally disruptions resulting from Quaternary climatic changes. When comparing subterranean and epigean genera, our results show that contrasting mechanisms drove their diversification and therefore current diversity pattern. The Australasian Hydroporini radiation reflects a combination of processes that promoted both diversification

  16. Epistasis can accelerate adaptive diversification in haploid asexual populations.

    Science.gov (United States)

    Griswold, Cortland K

    2015-03-01

    A fundamental goal of the biological sciences is to determine processes that facilitate the evolution of diversity. These processes can be separated into ecological, physiological, developmental and genetic. An ecological process that facilitates diversification is frequency-dependent selection caused by competition. Models of frequency-dependent adaptive diversification have generally assumed a genetic basis of phenotype that is non-epistatic. Here, we present a model that indicates diversification is accelerated by an epistatic basis of phenotype in combination with a competition model that invokes frequency-dependent selection. Our model makes use of a genealogical model of epistasis and insights into the effects of balancing selection on the genealogical structure of a population to understand how epistasis can facilitate diversification. The finding that epistasis facilitates diversification may be informative with respect to empirical results that indicate an epistatic basis of phenotype in experimental bacterial populations that experienced adaptive diversification.

  17. Distinct Processes Drive Diversification in Different Clades of Gesneriaceae.

    Science.gov (United States)

    Roalson, Eric H; Roberts, Wade R

    2016-07-01

    Using a time-calibrated phylogenetic hypothesis including 768 Gesneriaceae species (out of [Formula: see text]3300 species) and more than 29,000 aligned bases from 26 gene regions, we test Gesneriaceae for diversification rate shifts and the possible proximal drivers of these shifts: geographic distributions, growth forms, and pollination syndromes. Bayesian Analysis of Macroevolutionary Mixtures analyses found five significant rate shifts in Beslerieae, core Nematanthus, core Columneinae, core Streptocarpus, and Pacific Cyrtandra These rate shifts correspond with shifts in diversification rates, as inferred by Binary State Speciation and Extinction Model and Geographic State Speciation and Extinction model, associated with hummingbird pollination, epiphytism, unifoliate growth, and geographic area. Our results suggest that diversification processes are extremely variable across Gesneriaceae clades with different combinations of characters influencing diversification rates in different clades. Diversification patterns between New and Old World lineages show dramatic differences, suggesting that the processes of diversification in Gesneriaceae are very different in these two geographic regions.

  18. Determinants of exports diversifications around the world: 1962 - 2000

    OpenAIRE

    Manuel Agosin; Roberto Álvarez; Claudio Bravo-Ortega; Esteban Puentes

    2010-01-01

    Using a large dataset of countries during the last forty years, this paper analyzes the main determinants of export diversification. We explore the role of several factors and we use three different indicators of export diversification. We find robust evidence across specifications and indicators that trade openness induces higher specialization and does not favor export diversification. In contrast, financial development helps countries to diversify their exports. Looking at the effects of e...

  19. Diversification and corporate social performance in manufacturing companies

    OpenAIRE

    Patrisia, Dina; Dastgir, Shabbir

    2016-01-01

    The effects of diversification on financial performance are well-established, less so the way in which diversification influences company behaviour towards stakeholder demand and social concern. This paper investigates the relationship between business diversification and corporate social performance (CSP) in an industrial setting, in Indonesia. CSP is measured with an index constructed from content and disclosure analysis of annual company reports in line with global reporting initiative sta...

  20. Corporate Diversification and Firm Performance: Evidence from Asian Hotel Industry

    Directory of Open Access Journals (Sweden)

    Ooi Chai-Aun

    2014-01-01

    Full Text Available The unstable environment of hotel industry which is driven by the fluctuation of tourism demand has motivated this study to look into the best diversification strategy for firm performance betterment. 42 hotel firms are investigated across 4 Asian economies, from year 2001 to 2012. Our results suggest that unrelated industrial diversification is the only alternative to improve hotel firm performance. Unrelated international diversification instead has a significant negative effect towards firm performance. Our results further show that board of directors implies a significant link to the relationship between diversification and firm performance, only in a crisis period.

  1. Diversification as a Circumvention Strategy to Institutional Constraints in China

    DEFF Research Database (Denmark)

    Xie, Peihong; Li, Xin; Wu, Sibin

    While unrelated diversification (i.e., conglomeration) is deemed value-destroying in the West, many Chinese private firms have been enthusiastically pursuing such a growth strategy. Conventional institutional view of diversification sees conglomerates as responses to market imperfections...... the socially counterproductive rent-seeking aspects of conglomeration strategy in institution-weak countries (Khanna & Palepu, 2000). In this paper, we fill the gap by examining some unconventional diversifications and point out their rent-seeking nature in China. We have proposed an official...... diversification phenomenon and proposing a theoretical framework to account for it. The other is that we contribute to the institution-based view of strategy....

  2. Ecological Divergence, Adaptive Diversification, and the Evolution of Social Signaling Traits: An Empirical Study in Arid Australian Lizards.

    Science.gov (United States)

    Edwards, Danielle L; Melville, Jane; Joseph, Leo; Keogh, J Scott

    2015-12-01

    Species diversification often results from divergent evolution of ecological or social signaling traits. Theoretically, a combination of the two may promote speciation, however, empirical examples studying how social signal and ecological divergence might be involved in diversification are rare in general and typically do not consider range overlap as a contributing factor. We show that ecologically distinct lineages within the Australian sand dragon species complex (including Ctenophorus maculatus, Ctenophorus fordi, and Ctenophorus femoralis) have diversified recently, diverging in ecologically relevant and social signaling phenotypic traits as arid habitats expanded and differentiated. Diversification has resulted in repeated and independent invasion of distinct habitat types, driving convergent evolution of similar phenotypes. Our results suggest that parapatry facilitates diversification in visual signals through reinforcement as a hybridization-avoidance mechanism. We show that particularly striking variation in visual social signaling traits is better explained by the extent of lineage parapatry relative to ecological or phylogenetic divergence, suggesting that these traits reinforce divergence among lineages initiated by ecologically adaptive evolution. This study provides a rare empirical example of a repeated, intricate relationship between ecological and social signal evolution during diversification driven by ecological divergence and the evolution of new habitats, thereby supporting emergent theories regarding the importance of both ecological and social trait evolution throughout speciation.

  3. Organizational Mission and Revenue Diversification among Non-profit Sports Clubs

    Directory of Open Access Journals (Sweden)

    Christoph Breuer

    2013-11-01

    Full Text Available The beneficial effects of diversified income portfolios are well documented in previous research on non-profit organizations. This study examines how different types of organizational missions affect the level of revenue diversification of organizations in one industry, a question that was neglected in previous research. Based on contingency theory, it is assumed that different missions are associated with different funding sources. Since missions can be complementary or conflicting, specific attention needs to be paid to the combination of missions. The sport sector is chosen as an empirical setting because non-profit sports clubs can have various missions while their overall purpose is promoting sport. Panel data from a nationwide survey of non-profit sports clubs in Germany are used for the analysis. The regression results show that revenue diversification is significantly determined by organizational mission. Historically, typical mission statements like promoting elite sport, tradition, conviviality, non-sport programs, and youth sport have a positive effect on revenue diversification, while clubs with a commercial orientation and a focus on leisure and health sport have more concentrated revenues. The findings have implications for club management in the sense that some missions are associated with higher financial risk and that the combination of missions should be chosen carefully.

  4. Ordovician chitinozoan diversification events in China

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaofeng; CHEN; Xiaohong

    2004-01-01

    Correlative study of the Ordovician chitinozoan biostratigraphy in China with graptolite and conodont biozones, and comprehensive analysis of the sequence- and event-stratigraphic indicated that 17 chitinozoan zones and 5 main chitinozoan diversification events subsequently occurring could be recognized in the Ordovician System of China. The 5 events comprise: event 1-appearance of the earliest Ordovician chitinozoans, event 2-appearance of C. symmetrica, event 3-juvenile radiation of chitinozoans, event 4-appearance of chitinozoans with high diversity, and event 5-development of chitinozoans of deep-water facies. The age and feature of each event and its relation with the sea-level change and other geological event are discussed.

  5. Nursing home diversification requires caution by hospitals.

    Science.gov (United States)

    Monroe, S M

    1988-12-01

    Hospital executives considering diversifying into long-term care for the elderly need to understand the ways the nursing home acquisition market and the long-term care industry have changed in the past two years and how to best respond to those changes. Diversification into the nursing home business must be carefully planned, taking into account such factors as state Medicaid reimbursement policies; the respective advantages of buying an existing facility or constructing a new one; the need for executives with expertise in long-term care; and the financial requirements of the proposal.

  6. Glacier shrinkage and water resources in the Andes

    Science.gov (United States)

    Francou, Bernard; Coudrain, Anne

    For more than a century glaciers around the world have been melting as air temperatures rise due to a combination of natural processes and human activity. The disappearance of these glaciers can have wide-ranging effects, such as the creation of new natural hazards or changes in stream flow that could threaten water suppliesSome of the most dramatic melting has occurred in the Andes mountain range in South America. To highlight the climatic and glacial change in the Andes and to encourage the scientific community to strengthen the glacier observation network that stretches from Colombia to the Patagonian ice fields, the Instituto Nacional de Recursos Naturales (INRENA), Perú, and the Institute of Research and Development (IRD), France, recently organized the second Symposium on Mass Balance of Andean Glaciers in Huaráz,Perú.

  7. Zeolitización de rocas andesíticas

    Directory of Open Access Journals (Sweden)

    Plana, F.

    1989-12-01

    Full Text Available The study of some andesites from King George Island (South Shetland Islands, Anctartica has pointed out the existence of a hydrothermal alteration process going rise to a zeolitic secondary minerals of low-temperature assemblages. Two paragenesis have been identified (Smectite-Bytownite-Mordenite, Smectite-Albite-Laumontite which reflecting different conditions durign the hydrothermal alteration of these andesitic rocksEl estudio de rocas andesíticas de la Isla King George (Archipiélago de las Shetland del Sur, Antártida pone de manifiesto la existencia de procesos de alteración hidrotermal con la formación de minerales zeolíticos secundarios pertenecientes a asociaciones de baja temperatura. Se han identificado dos paragénesis (Esmectitas-Bytownita-Mordenita, Esmectitas-AlbitaLaumontita que reflejan distintas condiciones durante la alteración hidrotermal de dichas rocas andesíticas.

  8. Migrating deformation in the Central Andes from enhanced orographic rainfall

    Science.gov (United States)

    Norton, Kevin; Schlunegger, Fritz

    2011-12-01

    Active shortening in the Central Andes shifted from the western to the eastern margin between 10-7Ma. Here we propose that this shift was primarily controlled by changes in erosion patterns. The uplift of the Andes blocked easterly winds, resulting in enhanced orographic rainfall on the eastern margin and reduced rainfall on the western margin. Lower erosion rates, associated with the arid conditions, caused the western margin to steepen inhibiting internal deformation and the migration of deformation to the eastern margin where it is active today. River channel profiles on the western margin are indicative of long-term transience from an older tectonic event whereas those on the eastern margin reflect ongoing coupled climatic-tectonic feedback. Both critical wedge theory and local-scale fault friction calculations support this interpretation. This work emphasizes the role that orographic rainfall and erosion can have on the orogen-scale development of mountain belts.

  9. Paleoatimetry of southern Tibet and the central Andes

    Science.gov (United States)

    Quade, J.; Dettinger, M. P.; DeCelles, P. G.; Leary, R.; Kapp, P. A.

    2011-12-01

    Here we explore a variety of isotopic systems to reconstruct paleoatitude in southern Tibet and the central Andes. A multi-system approach is essential since the necessary mineral archives are not always available, and because diagenetic resetting of some systems clearly occurs. In the central Andes at ~24°S, carbonate is rare due to hyperaridity, and where present, evaporation in soils and lakes completely alters the primary meteoric signal. Waters of hydration of volcanic glass are a much more promising target in this region given the prevalence of volcanic tuffs. We have analyzed the δD value of a suite of modern and ancient glasses back to 34 Ma that show little change in elevation in the western Cordillera of the Andes. By contrast, the eastern Cordillera of the Andes rose in the last 15 Ma. This pattern is consistent with gradual eastward propagation of the whole orogen at this latitude, including the trench, forearc, magmatic arc, and foreland. The paleoaltimetry of Tibet poses quite different challenges to those in South America. Volcanic glass archives are so far unavailable, whereas carbonate archives are common but in some cases diagenetically reset. We have focused on records of conventional δ18O values and clumped isotope thermometry. One must treat both archives with great caution due to resetting, especially clumped isotopes. Available evidence suggests that southern Tibet has been near current elevations since the early Miocene. For the pre- Miocene we present new isotopic/paleosol records found along the suture zone of India and Asia that we believe partly chronicle the rise of the suture zone from near sea-level to >4000 m today.

  10. Crustal-thickness variations in the central Andes

    Science.gov (United States)

    Beck, Susan L.; Zandt, George; Myers, Stephen C.; Wallace, Terry C.; Silver, Paul G.; Drake, Lawrence

    1996-05-01

    We estimated the crustal thickness along an east-west transect across the Andes at lat 20°S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband seismic stations (BANJO and SEDA). Waveforms of deep regional events in the downgoing Nazca slab and teleseismic earthquakes were processed to isolate the P-to-S converted phases from the Moho in order to compute the crustal thickness. We found crustal-thickness variations of nearly 40 km across the Andes. Maximum crustal thicknesses of 70 74 km under the Western Cordillera and the Eastern Cordillera thin to 32 38 km 200 km east of the Andes in the Chaco Plain. The central Altiplano at 20°S has crustal thicknesses of 60 to 65 km. The crust also appears to thicken from north (16°S, 55 60 km) to south (20°S, 70 74 km) along the Eastern Cordillera. The Subandean zone crust has intermediate thicknesses of 43 to 47 km. Crustal-thickness predictions for the Andes based on Airy-type isostatic behavior show remarkable overall correlation with observed crustal thickness in the regions of high elevation. In contrast, at the boundary between the Eastern Cordillera and the Subandean zone and in the Chaco Plain, the crust is thinner than predicted, suggesting that the crust in these regions is supported in part by the flexural rigidity of a strong lithosphere. With additional constraints, we conclude that the observation of Airy-type isostasy is consistent with thickening associated with compressional shortening of a weak lithosphere squeezed between the stronger lithosphere of the subducting Nazca plate and the cratonic lithosphere of the Brazilian craton.

  11. Permafrost Distribution Modeling in the Semi-Arid Chilean Andes

    OpenAIRE

    Azócar, Guillermo F.; Brenning, Alexander; Bodin, Xavier

    2016-01-01

    Mountain permafrost and rock glaciers in the dry Andes are of growing interest due to the increase in human activities in this remote area. Empirical models of mountain permafrost distribution based on the spatial analysis of intact and relict rock glaciers and mean annual air temperature (MAAT) have been established as a tool for regional-scale assessments of permafrost favorability across entire mountain ranges; however, this kind of model approach has never been applied for a large portion...

  12. Correlation dynamics and international diversification benefits

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Errunza, Vihang; Jacobs, Kris

    2014-01-01

    Forecasting the evolution of security co-movements is critical for asset pricing and portfolio allocation. Hence, we investigate patterns and trends in correlations over time using weekly returns for developed markets (DMs) and emerging markets (EMs) over the period 1973–2012. We show that it is ...... the increasing correlations in a long-only portfolio by adjusting the portfolio weights over time. However, we do find some evidence that adding EMs to a DM-only portfolio increases diversification benefits.......Forecasting the evolution of security co-movements is critical for asset pricing and portfolio allocation. Hence, we investigate patterns and trends in correlations over time using weekly returns for developed markets (DMs) and emerging markets (EMs) over the period 1973–2012. We show...... that it is possible to model co-movements for many countries simultaneously using BEKK, DCC, and DECO models. Empirically, we find that correlations have trended upward significantly for both DMs and EMs. Based on a time-varying measure of diversification benefits, we find that it is not possible to circumvent...

  13. Correlation Dynamics and International Diversification Benefits

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Errunza, Vihang R.; Jacobs, Kris

    Forecasting the evolution of security co-movements is critical for asset pricing and portfolio allocation. Hence, we investigate patterns and trends in correlations over time using weekly returns for developed markets (DMs) and emerging markets (EMs) during the period 1973-2012. We show that it i......-only portfolio to circumvent the increasing correlations by adjusting the portfolio weights over time. However, we do find some evidence that adding EMs to a DM-only portfolio increases diversification benefits.......Forecasting the evolution of security co-movements is critical for asset pricing and portfolio allocation. Hence, we investigate patterns and trends in correlations over time using weekly returns for developed markets (DMs) and emerging markets (EMs) during the period 1973-2012. We show...... that it is possible to model co-movements for many countries simultaneously using BEKK, DCC, and DECO models. Empirically, we find that correlations have significantly trended upward for both DMs and EMs. Based on a time-varying measure of diversification benefit, we find that it is not possible in a long...

  14. Fruit evolution and diversification in campanulid angiosperms.

    Science.gov (United States)

    Beaulieu, Jeremy M; Donoghue, Michael J

    2013-11-01

    With increases in both the size and scope of phylogenetic trees, we are afforded a renewed opportunity to address long-standing comparative questions, such as whether particular fruit characters account for much of the variation in diversity among flowering plant clades. Studies to date have reported conflicting results, largely as a consequence of taxonomic scale and a reliance on potentially conservative statistical measures. Here we examine a larger and older angiosperm clade, the Campanulidae, and infer the rates of character transitions among the major fruit types, emphasizing the evolution of the achene fruits that are most frequently observed within the group. Our analyses imply that campanulids likely originated bearing capsules, and that all subsequent fruit diversity was derived from various modifications of this dry fruit type. We also found that the preponderance of lineages bearing achenes is a consequence of not only being a fruit type that is somewhat irreversible once it evolves, but one that also seems to have a positive association with diversification rates. Although these results imply the achene fruit type is a significant correlate of diversity patterns observed across campanulids, we conclude that it remains difficult to confidently and directly view this character state as the actual cause of increased diversification rates.

  15. Diversification and Sustainable Development in Chinese Agriculture

    Institute of Scientific and Technical Information of China (English)

    Zhong Funing; Zhu Jing

    2004-01-01

    Feeding a growing population exceeding 1 billion is a big challenge to the Chinese government and has partly led to the self-sufficient policy in grain production and supply for decades. However, the efforts to push grain production everywhere have resulted in not only deterioration of the environment but also stagnation or even reduction in farmers'income as production costs continue to increase.This situation might be worsening after China's accession to the WTO that provides market access for bulk commodity imports. A sustainable development in Chinese agriculture depends on diversification, or structural adjustment, that allows Chinese farmers to fully utilize their comparative advantage in production of labor-intensive goods.Past experience has shown that diversification has contributed more than a half of the growth in Chinese agriculture during the reform period and reduced stresses on the environment at the same time. It is likely to contribute even more to Chinese agriculture in the future and in a sustainable manner.

  16. What's missing from avian global diversification analyses?

    Science.gov (United States)

    Reddy, Sushma

    2014-08-01

    The accumulation of vast numbers of molecular phylogenetic studies has contributed to huge knowledge gains in the evolutionary history of birds. This permits subsequent analyses of avian diversity, such as how and why diversification varies across the globe and among taxonomic groups. However, available genetic data for these meta-analyses are unevenly distributed across different geographic regions and taxonomic groups. To comprehend the impact of this variation on the interpretation of global diversity patterns, I examined the availability of genetic data for possible biases in geographic and taxonomic sampling of birds. I identified three main disparities of sampling that are geographically associated with latitude (temperate, tropical), hemispheres (East, West), and range size. Tropical regions, which host the vast majority of species, are substantially less studied. Moreover, Eastern regions, such as the Old World Tropics and Australasia, stand out as being disproportionately undersampled, with up to half of communities not being represented in recent studies. In terms of taxonomic discrepancies, a majority of genetically undersampled clades are exclusively found in tropical regions. My analysis identifies several disparities in the key regions of interest of global diversity analyses. Differential sampling can have considerable impacts on these global comparisons and call into question recent interpretations of latitudinal or hemispheric differences of diversification rates. Moreover, this review pinpoints understudied regions whose biota are in critical need of modern systematic analyses.

  17. The Trend of International Risk Diversification

    Directory of Open Access Journals (Sweden)

    Oana Mionel

    2013-10-01

    Full Text Available The goal of this paper is to analyze the international diversification of risk through portfolio diversification based on investments abroad, particularly by investing in currencies of emerging countries. The starting point of the analysis is the work of Harry Markowitz, Portfolio selection, a reference work for the global financial environment in which the author states that a portfolio is efficient if it provides the highest possible expected return for a given level of risk and the lowest possible level of risk for any expected rate of earnings. The information used for this study comes from numerous sources and of great importance to international financial markets. The results based on the used data and information provide a comprehensive scan of how Federal Reserve proposed a clustered index of currencies, the current trend of exchange, the emerging BRIC countries scenario for 2050 and sources of the volatile emerging markets. Thus, following the completion of this work, we consider it necessary to pay attention to the course of emerging markets whose economic development and openness plays a significant role in their penetration of international investors’ investment plan.

  18. Ecological causes of decelerating diversification in carnivoran mammals.

    Science.gov (United States)

    Machac, Antonin; Storch, David; Wiens, John J

    2013-08-01

    Clade diversification is a central topic in macroevolutionary studies. Recently, it has been shown that diversification rates appear to decelerate over time in many clades. What causes this deceleration remains unclear, but it has been proposed that competition for limited resources between sympatric, ecologically similar species slows diversification. Employing carnivoran mammals as a model system, we test this hypothesis using a comprehensive time-calibrated phylogeny. We also explore several conceptually related explanations including limited geographic area and limited rates of niche evolution. We find that diversification slowdowns are strong in carnivorans. Surprisingly, these slowdowns are independent of geographic range overlap between related species and are also decoupled from rates of niche evolution, suggesting that slowdowns are unrelated to competition and niche filling. When controlling for the effects of clade diversity, diversification slowdowns appear independent of geographic area. There is a significant effect of clade diversity on diversification slowdowns, but simulations show that this relationship may arise as a statistical artifact (i.e., greater clade diversity increases the ability of the gamma statistic to refute constant diversification). Overall, our results emphasize the need to test hypotheses about the causes of diversification slowdowns with ecological data, rather than assuming ecological processes from phylogenies alone.

  19. Interlinked diversification strategies: Evidence from farm business households

    OpenAIRE

    Khanal, Aditya; Mishra, Ashok

    2015-01-01

    We analyze the factors influencing farmer’s diversification decisions while taking into account the simultaneous decision making. Using a national data on farm-level in the US and a multivariate analysis, our study suggests that agricultural, structural, environmental, and income diversification strategies are interlinked.

  20. Diversification Management at Tertiary Education Level: A Review

    Science.gov (United States)

    Takwate, Kwaji Tizhe

    2016-01-01

    This paper examines the concept of management of diversification at tertiary education level in view of the growth of national secondary education system which vested high scramble for tertiary education was made in relation to question of access and expansion. This paper examines management of diversification at tertiary education level as a…

  1. Funding Reforms and Revenue Diversification--Patterns, Challenges and Rhetoric

    Science.gov (United States)

    Teixeira, Pedro; Koryakina, Tatyana

    2013-01-01

    In recent years, much has been written about the challenging financial context faced by many European higher education institutions, and the pressures towards funding diversification. However, the evidence available indicates that funding diversification has seldom lived up to the rhetorical expectations of marketization and privatization that…

  2. Irrational Diversification; An Examination of Individual Portfolio Choice

    NARCIS (Netherlands)

    2011-01-01

    textabstractWe study individual portfolio choice in a laboratory experiment and find strong evidence for heuristic behavior. The subjects tend to focus on the marginal distribution of an asset, while largely ignoring its diversification benefits. They follow a conditional 1/n diversification heurist

  3. High functional diversity stimulates diversification in experimental microbial communities.

    Science.gov (United States)

    Jousset, Alexandre; Eisenhauer, Nico; Merker, Monika; Mouquet, Nicolas; Scheu, Stefan

    2016-06-01

    There is a growing awareness that biodiversity not only drives ecosystem services but also affects evolutionary dynamics. However, different theories predict contrasting outcomes on when do evolutionary processes occur within a context of competition. We tested whether functional diversity can explain diversification patterns. We tracked the survival and diversification of a focal bacterial species (Pseudomonas fluorescens) growing in bacterial communities of variable diversity and composition. We found that high functional diversity reduced the fitness of the focal species and, at the same time, fostered its diversification. This pattern was linked to resource competition: High diversity increased competition on a portion of the resources while leaving most underexploited. The evolved phenotypes of the focal species showed a better use of underexploited resources, albeit at a cost of lower overall growth rates. As a result, diversification alleviated the impact of competition on the fitness of the focal species. We conclude that biodiversity can stimulate evolutionary diversification, provided that sufficient alternative niches are available.

  4. Has the connection between polyploidy and diversification actually been tested?

    Science.gov (United States)

    Kellogg, Elizabeth A

    2016-04-01

    Many major clades of angiosperms have several whole genome duplications (polyploidization events) in their distant past, suggesting that polyploidy drives or at least permits diversification. However, data on recently diverged groups are more equivocal, finding little evidence of elevated diversification following polyploidy. The discrepancy may be attributable at least in part to methodology. Many studies use indirect methods, such as chromosome numbers, genome size, and Ks plots, to test polyploidy, although these approaches can be misleading, and often lack sufficient resolution. A direct test of diversification following polyploidy requires a sequence-based approach that traces the history of nuclear genomes rather than species. These methods identify the point of coalescence of ancestral genomes, but may be misleading about the time and thus the extent of diversification. Limitations of existing methods mean that the connection between polyploidy and diversification has not been rigorously tested and remains unknown.

  5. Dynamics of clade diversification on the morphological hypercube

    CERN Document Server

    Gavrilets, S

    1998-01-01

    Understanding the relationship between taxonomic and morphological changes is important in identifying the reasons for accelerated morphological diversification early in the history of animal phyla. Here, a simple general model describing the joint dynamics of taxonomic diversity and morphological disparity is presented and applied to the data on the diversification of blastozoans. I show that the observed patterns of deceleration in clade diversification can be explicable in terms of the geometric structure of the morphospace and the effects of extinction and speciation on morphological disparity without invoking major declines in the size of morphological transitions or taxonomic turnover rates. The model allows testing of hypotheses about patterns of diversification and estimation of rates of morphological evolution. In the case of blastozoans, I find no evidence that major changes in evolutionary rates and mechanisms are responsible for the deceleration of morphological diversification seen during the per...

  6. Liquidity in diversification processes of industrial enterprises under crisis conditions

    Directory of Open Access Journals (Sweden)

    Mazurenok, Oksana Romanivna

    2012-11-01

    Full Text Available The aim of the article is to identify the main patterns of diversification in findingthe solutions at some mechanical engineering enterprises under profit lack conditions.Accordingly for the risks minimization and providing the high economic potential whilerealizing some diversification projects aimed at production processes improvement under crisisconditions it's necessary to determine the basic influencing factors and their interconnections in thesystem of diversification decisions concerning the choice of the most optimum diversificationstrategy.The main objectives of the study are to solve the problem of production optimization undercrisis condition, to increase its survival and efficiency. The general characteristics of the non-profitmaking enterprise diversification process are considered. The research resulted in the theoreticaljustification of the liquidity indices within diversification processes at the manufacturing sectorenterprises under crisis conditions.

  7. Corporate Diversification and Firm Performance: an Empirical Study

    Directory of Open Access Journals (Sweden)

    Olu Ojo

    2009-05-01

    Full Text Available The importance of diversification and performance in then strategic management literature is widely accepted among academics and practitioners . However, the proxies for performance and diversification that have been employed in past strategy research has not been unanimously agreed upon. Given the current state of confusion that exists with regard to the impact of corporate diversification on firm performance in selected Nigerian companies. The reason for increased interest in diversification has always been on the possibility that diversification is related to corporate performance. However , while this topic is rich in studies, empirical evidence semerging from various studies about the effect of diversification on performance have so far yield mixed results that are inconclusive and contradictory. In addition , despite the existence of these studies, very litlle attention has been given to the companies in developing countries including Nigeria. This means that there is a major gap in the relevant literature on developing countries which has to be covered by research. This research attempts to fill this gap by studying the situation of the Nigeria companies and providing more empirical evidence on the effects of corporate diversification on firm performance based on individual company-level data. Survey research design was adopted in this study with the application of simple random sampling tehnique in selecting our case study companies as well as our respondents. Primary data were collected through questionnaire. Data were analysed through descriptive statistics and correlation and coefficient of determination were used to test our hypothese. It was discovered that diversification impacted performance of these companies posivitely and we recommend that these companies should engage in geographical diversification in addition to other forms of diversification they are currently involved in for maximum performance.

  8. A review of the geology of the Argentinian Fuegian Andes

    Science.gov (United States)

    Olivero, Eduardo B.; Martinioni, Daniel R.

    2001-06-01

    Seven stratigraphic units reflect the tectonic evolution of the Argentinian Fuegian Andes: Basement (Paleozoic-Jurassic); Lemaire Formation (Upper Jurassic); Yahgan-Beauvoir formations (Lower Cretaceous); Cerro Matrero Formation (Upper Cretaceous); Rı´o Claro Formation (Paleocene); La Despedida Group (Eocene); and Cabo Peña Formation (uppermost Eocene-Lower Oligocene). Basement rocks (garnet, quartz-sericite, and chlorite schists; and amphibolites) are unconformably covered by the Lemaire Formation (rhyolites; basalts; slates; and acidic volcaniclastic breccias, tuffs, conglomerates, and turbidites), formed during extensional tectonism. The post-rift Yahgan Formation (deep-marine black mudstones, andesitic volcaniclastic turbidites and tuffs) interfingers northward with the Beauvoir Formation (slope and platform black mudstones), and covers the Lemaire Formation unconformably. The Yahgan Formation represents an andesitic, volcaniclastic apron, coeval with a Pacific volcanic-arc, filling a marginal basin floored with oceanic crust. The Late Cretaceous compressional orogeny resulted in tectonic inversion, closure of the marginal basin, peak metamorphism and folding, and initial uplifting of the Fuegian Andes. By the latest Cretaceous-earliest Paleogene, the Andes were exposed to subaerial erosion, and the lowest Danian Rı´o Claro Formation bears clear evidence of an Andean clastic provenance. The Rı´o Claro Formation represents the first molasse deposits of the foreland stage of evolution of the Fuegian Andes. Earliest Paleogene north-verging thrust propagation deformed the Rı´o Claro Formation and older units, producing northward depocenter migration. La Despedida Group rests unconformably on the Rı´o Claro Formation and is involved in the thrust and fold belt. Important Eocene compression resulted in thrusting of central Andean basement schists and the Lemaire Formation over Lower Cretaceous and continental Paleogene rocks, respectively. In the

  9. Evaluating internalization of multifunctionality by farm diversification: evidence from educational dairy farms in Japan.

    Science.gov (United States)

    Ohe, Yasuo

    2011-03-01

    Farm diversification by farmers' open-door policy generates opportunities for farmers to internalize externalities of multifunctionality. Although the educational function of agriculture is an example of such an open-door policy and is attracting growing attention, this function has been little explored. To promote farm diversification in this direction, this paper examined how and to what degree farmers internalize externalities of multifunctionality by focusing on the educational function provided by dairy farming, i.e., farming experience services, in Japan. The main findings were as follows. First, we can say that the educational function is determined by ordinary technical jointness as well as institutional jointness, which is represented by food culture and the agrarian heritage. Both the technical and institutional jointness enhanced the externality. Because of these two working factors, there is a U-shaped relationship between farm diversification and provision of farming experience services. Second, however, an empirical evaluation indicated that farmers only partially internalize educational externalities by treating them as supplementary services combined with processed milk products. Therefore, appropriate integrated management of these newly emerging educational services to become a viable market should be fully addressed in the future, especially for family farms.

  10. EDF and GDF diversification; La diversification d'EDF et de GDF

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-08

    In the last years Electricite de France (EDF) and Gaz de France (GDF) developed intervening strategies in a number of sectors opened to competition, the so-called strategies of diversification or complementary activities. These new strategies have multiple objectives as, for instance, prospective monopole evolution, increasing exigence of the consumers' demand, or else competence valuing. Ever since 1991, these strategic orientations developed with the support of public powers that worked out first measures of organization and monitoring. Although the frame was loose and rather tolerant, boosting EDF and GDF diversification was perceived by the concerned professionals as an aggression directed against them. Following a strong mobilization of professional organizations and a number of elected persons, in mid 1993, the minister of industry was impelled to tackle personally with the matter what resulted in an accurate system of framing. The GDF diversification is essentially characterized by a 'thermal pole' corresponding to the activities of heating operation. GDF controls, around the company Danto Rogeat and the old branches of Shell group, about 5% of a market of heating operation in France, i.e., represents the third place in a rather monopolized sector where the two main operators represent almost 75%. The EDF diversification is but more diffuse. Three main fields emerge distinctly: the waste processing, public lighting, and engineering. EDF is also present on more restraint markets as cartography, tele-surveillance, cable TV, aquaculture. The implementation of the system is presented where prerogatives of the Council of State on one hand and the Council of Competition on the other hand are stipulated. The disposition frame system is constituted of two measures stipulating the application of commendation from the two councils and provisions ensuring the transparency, respectively.

  11. Farm multifunctional diversification and agricultural landscape trasformations

    Directory of Open Access Journals (Sweden)

    Emilio Chiodo

    Full Text Available The work aims to analyze changes in agricultural landscape linked to transformations in agricultural productive system. The territory for analysis is situated along the “internal Marche ridge” of the Apennines, in the province of Ancona (Marche region, partly included in the Regional Natural Park “Gola della Rossa e Frassassi”. The work aims at elaborating an investigative methodology which can highlight the transformation of territorial structures and the dynamics that influence management of the territory and landscape in order to provide operative instructions for an integrated elaboration of instruments for urban planning and economic programming, specially for agricultural policies. Multi-functionality and diversification in agriculture are the instruments that can help agriculture to improve the economic value of products and at the same time to improve the quality of territory and landscape.

  12. Dynamic Dependence and Diversification in Corporate Credit

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Jin, Xisong

    We characterize dependence and tail dependence in corporate credit using a new class of dynamic copula models which can capture dynamic dependence and asymmetry in large samples of firms. We also document important differences between the dependence dynamics for credit spreads and equity returns....... Modeling a decade of weekly CDS spreads for 215 firms, we find that copula correlations are highly time-varying and persistent, and that they increase significantly in the financial crisis and have remained high since. Perhaps most importantly, tail dependence of CDS spreads increases even more than copula...... correlations during the crisis and remains high as well. The most important shocks to credit dependence occur in August of 2007 and in August of 2011, but interestingly these dates are not associated with significant changes to median credit spreads. The decrease in diversification potential caused...

  13. Isologous diversification a theory of cell differentiation

    CERN Document Server

    Kaneko, K; Kaneko, Kunihiko; Yomo, Tetsuya

    1996-01-01

    Isologous diversification theory for cell differentiation is proposed, based on simulations of interacting cells with biochemical networks and cell division process following consumption of some chemicals. According to the simulations of the interaction-based dynamical systems model, the following scenario of the cell differentiation is proposed. (1) Up to some threshold number, divisions bring about almost identical cells with synchronized biochemical oscillations. (2)As the number is increased the oscillations lose the synchrony, leading to groups of cells with different phases of oscillations. (3)Amplitudes of oscillation and averaged chemical compositions start to differ by groups of cells. The differentiated behavior of states is transmitted to daughter cells. (4)Recursivity is formed so that the daughter cells keep the identical chemical character. This ``memory" is made possible through the transfer of initial conditions. (5) Successive differentiation proceeds. Mechanism of tumor cell formation, origi...

  14. Human Capital Diversification within the Household

    DEFF Research Database (Denmark)

    Lilleør, Helene Bie

    Lack of primary schooling among rural children in developing countries is often attributed to credit constraints and household demand for child labour, implying that direct and indirect costs of schooling are high. Surprisingly few studies have considered the importance of parents' expected returns...... of investing in their childrens human capital, despite the fact that most parents rely on their children for old-age support and subsistence. In this paper, I propose an alternative model for human capital investment based on the household, rather than the individual child, incorporating the fact that parents...... bear the costs of educating all their children and face uncertainty about the level and share of future returns. This uncertainty can make it optimal for parents to ensure a certain degree of human capital diversification within the household. The model implications allow me to test whether...

  15. Human Capital Diversification within the Household

    DEFF Research Database (Denmark)

    Lilleør, Helene Bie

    bear the costs of educating all their children and face uncertainty about the level and share of future returns. This uncertainty can make it optimal for parents to ensure a certain degree of human capital diversification within the household. The model implications allow me to test whether......Lack of primary schooling among rural children in developing countries is often attributed to credit constraints and household demand for child labour, implying that direct and indirect costs of schooling are high. Surprisingly few studies have considered the importance of parents' expected returns...... of investing in their childrens human capital, despite the fact that most parents rely on their children for old-age support and subsistence. In this paper, I propose an alternative model for human capital investment based on the household, rather than the individual child, incorporating the fact that parents...

  16. Diversity begets diversity: host expansions and the diversification of plant-feeding insects

    Directory of Open Access Journals (Sweden)

    Nylin Sören

    2006-01-01

    Full Text Available Abstract Background Plant-feeding insects make up a large part of earth's total biodiversity. While it has been shown that herbivory has repeatedly led to increased diversification rates in insects, there has been no compelling explanation for how plant-feeding has promoted speciation rates. There is a growing awareness that ecological factors can lead to rapid diversification and, as one of the most prominent features of most insect-plant interactions, specialization onto a diverse resource has often been assumed to be the main process behind this diversification. However, specialization is mainly a pruning process, and is not able to actually generate diversity by itself. Here we investigate the role of host colonizations in generating insect diversity, by testing if insect speciation rate is correlated with resource diversity. Results By applying a variant of independent contrast analysis, specially tailored for use on questions of species richness (MacroCAIC, we show that species richness is strongly correlated with diversity of host use in the butterfly family Nymphalidae. Furthermore, by comparing the results from reciprocal sister group selection, where sister groups were selected either on the basis of diversity of host use or species richness, we find that it is likely that diversity of host use is driving species richness, rather than vice versa. Conclusion We conclude that resource diversity is correlated with species richness in the Nymphalidae and suggest a scenario based on recurring oscillations between host expansions – the incorporation of new plants into the repertoire – and specialization, as an important driving force behind the diversification of plant-feeding insects.

  17. Diversification rates and species richness across the Tree of Life.

    Science.gov (United States)

    Scholl, Joshua P; Wiens, John J

    2016-09-14

    Species richness varies dramatically among clades across the Tree of Life, by over a million-fold in some cases (e.g. placozoans versus arthropods). Two major explanations for differences in richness among clades are the clade-age hypothesis (i.e. species-rich clades are older) and the diversification-rate hypothesis (i.e. species-rich clades diversify more rapidly, where diversification rate is the net balance of speciation and extinction over time). Here, we examine patterns of variation in diversification rates across the Tree of Life. We address how rates vary across higher taxa, whether rates within higher taxa are related to the subclades within them, and how diversification rates of clades are related to their species richness. We find substantial variation in diversification rates, with rates in plants nearly twice as high as in animals, and rates in some eukaryotes approximately 10-fold faster than prokaryotes. Rates for each kingdom-level clade are then significantly related to the subclades within them. Although caution is needed when interpreting relationships between diversification rates and richness, a positive relationship between the two is not inevitable. We find that variation in diversification rates seems to explain most variation in richness among clades across the Tree of Life, in contrast to the conclusions of previous studies.

  18. Courting disaster: How diversification rate affects fitness under risk.

    Science.gov (United States)

    Ratcliff, William C; Hawthorne, Peter; Libby, Eric

    2015-01-01

    Life is full of risk. To deal with this uncertainty, many organisms have evolved bet-hedging strategies that spread risk through phenotypic diversification. These rates of diversification can vary by orders of magnitude in different species. Here we examine how key characteristics of risk and organismal ecology affect the fitness consequences of variation in diversification rate. We find that rapid diversification is strongly favored when the risk faced has a wide spatial extent, with a single disaster affecting a large fraction of the population. This advantage is especially great in small populations subject to frequent disaster. In contrast, when risk is correlated through time, slow diversification is favored because it allows adaptive tracking of disasters that tend to occur in series. Naturally evolved diversification mechanisms in diverse organisms facing a broad array of environmental risks largely support these results. The theory presented in this article provides a testable ecological hypothesis to explain the prevalence of slow stochastic switching among microbes and rapid, within-clutch diversification strategies among plants and animals.

  19. Geochemical composition of river loads in the Tropical Andes: first insights from the Ecuadorian Andes

    Science.gov (United States)

    Tenorio Poma, Gustavo; Govers, Gerard; Vanacker, Veerle; Bouillon, Steven; Álvarez, Lenín; Zhiminaicela, Santiago

    2015-04-01

    Processes governing the transport of total suspended material (TSM), total dissolved solids (TDS) and particulate organic carbon (POC) are currently not well known for Tropical Andean river systems. We analyzed the geochemical behavior and the budgets of the particulate and dissolved loads for several sub-catchments in the Paute River basin in the southern Ecuadorian Andes, and examined how anthropogenic activities influenced the dynamics of riverine suspended and dissolved loads. We gathered a large dataset by regularly sampling 8 rivers for their TSM, POC, and TDS. Furthermore, we determined the major elements in the dissolved load and stable isotope composition (δ13C) of both the POC, and the dissolved inorganic carbon (DIC). The rivers that were sampled flow through a wide range of land uses including: 3 nature conservation areas (100 - 300 Km²), an intensive grassland and arable zone (142 Km²); downstream of two cities (1611 and 443 Km²), and 2 degraded basins (286 and 2492 Km²). We described the geochemical characteristics of the river loads both qualitatively and quantitatively. Important differences in TSM, POC and TDS yields were found between rivers: the concentration of these loads increases according with human activities within the basins. For all rivers, TSM, TDS and POC concentrations were dependent on discharge. Overall, a clear relation between TSM and POC (r²=0.62) was observed in all tributaries. The C:N ratios and δ13CPOC suggest that the POC in most rivers is mainly derived from soil organic matter eroded from soils dominated by C3 vegetation (δ13CPOC < -22‰). Low Ca:Si ratios (<1)and high δ13CDIC (-9 to -4) in the Yanuncay, Tomebamba1 and Machángara, rivers suggest that weathering of silica rocks is dominant in these catchments, and that the DIC is mainly derived from the soil or atmospheric CO2. In contrast, the Ca:Si ratio was high for the Burgay and Jadán rivers (1-13), and the low δ13CDIC values (-9 to -15) suggest that

  20. The benefit of regional diversification of cogeneration investments in Europe: A mean-variance portfolio analysis

    Energy Technology Data Exchange (ETDEWEB)

    Westner, Guenther, E-mail: guenther.westner@eon-energie.co [E.ON Energy Projects GmbH, Arnulfstrasse 56, 80335 Munich (Germany); Madlener, Reinhard, E-mail: rmadlener@eonerc.rwth-aachen.d [Institute for Future Energy Consumer Needs and Behavior (FCN), Faculty of Business and Economics/E.ON Energy Research Center, RWTH Aachen University, Mathieustrasse 6, 52074 Aachen (Germany)

    2010-12-15

    The EU Directive 2004/8/EC, concerning the promotion of cogeneration, established principles on how EU member states can support combined heat and power generation (CHP). Up to now, the implementation of these principles into national law has not been uniform, and has led to the adoption of different promotion schemes for CHP across the EU member states. In this paper, we first give an overview of the promotion schemes for CHP in various European countries. In a next step, we take two standard CHP technologies, combined-cycle gas turbines (CCGT-CHP) and engine-CHP, and apply exemplarily four selected support mechanisms used in the four largest European energy markets: feed-in tariffs in Germany; energy efficiency certificates in Italy; benefits through tax reduction in the UK; and purchase obligations for power from CHP generation in France. For contracting companies, it could be of interest to diversify their investment in new CHP facilities regionally over several countries in order to reduce country and regulatory risk. By applying the Mean-Variance Portfolio (MVP) theory, we derive characteristic return-risk profiles of the selected CHP technologies in different countries. The results show that the returns on CHP investments differ significantly depending on the country, the support scheme, and the selected technology studied. While a regional diversification of investments in CCGT-CHP does not contribute to reducing portfolio risks, a diversification of investments in engine-CHP can decrease the risk exposure. - Research highlights: {yields}Preconditions for CHP investments differ significantly between the EU member states. {yields}Regional diversification of CHP investments can reduce the total portfolio risk. {yields}Risk reduction depends on the chosen CHP technology.

  1. Is tourism damaging ecosystems in the Andes? Current knowledge and an agenda for future research.

    Science.gov (United States)

    Barros, Agustina; Monz, Christopher; Pickering, Catherine

    2015-03-01

    Despite the popularity of tourism and recreation in the Andes in South America and the regions conservation value, there is limited research on the ecological impacts of these types of anthropogenic use. Using a systematic quantitative literature review method, we found 47 recreation ecology studies from the Andes, 25 of which used an experimental design. Most of these were from the Southern Andes in Argentina (13 studies) or Chile (eight studies) with only four studies from the Northern Andes. These studies documented a range of impacts on vegetation, birds and mammals; including changes in plant species richness, composition and vegetation cover and the tolerance of wildlife of visitor use. There was little research on the impacts of visitors on soils and aquatic systems and for some ecoregions in the Andes. We identify research priorities across the region that will enhance management strategies to minimise visitor impacts in Andean ecosystems.

  2. Team-up Crop Diversification and Weed Management: PRODIVA

    DEFF Research Database (Denmark)

    Gerowitt, B.; Melander, B.; Krawczyk, R.;

    2015-01-01

    the results. Neither are crop diversification methods restricted to Organic Farming, nor can IWM (Integrated Weed Management) be successfully implemented without respecting the role of weeds in agro-ecosystems. The project “PRODIVA - Crop diversification and weeds“ is supported within the ERA-net CORE Organic......The research-network PRODIVA focuses on a better utilization of crop diversification for weed management in North European arable cropping systems. The goal is to maintain diverse arable weed vegetation that is manageable in the long-term and could fulfil other necessary systemfunctions including...

  3. Diversification in Private Equity Funds : On Knowledge-sharing, Risk-aversion and Limited-attention

    NARCIS (Netherlands)

    Humphery-Jenner, M.

    2011-01-01

    This paper examines diversification as a source of value creation and destruction in private equity. The literature has focused on the `diversification discount' in corporations. It has not analyzed diversification in PE-funds, where diversification might increase value by ameliorating managerial ri

  4. The benefit of regional diversification of cogeneration investments in Europe. A mean-variance portfolio analysis

    Energy Technology Data Exchange (ETDEWEB)

    Westner, Guenther; Madlener, Reinhard [E.ON Energy Projects GmbH, Arnulfstrasse 56, 80335 Munich (Germany)

    2010-12-15

    The EU Directive 2004/8/EC, concerning the promotion of cogeneration, established principles on how EU member states can support combined heat and power generation (CHP). Up to now, the implementation of these principles into national law has not been uniform, and has led to the adoption of different promotion schemes for CHP across the EU member states. In this paper, we first give an overview of the promotion schemes for CHP in various European countries. In a next step, we take two standard CHP technologies, combined-cycle gas turbines (CCGT-CHP) and engine-CHP, and apply exemplarily four selected support mechanisms used in the four largest European energy markets: feed-in tariffs in Germany; energy efficiency certificates in Italy; benefits through tax reduction in the UK; and purchase obligations for power from CHP generation in France. For contracting companies, it could be of interest to diversify their investment in new CHP facilities regionally over several countries in order to reduce country and regulatory risk. By applying the Mean-Variance Portfolio (MVP) theory, we derive characteristic return-risk profiles of the selected CHP technologies in different countries. The results show that the returns on CHP investments differ significantly depending on the country, the support scheme, and the selected technology studied. While a regional diversification of investments in CCGT-CHP does not contribute to reducing portfolio risks, a diversification of investments in engine-CHP can decrease the risk exposure. (author)

  5. Choosing a growth strategy: diversification versus vertical integration.

    Science.gov (United States)

    Placella, L E

    1986-11-01

    Why is it important to differentiate "system building" from "business diversification"? The author explains the differences between the two concepts and how they should be incorporated in a multihospital system's strategic business plan.

  6. Determinants of Farmers’ Agricultural Diversification: The Case of Cambodia

    Directory of Open Access Journals (Sweden)

    Kimty Seng

    2014-08-01

    Full Text Available A Heckman sample selection approach is employed with the data on Cambodia Socio-Economic Survey CSES-2007 to explore price and non-price factors determining farmers’ crop diversification decision, and consequently affecting diversification intensity. "The findings suggest that high relative price discourages farmers from diversifying crops." Irrigation, agricultural equipment ownership and farming expenditure have significantly positive effects on the decision, and sequentially increasing the intensity. Arable land size per household member, agricultural and transportation equipments have positive correlation with the diversification decision. Small scale of farming is a major hindrance to the decision, and consequently reducing the intensity. Land dispute, one of the main institutional matters in Cambodia, is found to have significantly negative marginal-effect on farmers’ decision on crop diversification.

  7. Portfolio Diversification with Commodity Futures: Properties of Levered Futures

    NARCIS (Netherlands)

    Woodard, J.D.; Egelkraut, T.M.; Garcia, P.; Pennings, J.M.E.

    2005-01-01

    Portfolio Diversification with Commodity Futures: Properties of Levered Futures This study extends previous work on the impact of commodity futures on portfolio performance by explicitly incorporating levered futures into the portfolio optimization problem. Using data on nine individual commodity fu

  8. The marginal benefit of diversification in commercial real estate portfolios

    OpenAIRE

    Lee, Stephen L.

    2005-01-01

    The number of properties to hold to achieve a well-diversified real estate property portfolio presents a puzzle, as the estimated number is considerably higher than that seen in actual portfolios. However, Statman (1987) argues that investors should only increase the number of holdings as long as the marginal benefits of diversification exceed their costs. Using this idea we find that the marginal benefits of diversification in real estate portfolios are so small that investors are probably r...

  9. Diversification and Community Bank Performance during a Financial Crisis

    Directory of Open Access Journals (Sweden)

    Kathy Estes

    2014-11-01

    Full Text Available Many U.S. banks failed or performed poorly during the recent financial crisis.  Although the costliest failures were large institutions, the majority of failures were community banks (less than $1 billion in total assets.  Community banks, which are considered instrumental in small business lending and employment growth, face different risks and challenges than their larger counterparts, including a lack of economies of scale and scope and exclusion from “too-big-to-fail” status.  These challenges, coupled with the recent failures, motivate research into potential strategies managers can use to improve performance.  This study examined the relationship between three potential diversification strategies and community bank risk-adjusted performance from 2007 to 2011.  Understanding these relationships could improve management’s decision-making, allowing them to choose risk-mitigating strategies during a severe economic downturn.  Herfindahl-Hirschman Indexes (HHIs were calculated as proxies for geographic, activity, and asset diversification.  Multiple regression models for each of the five years were used to calculate the impact of diversification variables on risk-adjusted ROA.  The results show that diversification in all areas is directly related to performance; however, only the asset diversification relationship is significant.  To the extent possible for community banks, diversification may improve risk-adjusted performance.

  10. Early diversification trend and Asian origin for extent bat lineages.

    Science.gov (United States)

    Yu, W; Wu, Y; Yang, G

    2014-10-01

    Bats are a unique mammalian group, which belong to one of the largest and most diverse mammalian radiations, but their early diversification is still poorly understood, and conflicting hypotheses have emerged regarding their biogeographic history. Understanding their diversification is crucial for untangling the enigmatic evolutionary history of bats. In this study, we elucidated the rate of diversification and the biogeographic history of extant bat lineages using genus-level chronograms. The results suggest that a rapid adaptive radiation persisted from the emergence of crown bats until the Early Eocene Climatic Optimum, whereas there was a major deceleration in diversification around 35-49 Ma. There was a positive association between changes in the palaeotemperature and the net diversification rate until 35 Ma, which suggests that the palaeotemperature may have played an important role in the regulation of ecological opportunities. By contrast, there were unexpectedly higher diversification rates around 25-35 Ma during a period characterized by intense and long-lasting global cooling, which implies that intrinsic innovations or adaptations may have released some lineages from the intense selective pressures associated with these severe conditions. Our reconstruction of the ancestral distribution suggests an Asian origin for bats, thereby indicating that the current panglobal but disjunct distribution pattern of extant bats may be related to events involving seriate cross-continental dispersal and local extinction, as well as the influence of geological events and the expansion and contraction of megathermal rainforests during the Tertiary.

  11. Protoplanetary Disk Structure With Grain Evolution: the ANDES Model

    CERN Document Server

    Akimkin, V; Wiebe, D; Semenov, D; Pavlyuchenkov, Ya; Vasyunin, A; Birnstiel, T; Henning, Th

    2013-01-01

    We present a self-consistent model of a protoplanetary disk: 'ANDES' ('AccretioN disk with Dust Evolution and Sedimentation'). ANDES is based on a flexible and extendable modular structure that includes 1) a 1+1D frequency-dependent continuum radiative transfer module, 2) a module to calculate the chemical evolution using an extended gas-grain network with UV/X-ray-driven processes surface reactions, 3) a module to calculate the gas thermal energy balance, and 4) a 1+1D module that simulates dust grain evolution. For the first time, grain evolution and time-dependent molecular chemistry are included in a protoplanetary disk model. We find that grain growth and sedimentation of large grains to the disk midplane lead to a dust-depleted atmosphere. Consequently, dust and gas temperatures become higher in the inner disk (R 50 AU), in comparison with the disk model with pristine dust. The response of disk chemical structure to the dust growth and sedimentation is twofold. First, due to higher transparency a partl...

  12. Cryptic lineages and diversification of an endemic anole lizard (Squamata, Dactyloidae) of the Cerrado hotspot.

    Science.gov (United States)

    Guarnizo, Carlos E; Werneck, Fernanda P; Giugliano, Lilian G; Santos, Marcella G; Fenker, Jéssica; Sousa, Lucas; D'Angiolella, Annelise B; Dos Santos, Adriana R; Strüssmann, Christine; Rodrigues, Miguel T; Dorado-Rodrigues, Tainá F; Gamble, Tony; Colli, Guarino R

    2016-01-01

    The Cerrado is a wide Neotropical savanna with tremendously high endemic diversity. Yet, it is not clear what the prevalent processes leading to such diversification are. We used the Cerrado-endemic lizard Norops meridionalis to investigate the main abiotic factors that promoted genetic divergence, the timings of these divergence events, and how these relate to cryptic diversity in the group. We sequenced mitochondrial and nuclear genes from 21 sites of N. meridionalis to generate species tree, divergence time estimations, and estimate species limits. We also performed population-level analysis and estimated distribution models to test the roles of niche conservatism and divergence in the group diversification. We found that N. meridionalis is composed by at least five cryptic species. Divergence time estimations suggest that the deepest branches split back into the early-mid Miocene, when most of the geophysical activity of the Cerrado took place. The deep divergences found in N. meridionalis suggest that beta anoles invaded South America much earlier than previously thought. Recent published evidence supports this view, indicating that the Panama gap closed as early as 15 mya, allowing for an early invasion of Norops into South America. The spatial pattern of diversification within N. meridionalis follows a northwest-southeast direction, which is consistent across several species of vertebrates endemic to the Cerrado. Also, we found evidence for non-stationary isolation by distance, which occurs when genetic differentiation depends on space. Our preliminary data in two out of five lineages suggest that niche conservatism is an important mechanism that promoted geographic fragmentation in the group.

  13. Evolutionary Roots and Diversification of the Genus Aeromonas

    Science.gov (United States)

    Sanglas, Ariadna; Albarral, Vicenta; Farfán, Maribel; Lorén, J. G.; Fusté, M. C.

    2017-01-01

    Despite the importance of diversification rates in the study of prokaryote evolution, they have not been quantitatively assessed for the majority of microorganism taxa. The investigation of evolutionary patterns in prokaryotes constitutes a challenge due to a very scarce fossil record, limited morphological differentiation and frequently complex taxonomic relationships, which make even species recognition difficult. Although the speciation models and speciation rates in eukaryotes have traditionally been established by analyzing the fossil record data, this is frequently incomplete, and not always available. More recently, several methods based on molecular sequence data have been developed to estimate speciation and extinction rates from phylogenies reconstructed from contemporary taxa. In this work, we determined the divergence time and temporal diversification of the genus Aeromonas by applying these methods widely used with eukaryotic taxa. Our analysis involved 150 Aeromonas strains using the concatenated sequences of two housekeeping genes (approximately 2,000 bp). Dating and diversification model analyses were performed using two different approaches: obtaining the consensus sequence from the concatenated sequences corresponding to all the strains belonging to the same species, or generating the species tree from multiple alignments of each gene. We used BEAST to perform a Bayesian analysis to estimate both the phylogeny and the divergence times. A global molecular clock cannot be assumed for any gene. From the chronograms obtained, we carried out a diversification analysis using several approaches. The results suggest that the genus Aeromonas began to diverge approximately 250 millions of years (Ma) ago. All methods used to determine Aeromonas diversification gave similar results, suggesting that the speciation process in this bacterial genus followed a rate-constant (Yule) diversification model, although there is a small probability that a slight

  14. Diversification patterns in cosmopolitan earthworms: similar mode but different tempo.

    Science.gov (United States)

    Fernández, Rosa; Novo, Marta; Marchán, Daniel F; Díaz Cosín, Darío J

    2016-01-01

    Comparative phylogeography of widespread species that span the same geographic areas can elucidate the influence of historical events on current patterns of biodiversity, identify patterns of co-vicariance, and therefore aid the understanding of general evolutionary processes. Soil-dwelling animals present characteristics that make them suitable for testing the effect of the palaeogeographical events on their distribution and diversification, such as their low vagility and population structure. In this study, we shed light on the spatial lineage diversification and cladogenesis of two widely-distributed cosmopolitan and invasive earthworms (Aporrectodea rosea and A. trapezoides) in their putative ancestral area of origin, the Western Palearctic, and a few populations in North America. Molecular analyses were conducted on mitochondrial and nuclear markers from 220 (A. rosea) and 198 (A. trapezoides) individuals collected in 56 and 57 localities, respectively. We compared the lineage diversification pattern, genetic variability and cladogenesis in both species. Our findings showed that both species underwent a similar diversification from the Western Mediterranean plates to (i) Northern Europe and (ii) the Iberian Peninsula, establishing their two main lineages. Their diversification was in concordance with the main palaeogeographical events in the Iberian Peninsula and Western Mediterranean, followed by a later colonization of North America from individuals derived exclusively from the Eurosiberian lineage. Their diversification occurred at different times, with the diversification of A. rosea being potentially more ancient. Cladogenesis in both species seems to have been modelled only by the Mediterranean plate shifts, ignoring historical climatic oscillations such as the Messinian salinity crisis. Their high genetic variability, strong population structure, lack of gene flow and stepping-stone-like cladogenesis suggest the existence of different cryptic lineages

  15. Origin and diversification of TRIM ubiquitin ligases.

    Directory of Open Access Journals (Sweden)

    Ignacio Marín

    Full Text Available Most proteins of the TRIM family (also known as RBCC family are ubiquitin ligases that share a peculiar protein structure, characterized by including an N-terminal RING finger domain closely followed by one or two B-boxes. Additional protein domains found at their C termini have been used to classify TRIM proteins into classes. TRIMs are involved in multiple cellular processes and many of them are essential components of the innate immunity system of animal species. In humans, it has been shown that mutations in several TRIM-encoding genes lead to diverse genetic diseases and contribute to several types of cancer. They had been hitherto detected only in animals. In this work, by comprehensively analyzing the available diversity of TRIM and TRIM-like protein sequences and evaluating their evolutionary patterns, an improved classification of the TRIM family is obtained. Members of one of the TRIM subfamilies defined, called Subfamily A, turn to be present not only in animals, but also in many other eukaryotes, such as fungi, apusozoans, alveolates, excavates and plants. The rest of subfamilies are animal-specific and several of them originated only recently. Subfamily A proteins are characterized by containing a MATH domain, suggesting a potential evolutionary connection between TRIM proteins and a different type of ubiquitin ligases, known as TRAFs, which contain quite similar MATH domains. These results indicate that the TRIM family emerged much earlier than so far thought and contribute to our understanding of its origin and diversification. The structural and evolutionary links with the TRAF family of ubiquitin ligases can be experimentally explored to determine whether functional connections also exist.

  16. VH replacement in primary immunoglobulin repertoire diversification.

    Science.gov (United States)

    Sun, Amy; Novobrantseva, Tatiana I; Coffre, Maryaline; Hewitt, Susannah L; Jensen, Kari; Skok, Jane A; Rajewsky, Klaus; Koralov, Sergei B

    2015-02-01

    The genes encoding the variable (V) region of the B-cell antigen receptor (BCR) are assembled from V, D (diversity), and J (joining) elements through a RAG-mediated recombination process that relies on the recognition of recombination signal sequences (RSSs) flanking the individual elements. Secondary V(D)J rearrangement modifies the original Ig rearrangement if a nonproductive original joint is formed, as a response to inappropriate signaling from a self-reactive BCR, or as part of a stochastic mechanism to further diversify the Ig repertoire. VH replacement represents a RAG-mediated secondary rearrangement in which an upstream VH element recombines with a rearranged VHDHJH joint to generate a new BCR specificity. The rearrangement occurs between the cryptic RSS of the original VH element and the conventional RSS of the invading VH gene, leaving behind a footprint of up to five base pairs (bps) of the original VH gene that is often further obscured by exonuclease activity and N-nucleotide addition. We have previously demonstrated that VH replacement can efficiently rescue the development of B cells that have acquired two nonproductive heavy chain (IgH) rearrangements. Here we describe a novel knock-in mouse model in which the prerearranged IgH locus resembles an endogenously rearranged productive VHDHJH allele. Using this mouse model, we characterized the role of VH replacement in the diversification of the primary Ig repertoire through the modification of productive VHDHJH rearrangements. Our results indicate that VH replacement occurs before Ig light chain rearrangement and thus is not involved in the editing of self-reactive antibodies.

  17. The timing of Timezyme diversification in vertebrates.

    Science.gov (United States)

    Cazaméa-Catalan, Damien; Besseau, Laurence; Falcón, Jack; Magnanou, Elodie

    2014-01-01

    All biological functions in vertebrates are synchronized with daily and seasonal changes in the environment by the time keeping hormone melatonin. Its nocturnal surge is primarily due to the rhythmic activity of the arylalkylamine N-acetyl transferase AANAT, which thus became the focus of many investigations regarding its evolution and function. Various vertebrate isoforms have been reported from cartilaginous fish to mammals but their origin has not been clearly established. Using phylogeny and synteny, we took advantage of the increasing number of available genomes in order to test whether the various rounds of vertebrate whole genome duplications were responsible for the diversification of AANAT. We highlight a gene secondary loss of the AANAT2 in the Sarcopterygii, revealing for the first time that the AAANAT1/2 duplication occurred before the divergence between Actinopterygii (bony fish) and Sarcopterygii (tetrapods, lobe-finned fish, and lungfish). We hypothesize the teleost-specific whole genome duplication (WDG) generated the appearance of the AANAT1a/1b and the AANAT2/2'paralogs, the 2' isoform being rapidly lost in the teleost common ancestor (ray-finned fish). We also demonstrate the secondary loss of the AANAT1a in a Paracantopterygii (Atlantic cod) and of the 1b in some Ostariophysi (zebrafish and cave fish). Salmonids present an even more diverse set of AANATs that may be due to their specific WGD followed by secondary losses. We propose that vertebrate AANAT diversity resulted from 3 rounds of WGD followed by previously uncharacterized secondary losses. Extant isoforms show subfunctionalized localizations, enzyme activities and affinities that have increased with time since their emergence.

  18. Revisiting the vanishing refuge model of diversification.

    Science.gov (United States)

    Damasceno, Roberta; Strangas, Maria L; Carnaval, Ana C; Rodrigues, Miguel T; Moritz, Craig

    2014-01-01

    Much of the debate around speciation and historical biogeography has focused on the role of stabilizing selection on the physiological (abiotic) niche, emphasizing how isolation and vicariance, when associated with niche conservatism, may drive tropical speciation. Yet, recent re-emphasis on the ecological dimensions of speciation points to a more prominent role of divergent selection in driving genetic, phenotypic, and niche divergence. The vanishing refuge model (VRM), first described by Vanzolini and Williams (1981), describes a process of diversification through climate-driven habitat fragmentation and exposure to new environments, integrating both vicariance and divergent selection. This model suggests that dynamic climates and peripheral isolates can lead to genetic and functional (i.e., ecological and phenotypic) diversity, resulting in sister taxa that occupy contrasting habitats with abutting distributions. Here, we provide predictions for populations undergoing divergence according to the VRM that encompass habitat dynamics, phylogeography, and phenotypic differentiation across populations. Such integrative analyses can, in principle, differentiate the operation of the VRM from other speciation models. We applied these principles to a lizard species, Coleodactylus meridionalis, which was used to illustrate the model in the original paper. We incorporate data on inferred historic habitat dynamics, phylogeography and thermal physiology to test for divergence between coastal and inland populations in the Atlantic Forest of Brazil. Environmental and genetic analyses are concordant with divergence through the VRM, yet physiological data are not. We emphasize the importance of multidisciplinary approaches to test this and alternative speciation models while seeking to explain the extraordinarily high genetic and phenotypic diversity of tropical biomes.

  19. The timing of Timezyme diversification in vertebrates.

    Directory of Open Access Journals (Sweden)

    Damien Cazaméa-Catalan

    Full Text Available All biological functions in vertebrates are synchronized with daily and seasonal changes in the environment by the time keeping hormone melatonin. Its nocturnal surge is primarily due to the rhythmic activity of the arylalkylamine N-acetyl transferase AANAT, which thus became the focus of many investigations regarding its evolution and function. Various vertebrate isoforms have been reported from cartilaginous fish to mammals but their origin has not been clearly established. Using phylogeny and synteny, we took advantage of the increasing number of available genomes in order to test whether the various rounds of vertebrate whole genome duplications were responsible for the diversification of AANAT. We highlight a gene secondary loss of the AANAT2 in the Sarcopterygii, revealing for the first time that the AAANAT1/2 duplication occurred before the divergence between Actinopterygii (bony fish and Sarcopterygii (tetrapods, lobe-finned fish, and lungfish. We hypothesize the teleost-specific whole genome duplication (WDG generated the appearance of the AANAT1a/1b and the AANAT2/2'paralogs, the 2' isoform being rapidly lost in the teleost common ancestor (ray-finned fish. We also demonstrate the secondary loss of the AANAT1a in a Paracantopterygii (Atlantic cod and of the 1b in some Ostariophysi (zebrafish and cave fish. Salmonids present an even more diverse set of AANATs that may be due to their specific WGD followed by secondary losses. We propose that vertebrate AANAT diversity resulted from 3 rounds of WGD followed by previously uncharacterized secondary losses. Extant isoforms show subfunctionalized localizations, enzyme activities and affinities that have increased with time since their emergence.

  20. Did growth of high Andes slow down Nazca plate subduction?

    Science.gov (United States)

    Quinteros, J.; Sobolev, S. V.

    2010-12-01

    The convergence velocity rate of the Nazca and South-American plate and its variations during the last 100 My are quite well-known from the global plate reconstructions. The key observation is that the rate of Nazca plate subduction has decreased by about 2 times during last 20 Myr and particularly since 10 Ma. During the same time the Central Andes have grown to its present 3-4 km height. Based on the thin-shell model, coupled with mantle convection, it was suggested that slowing down of Nazca plate resulted from the additional load exerted by the Andes. However, the thin-shell model, that integrates stresses and velocities vertically and therefore has no vertical resolution, is not an optimal tool to model a subduction zone. More appropriate would be modeling it with full thermomechanical formulation and self-consistent subduction. We performed a set of experiments to estimate the influence that an orogen like the Andes could have on an ongoing subduction. We used an enhanced 2D version of the SLIM-3D code suitable to simulate the evolution of a subducting slab in a self-consistent manner (gravity driven) at vertical crossections through upper mantle, transition zone and shallower lower mantle. The model utilizes non-linear temperature- and stress-dependant visco-elasto-plastic rheology and phase transitions at 410 and 660 km depth. We started from a reference case with a similar configuration as both Nazca and South-America plates. After some Mys of slow kinematicaly imposed subduction, to develop a coherent thermo-mechanical state, subduction was totally dynamic. On the other cases, the crust was slowly thickened artificially during 10 My to generate the Andean topography. Although our first results show no substantial changes on the velocity pattern of the subduction, we, however, consider this result as preliminary. At the meeting we plan to report completed and verified modeling results and discuss other possible cases of the late Cenozoic slowing down of

  1. Oroclinal Bending and Mountain Uplift in the Central Andes

    Science.gov (United States)

    Mpodozis, C.; Arriagada, C.; Roperch, P.

    2007-05-01

    The large paleomagnetic database now available for the Central Andes permits a good understanding of the overall spatial and temporal variations of rotations. Mesozoic to Early Paleogene rocks along the forearc of northern Chile (23°-28°S) record significant clockwise rotations (>25°) [Arriagada et al., 2006, Tectonics, doi:10.1029/2005TC001923]. Along the forearc of southern Peru, counterclockwise rotations recorded within flat lying red-beds (Moquegua Formation) increase from about -30° at 17.5°S to - 45° at15.5°S and decrease through time from the late Eocene to the late Oligocene-early Miocene [Roperch et al., 2006, Tectonics, doi:10.1029/2005TC001882]. Recently published thermo-chronological studies show evidence for strong exhumation within Bolivian Eastern Cordillera and the Puna plateau starting in the Eocene while structural studies indicate that the majority of crustal shortening in the Eastern Cordillera occurred during the Eocene-Oligocene, although the final stages of deformation may have continued through the Early Miocene. Rotations in the Peruvian and north Chilean forearc thus occurred at the same time than deformation and exhumation/uplift within the Eastern Cordillera. In contrast Neogene forearc rocks in southern Peru and northern Chile do not show evidences of rotation but low magnitude (10°) counterclockwise rotations are usually found in mid to late Miocene rocks from the northern Altiplano. These Neogene rotations are concomitant with shortening in the Sub-Andean zone and sinistral strike-slip faulting along the eastern edge of the northern Altiplano. We interpret the rotation pattern along the southern Peru and north Chile forearc as a result of strong late Eocene- late Oligocene oroclinal bending of the Central Andes associated with shortening gradients along the Eastern Cordillera associated both with the Abancay deflection and the Arica bend. The amount and spatial distribution of pre-Neogene shortening needed to account for

  2. Molecular method for the detection of Andes hantavirus infection: validation for clinical diagnostics.

    Science.gov (United States)

    Vial, Cecilia; Martinez-Valdebenito, Constanza; Rios, Susana; Martinez, Jessica; Vial, Pablo A; Ferres, Marcela; Rivera, Juan C; Perez, Ruth; Valdivieso, Francisca

    2016-01-01

    Hantavirus cardiopulmonary syndrome is a severe disease caused by exposure to New World hantaviruses. Early diagnosis is difficult due to the lack of specific initial symptoms. Antihantavirus antibodies are usually negative until late in the febrile prodrome or the beginning of cardiopulmonary phase, while Andes hantavirus (ANDV) RNA genome can be detected before symptoms onset. We analyzed the effectiveness of quantitative reverse transcription polymerase chain reaction (RT-qPCR) as a diagnostic tool detecting ANDV-Sout genome in peripheral blood cells from 78 confirmed hantavirus patients and 166 negative controls. Our results indicate that RT-qPCR had a low detection limit (~10 copies), with a specificity of 100% and a sensitivity of 94.9%. This suggests the potential for establishing RT-qPCR as the assay of choice for early diagnosis, promoting early effective care of patients, and improving other important aspects of ANDV infection management, such as compliance of biosafety recommendations for health personnel in order to avoid nosocomial transmission.

  3. [Breastfeeding, complimentary feeding practices and childhood malnutrition in the Bolivian Andes].

    Science.gov (United States)

    Cruz Agudo, Yesmina; Jones, Andrew D; Berti, Peter R; Larrea Macías, Sergio

    2010-03-01

    Northern Potosi is one of the poorest parts of Bolivia with the highest indicators of rural poverty, malnutrition and food insecurity in the Bolivian Andes. The objective of this research was to characterize the levels of malnutrition and describe infant feeding practices in Potosi, Bolivia and use this information to develop an effective, gender sensitive and culturally relevant intervention encouraging good infant feeding practices. Standard methods were used to collect anthropometric data. Weight and height data were collected for 400 children under five years of age from 30 communities. In six of these communities, interviews and focus group discussions were conducted with 33 mothers and other families in addition to household observational data that were collected to describe infant feeding practices. Nearly 20% of children were underweight; stunting was widespread as well. 38% of mothers initiated breastfeeding 12 hours or more after birth. 39% of mothers initiated complementary feeding in the first three months following birth. The type of complementary food given to children was usually inadequate. With this research we could see that nutritional deficiencies often begin when the mother starts breastfeeding and when first introduced complementary feeding. Interventions aimed at improving maternal and child nutrition will require changes in parents' behavior, greater recognition and community support of the importance of child feeding, and the inclusion of strategies to reach young people, involve men, and make high quality nutrition promotion more widely available in the communities.

  4. Efficient Use of Cogeneration and Fuel Diversification

    Directory of Open Access Journals (Sweden)

    Kunickis M.

    2015-12-01

    Full Text Available Energy policy of the European Community is implemented by setting various goals in directives and developing support mechanisms to achieve them. However, very often these policies and legislation come into contradiction with each other, for example Directive 2009/28/EC on the promotion of the use of energy from renewable sources and Directive 2012/27/EU on energy efficiency, repealing Directive 2004/8/EC on the promotion of cogeneration based on a useful heat demand.

  5. Heterostyly accelerates diversification via reduced extinction in primroses.

    Science.gov (United States)

    de Vos, Jurriaan M; Hughes, Colin E; Schneeweiss, Gerald M; Moore, Brian R; Conti, Elena

    2014-06-01

    The exceptional species diversity of flowering plants, exceeding that of their sister group more than 250-fold, is especially evident in floral innovations, interactions with pollinators and sexual systems. Multiple theories, emphasizing flower-pollinator interactions, genetic effects of mating systems or high evolvability, predict that floral evolution profoundly affects angiosperm diversification. However, consequences for speciation and extinction dynamics remain poorly understood. Here, we investigate trajectories of species diversification focusing on heterostyly, a remarkable floral syndrome where outcrossing is enforced via cross-compatible floral morphs differing in placement of their respective sexual organs. Heterostyly evolved at least 20 times independently in angiosperms. Using Darwin's model for heterostyly, the primrose family, we show that heterostyly accelerates species diversification via decreasing extinction rates rather than increasing speciation rates, probably owing to avoidance of the negative genetic effects of selfing. However, impact of heterostyly appears to differ over short and long evolutionary time-scales: the accelerating effect of heterostyly on lineage diversification is manifest only over long evolutionary time-scales, whereas recent losses of heterostyly may prompt ephemeral bursts of speciation. Our results suggest that temporal or clade-specific conditions may ultimately determine the net effects of specific traits on patterns of species diversification.

  6. Tree of life reveals clock-like speciation and diversification.

    Science.gov (United States)

    Hedges, S Blair; Marin, Julie; Suleski, Michael; Paymer, Madeline; Kumar, Sudhir

    2015-04-01

    Genomic data are rapidly resolving the tree of living species calibrated to time, the timetree of life, which will provide a framework for research in diverse fields of science. Previous analyses of taxonomically restricted timetrees have found a decline in the rate of diversification in many groups of organisms, often attributed to ecological interactions among species. Here, we have synthesized a global timetree of life from 2,274 studies representing 50,632 species and examined the pattern and rate of diversification as well as the timing of speciation. We found that species diversity has been mostly expanding overall and in many smaller groups of species, and that the rate of diversification in eukaryotes has been mostly constant. We also identified, and avoided, potential biases that may have influenced previous analyses of diversification including low levels of taxon sampling, small clade size, and the inclusion of stem branches in clade analyses. We found consistency in time-to-speciation among plants and animals, ∼2 My, as measured by intervals of crown and stem species times. Together, this clock-like change at different levels suggests that speciation and diversification are processes dominated by random events and that adaptive change is largely a separate process.

  7. Increased diversification rates follow shifts to bisexuality in liverworts.

    Science.gov (United States)

    Laenen, Benjamin; Machac, Antonin; Gradstein, S Robbert; Shaw, Blanka; Patiño, Jairo; Désamoré, Aurélie; Goffinet, Bernard; Cox, Cymon J; Shaw, A Jonathan; Vanderpoorten, Alain

    2016-05-01

    Shifts in sexual systems are one of the key drivers of species diversification. In contrast to angiosperms, unisexuality prevails in bryophytes. Here, we test the hypotheses that bisexuality evolved from an ancestral unisexual condition and is a key innovation in liverworts. We investigate whether shifts in sexual systems influence diversification using hidden state speciation and extinction analysis (HiSSE). This new method compares the effects of the variable of interest to the best-fitting latent variable, yielding robust and conservative tests. We find that the transitions in sexual systems are significantly biased toward unisexuality, even though bisexuality is coupled with increased diversification. Sexual systems are strongly conserved deep within the liverwort tree but become much more labile toward the present. Bisexuality appears to be a key innovation in liverworts. Its effects on diversification are presumably mediated by the interplay of high fertilization rates, massive spore production and long-distance dispersal, which may separately or together have facilitated liverwort speciation, suppressed their extinction, or both. Importantly, shifts in liverwort sexual systems have the opposite effect when compared to angiosperms, leading to contrasting diversification patterns between the two groups. The high prevalence of unisexuality among liverworts suggests, however, a strong selection for sexual dimorphism.

  8. Income Diversification: A Strategy for Rural Region Risk Management

    Directory of Open Access Journals (Sweden)

    Jinhong Wan

    2016-10-01

    Full Text Available Recent literature shows that income diversification is an important strategy for rural households to manage drought risk in arid and semiarid regions. This article examines whether income diversification can help rural households to overcome the adverse impact of drought in Northern China. Based on field interview data from 291 rural households in 13 townships of Northern China, we found that rural households tend to have a more diversified portfolio of income; the spatial location of rural households determines the type and number of income sources, the degree of income diversification, and the income combinations, especially under the context of frequent drought strikes. These results indicate that income diversification could help rural households to reduce the adverse impact of drought, enhance their resistance and resilience to drought, and make their livelihood system more stable. Income diversification not only is a useful strategy in terms of managing disaster risk and improving social welfare, but also may offer a new perspective for the research of vulnerability, resilience, and adaptive ability of rural social-ecosystem.

  9. Gastrointestinal parasites of Lamas in the Bolivian Andes

    DEFF Research Database (Denmark)

    Nissen, Anne Malene; Nees, Ellinor Spörndly; Monrad, Jesper

    A cross sectional study was conducted to determine prevalences and intensities of gastrointestinal (GIT) parasites in lamas in the Bolivian Andes. A quantitative and qualitative necro-copro-parasitlogical study was performed on 33 lamas between October and December 2007. At the time of necropsy the......  lamas were aged 1½  to >4 years. They originated from 14 different farms in the most lama dense areas of Bolivia: Oruro, Potosi, La Paz and the highlands above Cochabamba. In total 16 different species of nematodes, one cestode species, one trematode species, and one coccidian genus were detected...... %); in the liver: Fasciola hepatica (12 %); in faeces Eimeria spp. (82 %). Pathological changes in the liver were ascribed to be most probably caused by L. chavezi larva migration. The latter species, considered to be the very most pathogenic of all lama GIT nematode species, was also the species detected...

  10. Record Solar UV Irradiance in the Tropical Andes

    Directory of Open Access Journals (Sweden)

    Nathalie A. Cabrol

    2014-07-01

    Full Text Available High elevation, thin ozone layer, and clear sky produce intense ultraviolet (UV radiation in the tropical Andes. Recent models suggest that tropical stratospheric ozone will slightly decrease in the coming decades, potentially resulting in more UV anomalies. Data collected between 4,300-5,916 m above sea level (asl in Bolivia show how this trend could dramatically impact surface solar irradiance. During 61 days, two Eldonet dosimeters recorded extreme UV-B irradiance equivalent to a UV index (UVI of 43.3, which is the highest ground value ever reported. If they become more common, events of this magnitude may have societal and ecological implications, which make understanding the process leading to their generation critical. Our data show that this event and other major UV spikes were consistent with rising UV-B/UV-A ratios in the days to hours preceding the spikes, trajectories of negative ozone anomalies (NOAs, and radiative transfer modeling.

  11. Agricultura y ganaderia en Taya, pueblo de los Andes Peruanos

    OpenAIRE

    Pouget, Cécile

    1988-01-01

    Mémoire de fin d'études présentant les activités agricoles des paysans de Taya, village des Andes péruviennes situé sur des pentes très fortes entre 3000 et 3500 mètres d'altitude. Les paysans y cultivent le maïs et les pommes de terre pour leur propre consommation, mais aussi la luzerne destinée aux vaches laitières. Avec le lait, ils font des fromages qu'ils vendent. L'organisation de l'occupation du sol montre que malgré l'érosion, le manque d'eau et d'argent, les paysans continuent ce typ...

  12. A new species of Trechisibus from Peruvian Andes (Coleoptera: Carabidae, Trechinae

    Directory of Open Access Journals (Sweden)

    Pedro Delgado

    2016-06-01

    Full Text Available In this work the new species Trechisibus (s. str. delestali sp. n., is described from the southern Peruvian Andes. The morphological differences with the geographically closest species of the subgenus are also presented and discussed.

  13. Lake Andes National Wildlife Refuge: Narrative report: January 1 through December 31, 1965

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR and WPA outlines Refuge accomplishments during the 1965 calendar year. The report begins by summarizing the weather...

  14. Narrative report: January 1 through December 31, 1964: Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR outlines Refuge accomplishments during the 1964 calendar year. The report begins by summarizing the weather...

  15. Narrative report: Lake Andes National Wildlife Refuge: January 1 through April 30, 1960

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from January through April of 1960. The report begins by summarizing the weather conditions,...

  16. [Lake Andes National Wildlife Refuge: Narrative report: January to April, 1959

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from January through April of 1959. The report begins by summarizing the weather conditions,...

  17. Lake Andes Wetland Management District Annual narrative report: Calendar year 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes Wetland Management District outlines District accomplishments during the 1987 calendar year. The report begins with an...

  18. Narrative report: January, February, March, and April, 1962: Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from January through April of 1962. The report begins by summarizing the weather conditions,...

  19. Narrative report: Lake Andes National Wildlife Refuge: May 1 through August 31, 1959

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from May through August of 1959. The report begins by summarizing the weather conditions,...

  20. [Lake Andes National Wildlife Refuge: Narrative report: January to April, 1955

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from January through April of 1955. The report begins by summarizing the weather conditions,...

  1. Lake Andes Wetland Management District: Annual narrative report : Calendar year 1978

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes Wetland Management District outlines Refuge accomplishments during the 1978 calendar year. The report begins with an...

  2. Lake Andes Waterfowl Production Area: Narrative report: January 1 through December 31, 1967

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR- Waterfowl Production Area outlines Refuge accomplishments during the 1967 calendar year. The report begins by...

  3. Lake Andes Wetlands District: Narrative report: January 1 through December 31, 1971

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes Wetlands District outlines Refuge accomplishments during the 1971 calendar year. The report begins by summarizing the...

  4. Lake Andes [Wetland Management District]: Narrative report: January 1 through December 31, 1972

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes Wetlands District outlines Refuge accomplishments during the 1972 calendar year. The report begins by summarizing the...

  5. [Lake Andes Wetland Management District: Narrative report : July 1, 1975 through December 31, 1976

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes Wetland Management District outlines Refuge accomplishments during the 1976 calendar year. The report begins with an...

  6. Lake Andes Wetland District: Narrative report: January 1 through December 31, 1970

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes Wetlands District outlines Refuge accomplishments during the 1970 calendar year. The report begins by summarizing the...

  7. Lake Andes Wetlands District: Narrative report: January 1 through December 31, 1969

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes Wetlands District outlines Refuge accomplishments during the 1969 calendar year. The report begins by summarizing the...

  8. Planning and accomplishment narrative: Lake Andes Wetlands District: July 1, 1972 through June 30, 1973

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes Wetlands District describes Refuge activities during the 1973 fiscal year. Highlights and accomplishments are described.

  9. Lake Andes Wetlands District: Narrative report: January 1 through December 31, 1968

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes Wetlands District outlines Refuge accomplishments during the 1968 calendar year. The report begins by summarizing the...

  10. Lake Andes Wetland Management District: Annual narrative report : Calendar year 1977

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes Wetland Management District outlines Refuge accomplishments during the 1977 calendar year. The report begins with an...

  11. Lake Andes Wetland Management District: Annual narrative report : Calendar year 1979

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes Wetland Management District outlines Refuge accomplishments during the 1979 calendar year. The report begins with an...

  12. Phase 1 Watershed Assessment Final Report: Lake Andes Watershed, Charles Mix County, South Dakota.

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Lake Andes was included in the 1998 South Dakota 303(d) list as an impairment-related Total Maximum Daily Load waterbody. In 1922 Congress passed a bill that...

  13. Lake Andes National Wildlife Refuge: Narrative report: January 1 through December 31, 1967

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR outlines Refuge accomplishments during the 1967 calendar year. The report begins by summarizing the weather...

  14. Lake Andes National Wildlife Refuge: Narrative report: January 1 through December 31, 1969

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR outlines Refuge accomplishments during the 1969 calendar year. The report begins by summarizing the weather...

  15. Lake Andes National Wildlife Refuge: Narrative report: January 1 through December 31, 1966

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR outlines Refuge accomplishments during the 1966 calendar year. The report begins by summarizing the weather...

  16. Narrative report: September, October, November, and December, 1962: Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from September through December of 1962. The report begins by summarizing the weather...

  17. Lake Andes Wetland Management District : Annual narrative report : Calendar year 1980

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes WMD outlines Refuge accomplishments during the 1980 calendar year. The report begins with an introduction to the Refuge and...

  18. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1980

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments during the 1980 calendar year. The report begins with an introduction to the Refuge and...

  19. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1979

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments during the 1979 calendar year. The report begins with an introduction to the Refuge and...

  20. Narrative report: January, February, March, and April, 1963: Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from January through April of 1963. The report begins by summarizing the weather conditions,...

  1. Lake Assessment Project Report, Lake Andes: Charles Mix County, South Dakota

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Lake Andes was included in the 1998 South Dakota 303(d) list as an impairment-related Total Maximum Daily Load waterbody. In 1922 Congress passed a bill that...

  2. [Lake Andes National Wildlife Refuge: Narrative report: September to December, 1953

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes NWR outlines Refuge accomplishments from September through December of 1953. The report begins by summarizing the weather...

  3. Annual narrative report: Lake Andes National Wildlife Refuge and Management District: Calendar year 1974

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report summarizes activities on Lake Andes NWR during the 1974 calendar year. Monthly activities reports are provided. Resource management- including...

  4. Lake Andes Wetland Management District Annual narrative report: Calendar year 1988

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Lake Andes Wetland Management District outlines District accomplishments during the 1988 calendar year. The report begins with an...

  5. Complex brittle deformation pattern along the Southern Patagonian Andes (Argentina)

    Science.gov (United States)

    Barberón, Vanesa; Sue, Christian; Ronda, Gonzalo; Ghiglione, Matías

    2016-04-01

    The Southern Patagonian Andes is located in the southern extreme of the Pacific subduction zone, where the Antartic oceanic plate sinks underneath South America. The history of the area begins with compression during Paleozoic, Jurassic extension associated to the rift and opening of the South Atlantic Ocean, then a sag stage in the Lower Cretaceous followed by a foreland phase as a result of plate tectonics (Ghiglione et al., 2016). The kinematic study is concentrated in the Argentinean foothills, between 46°40' and 48° SL. We measured around 800 fault planes and their striaes with the sense of movement in order to characterize the stress field. The software used to make the stress inversion were Tensor (Delvaux, 2011) and Multiple Inverse Method MIM (Yamaji et al., 2011). The stress field map was built with the results of the MIM. We present new data from 48 sites located in the northern sector of the Southern Patagonian Andes. The measurements were made in several rocks from Paleozoic to Lower Cretaceous, even though most were taken in pyroclastic jurassic rocks from El Quemado Complex. Paleostress tensors obtained are mostly strike-slip, although a 25% is normal and there are a few compresional. The pattern of faults found is complex. In some sites the tensor can be locally linked to satellite images and observations from the field or be related to a major thrust front. There is no clear correlation between the age and/or lithology with the tensor since the youngest rocks measured are Lower Cretaceous. Probably there are several generations of family faults connected to different and recent tectonic phases then the paleostress tensors might correspond to the latest tectonic events.

  6. PROTOPLANETARY DISK STRUCTURE WITH GRAIN EVOLUTION: THE ANDES MODEL

    Energy Technology Data Exchange (ETDEWEB)

    Akimkin, V.; Wiebe, D.; Pavlyuchenkov, Ya. [Institute of Astronomy of the RAS, Pyatnitskaya str. 48, Moscow (Russian Federation); Zhukovska, S.; Semenov, D.; Henning, Th. [Max-Planck-Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Vasyunin, A. [Department of Chemistry, The University of Virginia, VA (United States); Birnstiel, T., E-mail: akimkin@inasan.ru, E-mail: dwiebe@inasan.ru, E-mail: pavyar@inasan.ru, E-mail: zhukovska@mpia.de, E-mail: semenov@mpia.de, E-mail: henning@mpia.de, E-mail: anton.vasyunin@gmail.com, E-mail: tbirnstiel@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-03-20

    We present a self-consistent model of a protoplanetary disk: 'ANDES' ('AccretioN disk with Dust Evolution and Sedimentation'). ANDES is based on a flexible and extendable modular structure that includes (1) a 1+1D frequency-dependent continuum radiative transfer module, (2) a module to calculate the chemical evolution using an extended gas-grain network with UV/X-ray-driven processes and surface reactions, (3) a module to calculate the gas thermal energy balance, and (4) a 1+1D module that simulates dust grain evolution. For the first time, grain evolution and time-dependent molecular chemistry are included in a protoplanetary disk model. We find that grain growth and sedimentation of large grains onto the disk midplane lead to a dust-depleted atmosphere. Consequently, dust and gas temperatures become higher in the inner disk (R {approx}< 50 AU) and lower in the outer disk (R {approx}> 50 AU), in comparison with the disk model with pristine dust. The response of disk chemical structure to the dust growth and sedimentation is twofold. First, due to higher transparency a partly UV-shielded molecular layer is shifted closer to the dense midplane. Second, the presence of big grains in the disk midplane delays the freeze-out of volatile gas-phase species such as CO there, while in adjacent upper layers the depletion is still effective. Molecular concentrations and thus column densities of many species are enhanced in the disk model with dust evolution, e.g., CO{sub 2}, NH{sub 2}CN, HNO, H{sub 2}O, HCOOH, HCN, and CO. We also show that time-dependent chemistry is important for a proper description of gas thermal balance.

  7. Síndrome pulmonar por hantavirus Andes en Chile CARDIOPULMONARY SYNDROME DUE TO ANDES VIRUS IN CHILE

    Directory of Open Access Journals (Sweden)

    CONSTANZA CASTILLO H.

    2002-01-01

    Full Text Available Desde 1993 han ocurrido 204 casos de Síndrome Cardiopulmonar por Hantavirus (SCPH en Chile. Los brotes epidémicos comenzaron en el sur y avanzan hacia el norte del país. Los más afectados son varones jóvenes, obreros agrícolas o forestales. En Chile, el SCPH es causado por el virus Andes, cuyo reservorio es el Oligorizomys longicaudatus (ratón de cola larga, que se distribuye desde la III Región al sur. El cuadro clínico es similar al descrito en EE.UU., caracterizado por una fase prodrómica que simula un estado gripal o cuadro gastrointestinal febril y que agrava por la aparición de edema pulmonar agudo e inestabilidad hemodinámica (fase cardiopulmonar. Sin embargo, cursa con mayores alteraciones hemorragí-paras y compromiso renal. La mortalidad inicial fue sobre 50% y actualmente es de alrededor del 33,3%. La presente revisión incluye: historia de la enfermedad, reservorio, modos de transmisión, patogenia, cuadro clínico, diagnóstico, tratamiento y medidas de prevenciónSince 1993, 204 cases of Hantavirus cardiopulmonary syndrome (HCPS occurred in Chile. Epidemic began in the south and moved thereafter to the northern regions. The disease affected predominantly young males, who worked in agricultural labours or as timber workers. The HCPS in Chile is caused by the Andes virus. The reservoir is the wild rat Oligoryzomis longicaudatus distributed from the III to the XII Region. The clinical features are similar to those described for Sin Nombre Virus. The disease has a prodromal stage characterised by fever, muscular pain, with or without gastrointestinal manifestations, followed by the rapid onset of respiratory insufficiency and haemodynamic unstability. Andes virus courses more often with haemorrhagic disorders and overt renal failure, than Sin Nombre Virus. The initial mortality was over 50% and declined to 33,3% in the last year. History of hantavirus-diseases, reservoir, and mode of contagion, pathogenesis, clinical

  8. An elusive new species of Marsupial Frog (Anura: Hemiphractidae: Gastrotheca from the Andes of northern Peru

    Directory of Open Access Journals (Sweden)

    William E. Duellman

    2013-06-01

    Full Text Available A new species of marsupial frog, genus Gastrotheca, is described from high-elevation grasslands in the Andes in Región Amazonas in northernPeru, where even calling males are well hidden in deep moss. The new species is distinguished from all congeners by its unique color pattern that includes a narrow, blackbordered, yellow middorsal stripe. The species apparently belongs to the Gastrotheca plumbea Group, which ranges in the Andes from northern Colombia to northern Peru.

  9. DNA barcode libraries provide insight into continental patterns of avian diversification.

    Directory of Open Access Journals (Sweden)

    Darío A Lijtmaer

    Full Text Available BACKGROUND: The causes for the higher biodiversity in the Neotropics as compared to the Nearctic and the factors promoting species diversification in each region have been much debated. The refuge hypothesis posits that high tropical diversity reflects high speciation rates during the Pleistocene, but this conclusion has been challenged. The present study investigates this matter by examining continental patterns of avian diversification through the analysis of large-scale DNA barcode libraries. METHODOLOGY AND PRINCIPAL FINDINGS: Standardized COI datasets from the avifaunas of Argentina, the Nearctic, and the Palearctic were analyzed. Average genetic distances between closest congeners and sister species were higher in Argentina than in North America reflecting a much higher percentage of recently diverged species in the latter region. In the Palearctic genetic distances between closely related species appeared to be more similar to those of the southern Neotropics. Average intraspecific variation was similar in Argentina and North America, while the Palearctic fauna had a higher value due to a higher percentage of variable species. Geographic patterning of intraspecific structure was more complex in the southern Neotropics than in the Nearctic, while the Palearctic showed an intermediate level of complexity. CONCLUSIONS AND SIGNIFICANCE: DNA barcodes can reveal continental patterns of diversification. Our analysis suggests that avian species are older in Argentina than in the Nearctic, supporting the idea that the greater diversity of the Neotropical avifauna is not caused by higher recent speciation rates. Species in the Palearctic also appear to be older than those in the Nearctic. These results, combined with the patterns of geographic structuring found in each region, suggest a major impact of Pleistocene glaciations in the Nearctic, a lesser effect in the Palearctic and a mild effect in the southern Neotropics.

  10. Glaciation and topographic evolution of the Central Patagonian Andes since 6 Ma

    Science.gov (United States)

    Christeleit, E. C.; Laemel, R.; De Wolf, W. E.; Shuster, D. L.; Brandon, M. T.

    2013-12-01

    New and existing thermochronological data are used to model glacial erosion and topographic evolution of the central Patagonian Andes (~47S) over the last 6 Ma. The modern Andes are cut by large valleys and fjords with local valley relief of at least 2.5 km. It is currently thought that a formerly uniformly high Andes was 'buzzed' down to the elevation of the equilibrium line altitude, presumably in the last 2 Ma concurrent with late Cenozoic global cooling. However, studies of glacial debris show that glaciers were present in Patagonia as early as 6 Ma. The extent of these early glaciations is unclear, but recent work suggests that glacial valleys in the central Patagonian Andes were carved at a steady rate beginning at 6 Ma, implying that valley incision may be an important process in the topographic evolution of glaciated mountain ranges, rather than cirque retreat. To understand how valley relief has formed in the Andes, we dated 30 samples from Steffen Fjord in Chile using apatite (U-Th)/He thermochronology. We use this new data and existing thermochronological data in the region to estimate the topographic form of the central Andes at 6 Ma and model how the valley relief has evolved since the initiation of glaciation using Pecube.

  11. Can Google Trends search queries contribute to risk diversification?

    Science.gov (United States)

    Kristoufek, Ladislav

    2013-01-01

    Portfolio diversification and active risk management are essential parts of financial analysis which became even more crucial (and questioned) during and after the years of the Global Financial Crisis. We propose a novel approach to portfolio diversification using the information of searched items on Google Trends. The diversification is based on an idea that popularity of a stock measured by search queries is correlated with the stock riskiness. We penalize the popular stocks by assigning them lower portfolio weights and we bring forward the less popular, or peripheral, stocks to decrease the total riskiness of the portfolio. Our results indicate that such strategy dominates both the benchmark index and the uniformly weighted portfolio both in-sample and out-of-sample.

  12. A glimpse on the pattern of rodent diversification

    DEFF Research Database (Denmark)

    Fabre, Pierre-Henri Fréderic; Hautier, Lionel; Dimitrov, Dimitar Stefanov;

    2012-01-01

    a rodent maximum likelihood phylogeny inferred from a molecular supermatrix. It is based on 11 mitochondrial and nuclear genes that covers 1,265 species, i.e., respectively 56% and 81% of the known specific and generic rodent diversity. The inferred topology recovered all Rodentia clades proposed by recent...... in diversification rates within the major clades: two in Castorimorpha, three in Ctenohystrica, 6 within the squirrel-related clade and 24 in the Myomorpha clade. The majority of these shifts occurred within the most recent familial rodent radiations: the Cricetidae and Muridae clades. Using the topological...... imbalances and the time line we discuss the potential role of different diversification factors that might have shaped the rodents radiation. CONCLUSIONS:The present glimpse on the diversification pattern of rodents can be used for further comparative meta-analyses. Muroid lineages have a greater degree...

  13. Construction Industry Products Diversification by Implementation of BIM

    Directory of Open Access Journals (Sweden)

    Sergey Kalinichuk

    2013-10-01

    Full Text Available One way to increase the effectiveness and economic stability of a construction company is product diversification. Intention to diversify construction products can be initiated for such reasons as necessity of capital injection, reducing of risks and costs of production, desire for optimization of delivery system, increasing economic competitiveness, etc. BIM can help to solve assigned tasks by diversification and optimize system operation as a whole. It becomes an actuality especially under conditions of severe competition when the possibility of attaining a work contract is reduced by increased focus.

  14. Industrial diversification and performance in an emerging market

    Directory of Open Access Journals (Sweden)

    Yücel Emel

    2016-01-01

    Full Text Available In this study, we investigated the relationship between industrial diversification and firm performance using a market-based performance measure and an accounting measure. We used the data of the firms listed on Borsa Istanbul during the period between 2006 and 2012. The results of the panel data indicate that there is a significant positive relationship between diversification and performance. We found that diversified firms outperformed the single firms. As is compatible with a resource-based approach, it was found that diversified firms tended to use their resources more efficiently compared to single firms.

  15. Diversification strategies in the pesticide industry: from seeds to biopesticides

    Directory of Open Access Journals (Sweden)

    Victor Pelaez

    Full Text Available ABSTRACT: The pesticide industry has undergone a diversification process led by six leading companies (Monsanto, Syngenta, Bayer, Dow, DuPont, BASF that control roughly 68% of the world market. This growth, initiated in the second half of the 1990s, occurred through deals and acquisitions of companies from the seed and biopesticide markets. This paper analyzes these diversification strategies, which have involved a capital mobilization process based on the exploitation of economies of scope and management of complementary assets. This aims to minimize the risks of investment in consolidated markets as well as in new ones.

  16. The keys to successful diversification: lessons from leading hospital systems.

    Science.gov (United States)

    Shortell, S M; Morrison, E; Hughes, S

    1989-01-01

    Hospitals have engaged in a variety of diversification activities over the past five years--many of which have not met expectations. Based on a nationwide study of 570 hospitals belonging to eight leading hospital systems (both investor-owned and not-for-profit), four key factors are identified that differentiate the winners from the losers. These include strategies for working effectively with physicians; learning to combine centralized and decentralized strategic planning approaches; understanding partially related diversification; and effectively applying the experience curve. Putting these lessons to work will increase the probability of a more effectively diversified health care system in the future.

  17. The dynamics of mobile promoters: Enhanced stability in promoter regions.

    Science.gov (United States)

    Rabbani, Mahnaz; Wahl, Lindi M

    2016-10-21

    Mobile promoters are emerging as a new class of mobile genetic elements, first identified by examining prokaryote genome sequences, and more recently confirmed by experimental observations in bacteria. Recent datasets have identified over 40,000 putative mobile promoters in sequenced prokaryote genomes, however only one-third of these are in regions of the genome directly upstream from coding sequences, that is, in promoter regions. The presence of many promoter sequences in non-promoter regions is unexplained. Here we develop a general mathematical model for the dynamics of mobile promoters, extending previous work to capture the dynamics both within and outside promoter regions. From this general model, we apply rigorous model selection techniques to identify which parameters are statistically justified in describing the available mobile promoter data, and find best-fit values of these parameters. Our results suggest that high rates of horizontal gene transfer maintain the population of mobile promoters in promoter regions, and that once established at these sites, mobile promoters are rarely lost, but are commonly copied to other genomic regions. In contrast, mobile promoter copies in non-promoter regions are more numerous and more volatile, experiencing substantially higher rates of duplication, loss and diversification.

  18. Factors Affecting Nonfarm Income Diversification among Rural Farm Households in Central Nepal

    Directory of Open Access Journals (Sweden)

    Raju Ghimire

    2014-06-01

    Full Text Available Nonfarm activities play an important role in the determination of rural household income, consumption expenditure, and household food security. However, much less studies have been devoted to the factors that influence nonfarm income diversification by farm household in developing countries. Using cross-sectional data and a probit model, this study attempts to determine the factors influencing nonfarm income diversification decisions by farm households in Central Nepal. The result reveals that household characteristics such as age, gender and education of the household head, and family size play a significant role in nonfarm work decisions. The households with larger farm size are less likely to participate in nonfarm work than their counterpart. Additionally, for those remains in the rural households, distance to road and market hinders the opportunities for nonfarm work. Finally, regional differences also exist in participating nonfarm activities among farm households. This study suggests that government policy should pay more attention on education, gender and infrastructures such as road and markets, to reduce the entry barriers and facilitate easier access to nonfarm activities. Also, nonfarm activities need to be promoted and incorporated in governmental plans and policies for balanced development between hills and terai areas.

  19. Post-polyploidisation morphotype diversification associates with gene copy number variation

    Science.gov (United States)

    Schiessl, Sarah; Huettel, Bruno; Kuehn, Diana; Reinhardt, Richard; Snowdon, Rod

    2017-01-01

    Genetic models for polyploid crop adaptation provide important information relevant for future breeding prospects. A well-suited model is Brassica napus, a recent allopolyploid closely related to Arabidopsis thaliana. Flowering time is a major adaptation trait determining life cycle synchronization with the environment. Here we unravel natural genetic variation in B. napus flowering time regulators and investigate associations with evolutionary diversification into different life cycle morphotypes. Deep sequencing of 35 flowering regulators was performed in 280 diverse B. napus genotypes. High sequencing depth enabled high-quality calling of single-nucleotide polymorphisms (SNPs), insertion-deletions (InDels) and copy number variants (CNVs). By combining these data with genotyping data from the Brassica 60 K Illumina® Infinium SNP array, we performed a genome-wide marker distribution analysis across the 4 ecogeographical morphotypes. Twelve haplotypes, including Bna.FLC.A10, Bna.VIN3.A02 and the Bna.FT promoter on C02_random, were diagnostic for the diversification of winter and spring types. The subspecies split between oilseed/kale (B. napus ssp. napus) and swedes/rutabagas (B. napus ssp. napobrassica) was defined by 13 haplotypes, including genomic rearrangements encompassing copies of Bna.FLC, Bna.PHYA and Bna.GA3ox1. De novo variation in copies of important flowering-time genes in B. napus arose during allopolyploidisation, enabling sub-functionalisation that allowed different morphotypes to appropriately fine-tune their lifecycle. PMID:28165502

  20. Phylogenetic distribution of extant richness suggests metamorphosis is a key innovation driving diversification in insects.

    Science.gov (United States)

    Rainford, James L; Hofreiter, Michael; Nicholson, David B; Mayhew, Peter J

    2014-01-01

    Insects and their six-legged relatives (Hexapoda) comprise more than half of all described species and dominate terrestrial and freshwater ecosystems. Understanding the macroevolutionary processes generating this richness requires a historical perspective, but the fossil record of hexapods is patchy and incomplete. Dated molecular phylogenies provide an alternative perspective on divergence times and have been combined with birth-death models to infer patterns of diversification across a range of taxonomic groups. Here we generate a dated phylogeny of hexapod families, based on previously published sequence data and literature derived constraints, in order to identify the broad pattern of macroevolutionary changes responsible for the composition of the extant hexapod fauna. The most prominent increase in diversification identified is associated with the origin of complete metamorphosis, confirming this as a key innovation in promoting insect diversity. Subsequent reductions are recovered for several groups previously identified as having a higher fossil diversity during the Mesozoic. In addition, a number of recently derived taxa are found to have radiated following the development of flowering plant (angiosperm) floras during the mid-Cretaceous. These results reveal that the composition of the modern hexapod fauna is a product of a key developmental innovation, combined with multiple and varied evolutionary responses to environmental changes from the mid Cretaceous floral transition onward.

  1. In the shadow of phylogenetic uncertainty: the recent diversification of Lysandra butterflies through chromosomal change.

    Science.gov (United States)

    Talavera, Gerard; Lukhtanov, Vladimir A; Rieppel, Lukas; Pierce, Naomi E; Vila, Roger

    2013-12-01

    The phylogeny of the butterfly genus Lysandra (Lycaenidae, Polyommatinae) has been intractable using both molecular and morphological characters, which could be a result of speciation due to karyotype instability. Here we reconstruct the phylogeny of the group using multi-locus coalescent-based methods on seven independent genetic markers. While the genus is ca. 4.9 Mya old, the diversification of the extant lineages was extremely recent (ca. 1.5 Mya) and involved multiple chromosomal rearrangements. We find that relationships are uncertain due to both incomplete lineage sorting and hybridization. Minimizing the impact of reticulation in inferring the species tree by testing for mitochondrial introgression events yields a partially resolved tree with three main supported clades: L. punctifera+L. bellargus, the corydonius taxa, and L. coridon+the Iberian taxa, plus three independent lineages without apparently close relatives (L. ossmar, L. syriaca and L. dezina). Based on these results and new karyotypic data, we propose a rearrangement recognizing ten species within the genus. Finally, we hypothesize that chromosomal instability may have played a crucial role in the Lysandra recent diversification. New chromosome rearrangements might be fixed in populations after severe bottlenecks, which at the same time might promote rapid sorting of neutral molecular markers. We argue that population bottlenecks might be a prerequisite for chromosomal speciation in this group.

  2. Testing the island effect on phenotypic diversification: insights from the Hemidactylus geckos of the Socotra Archipelago.

    Science.gov (United States)

    Garcia-Porta, Joan; Šmíd, Jiří; Sol, Daniel; Fasola, Mauro; Carranza, Salvador

    2016-04-13

    Island colonization is often assumed to trigger extreme levels of phenotypic diversification. Yet, empirical evidence suggests that it does not always so. In this study we test this hypothesis using a completely sampled mainland-island system, the arid clade of Hemidactylus, a group of geckos mainly distributed across Africa, Arabia and the Socotra Archipelago. To such purpose, we generated a new molecular phylogeny of the group on which we mapped body size and head proportions. We then explored whether island and continental taxa shared the same morphospace and differed in their disparities and tempos of evolution. Insular species produced the most extreme sizes of the radiation, involving accelerated rates of evolution and higher disparities compared with most (but not all) of the continental groups. In contrast, head proportions exhibited constant evolutionary rates across the radiation and similar disparities in islands compared with the continent. These results, although generally consistent with the notion that islands promote high morphological disparity, reveal at the same time a complex scenario in which different traits may experience different evolutionary patterns in the same mainland-island system and continental groups do not always present low levels of morphological diversification compared to insular groups.

  3. Unrelated Diversification and Firm Performance: 1980-2007 Evidence from Italy

    Directory of Open Access Journals (Sweden)

    Raffaele Staglianò

    2012-03-01

    Full Text Available The goal of this article is to examine the relationship between unrelated diversification and performance. Results indicate that diversified firms, investing in activities far from the corebusiness, have high performance. Unrelated diversification positively affects firms’ performance. In addition, the estimation methods applied are fundamental in order to verify if there are endogeneity problems in the diversification decision and evaluate the effective role of diversification on performance.

  4. Tightly congruent bursts of lineage and phenotypic diversification identified in a continental ant radiation

    NARCIS (Netherlands)

    Price, Shauna L; Etienne, Rampal S; Powell, Scott

    2016-01-01

    Adaptive diversification is thought to be shaped by ecological opportunity. A prediction of this ecological process of diversification is that it should result in congruent bursts of lineage and phenotypic diversification, but few studies have found this expected association. Here, we study the rela

  5. Scale and technological factors in the diversification structure of business firms

    NARCIS (Netherlands)

    Castaldi, C; Milakovic, M; Secchi, A

    2006-01-01

    We present empirical evidence on diversification patterns in Italian manufacturing firms, where we observe a robust relationship between firm size and diversification levels. The overall findings support the 'resource-' and 'competence-based' theories of corporate diversification. In addition, we al

  6. Diversification of farm enterprises in the USA: legal incentives and legal obstacles

    NARCIS (Netherlands)

    Grossman, M.R.

    2010-01-01

    This article focuses on legal incentives and legal obstacles to diversification in the US. It first outlines some farm characteristics that may influence diversification. It then turns to the possible impact of the agricultural tenancy relationship on diversification and the relevance of land-use re

  7. European Market Portfolio Diversification Strategies across the GFC

    NARCIS (Netherlands)

    D.E. Allen (David); M.J. McAleer (Michael); R.J. Powell (Robert); A.K. Singh (Abhay)

    2014-01-01

    markdownabstract__Abstract__ is paper features an analysis of the effectiveness of a range of portfolio diversification strategies as applied to a set of daily arithmetically compounded returns on a set of ten market indices representing the major European markets for a nine year period from the be

  8. Divergolide congeners illuminate alternative reaction channels for ansamycin diversification.

    Science.gov (United States)

    Ding, Ling; Franke, Jakob; Hertweck, Christian

    2015-02-14

    Isolation and structure elucidation of six new divergolides reveal unusual ansamycin diversification reactions including formation of the unusual isobutenyl side chain from a branched polyketide synthase extender unit, azepinone ring closure, macrolide ring contraction and formation of a seco variant by a neighboring group-assisted decarboxylation.

  9. Globalisation and Diversification: Two Opposing Influences on Local Literacies.

    Science.gov (United States)

    Barton, David

    1994-01-01

    Discusses globalization and diversification within four language issues for adult literacy: (1) the spread of a small number of world languages, (2) development of the varieties of language, (3) choice of language for education and official life, and (4) disappearing languages. (JP)

  10. The significance of diversification for rural livelihood systems

    NARCIS (Netherlands)

    Niehof, A.

    2004-01-01

    There is an increasing awareness that diversification plays a strategic role in rural livelihood systems. The principal question to be addressed in this paper pertains to the conditions and the ways in which rural households diversify their livelihood activities and strategies. To answer this questi

  11. The Downside Risk of Heavy Tails induces Low Diversification

    NARCIS (Netherlands)

    N. Hyung (Namwon); C.G. de Vries (Casper)

    2010-01-01

    textabstractActual portfolios contain fewer stocks than are implied by standard financial analysis that balances the costs of diversification against the benefits in terms of the standard deviation of the returns. Suppose a safety first investor cares about downside risk and recognizes the heavy tai

  12. Modelling conditional correlations for risk diversification in crude oil markets

    NARCIS (Netherlands)

    C-L. Chang (Chia-Lin); M.J. McAleer (Michael); R. Tansuchat (Roengchai)

    2009-01-01

    textabstractThis paper estimates univariate and multivariate conditional volatility and conditional correlation models of spot, forward and futures returns from three major benchmarks of international crude oil markets, namely Brent, WTI and Dubai, to aid in risk diversification. Conditional correla

  13. The impact of internationalization and diversification on construction industry performance

    NARCIS (Netherlands)

    Horta, Isabel M.; Kapelko, Magdalena; Oude Lansink, Alfons; Camanho, Ana S.

    2016-01-01

    This paper investigates the impact of internationalization and diversification strategies on the financial performance of construction industry companies. The results obtained can guide the design of strategies to pursue company growth and achieve competitive advantage. The evaluation of companie

  14. The Diversification Benefits of Free Trade in House Value

    NARCIS (Netherlands)

    Dröes, M.I.; Garretsen, H; Manshanden, W.J.J.

    2012-01-01

    This paper finds that homeowners could substantially reduce house price risk if they would reinvest their housing wealth in a market portfolio of houses. Free trade in the value of the house among homeowners would allow them to do so. To quantify the diversification benefits of free trade in house v

  15. ANALYSIS OF INVESTMENT DIVERSIFICATION OF THE PRECIOUS METALS

    Directory of Open Access Journals (Sweden)

    Ivan I. Agafonov

    2013-01-01

    Full Text Available Analysis of the impact of investment portfolio of precious metals on its minimum risk with limited mean income is carried out based on the data from the beginning of 2009 to the July of 2013. Vector and matrix criteria of assessment of the effects of investment diversification at the precious metals market are offered.

  16. Farm Diversification into Tourism--Implications for Social Identity?

    Science.gov (United States)

    Brandth, Berit; Haugen, Marit S.

    2011-01-01

    This article deals with how diversification and transformation of farming into tourism may influence the social identity of farmers. Based on a study of 19 farms run by couples engaged with agritourism, it shows how the development of tourism on the farms can be understood in a perspective of repeasantization; and how the couples draw on their…

  17. The historical biogeography of groupers: Clade diversification patterns and processes.

    Science.gov (United States)

    Ma, Ka Yan; Craig, Matthew Thomas; Choat, John Howard; van Herwerden, Lynne

    2016-07-01

    Groupers (family Epinephelidae) are a clade of species-rich, biologically diverse reef fishes. Given their ecological variability and widespread distribution across ocean basins, it is important to scrutinize their evolutionary history that underlies present day distributions. This study investigated the patterns and processes by which grouper biodiversity has been generated and what factors have influenced their present day distributions. We reconstructed a robust, time-calibrated molecular phylogeny of Epinephelidae with comprehensive (∼87%) species sampling, whereby diversification rates were estimated and ancestral ranges were reconstructed. Our results indicate that groupers originated in what is now the East Atlantic during the mid-Eocene and diverged successively to form six strongly supported main clades. These clades differ in age (late Oligocene to mid-Miocene), geographic origin (West Atlantic to West Indo-Pacific) and temporal-spatial diversification pattern, ranging from constant rates of diversification to episodes of rapid radiation. Overall, divergence within certain biogeographic regions was most prevalent in groupers, while vicariant divergences were more common in Tropical Atlantic and East Pacific groupers. Our findings reveal that both biological and geographical factors have driven grouper diversification. They also underscore the importance of scrutinizing group-specific patterns to better understand reef fish evolution.

  18. Classroom Diversification: A Strategic View of Educational Productivity

    Science.gov (United States)

    Lopez, Omar S.

    2007-01-01

    This article advances a theory of educational productivity based on a paradigm of classroom diversification that defines a strategic view of the education production process. The paradigm's underlying premise is that classroom student performance, and the instructional interactions that produce such outcomes, depend on economies derived from the…

  19. A Real Options Perspective on R&D Portfolio Diversification

    NARCIS (Netherlands)

    S. van Bekkum (Sjoerd); H.P.G. Pennings (Enrico); J.T.J. Smit (Han)

    2008-01-01

    textabstractThis paper shows that the presence of conditional staging in R&D (Research & Development) has a critical impact on portfolio risk, and changes diversification arguments when a portfolio is constructed. When R&D projects exhibit option-like characteristics, correlation between projects pl

  20. A Real Options Perspective On R&D Portfolio Diversification

    NARCIS (Netherlands)

    S. van Bekkum (Sjoerd); H.P.G. Pennings (Enrico); J.T.J. Smit (Han)

    2009-01-01

    textabstractThis paper shows that the conditionality of investment decisions in R&D has a critical impact on portfolio risk, and implies that traditional diversification strategies should be reevaluated when a portfolio is constructed. Real option theory argues that research projects have conditiona

  1. Global Investing: Diversification Enhances Return and Controls Risk.

    Science.gov (United States)

    Morrell, Louis R.

    1995-01-01

    As the business environment becomes more global, so should a college or university's investment portfolio. Global diversification is becoming increasingly important in controlling risk and enhancing return. This article examines the size of bond markets and returns on bond investments in several nations, performance of world equity markets, and…

  2. A Real Options Perspective On R&D Portfolio Diversification

    NARCIS (Netherlands)

    S. van Bekkum (Sjoerd); H.P.G. Pennings (Enrico); J.T.J. Smit (Han)

    2009-01-01

    textabstractThis paper shows that the conditionality of investment decisions in R&D has a critical impact on portfolio risk, and implies that traditional diversification strategies should be reevaluated when a portfolio is constructed. Real option theory argues that research projects have condition

  3. Increased diversification rates follow shifts to bisexuality in liverworts

    DEFF Research Database (Denmark)

    Laenen, Benjamin; Machac, Antonin; Gradstein, S. Robbert

    2016-01-01

    Shifts in sexual systems are one of the key drivers of species diversification. In contrast to angiosperms, unisexuality prevails in bryophytes. Here, we test the hypotheses that bisexuality evolved from an ancestral unisexual condition and is a key innovation in liverworts. We investigate whether...

  4. Diversification of Energy-Decisive Option for China

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ Diversification of energy will become an important objective for China's energy development strategy in the next 15 years as the world enters into a period of energy shortage.Based on the statistical data released by International Energy Agency, China became the second largest crude consumer in the world in 2003 only after the United States.

  5. Evolution and diversification of the basal transcription machinery.

    Science.gov (United States)

    Duttke, Sascha H C

    2015-03-01

    Transcription initiation was once thought to be regulated primarily by sequence-specific transcription factors with the basal transcription machinery being largely invariant. Gradually it became apparent that the basal transcription machinery greatly diversified during evolution and new studies now demonstrate that diversification of the TATA-binding protein (TBP) family yielded specialized and largely independent transcription systems.

  6. Product and Market Diversification in Turkey’s Foreign Trade

    Directory of Open Access Journals (Sweden)

    Birol Erkan

    2014-01-01

    Full Text Available One of the most important criteria in determining the economic size and the level of mastery of countries in international markets is the ratio of the volume of foreign trade to GDP. With this criterion, reducing the concentration (increasing the diversify in foreign trade on the basis product and market plays an important role in helping countries achieve competitive advantage in the global economy. Turkey’s foreign trade strategy in recent years, primarily has to reduce the trade deficit (and current account deficit by increasing the export. However, increasing diversification in foreign trade on the basis both product and market has been revealed as an important goal by economy policy makers. In this study covering the years 1990-2012, the level of product and market diversification in Turkey’s export and import was determined by using Concentration Ratio of Commerce, GiniHirschman Index, Entropy Index, Deviation Index and Penetration Index. In this connection, it has been found that Turkey is successful market diversification, on the other hand, unsuccessfull product diversification

  7. Large slope failures in the La Paz basin, Bolivian Andes

    Science.gov (United States)

    Roberts, N. J.; Hermanns, R. L.; Rabus, B.; Guzmán, M. A.; Minaya, E.; Clague, J. J.

    2014-12-01

    The La Paz basin in the eastern Bolivian Andes has been a hotspot for large-scale, deep-seated gravitational slope deformation during the Holocene. In less than 2 Ma, a network of steep-sided valleys up to 800 m deep formed in sediments of the Altiplano Plateau and underlying basement rocks. We characterize the distribution, extent, mechanisms, and modern activity of large-scale failures within this landscape using optical image interpretation, existing geologic maps, synthetic RADAR interferometry (InSAR), and field investigation. Deposits of nearly 20 landslides larger than 100 Mm3 occur within the basin. Most failures have occurred in weakly lithified Late Miocene to Pliocene sedimentary rocks and include earth flows, translational and rotational landslides, and plug flows. Failures in underlying tectonized Paleozoic sedimentary rocks include bedding-parallel rockslides. The largest failure is the 3 km3 Achcocalla earth flow (ca. 11 ka BP), which ran out ~20 km. Other dated events span the period from the early Holocene to nearly the Colonial historic period. InSAR results show that many large slope failures, including the Achocalla earth flow, are currently moving at rates of a few centimeters to a few decimeters per year. Rapid deposition, shallow burial, and rapid incision of the basin fills produced steep slopes in weak geologic materials that, coupled with groundwater discharge from the valley walls, are the primary controls on instability. In contrast, the Altiplano surface has changed little in 2 Ma and the adjacent slopes of the Cordilleran Real, although steep, are relatively stable. Of the over 100 landslides that have occurred in the city of La Paz since the early twentieth century, most are at the margins of large, deep-seated prehistoric failures, and two of the most damaging historic landslides (Hanko-Hanko, 1582; Pampahasi, 2011) were large-scale reactivations of previously failed slopes. Improved understanding of large, deep-seated landslides in

  8. Haploinsufficiency of activation-induced deaminase for antibody diversification and chromosome translocations both in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Isora V Sernández

    Full Text Available The humoral immune response critically relies on the secondary diversification of antibodies. This diversification takes places through somatic remodelling of the antibody genes by two molecular mechanisms, Class Switch Recombination (CSR and Somatic Hypermutation (SHM. The enzyme Activation Induced Cytidine Deaminase (AID initiates both SHM and CSR by deaminating cytosine residues on the DNA of immunoglobulin genes. While crucial for immunity, AID-catalysed deamination is also the triggering event for the generation of lymphomagenic chromosome translocations. To address whether restricting the levels of AID expression in vivo contributes to the regulation of its function, we analysed mice harbouring a single copy of the AID gene (AID(+/-. AID(+/- mice express roughly 50% of normal AID levels, and display a mild hyperplasia, reminiscent of AID deficient mice and humans. Moreover, we found that AID(+/- cells have an impaired competence for CSR and SHM, which indicates that AID gene dose is limiting for its physiologic function. We next evaluated the impact of AID reduction in AID(+/- mice on the generation of chromosome translocations. Our results show that the frequency of AID-promoted c-myc/IgH translocations is reduced in AID(+/- mice, both in vivo and in vitro. Therefore, AID is haploinsufficient for antibody diversification and chromosome translocations. These findings suggest that limiting the physiologic levels of AID expression can be a regulatory mechanism that ensures an optimal balance between immune proficiency and genome integrity.

  9. Interglacial microrefugia and diversification of a cactus species complex: phylogeography and palaeodistributional reconstructions for Pilosocereus aurisetus and allies.

    Science.gov (United States)

    Bonatelli, Isabel A S; Perez, Manolo F; Peterson, A Townsend; Taylor, Nigel P; Zappi, Daniela C; Machado, Marlon C; Koch, Ingrid; Pires, Adriana H C; Moraes, Evandro M

    2014-06-01

    The role of Pleistocene climate changes in promoting evolutionary diversification in global biota is well documented, but the great majority of data regarding this subject come from North America and Europe, which were greatly affected by glaciation. The effects of Pleistocene changes on cold- and/or dry-adapted species in tropical areas where glaciers were not present remain sparsely investigated. Many such species are restricted to small areas surrounded by unfavourable habitats, which may represent potential interglacial microrefugia. Here, we analysed the phylogeographic structure and diversification history of seven cactus species in the Pilosocereus aurisetus complex that are restricted to rocky areas with high diversity and endemism within the Neotropical savannas of eastern South America. We combined palaeodistributional estimates with standard phylogeographic approaches based on two chloroplast DNA regions (trnT-trnL and trnS-trnG), exon 1 of the nuclear gene PhyC and 10 nuclear microsatellite loci. Our analyses revealed a phylogeographic history marked by multiple levels of distributional fragmentation, isolation leading to allopatric differentiation and secondary contact among divergent lineages within the complex. Diversification and demographic events appear to have been affected by the Quaternary climatic cycles as a result of isolation in multiple patches of xerophytic vegetation. These small patches presently harbouring P. aurisetus populations seem to operate as microrefugia, both at present and during Pleistocene interglacial periods; the role of such microrefugia should be explored and analysed in greater detail.

  10. Origin and intra-island diversification of Sulawesi endemic Adrianichthyidae.

    Science.gov (United States)

    Mokodongan, Daniel F; Yamahira, Kazunori

    2015-12-01

    Although the family Adrianichthyidae is broadly distributed throughout East and Southeast Asia, 19 endemic species, over half of the family, are distributed in Sulawesi, which is an island in Wallacea. However, it remains unclear how this Adrianichthyidae biodiversity hotspot was shaped. In this study, we reconstructed molecular phylogenies for the Sulawesi adrianichthyids and estimated the divergence times of major lineages to infer the detailed history of their origin and subsequent intra-island diversification. The mitochondrial and nuclear phylogenies revealed that Sulawesi adrianichthyids are monophyletic, which indicates that they diverged from a single common ancestor. Species in the earliest branching lineages are currently distributed in the central and southeastern parts of the island, indicating that the common ancestor colonized Sula Spur, which is a large promontory that projects from the Australian continental margin, from Asia by oversea dispersal c.a. 20Mya. The first diversification event on Sulawesi, the split of the genus Adrianichthys, occurred c.a. 16Mya, and resulted in the nesting of Adrianichthys within Oryzias. Strong geographic structure was evident in the phylogeny; many species in the lineages branching off early are riverine and widely distributed in the southeastern and southwestern arms of Sulawesi, which suggests that oversea dispersal between tectonic subdivisions of this island during the late Miocene (7-5Mya) contributed to the distributions and diversification of the early branching lineages. In contrast, most species in the lineages branched off later are endemic to a single tectonic lake or lake system in the central Sulawesi, suggesting that habitat fragmentation due to the Pliocene collisions (c.a. 4Mya) among the tectonic subdivisions was the primary factor for diversification of the late branching, lacustrine lineages. Adrianichthys and some Oryzias in a certain late branching lineage are sympatric in Lake Poso, which

  11. Diversification of the yellow-shouldered bats, genus Sturnira (Chiroptera, Phyllostomidae), in the New World tropics.

    Science.gov (United States)

    Velazco, Paúl M; Patterson, Bruce D

    2013-09-01

    The Yellow-shouldered bats, Genus Sturnira, are widespread, diverse, and abundant throughout the Neotropical Region, but little is known of their phylogeny and biogeography. We collected 4409 bp of DNA from three mitochondrial (cyt-b, ND2, D-loop) and two nuclear (RAG1, RAG2) sequences from 138 individuals representing all but two recognized species of Sturnira and five other phyllostomid bats used as outgroups. The sequence data were subjected to maximum parsimony, maximum likelihood, and Bayesian inference analyses. Results overwhelmingly support the monophyly of the genus Sturnira but not continued recognition of Corvira as a subgenus; the two species (bidens and nana) allocated to that group constitute separate, basal branches on the phylogeny. A total of 21 monophyletic putatively species-level groups were recovered; pairs were separated by an average 7.09% (SD=1.61) pairwise genetic distance in cyt-b, and three of these groups are apparently unnamed. Several well-supported clades are evident, including a complex of seven species formerly confused with S. lilium, a species that is actually limited to the Brazilian Shield. We used four calibration points to construct a time-tree for Sturnira, using BEAST. Sturnira diverged from other stenodermatines in the mid-Miocene, and by the end of that epoch (5.3 Ma), three basal lineages were present. Most living species belong to one of two clades, A and B, which appeared and diversified shortly afterwards, during the Pliocene. Both parsimony (DIVA) and likelihood (Lagrange) methods for reconstructing ancestral ranges indicate that the radiation of Sturnira is rooted in the Andes; all three basal lineages (in order, bidens, nana, and aratathomasi) have strictly or mainly Andean distributions. Only later did Sturnira colonize the Pacific lowlands (Chocó) and thence Central America. Sturnira species that are endemic to Central America appeared after the final emergence of the Panamanian landbridge ~3 Ma. Despite its

  12. Gravity modelling of the Ramadas Caldera (Argentinean Puna, central Andes)

    Energy Technology Data Exchange (ETDEWEB)

    Casas, A. [Barcelona Univ. (Spain). Facultad de Geologia; Hernandez, E.; Marti, J. [Consejo Superior de Investigaciones Cientificas, Barcelona (Spain). Inst. de Ciencias de la Terra Jaume Almera; Petrinovic, I. [Universidad Nacional de Salta (Argentina)

    1995-12-31

    In order to identify and characterize the event area of abundant Upper Miocene proximal rhyolitic pyroclastic deposits and extrusive domes which concentrate in the Ramadas area, near Sant`Antonio de los Cobres (Salta) at the Puna Altiplano (Central Andes), a detailed gravity survey has been carried out. Regional Bouguer gravity data were augmented with new 173 gravity observations measured sufficiently close-spaced to resolve the short wavelength produced by the structure of interest. Besides, the geophysical survey was done in conjunction with geologic and geochemical studies which were critically important to our interpretation. After the separation of the regional trend, the residual anomaly map displays a circular gravity low reaching-80 m Gal centered over scarce outcrops of rhyolitic and pyroclastic. This gravity low is interpreted as produced by block subsidence along ring fractures during eruption and/or deflation of the chamber. As the accumulation of thick, low density rock types in the zone of collapse is responsible of the prominent negative gravity anomalies, them has been used to estimated the thickness of caldera infill. (author). 8 refs., 4 figs

  13. The Grenville-age basement of the Andes

    Science.gov (United States)

    Ramos, Victor A.

    2010-01-01

    The analysis of the basement of the Andes shows the strong Grenville affinities of most of the inliers exposed in the different terranes from Colombia to Patagonia. The terranes have different histories, but most of them participated in the Rodinia supercontinent amalgamation during the Mesoproterozoic between 1200 and 1000 Ma. After Rodinia break-up some terranes were left in the Laurentian side such as Cuyania and Chilenia, while others stayed in the Gondwanan side. Some of the terranes once collided with the Amazon craton remained attached, experiencing diverse rifting episodes all along the Phanerozoic, as the Arequipa and Pampia terranes. Some other basement inliers were detached in the Neoproterozoic and amalgamated again to Gondwana in the Early Cambrian, Middle Ordovician or Permian times. A few basement inliers with Permian metamorphic ages were transferred to Gondwana after Pangea break-up from the Laurentian side. Some of them were part of the present Middle America terrane. An exceptional case is the Oaxaquia terrane that was detached from the Gondwana margin after the Early Ordovician and is now one of the main Mexican terranes that collided with Laurentia. These displacements, detachments, and amalgamations indicate a complex terrane transfer between Laurentia and Gondwana during Paleozoic times, following plate reorganizations and changes in the absolute motion of Gondwana.

  14. [Medical education at Universidad de los Andes, Santiago, Chile].

    Science.gov (United States)

    Orrego Vicuña, F

    1997-07-01

    Universidad de los Andes School of Medicine started in 1991 with a new medical curriculum aimed at providing a medical education for its students, that is, it attempts to give, together with technical proficiency in medical matters, formation of character and a strong ethical attitude. The curriculum lasts for seven years: five of basic, pre-clinical and clinical theoretical and practical courses, followed by two years of internships in Internal Medicine, Surgery, Obstetrics and Pediatrics, plus a four month period of an elective internship. The courses have an integrated design, in which each matter is presented from multiple perspectives, e.g. in Internal Medicine together with the clinical aspects of disease, the pathophysiology and the pharmacology of the drugs used are presented. Also the Pathology of each disease is given in coordination in the Pathology course. General educational matters such as Anthropology, Psychology, Origin of Living Beings, Theology and Medical Ethics are interspersed in the curriculum. An important feature is the personal counselling system, in which each student may choose an academic counsellor and discuss with him (her) the subjects of his choosing. Clinical practice is given in a system that includes five hospitals and five private clinics that range from general medical practice to Psychiatry or Ophthalmology.

  15. Meteorological Conditions of Floods In The Chilean Andes Mountains

    Science.gov (United States)

    Vergara, J.

    Catastrophic floods occurred on mountains River during 2000 and 2001. The meteo- rological conditions of flood during the last five years have analyzed. For example, the flood of June 29 of 2000 occurred after one of extremely wettest June of the last 40 years were snowfall was 991cm in the Aconcagua Valley. Infrequently storms activ- ity generated a huge snowfall and rainfall over the Andes mountains on June of 2000 (1525mm in El Maule Valley) and the end of the unusually period, the flood was trig- gered by rising temperatures on the mountains and heavy rain (199mm in 24 hours) fall over the fresh snow on the morning of June 29 and floods wave developed and moved down along of the all river located on Central part of Chile, the foods peak was 2970.5m3/s on the El Maule basin in the morning of June 29. The regional meteoro- logical models with the hydrological forecasting was used for alert of the floods.

  16. Paleomagnetism of Permian and Triassic rock, central Chilean Andes

    Science.gov (United States)

    Forsythe, Randall D.; Kent, Dennis V.; Mpodozis, Constantino; Davidson, John

    The first paleomagnetic data from Permian and Triassic formations west of the Andean divide are presented. Four formations of Permian or Triassic age in the central Chilean Andes have been investigated: two are located in the coastal ranges, and two are in the main cordillera. Of the formations in the main cordillera (Pastos Blancos and Matahuaico formations), only the Pastos Blancos Formation has yielded characteristic directions. While a fold test is absent, magnetizations are most likely secondary and yield pre-tilt corrected concordant inclinations, but yield declinations discordant 30° clockwise in comparison to the South American apparent polar wander path. Both formations from the coastal ranges (Cifuncho and Pichidangui formations) yielded stable directions. Postfolding magnetizations in the Cifuncho Formation also show declinations discordant 30° clockwise and concordant inclinations. The Pichidangui Formation has two stable components: one of postfolding age is concordant to apparent polar wander path data, and one of probable prefolding (Late Triassic) age is concordant in declination, but discordant in inclination. Further work is needed to better define the prefolding magnetizations in the Pichidangui Formation, but at present these preliminary results are the first paleomagnetic signs of displaced terranes along the Pacific margin of Chile. If correct, the results suggest that the Pichidangui Formation was some 15° of latitude farther south during the Late Triassic and had likely moved northward to its present latitudinal position with respect to cratonic South America by Middle to Late Jurassic.

  17. Quaternary Glaciations in the Rio Mendoza Valley, Argentine Andes

    Science.gov (United States)

    Espizua, Lydia E.

    1993-09-01

    In the Rio Mendoza valley, five Pleistocene drifts and one Holocene drift are distinguished by multiple relative-age criteria, including surface-rock weathering, development of rock varnish, moraine morphology, soil-profile development, and stratigraphic relationships. Several absolute ages suggest a preliminary chronology. During the oldest (Uspallata) glaciation, a system of valley glaciers flowed 110 km from the Andean drainage divide and 80 km from Cerro Aconcagua to terminate at 1850 m. Drift of this ice advance is older than a widespread tephra dated by fission-track at 360,000 ± 36,000 yr. During the Punta de Vacas advance, ice terminated at 2350 m, while during the subsequent Penitentes advance, the glacier system ended at 2500 m. A travertine layer overlying Penitentes Drift has U-series age of 24,200 ± 2000 yr B.P. The distribution of Horcones Drift, which is inferred to represent the last glacial maximum, delimits an independent ice stream that flowed 22 km down Horcones valley to 2750 m. A later readvance (Almacenes) reached 3250 m. Confluencia Drift is considered to be Neoglacial in age and extends downvalley to 3300 m. The moraine sequence is compared with those studied by Caviedes (1972) along Rio Aconcagua on the Chilean flank of the Andes.

  18. Bofedales: high altitude peatlands of the central Andes Bofedales: turberas de alta montaña de los Andes centrales

    Directory of Open Access Journals (Sweden)

    FRANCISCO A SQUEO

    2006-06-01

    Full Text Available There is an exceptional group of alpine peatlands in the world situated in the arid grasslands of the central Andes. The peatlands in northern Chile occur in the most arid part of their range. Members of the Juncaceae are the primary peat-forming plant species. Fresh and mildly saline groundwaters originate from glaciers, snowmelt and rain are the water sources for the northern Chile peatlands. Paleoecological investigations suggest that some peatlands are recent features of the landscape having developed within the last three thousand years or less. These peatlands are unique, extremely fragile water features sensitive to climate changes and human disturbances such as regional mining activity. Much more work is required to develop scientifically based sound management and conservation programs for the rare plants and animals that live in them and to ensure the future livelihoods of the indigenous peoples who depend on themExiste un grupo excepcional de turberas (bofedales de alta montaña en el mundo situados en la estepa árida de los Andes centrales. Los bofedales en el norte de Chile están presentes en la parte más árida de su rango. Las principales especies de plantas responsables de la formación de turba corresponden a miembros de Juncaceae. El agua fresca y medianamente salina de los bofedales proviene de agua subterránea asociada a riachuelos proveniente de glaciares, derretimiento de nieve y lluvia. Investigaciones paleoecológicas sugieren que algunos bofedales son integrantes recientes del paisaje, habiéndose desarrollado durante los últimos tres mil años o menos. Estos bofedales son entidades únicas, extremadamente frágiles por su dependencia del agua, sensibles a los cambios climáticos y vulnerables a la alteración humana tal como la actividad minera en la región. Se requiere mucho más trabajo para desarrollar programas de manejo y conservación, con sólidas bases científicas, de las plantas y animales que viven en

  19. Linchamientos y conflicto político en Los Andes Lynchings and Political conflict in The Andes

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    Carlos M. Vilas

    2007-06-01

    Full Text Available En 2004, los alcaldes de dos municipalidades de la región aimara de los Andes fueron linchados en la aparente culminación de agudos conflictos políticos internos y entre las respectivas comunidades y el Estado central. En este artículo se discuten ambos casos con el fin de ilustrar las transformaciones experimentadas en años recientes en la organización y la dinámica interna de las comunidades andinas, y de la articulación conflictiva de la política local en los procesos e instituciones de más amplio alcance. Precariedad social e incapacidad o renuencia del Estado para responder con eficacia a demandas básicas de determinados grupos de población configuran enmarcamientos socioeconómicos e institucionales de los linchamientos. En contraste con enfoques que enfatizan en factores culturales tradicionales o en un supuesto nacionalismo indígena, en el artículo se destaca la gravitación de fenómenos y procesos político- institucionales recientes en la transformación cultural y política de las comunidades, en el modo en que éstas procesan sus conflictos internos y con el Estado central.In 2004, two municipalitys mayors form the aimara Andes of Peru and Bolivia were subjected to mass lynchings as a result of the apparent culmination of violent political confrontations. This paper deals with these events as dramatic illustrations of the transformations the Andean communities experienced during recent decades in their internal dynamics, as well as in the articulation of local politics to processes and institutions beyond the communal limits. Structural precariousness combined with the state's inability or reluctance to come to terms with social or political demands from relevant segments of the people in the communities set the socioeconomic and institutional stage for lynchings. In contrast with approaches relating these events to an alleged indigenous cultural identity, the analysis points to the impact of the communities' political

  20. Land Cover Change in the Andes of Southern Ecuador—Patterns and Drivers

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    Giulia F. Curatola Fernández

    2015-03-01

    Full Text Available In the megadiverse tropical mountain forest in the Andes of southern Ecuador, a global biodiversity hotspot, the use of fire to clear land for cattle ranching is leading to the invasion of an aggressive weed, the bracken fern, which is threatening diversity and the provisioning of ecosystem services. To find sustainable land use options adapted to the local situation, a profound knowledge of the long-term spatiotemporal patterns of land cover change and its drivers is necessary, but hitherto lacking. The complex topography and the high cloud frequency make the use of remote sensing in this area a challenge. To deal with these conditions, we pursued specific pre-processing steps before classifying five Landsat scenes from 1975 to 2001. Then, we quantified land cover changes and habitat fragmentation, and we investigated landscape changes in relation to key spatial elements (altitude, slope, and distance from roads. Good classification results were obtained with overall accuracies ranging from 94.5% to 98.5% and Kappa statistics between 0.75 and 0.98. Forest was strongly fragmented due to the rapid expansion of the arable frontier and the even more rapid invasion by bracken. Unexpectedly, more bracken-infested areas were converted to pastures than vice versa, a practice that could alleviate pressure on forests if promoted. Road proximity was the most important spatial element determining forest loss, while for bracken the altitudinal range conditioned the degree of invasion in deforested areas. The annual deforestation rate changed notably between periods: ~1.5% from 1975 to 1987, ~0.8% from 1987 to 2000, and finally a very high rate of ~7.5% between 2000 and 2001. We explained these inconstant rates through some specific interrelated local and national political and socioeconomic drivers, namely land use policies, credit and tenure incentives, demography, and in particular, a severe national economic and bank crisis.

  1. Giant magmatic water reservoir beneath Uturuncu volcano and Altiplano-Puna region (Central Andes)

    Science.gov (United States)

    Laumonier, Mickael; Gaillard, Fabrice; Muir, Duncan; Blundy, Jon; Unsworth, Martyn

    2016-04-01

    Volcanism at continental arcs is the surface manifestation of long-lived crustal magmatic processes whereby mantle-derived hydrous basalt magma differentiates to more silica-rich magmas by a combination of crystallization and crustal melting. What erupts is just a fraction of the total volume of magma produced by these processes; the unerupted, plutonic residues solidify and are inaccessible to direct study until millions of years of uplift and erosion bring them to the surface. In contrast, geophysical surveys, using electromagnetic and seismic waves, can provide real-time images of subduction zone magmatic systems. Several such studies have revealed that arc volcanoes are underlain by large partially molten regions at depths of >10 km, the largest known example being the Altiplano-Puna magma body (APMB) in central Andes. Interpreting such geophysical images in terms of amount, composition and distribution of partial melts is limited by our lack of knowledge of the physical properties of silicate melts at elevated pressures and temperatures. Here we present high-pressure, in situ experimental data showing that the electrical conductivity of andesitic melts is primarily controlled by their dissolved water contents. Linking our new measurements to petrological constraints from andesites erupted on the Altiplano, we show that the APMB is composed of 10-20% of an andesitic melt containing 8-10 wt% dissolved water. This implies that the APMB is a giant water anomaly in the global subduction system, with a total mass of dissolved magmatic water about half of the water contained within the Adriatic Sea. In addition to the controls on the physical properties of the melts, the abundance of dissolved water governs the structural levels of magma ponding, equivalent to the depth of water saturation, where degassing and crystallisation promote partial melting and weakening of the upper crust. Unexpectedly, very high concentrations of water in andesite magmas shall impede their

  2. LASER: A Maximum Likelihood Toolkit for Detecting Temporal Shifts in Diversification Rates From Molecular Phylogenies

    Directory of Open Access Journals (Sweden)

    Daniel L. Rabosky

    2006-01-01

    Full Text Available Rates of species origination and extinction can vary over time during evolutionary radiations, and it is possible to reconstruct the history of diversification using molecular phylogenies of extant taxa only. Maximum likelihood methods provide a useful framework for inferring temporal variation in diversification rates. LASER is a package for the R programming environment that implements maximum likelihood methods based on the birth-death process to test whether diversification rates have changed over time. LASER contrasts the likelihood of phylogenetic data under models where diversification rates have changed over time to alternative models where rates have remained constant over time. Major strengths of the package include the ability to detect temporal increases in diversification rates and the inference of diversification parameters under multiple rate-variable models of diversification. The program and associated documentation are freely available from the R package archive at http://cran.r-project.org.

  3. Reciprocal diversification in a complex plant-herbivore-parasitoid food web

    Directory of Open Access Journals (Sweden)

    Bokma Folmer

    2007-11-01

    Full Text Available Abstract Background Plants, plant-feeding insects, and insect parasitoids form some of the most complex and species-rich food webs. According to the classic escape-and-radiate (EAR hypothesis, these hyperdiverse communities result from coevolutionary arms races consisting of successive cycles of enemy escape, radiation, and colonization by new enemy lineages. It has also been suggested that "enemy-free space" provided by novel host plants could promote host shifts by herbivores, and that parasitoids could similarly drive diversification of gall form in insects that induce galls on plants. Because these central coevolutionary hypotheses have never been tested in a phylogenetic framework, we combined phylogenetic information on willow-galling sawflies with data on their host plants, gall types, and enemy communities. Results We found that evolutionary shifts in host plant use and habitat have led to dramatic prunings of parasitoid communities, and that changes in gall phenotype can provide "enemy-free morphospace" for millions of years even in the absence of host plant shifts. Some parasites have nevertheless managed to colonize recently-evolved gall types, and this has apparently led to adaptive speciation in several enemy groups. However, having fewer enemies does not in itself increase speciation probabilities in individual sawfly lineages, partly because the high diversity of the enemy community facilitates compensatory attack by remaining parasite taxa. Conclusion Taken together, our results indicate that niche-dependent parasitism is a major force promoting ecological divergence in herbivorous insects, and that prey divergence can cause speciation in parasite lineages. However, the results also show that the EAR hypothesis is too simplistic for species-rich food webs: instead, diversification seems to be spurred by a continuous stepwise process, in which ecological and phenotypic shifts in prey lineages are followed by a lagged evolutionary

  4. ANALYSIS OF DIVERSIFICATION EFFORTS IN AGRICULTURAL EDUCATION

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    PROCHÁZKA, Petr

    2011-09-01

    Full Text Available Study of agriculture enjoys less popularity over time in most of the developed countries, including Canada and the Czech Republic. Analysis in this paper provides interesting findings about activities of agricultural universities to increase enrollment into their programs. While the study is focused on Canada, it is possible to draw implications also for the Czech Republic as many of the characteristics pertaining to the education and agricultural sectors are similar. Enrollment into educational programs in agriculture in North America has been steadily declining in the last several decades. While the overall share of agriculture on national gross domestic product has also been falling, the need for qualified people in agriculture is still eminent as the shift to sustainable agriculture appears to be one of the key priorities of governments in the US and Canada. One of the ways how to facilitate interest of prospective students to study agriculture is to diversify the programs through offering of more major options. It is important to study the motivation and other stimuli for the choice of major in order to adapt the educational programs and attract more students. In the paper, factors influencing the choice of major are studied by analyzing survey data from the only agricultural college in Atlantic Canada. The results show significant differences in the socio-economic background among the prospective students based on the choice of major. For example, students interested in social sciences much more appraise more choices of major than students in biophysical fields. Based on the findings from the analysis, several recommendations are made. It is suggested, for example, that for students interested in biophysical sciences, sport plays an important role and thus, appropriate promotional campaign about recreation and sport facilities of a post-secondary agricultural educational institutions should be conducted. Analysis in this paper may serve

  5. Efficient Use of Cogeneration and Fuel Diversification

    Science.gov (United States)

    Kunickis, M.; Balodis, M.; Sarma, U.; Cers, A.; Linkevics, O.

    2015-12-01

    Energy policy of the European Community is implemented by setting various goals in directives and developing support mechanisms to achieve them. However, very often these policies and legislation come into contradiction with each other, for example Directive 2009/28/EC on the promotion of the use of energy from renewable sources and Directive 2012/27/EU on energy efficiency, repealing Directive 2004/8/EC on the promotion of cogeneration based on a useful heat demand. In this paper, the authors attempt to assess the potential conflicts between policy political objectives to increase the share of high-efficiency co-generation and renewable energy sources (RES), based on the example of Riga district heating system (DHS). If a new heat source using biomass is built on the right bank of Riga DHS to increase the share of RES, the society could overpay for additional heat production capacities, such as a decrease in the loading of existing generating units, thereby contributing to an inefficient use of existing capacity. As a result, the following negative consequences may arise: 1) a decrease in primary energy savings (PES) from high-efficiency cogeneration in Riga DHS, 2) an increase in greenhouse gas (GHG) emissions in the Baltic region, 3) the worsening security situation of electricity supply in the Latvian power system, 4) an increase in the electricity market price in the Lithuanian and Latvian price areas of Nord Pool power exchange. Within the framework of the research, calculations of PES and GHG emission volumes have been performed for the existing situation and for the situation with heat source, using biomass. The effect of construction of biomass heat source on power capacity balances and Nord Pool electricity prices has been evaluated.

  6. Polyphyly of the hawk genera Leucopternis and Buteogallus (Aves, Accipitridae: multiple habitat shifts during the Neotropical buteonine diversification

    Directory of Open Access Journals (Sweden)

    Bermingham Eldredge

    2006-02-01

    at least twice in the group. Furthermore, species found to the east and west of the Andes (cis-Andean and trans-Andean, respectively are not reciprocally monophyletic, nor are forest and non-forest species. Conclusion The polyphyly of Leucopternis, Buteogallus and Buteo establishes a lack of concordance of current Accipitridae taxonomy with the mtDNA phylogeny for the group, and points to the need for further phylogenetic analysis at all taxonomic levels in the family as also suggested by other recent analyses. Habitat shifts, as well as cis- and trans-Andean disjunctions, took place more than once during buteonine diversification in the Neotropical region. Overemphasis of the black and white plumage patterns has led to questionable conclusions regarding the relationships of Leucopternis species, and suggests more generally that plumage characters should be used with considerable caution in the taxonomic evaluation of the Accipitridae.

  7. Structure and tectonic evolution of the Fuegian Andes (southernmost South America) in the framework of the Scotia Arc development

    Science.gov (United States)

    Torres Carbonell, Pablo J.; Dimieri, Luis V.; Olivero, Eduardo B.; Bohoyo, Fernando; Galindo-Zaldívar, Jesús

    2014-12-01

    The major structural and tectonic features of the Fuegian Andes provide an outstanding onshore geological framework that aids in the understanding of the tectonic evolution of the Scotia Arc, mainly known from offshore studies. The orogenic history of the Fuegian Andes (Late Cretaceous-Miocene) is thus compared and integrated with the tectonic history of the Scotia Sea. Late Cretaceous-Paleocene structures in the Fuegian Andes suggest a N-directed contraction consistent with an oroclinal bending of the southernmost South America-Antarctic Peninsula continental bridge. This N-directed contraction in the Fuegian Andes continued during the spreading of the West Scotia Ridge, between 40-50 and 10 Ma ago. The onset of major strike-slip faulting in Tierra del Fuego is considered here to be not older than the late Miocene, consistent with the recent history of the North Scotia Ridge; thus forming part of a tectonic regime superposed to the prior contraction in the Fuegian Andes.

  8. Not going with the flow: a comprehensive time-calibrated phylogeny of dragonflies (Anisoptera: Odonata: Insecta) provides evidence for the role of lentic habitats on diversification.

    Science.gov (United States)

    Letsch, Harald; Gottsberger, Brigitte; Ware, Jessica L

    2016-03-01

    Ecological diversification of aquatic insects has long been suspected to have been driven by differences in freshwater habitats, which can be classified into flowing (lotic) waters and standing (lentic) waters. The contrasting characteristics of lotic and lentic freshwater systems imply different ecological constraints on their inhabitants. The ephemeral and discontinuous character of most lentic water bodies may encourage dispersal by lentic species in turn reducing geographical isolation among populations. Hence, speciation probability would be lower in lentic species. Here, we assess the impact of habitat use on diversification patterns in dragonflies (Anisoptera: Odonata). Based on the eight nuclear and mitochondrial genes, we inferred species diversification with a model-based evolutionary framework, to account for rate variation through time and among lineages and to estimate the impact of larval habitat on the potentially nonrandom diversification among anisopteran groups. Ancestral state reconstruction revealed lotic fresh water systems as their original primary habitat, while lentic waters have been colonized independently in Aeshnidae, Corduliidae and Libellulidae. Furthermore, our results indicate a positive correlation of speciation and lentic habitat colonization by dragonflies: speciation rates increased in lentic Aeshnidae and Libellulidae, whereas they remain mostly uniform among lotic groups. This contradicts the hypothesis of inherently lower speciation in lentic groups and suggests species with larger ranges are more likely to diversify, perhaps due to higher probability of larger areas being dissected by geographical barriers. Furthermore, larger range sizes may comprise more habitat types, which could also promote speciation by providing additional niches, allowing the coexistence of emerging species.

  9. Carbon stabilization mechanisms in soils in the Andes

    Science.gov (United States)

    Jansen, Boris; Cammeraat, Erik

    2015-04-01

    The volcanic ash soils of the Andes contain very large stocks of soil organic matter (SOM) per unit area. Consequently, they constitute significant potential sources or sinks of the greenhouse gas CO2. Climate and/or land use change potentially have a strong effect on these large SOM stocks. To clarify the role of chemical and physical stabilisation mechanisms in volcanic ash soils in the montane tropics, we investigated carbon stocks and stabilization mechanisms in the top- and subsoil along an altitudinal transect in the Ecuadorian Andes. The transect encompassed a sequence of paleosols under forest and grassland (páramo), including a site where vegetation cover changed in the last century. We applied selective extraction techniques, performed X-ray diffraction analyses of the clay fraction and estimated pore size distributions at various depths in the top- and subsoil along the transect. In addition, from several soils the molecular composition of SOM was further characterized with depth in the current soil as well as the entire first and the top of the second paleosol using GC/MS analyses of extractable lipids and Pyrolysis-GC/MS analyses of bulk organic matter. Our results show that organic carbon stocks in the mineral soil under forest a páramo vegetation were roughly twice as large as global averages for volcanic ash soils, regardless of whether the first 30cm, 100cm or 200cm were considered. We found the carbon stabilization mechanisms involved to be: i) direct stabilization of SOM in organo-metallic (Al-OM) complexes; ii) indirect protection of SOM through low soil pH and toxic levels of Al; and iii) physical protection of SOM due to a very high microporosity of the soil (Tonneijck et al., 2010; Jansen et al. 2011). When examining the organic carbon at a molecular level, interestingly we found extensive degradation of lignin in the topsoil while extractable lipids were preferentially preserved in the subsoil (Nierop and Jansen, 2009). Both vegetation

  10. Possible future lakes in the Andes of Peru

    Science.gov (United States)

    Colonia, Daniel; Haeberli, Wilfried; Torres, Judith; Giraldez, Claudia; Schauwecker, Simone; Santiago, Alexzander; Cochachin, Alejo; Huggel, Christian

    2015-04-01

    Climate change has caused large losses of glacier mass in the Andes of Peru. Also, given the projected changes in climate, based on different IPCC scenarios for 2050 and 2080, simulations with a tropical glacier-climate model indicate that glaciers will continue to retreat. According to the national Peruvian glacier inventories 43% of glacier area has disappeared between 1970 and 2003-2010 in the 19 snowy mountain ranges and a total of 8 355 new lakes have formed in deglaciating terrain. With glacier retreat new lakes form in parts of the glacier tongue where there is an overdeepening, and these lakes can be a source of natural hazards to downstrean populations. Therefore, the identification of possible future lakes is important to plan for preventive measures concerning possible lake outbursts as well as to understand changes in freshwater storage in the corresponding source areas. Modeling of glacier-bed overdeepenings and possible future lakes forming in such topographic depressions when becoming ice-free was done using the SRTM DEM from the year 2000 with a 90 m resolution and the 2003-2010 glacier outlines from the recently published national glacier inventory of Perú. The GIS-based analysis followed three main steps: (1) identification of flat glacier areas with less than 10° surface slope as a first-order spatial approximation to possible occurrences of glacier-bed overdeepenings; (2) application, using Google Earth, of three morphological indications of glacier-bed overdeepenings following Frey et al. (2010): steepening surface slope, onset of crevasse formation, lateral flow-narrowing; and (3) verification of the results from steps (1) and (2) by comparison with GlabTop modeling of bed topographies following Linsbauer et al. (2012) using the SRTM DEM, contour lines and constructed branch lines for all glaciers. A pilot study has already been carried out for the Cordillera Blanca. The results show that 31 major new lakes may form in the future. The total

  11. Origin and diversification of a metabolic cycle in oligomer world.

    Science.gov (United States)

    Nishio, Tomoaki; Narikiyo, Osamu

    2013-02-01

    Based on the oligomer-world hypothesis we propose an abstract model where the molecular recognition among oligomers is described in the shape space. The origin of life in the oligomer world is regarded as the establishment of a metabolic cycle in a primitive cell. The cycle is sustained by the molecular recognition. If an original cell acquires the ability of the replication of oligomers, the relationship among oligomers changes due to the poor fidelity of the replication. This change leads to the diversification of metabolic cycles. The selection among diverse cycles is the basis of the evolution. The evolvability is one of the essential characters of life. We demonstrate the origin and diversification of the metabolic cycle by the computer simulation of our model. Such a simulation is expected to be the simplified demonstration of what actually occurred in the primordial soup. Our model describes an analog era preceding the digital era based on the genetic code.

  12. Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda.

    Science.gov (United States)

    Smith, Frank W; Goldstein, Bob

    2016-10-31

    The origin and diversification of segmented metazoan body plans has fascinated biologists for over a century. The superphylum Panarthropoda includes three phyla of segmented animals-Euarthropoda, Onychophora, and Tardigrada. This superphylum includes representatives with relatively simple and representatives with relatively complex segmented body plans. At one extreme of this continuum, euarthropods exhibit an incredible diversity of serially homologous segments. Furthermore, distinct tagmosis patterns are exhibited by different classes of euarthropods. At the other extreme, all tardigrades share a simple segmented body plan that consists of a head and four leg-bearing segments. The modular body plans of panarthropods make them a tractable model for understanding diversification of animal body plans more generally. Here we review results of recent morphological and developmental studies of tardigrade segmentation. These results complement investigations of segmentation processes in other panarthropods and paleontological studies to illuminate the earliest steps in the evolution of panarthropod body plans.

  13. DIVERSIFICATION OF UNIVERSITY INCOME – POLISH PRACTICE AND INTERNATIONAL SOLUTIONS

    Directory of Open Access Journals (Sweden)

    Andrzej Rozmus

    2013-02-01

    Full Text Available In the face of global economic problems European (and not only European universities are forced to diversify their income. The constant and stable stream of governmental funds for education is beginning to dry up. For the majority of Polish universities the main and noticeably dominant source of income are the revenues from teaching activity. Thus the current diversification of universities’ revenues appears to be just a fiction. The situation is even worse because of both the global economic crisis and the imminent decrease in the birth rate. Polish universities should follow funding models of foreign leaders, who successfully deal with diversification of their revenues. Obviously we cannot compare such universities as Harvard or Oxford with Polish universities, but some of their solutions are worth following. Only by diversifying sources of their revenues will Polish universities be able to compete with the foreign leaders and secure a stable basis for development and use of their potential.

  14. Flood protection diversification to reduce probabilities of extreme losses.

    Science.gov (United States)

    Zhou, Qian; Lambert, James H; Karvetski, Christopher W; Keisler, Jeffrey M; Linkov, Igor

    2012-11-01

    Recent catastrophic losses because of floods require developing resilient approaches to flood risk protection. This article assesses how diversification of a system of coastal protections might decrease the probabilities of extreme flood losses. The study compares the performance of portfolios each consisting of four types of flood protection assets in a large region of dike rings. A parametric analysis suggests conditions in which diversifications of the types of included flood protection assets decrease extreme flood losses. Increased return periods of extreme losses are associated with portfolios where the asset types have low correlations of economic risk. The effort highlights the importance of understanding correlations across asset types in planning for large-scale flood protection. It allows explicit integration of climate change scenarios in developing flood mitigation strategy.

  15. Diversification and corporate restructuring revisited. Back to square one?

    Science.gov (United States)

    Liszewski, D M

    1988-06-01

    An historical overview of corporate restructuring in the health care industry is presented. Initial reasons for forming multicorporate structures centered on avoiding regulations governing certified home health agencies and maximizing third party payer reimbursement. As competition increased, home care agencies employed diversification strategies for survival and reorganized their single corporate structures to launch new businesses and engage in profit-making activities. Corporate restructuring is a time-consuming and complex endeavor that should only be undertaken as a part of an agency's strategic plan. Evaluating an agency's corporate structure is a continual process and the criteria for evaluating change over time. The current experience with diversification in the health care industry suggests that the proliferation of multicorporate structures is stemming as health care providers begin to refocus on their core business.

  16. High resolution precipitation climatology for the Andes of South Ecuador

    Science.gov (United States)

    Trachte, Katja; Bendix, Jörg

    2014-05-01

    The climate of Ecuador is strongly dominated by the complex structure of the Andes Mountains. Due to their heights and north-south orientation they act like a barrier, which cause delineation between the western and eastern flanks, as well as the inner-Andean areas. Commonly the Ecuadorian climate is classified in three zones, Costa, Interandina and Oriente. Existing precipitation products such as the GPCC or TRMM data are enabled to represent these climate zones, but because of their spatial resolution, they pass to capture the different regimes within a zone. Especially the inner-Andean region (Interandina) with its characteristic complex terrain shows spatially high climate variability. Local circulation systems, e.g. mountain-valley breezes as well as effects of windward and lee-side, drive the climate conditions allowing for the differentiation of air temperature and rainfall distribution on relative small scales. These highly variable patterns are also reflected by the diversity of ecosystems, e.g. rainforest, dry forest and Paramo, in a relative small area. In order to represent the local systems a dynamical downscaling approach for the Ecuadorian region is applied. In doing so the Weather Research and Forecasting (WRF) model is used. A suitable model setup was evaluated within a sensitivity study, where various parametrization schemes were tested. The most suitable physics combination was used for a 30 year hint cast simulation. The poster presents first results of the high resolution climate simulations. On the basis of the spatial distribution of rainfall patterns distinct precipitation regimes within the Interandina will be shown. The aim is to highlight and discuss the importance of the adequately representation of the terrain in mountainous regions like the Andean Mountains.

  17. Evolution of Irruputuncu volcano, Central Andes, northern Chile

    Science.gov (United States)

    Rodríguez, I.; Roche, O.; Moune, S.; Aguilera, F.; Campos, E.; Pizarro, M.

    2015-11-01

    The Irruputuncu is an active volcano located in northern Chile within the Central Andean Volcanic Zone (CAVZ) and that has produced andesitic to trachy-andesitic magmas over the last ˜258 ± 49 ka. We report petrographical and geochemical data, new geochronological ages and for the first time a detailed geological map representing the eruptive products generated by the Irruputuncu volcano. The detailed study on the volcanic products allows us to establish a temporal evolution of the edifice. We propose that the Irruputuncu volcanic history can be divided in two stages, both dominated by effusive activity: Irruputuncu I and II. The oldest identified products that mark the beginning of Irruputuncu I are small-volume pyroclastic flow deposits generated during an explosive phase that may have been triggered by magma injection as suggested by mingling features in the clasts. This event was followed by generation of large lava flows and the edifice grew until destabilization of its SW flank through the generation of a debris avalanche, which ended Irruputuncu I. New effusive activity generated lavas flows to the NW at the beginning of Irruputuncu II. In the meantime, lava domes that grew in the summit were destabilized, as shown by two well-preserved block-and-ash flow deposits. The first phase of dome collapse, in particular, generated highly mobile pyroclastic flows that propagated up to ˜8 km from their source on gentle slopes as low as 11° in distal areas. The actual activity is characterized by deposition of sulfur and permanent gas emissions, producing a gas plume that reaches 200 m above the crater. The maximum volume of this volcanic system is of ˜4 km3, being one of the smallest active volcano of Central Andes.

  18. The Little Ice Age in the tropical Andes

    Science.gov (United States)

    Jomelli, V.; Cooley, D.; Naveau, P.; Rabatel, A.

    2003-12-01

    The period known as the Little Ice Age, from the 17th to the 19th century, brought a cooling of around 0.5 degrees Celsius as well as varyingly humid episodes Eurasia and North America. Because of a lack of long paleoclimatic time series in the tropical Andes, it is still unclear if similar cooling occurred over these tropical and Southern Hemisphere regions. Furthermore, if changes did take place, it is currently not well established if they were temporally synchronous or shifted with respect of the variations in the Northern Hemisphere or the globe. To look into this important climatic question and for advancing our understanding of the past climate links between the tropics and higher latitudes, 25 glaciers located in Bolivia and in Peru were carefully selected. Glacial activity and environmental changes were analyzed using lichenometry. Largest lichen diameters were measured in the different glacial basins. To better analyze these maximum diameters and to more appropriately represent uncertainty and the character of this collected data, age estimates of the different moraine systems were derived using extreme value theory rather than the traditional averaging. The results reveal two particular phases of glacier growth, 1550-1600 and 1800-1850. These two phases have also been identified in other proxy records, such as ice-cores and documentary data (particularly from church chronicles). In order to understand the climatic changes that could have contributed to the glacial variations, a simple model based on both precipitations and temperatures is applied to estimate mass balance questions in the basins. A cooling of the order of 0.5 C seems to be the most consistent with the data. Finally, these findings are compared with the better-known histories of Northern Hemisphere mid-latitude glaciers.

  19. The nature of orogenic crust in the central Andes

    Science.gov (United States)

    Beck, Susan L.; Zandt, George

    2002-10-01

    The central Andes (16°-22°S) are part of an active continental margin mountain belt and the result of shortening of the weak western edge of South America between the strong lithospheres of the subducting Nazca plate and the underthrusting Brazilian shield. We have combined receiver function and surface wave dispersion results from the BANJO-SEDA project with other geophysical studies to characterize the nature of the continental crust and mantle lithospheric structure. The major results are as follows: (1) The crust supporting the high elevations is thick and has a felsic to intermediate bulk composition. (2) The relatively strong Brazilian lithosphere is underthrusting as far west (65.5°W) as the high elevations of the western part of the Eastern Cordillera (EC) but does not underthrust the entire Altiplano. (3) The subcrustal lithosphere is delaminating piecemeal under the Altiplano-EC boundary but is not completely removed beneath the central Altiplano. The Altiplano crust is characterized by a brittle upper crust decoupled from a very weak lower crust that is dominated by ductile deformation, leading to lower crustal flow and flat topography. In contrast, in the high-relief, inland-sloping regions of the EC and sub-Andean zone, the upper crust is still strongly coupled across the basal thrust of the fold-thrust belt to the underthrusting Brazilian Shield lithosphere. Subcrustal shortening between the Altiplano and Brazilian lithosphere appears to be accommodated by delamination near the Altiplano-EC boundary. Our study suggests that orogenic reworking may be an important part of the "felsification" of continental crust.

  20. Glacier loss and emerging hydrologic vulnerabilities in the Peruvian Andes

    Science.gov (United States)

    Mark, B. G.; McKenzie, J. M.; Baraer, M.; Lagos, P.; Lautz, L.; Carey, M.; Bury, J.; Crumley, R.; Wigmore, O.; Somers, L. D.

    2015-12-01

    Accelerating glacier recession in the tropical Andes is transforming downstream hydrology, while increasing demands for water by end-users (even beyond the watershed limits) is complicating the assessment of vulnerability. Future scenarios of hydro-climatic vulnerability require a better understanding of coupled hydrologic and human systems, involving both multiscale process studies and more robust models of glacier-climate interactions. We synthesize research in two proglacial valleys of glacierized mountain ranges in different regions of Peru that are both in proximity to growing water usage from urban sectors, agriculture, hydroelectric generation, and mining. In both the Santa River watershed draining the Cordillera Blanca and the Shullcas River watershed below Hyuatapallana Mountain in Junin, glaciers have receded over 25% since the 1980s. Historical runoff and glacier data, combined with glacier-climate modeling, show a long-term decrease in discharge resulting from a net loss of stored water. We find evidence that this altered hydrology is transforming proglacial wetland ecology and water quality, even while water resource use has intensified. Beyond glaciers, our results show that over 60% of the dry season base flow in each watershed is groundwater sourced from heterogeneous aquifers. Municipal water supply in Huancayo already relies on 18 groundwater wells. Perceptions of water availability and actual water use practices remain relatively divorced from the actual water resources provided from each mountain range. Critical changes in glacier volume and water supply are not perceived or acknowledged consistently amongst different water users, nor reflected in water management decisions. In order to identify, understand, model, and adapt to climate-glacier-water changes, it is vital to integrate the analysis of water availability and groundwater processes (the domain of hydrologists) with that of water use (the focus for social scientists). Attention must be

  1. Bayesian spatiotemporal interpolation of rainfall in the Central Chilean Andes

    Science.gov (United States)

    Ossa-Moreno, Juan; Keir, Greg; McIntyre, Neil

    2016-04-01

    Water availability in the populous and economically significant Central Chilean region is governed by complex interactions between precipitation, temperature, snow and glacier melt, and streamflow. Streamflow prediction at daily time scales depends strongly on accurate estimations of precipitation in this predominantly dry region, particularly during the winter period. This can be difficult as gauged rainfall records are scarce, especially in the higher elevation regions of the Chilean Andes, and topographic influences on rainfall are not well understood. Remotely sensed precipitation and topographic products can be used to construct spatiotemporal multivariate regression models to estimate rainfall at ungauged locations. However, classical estimation methods such as kriging cannot easily accommodate the complicated statistical features of the data, including many 'no rainfall' observations, as well as non-normality, non-stationarity, and temporal autocorrelation. We use a separable space-time model to predict rainfall using the R-INLA package for computationally efficient Bayesian inference, using the gridded CHIRPS satellite-based rainfall dataset and digital elevation models as covariates. We jointly model both the probability of rainfall occurrence on a given day (using a binomial likelihood) as well as amount (using a gamma likelihood or similar). Correlation in space and time is modelled using a Gaussian Markov Random Field (GMRF) with a Matérn spatial covariance function which can evolve over time according to an autoregressive model if desired. It is possible to evaluate the GMRF at relatively coarse temporal resolution to speed up computations, but still produce daily rainfall predictions. We describe the process of model selection and inference using an information criterion approach, which we use to objectively select from competing models with various combinations of temporal smoothing, likelihoods, and autoregressive model orders.

  2. Two New Species of Black Flies (Diptera: Simuliidae) from the High Andes of Colombia.

    Science.gov (United States)

    Mantilla, Juan S; Moncada, Ligia I; Matta, Nubia E; Adler, Peter H

    2013-01-01

    The females, males, pupae, and larvae of two new species of Simulium are described and illustrated from a small stream 3950 m above sea level in the Lake Otún area of the Colombian Andes Mountains. Simulium (Pternaspatha) quimbayium n. sp. represents a 630-km northeastern extension of the distributional range of previously known members of the subgenus Pternaspatha, and Simulium (Psilopelmia) machetorum n. sp. represents the highest altitude recorded for a species of the subgenus Psilopelmia. These species illustrate the unique simuliid biodiversity in the páramo ecosystem of the high northern Andes.

  3. Thermochronology and tectonics of the Mérida Andes and the Santander Massif, NW South America

    Science.gov (United States)

    van der Lelij, Roelant; Spikings, Richard; Mora, Andrés

    2016-04-01

    New apatite U-Pb and multiphase 40Ar/39Ar data constrain the high to medium temperature (~ 500 °C-~ 300 °C) thermal histories of igneous and metamorphic rocks exposed in the Mérida Andes of Venezuela, and new apatite and zircon fission track data constrain the ~ 500 °C-~ 60 °C thermal histories of pre-Jurassic igneous and metamorphic rocks of the adjacent Santander Massif of Colombia. Computed thermal history envelopes using apatite U-Pb dates and grain size information from an Early Palaeozoic granodiorite in the Mérida Andes suggest that it cooled from > 500 °C to histories. The generally accepted timing of amalgamation of Pangaea along the Ouachita-Marathon suture pre-dates Late Permian to Triassic cooling recorded in basement rocks of the Mérida Andes by > 30 Ma, and its effect on rocks preserved in north-western South America is unknown. We interpret late Permian to Triassic cooling in the Mérida Andes to be driven by exhumation. Previous studies have suggested that a short phase of shortening and anatexis is recorded at ~ 253 Ma in the Maya Block, which may have been adjacent to the basement rocks of the Mérida Andes in the Late Permian. The coeval onset of exhumation in the Mérida Andes may be a result of increased coupling in the magmatic arc, which was located along the western margin of Pangaea. Triassic extension is documented in the Central Cordillera of Colombia and Ecuador between ~ 240 Ma and ~ 215 Ma, although extension at this time has not been clearly identified in the Mérida Andes or the Santander Massif. Permian to Triassic cooling is not recorded in the structurally isolated Caparo Block in the southern Mérida Andes, suggesting that it may have constituted a distinct fault block in the Triassic. New fission track data from the Santander Massif suggest that it started exhuming at ~ 40 Ma during a period of accelerated convergence between the Nazca/Farallòn Plate and the western margin of South America. Exhumation in the Santander

  4. Note---Naive Diversification and Portfolio Risk---A Note

    OpenAIRE

    Ron Bird; Mark Tippett

    1986-01-01

    A number of authors have used the portfolio standard deviation to model the risk reduction advantages of naive diversification. Other authors have pointed out that when risk is modelled by the portfolio's variance the modelling process becomes much simpler and is computationally more efficient. In this note we derive an exact parametric relationship between portfolio standard deviation and size and thus highlight the dangers of using the standard deviation in conjunction with O.L.S. regressio...

  5. Political Risk and the Benefits of International Portfolio Diversification

    OpenAIRE

    Jean-Claude Cosset; Jean-Marc Suret

    1995-01-01

    This paper examines the benefits of portfolio investment in the stock markets of politically risky countries by evaluating the effects of political risk constraints on the performance of a portfolio of international stocks. We use monthly data on political risk ratings and stock returns for a sample of thirty-six countries from April 1982 to December 1991. Ex-post and ex-ante portfolio selection strategies are developed to assess the gains from international diversification. Efficient sets ar...

  6. Diversification in China's Onshore Oil Industry Jumps Rapidly

    Institute of Scientific and Technical Information of China (English)

    Wang Huangjin

    1996-01-01

    @@ CNPC witnessed the rapid developments of diversification business through concerted efforts,leading to an encouraging prospect for synchronized growth of speed and economic benefits during the Eighth Five-Year Plan period. In 1995. CNPC scored from sales an income of 22.28billion yuan with a profits and taxes of 1.6 billion yuan, and had an cmployment of 452 000 people.

  7. Macroevolutionary dynamics in the early diversification of Asteraceae.

    Science.gov (United States)

    Panero, Jose L; Crozier, Bonnie S

    2016-06-01

    Spatial and temporal differences in ecological opportunity can result in disparity of net species diversification rates and consequently uneven distribution of taxon richness across the tree of life. The largest eudicotyledonous plant family Asteraceae has a global distribution and at least 460 times more species than its South American endemic sister family Calyceraceae. In this study, diversification rate dynamics across Asteraceae are examined in light of the several hypothesized causes for the family's evolutionary success that could be responsible for rate change. The innovations of racemose capitulum and pappus, and a whole genome duplication event occurred near the origin of the family, yet we found the basal lineages of Asteraceae that evolved in South America share background diversification rates with Calyceraceae and their Australasian sister Goodeniaceae. Instead we found diversification rates increased gradually from the origin of Asteraceae approximately 69.5Ma in the late Cretaceous through the Early Eocene Climatic Optimum at least. In contrast to earlier studies, significant rate shifts were not strongly correlated with intercontinental dispersals or polyploidization. The difference is due primarily to sampling more backbone nodes, as well as calibrations placed internally in Asteraceae that resulted in earlier divergence times than those found in most previous relaxed clock studies. Two clades identified as having transformed rate processes are the Vernonioid Clade and a clade within the Heliantheae alliance characterized by phytomelanic fruit (PF Clade) that represents an American radiation. In Africa, subfamilies Carduoideae, Pertyoideae, Gymnarrhenoideae, Cichorioideae, Corymbioideae, and Asteroideae diverged in a relatively short span of only 6.5millionyears during the Middle Eocene.

  8. KirCII- promising tool for polyketide diversification

    DEFF Research Database (Denmark)

    Musiol-Kroll, Ewa Maria; Härtner, Thomas; Kulik, Andreas;

    2014-01-01

    Kirromycin is produced by Streptomyces collinus Tü 365. This compound is synthesized by a large assembly line of type I polyketide synthases and non-ribosomal peptide synthetases (PKS I/NRPS), encoded by the genes kirAI-kirAVI and kirB. The PKSs KirAI-KirAV have no acyltransferase domains integra...... introducing the non-native substrates in an in vivo context. Thus, KirCII represents a promising tool for polyketide diversification....

  9. Tempo and mode of diversification of lake Tanganyika cichlid fishes.

    Directory of Open Access Journals (Sweden)

    Julia J Day

    Full Text Available BACKGROUND: Understanding the causes of disparities in species diversity across taxonomic groups and regions is a fundamental aim in evolutionary biology. Addressing these questions is difficult because of the need for densely sampled phylogenies and suitable empirical systems. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigate the cichlid fish radiation of Lake Tanganyika and show that per lineage diversification rates have been more than six times slower than in the species flocks of Lakes Victoria and Malawi. The result holds even at peak periods of diversification in Lake Tanganyika, ruling out the age of the lake as an explanation for slow average rates, and is robust to uncertainties over the calibration of cichlid radiations in geological time. Moreover, Lake Tanganyika lineages, irrespective of different biological characteristics (e.g. sexually dichromatic versus sexually monochromatic clades, have diversified at similar rates, falling within typical estimates across a range of plant and animal clades. For example, the mostly sexually dichromatic haplochromines, which have speciated explosively in Lakes Victoria and Malawi, have displayed modest rates in Lake Tanganyika (where they are called Tropheini. CONCLUSION/SIGNIFICANCE: Our results show that either the Lake Tanganyika environment is less conducive for cichlid speciation or the remarkable diversifying abilities of the haplochromines were inhibited by the prior occupancy of older radiations. Although the results indicate a dominant role for the environment in shaping cichlid diversification, differences in the timing of diversification among the Tanganyikan tribes indicate that biological differences were still important for the dynamics of species build-up in the lake. While we cannot resolve the timing of the radiation relative to the origin of the lake, because of the lack of robust geological date calibrations for cichlids, our results are consistent with a scenario that the

  10. Dietary innovations spurred the diversification of ruminants during the Caenozoic.

    Science.gov (United States)

    Cantalapiedra, Juan L; Fitzjohn, Richard G; Kuhn, Tyler S; Fernández, Manuel Hernández; DeMiguel, Daniel; Azanza, Beatriz; Morales, Jorge; Mooers, Arne Ø

    2014-02-07

    Global climate shifts and ecological flexibility are two major factors that may affect rates of speciation and extinction across clades. Here, we connect past climate to changes in diet and diversification dynamics of ruminant mammals. Using novel versions of Multi-State Speciation and Extinction models, we explore the most likely scenarios for evolutionary transitions among diets in this clade and ask whether ruminant lineages with different feeding styles (browsing, grazing and mixed feeding) underwent differential rates of diversification concomitant with global temperature change. The best model of trait change had transitions from browsers to grazers via mixed feeding, with appreciable rates of transition to and from grazing and mixed feeding. Diversification rates in mixed-feeder and grazer lineages tracked the palaeotemperature curve, exhibiting higher rates during the Miocene thermal maxima. The origination of facultative mixed diet and grazing states may have triggered two adaptive radiations--one during the Oligocene-Miocene transition and the other during Middle-to-Late Miocene. Our estimate of mixed diets for basal lineages of both bovids and cervids is congruent with fossil evidence, while the reconstruction of browser ancestors for some impoverished clades--Giraffidae and Tragulidae--is not. Our results offer model-based neontological support to previous palaeontological findings and fossil-based hypothesis highlighting the importance of dietary innovations--especially mixed feeding--in the success of ruminants during the Neogene.

  11. Structural change and agricultural diversification since China’s reforms

    Directory of Open Access Journals (Sweden)

    Lihua Li

    2017-01-01

    Full Text Available Structural change is considered the major engine in fostering a country’s growth. In the agricultural sector, diversification is the commonly used development strategy to increase rural sector’s flexibility, and to respond to improving technologies and market conditions. This study examined agricultural development and transformation during China’s socio-economic reforms. In particular, it empirically investigated whether the change of China’s agricultural structure is consistent with structural change theory and observed outcomes from other countries. The degree of agricultural diversification was quantitatively measured at a regional scale using the Herfindahl index. An underdeveloped province in northwest China was studied to provide insights into the interaction among structural change, agricultural diversification, and implemented development policies. Aggregate-level analyses suggest that China’s agricultural transformation pattern is consistent with those of other developing countries. A specific provincial-level analysis shows that environmentally and economically disadvantaged regions are slower to diversify their economy than better endorsed regions.

  12. Eocene diversification of crown group rails (Aves: Gruiformes: Rallidae).

    Science.gov (United States)

    García-R, Juan C; Gibb, Gillian C; Trewick, Steve A

    2014-01-01

    Central to our understanding of the timing of bird evolution is debate about an apparent conflict between fossil and molecular data. A deep age for higher level taxa within Neoaves is evident from molecular analyses but much remains to be learned about the age of diversification in modern bird families and their evolutionary ecology. In order to better understand the timing and pattern of diversification within the family Rallidae we used a relaxed molecular clock, fossil calibrations, and complete mitochondrial genomes from a range of rallid species analysed in a Bayesian framework. The estimated time of origin of Rallidae is Eocene, about 40.5 Mya, with evidence of intrafamiliar diversification from the Late Eocene to the Miocene. This timing is older than previously suggested for crown group Rallidae, but fossil calibrations, extent of taxon sampling and substantial sequence data give it credence. We note that fossils of Eocene age tentatively assigned to Rallidae are consistent with our findings. Compared to available studies of other bird lineages, the rail clade is old and supports an inference of deep ancestry of ground-dwelling habits among Neoaves.

  13. Eocene diversification of crown group rails (Aves: Gruiformes: Rallidae.

    Directory of Open Access Journals (Sweden)

    Juan C García-R

    Full Text Available Central to our understanding of the timing of bird evolution is debate about an apparent conflict between fossil and molecular data. A deep age for higher level taxa within Neoaves is evident from molecular analyses but much remains to be learned about the age of diversification in modern bird families and their evolutionary ecology. In order to better understand the timing and pattern of diversification within the family Rallidae we used a relaxed molecular clock, fossil calibrations, and complete mitochondrial genomes from a range of rallid species analysed in a Bayesian framework. The estimated time of origin of Rallidae is Eocene, about 40.5 Mya, with evidence of intrafamiliar diversification from the Late Eocene to the Miocene. This timing is older than previously suggested for crown group Rallidae, but fossil calibrations, extent of taxon sampling and substantial sequence data give it credence. We note that fossils of Eocene age tentatively assigned to Rallidae are consistent with our findings. Compared to available studies of other bird lineages, the rail clade is old and supports an inference of deep ancestry of ground-dwelling habits among Neoaves.

  14. Max-Sum Diversification, Monotone Submodular Functions and Dynamic Updates

    CERN Document Server

    Borodin, Allan; Ye, Yuli

    2012-01-01

    Result diversification has many important applications in databases, operations research, information retrieval, and finance. In this paper, we study and extend a particular version of result diversification, known as max-sum diversification. More specifically, we consider the setting where we are given a set of elements in a metric space and a set valuation function $f$ defined on every subset. For any given subset $S$, the overall objective is a linear combination of $f(S)$ and the sum of the distances induced by $S$. The goal is to find a subset $S$ satisfying some constraints that maximizes the overall objective. This problem is first studied by Gollapudi and Sharma for modular set functions and for sets satisfying a cardinality constraint. We consider an extension of the modular case to the monotone submodular case, for which the previous algorithm no longer applies. Interestingly, we are able to match the 2-approximation using a natural, but different greedy algorithm. We then further extend the problem...

  15. Tightly congruent bursts of lineage and phenotypic diversification identified in a continental ant radiation.

    Science.gov (United States)

    Price, Shauna L; Etienne, Rampal S; Powell, Scott

    2016-04-01

    Adaptive diversification is thought to be shaped by ecological opportunity. A prediction of this ecological process of diversification is that it should result in congruent bursts of lineage and phenotypic diversification, but few studies have found this expected association. Here, we study the relationship between rates of lineage diversification and body size evolution in the turtle ants, a diverse Neotropical clade. Using a near complete, time-calibrated phylogeny we investigated lineage diversification dynamics and body size disparity through model fitting analyses and estimation of per-lineage rates of cladogenesis and phenotypic evolution. We identify an exceptionally high degree of congruence between the high rates of lineage and body size diversification in a young clade undergoing renewed diversification in the ecologically distinct Chacoan biogeographical region of South America. It is likely that the region presented turtle ants with novel ecological opportunity, which facilitated a nested burst of diversification and phenotypic evolution within the group. Our results provide a compelling quantitative example of tight congruence between rates of lineage and phenotypic diversification, meeting the key predicted pattern of adaptive diversification shaped by ecological opportunity.

  16. Active orogeny of the south-central Andes studied with GPS geodesy Orogenia activa de los Andes centro-australes estudiada mediante geodesia de GPS

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    E. Kendrick

    2006-12-01

    Full Text Available We present GPS measurements of the crustal velocity field in the southern Central Andes between the Santa Cruz corner and the Malargüe fold and thrust belt, and model this interseismic velocity field as the combination of an ephemeral, elastic signal associated with locking of the main plate boundary, and a steady and non-reversing component of displacement associated with localized backarc convergence and growth of the mountain belt. We find that this second component, i.e. the ongoing and permanent displacement of the forearc and the high Andes relative to the craton, can be modeled very well as a steady clockwise rotation of an Andean microplate about a pole located in southern Argentina. Near the Malargüe Basin, this microplate (or block is moving nearly parallel to the strike of the orogen, transporting material towards the bend in the central Andes. Farther north, in the southern limb of the Central Andes, the motion of this same crustal block is directed nearly perpendicular to the strike of the mountain belt. Our results suggest that permanent deformation rates in the backarc range from a maximum of ~ 6-7 mm/yr in the Bolivian Subandes to less than ~ 3 mm/yr in the Argentine Precordillera and Malargue fold and thrust belt. It is likely that most active backarc deformation is accruing in a narrow zone (~ 50 km wide associated with the backarc boundary (usually defined as the thrust front though at this stage it is impossible to distinguish whether specific backarc structures are actively accruing strain.Se presentan mediciones GPS del campo de velocidad en los Andes centro-australes entre el extremo norte de Santa Cruz y la faja plegada de Malargüe. Se modela el campo de velocidad intersísmico como la combinación de una señal elástico/efímera asociada con el anclaje del límite principal de placas, y una componente constante, no reversible de desplazamiento asociada con una convergencia localizada en el retroarco y crecimiento del

  17. Evolución tectonomagmática de los Andes bolivianos Tectonomagmaticevolution of the Bolivian Andes

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    Néstor Jiménez

    2009-10-01

    Full Text Available Los Andes bolivianos ocuparonuna posición de retroarco durante gran parte del Fanerozoico. En su evoluciónse reconoce una primera etapa, restringida al Paleozoico inferior, en la quehubo una gran transferencia de material sedimentario en la corteza superior, yuna segunda en la que predominó el reciclaje de la masa cortical. A lo largodel Paleozoico inferior, una cuenca marina epicratónica se formó entre elcratón de Amazonia, el macizo Arequipa-Antofalla, y el macizo Pampeanofuncionando inicialmente como cuenca de retroarco y luego como cuenca deantepaís hasta colmatarse en el Paleozoico superior. En este lapso ocurrierontres etapas de deformación: La fase oclóyica (límite Ordovícico-Silúrico decarácter restringido, la fase eohercínica (límite Devónico-Carbonífero, y lafase hercínica (Carbonífero Superior también de influencia areal restringida.En el Mesozoico, se registraron aún breves incursiones marinas antes que en elEoceno comience a edificarse una protocordillera. El solevantamiento general detoda la región centroandina, se inició en el Oligoceno Superior afectando alAltiplano y la Cordillera Oriental actuales. Este solevantamiento ocurrió entres etapas limitadas por la formación de superficies de erosión datadas en 18y 10 Ma. La ladera oeste de la Cordillera Oriental, denominada faja de Huarina,tuvo un rol muy importante en la evolución de la región centroandina. Además decobijar a gran parte del magmatismo de retroarco, en esta faja ocurrió la mayorsubsidencia de la cuenca paleozoica. En esta faja ocurrieron preferentementedurante el Mesozoico, procesos de rifting y de adelgazamiento litosférico. Enel Paleógeno, la faja de Huarinas fue la primera en ser solevantada aislando lacuenca altiplánica del interior del continente, y durante el OligocenoSuperior, se constituyó en el cinturón retrocabalgante del orógeno. Ladeformación en el Altiplano y la Cordillera Oriental concluyó hace 10 Ma cuandose form

  18. Patterns of MHC-G-Like and MHC-B Diversification in New World Monkeys.

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    Juan S Lugo

    Full Text Available The MHC class I (MHC-I region in New World monkeys (Platyrrhini has remained relatively understudied. To evaluate the diversification patterns and transcription behavior of MHC-I in Platyrrhini, we first analyzed public genomic sequences from the MHC-G-like subregion in Saimiri boliviensis, Ateles geoffroyi and Callicebus moloch, and from the MHC-B subregion in Saimiri boliviensis. While S. boliviensis showed multiple copies of both MHC-G-like (10 and -B (15 loci, A. geoffroyi and C. moloch had only three and four MHC-G-like genes, respectively, indicating that not all Platyrrhini species have expanded their MHC-I loci. We then sequenced MHC-G-like and -B cDNAs from nine Platyrrhini species, recovering two to five unique cDNAs per individual for both loci classes. In two Saguinus species, however, no MHC-B cDNAs were found. In phylogenetic trees, MHC-G-like cDNAs formed genus-specific clusters whereas the MHC-B cDNAs grouped by Platyrrhini families, suggesting a more rapid diversification of the former. Furthermore, cDNA sequencing in 12 capuchin monkeys showed that they transcribe at least four MHC-G-like and five MHC-B polymorphic genes, showing haplotypic diversity for gene copy number and signatures of positive natural selection at the peptide binding region. Finally, a quantitative index for MHC:KIR affinity was proposed and tested to predict putative interacting pairs. Altogether, our data indicate that i MHC-I genes has expanded differentially among Platyrrhini species, ii Callitrichinae (tamarins and marmosets MHC-B loci have limited or tissue-specific expression, iii MHC-G-like genes have diversified more rapidly than MHC-B genes, and iv the MHC-I diversity is generated mainly by genetic polymorphism and gene copy number variation, likely promoted by natural selection for ligand binding.

  19. The large universal Pantoea plasmid LPP-1 plays a major role in biological and ecological diversification

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    De Maayer Pieter

    2012-11-01

    Full Text Available Abstract Background Pantoea spp. are frequently isolated from a wide range of ecological niches and have various biological roles, as plant epi- or endophytes, biocontrol agents, plant-growth promoters or as pathogens of both plant and animal hosts. This suggests that members of this genus have undergone extensive genotypic diversification. One means by which this occurs among bacteria is through the acquisition and maintenance of plasmids. Here, we have analyzed and compared the sequences of a large plasmid common to all sequenced Pantoea spp. Results and discussion The Large PantoeaPlasmids (LPP-1 of twenty strains encompassing seven different Pantoea species, including pathogens and endo-/epiphytes of a wide range of plant hosts as well as insect-associated strains, were compared. The LPP-1 plasmid sequences range in size from ~281 to 794 kb and carry between 238 and 750 protein coding sequences (CDS. A core set of 46 proteins, encompassing 2.2% of the total pan-plasmid (2,095 CDS, conserved among all LPP-1 plasmid sequences, includes those required for thiamine and pigment biosynthesis. Phylogenetic analysis reveals that these plasmids have arisen from an ancestral plasmid, which has undergone extensive diversification. Analysis of the proteins encoded on LPP-1 also showed that these plasmids contribute to a wide range of Pantoea phenotypes, including the transport and catabolism of various substrates, inorganic ion assimilation, resistance to antibiotics and heavy metals, colonization and persistence in the host and environment, pathogenesis and antibiosis. Conclusions LPP-1 is universal to all Pantoea spp. whose genomes have been sequenced to date and is derived from an ancestral plasmid. LPP-1 encodes a large array of proteins that have played a major role in the adaptation of the different Pantoea spp. to their various ecological niches and their specialization as pathogens, biocontrol agents or benign saprophytes found in many diverse

  20. Evolution of crustal thickening in the central Andes, Bolivia

    Science.gov (United States)

    Eichelberger, Nathan; McQuarrie, Nadine; Ryan, Jamie; Karimi, Bobak; Beck, Susan; Zandt, George

    2015-09-01

    Paleoelevation histories from the central Andes in Bolivia have suggested that the geodynamic evolution of the region has been punctuated by periods of large-scale lithospheric removal that drive rapid increases in elevation at the surface. Here, we evaluate viable times and locations of material loss using a map-view reconstruction of the Bolivian orocline displacement field to forward-model predicted crustal thicknesses. Two volumetric models are presented that test assumed pre-deformation crustal thicknesses of 35 km and 40 km. Both models predict that modern crustal thicknesses were achieved first in the northern Eastern Cordillera (EC) by 30-20 Ma but remained below modern in the southern EC until ≤10 Ma. The Altiplano is predicted to have achieved modern crustal thickness after 10 Ma but only with a pre-deformation thickness of 50 km, including 10 km of sediment. At the final stage, the models predict 8-25% regional excess crustal volume compared to modern thickness, largely concentrated in the northern EC. The excess predicted volume from 20 to 0 Ma can be accounted for by: 1) crustal flow to the WC and/or Peru, 2) localized removal of the lower crust, or 3) a combination of the two. Only models with initial crustal thicknesses >35 km predict excess volumes sufficient to account for potential crustal thickness deficits in Peru and allow for lower crustal loss. However, both initial thickness models predict that modern crustal thicknesses were achieved over the same time periods that paleoelevation histories indicate the development of modern elevations. Localized removal of lower crust is only necessary in the northern EC where crustal thickness exceeds modern by 20 Ma, prior to paleoelevation estimates of modern elevations by 15 Ma. In the Altiplano, crustal thicknesses match modern values at 10 Ma and can only exceed modern values by 5 Ma, post-dating when modern elevations were thought to have been established. Collectively, these models predict that

  1. A millennium of metallurgy recorded by lake sediments from Morococha, Peruvian Andes.

    Science.gov (United States)

    Cooke, Colin A; Abbott, Mark B; Wolfe, Alexander P; Kittleson, John L

    2007-05-15

    To date, information concerning pre-Colonial metallurgy in South America has largely been limited to the archaeological record of artifacts. Here, we reconstruct a millennium of smelting activity in the Peruvian Andes using the lake-sediment stratigraphy of atmospherically derived metals (Pb, Zn, Cu, Ag, Sb, Bi, and Ti) and lead isotopic ratios (206Pb/ 207Pb) associated with smelting from the Morococha mining region in the central Peruvian Andes. The earliest evidence for metallurgy occurs ca. 1000 A.D., coinciding with the fall of the Wari Empire and decentralization of local populations. Smelting during this interval appears to have been aimed at copper and copper alloys, because of large increases in Zn and Cu relative to Pb. A subsequent switch to silver metallurgy under Inca control (ca. 1450 to conquest, 1533 A.D.) is indicated by increases in Pb, Sb, and Bi, a conclusion supported by further increases of these metals during Colonial mining, which targeted silver extraction. Rapid development of the central Andes during the 20th century raised metal burdens by an order of magnitude above previous levels. Our results represent the first evidence for pre-Colonial smelting in the central Peruvian Andes, and corroborate the sensitivity of lake sediments to pre-Colonial metallurgical activity suggested by earlier findings from Bolivia.

  2. Cloud forest restoration for erosion control in a Kichwa community of the Ecuadorian central Andes Mountains

    Science.gov (United States)

    Backus, L.; Giordanengo, J.; Sacatoro, I.

    2013-12-01

    The Denver Professional Chapter of Engineers Without Borders (EWB) has begun conducting erosion control projects in the Kichwa communities of Malingua Pamba in the Andes Mountains south of Quito, Ecuador. In many high elevation areas in this region, erosion of volcanic soils on steep hillsides (i.e., teach these skills to adjacent villages.

  3. High altitude C4 grasslands in the northern Andes: relicts from glacial conditions?

    NARCIS (Netherlands)

    Boom, A.; Mora, G.; Cleef, A.M.; Hooghiemstra, H.

    2001-01-01

    The altitudinal vegetation distribution in the northern Andes during glacial time differed from the present-day conditions as a result of temperature and precipitation change. New evidence indicate that as a response to a reduced atmospheric partial CO2 pressure (pCO2), the competitive balance betwe

  4. Deformation, deposition, and surface uplift in the hinterland of the Central Andes, Bolivia

    Science.gov (United States)

    Leier, A.; McQuarrie, N.; Garzione, C. N.; Eiler, J. M.

    2011-12-01

    Paleoelevation histories from mountain belts like the Central Andes of Bolivia provide important constraints on the timing and geodynamic mechanisms associated with surface uplift. New stable isotope data from paleosol carbonate nodules in the Altiplano and Eastern Cordillera of the Central Andes of Bolivia indicate a previously undocumented episode of surface uplift occurred in the region between ca. 24 and 17 Ma. Oxygen isotope and clumped-isotope thermometry values from paleosol carbonate in strata >24 Ma suggest paleoelevations as low as sea-level. Paleosol carbonate in strata ca. 17 Ma have oxygen isotope and clumped-isotope thermometry values, which using modern lapse rates, indicate an increase in elevation of approximately 3 km. Relatively undeformed Oligocene and Miocene strata overlap faulted Paleozoic rocks of the Bolivian Eastern Cordillera, indicating deposition and surface uplift post-dated and was decoupled from upper crustal deformation. Together, geological data from the area record an initial period of deformation and exhumation, a subsequent period of sediment deposition and overlap, and then an episode of surface uplift that was not accompanied by upper crustal deformation. We propose accommodation for the Oligocene-Miocene strata was associated with mantle and lowermost crustal processes, and the subsequent increase in surface elevation was an isostatic response to removal of dense material through delamination or drip. Combined with existing data sets in the Central Andes, these new data suggest multiple, regionally-variable, and diachronous periods of surface uplift occurred within the Central Andes during the Cenozoic Era.

  5. Bank Diversification Effects on Bank Performance and Risk Profile of Bank in Indonesia

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    Anthony Lukmawijaya

    2015-05-01

    Full Text Available We investigate the relationship of Indonesian bank diversification towards its long term performance and risk profile with Indonesian bank data from 2009 to 2013. Non-interest income to total operating income of the bank measures its bank diversification level. Bank value is measured by the adjusted Tobin's Q and risk profile which is broken down into total risk, idiosyncratic risk, and systematic risk. The result shows that bank non-interest income diversification has a positive influence on its franchise value. There is, however, no strong evidence that diversification can lower a bank's risk profile.

  6. Research on Ways to Promote Diversification of Ballroom Dancing in Institutions of Higher Education---A Case Study of Guangdong Institute of Science and Technology%普通高等院校交谊舞多元化推广的途径研究--以广东科学技术职业学院为例

    Institute of Scientific and Technical Information of China (English)

    李群凤

    2015-01-01

    The purpose of college physical education is to improve students’physical quality,cultivate their habits of doing sports, promote their physical and mental development and develop their lifelong sportsconsciousness.As a healthy culture and sports activity and an international social activity,ballroom dancing is animportant program in popularizing Sunshine Physical Education Curriculum and P.E.curriculum reform oncollege campus.Ballroom dancing is an effective way to develop physical and mental health of contemporarycollege students,the best form of meeting actual physical needs of contemporary college students and the best wayof cultivating lifelong sports consciousness of contemporary college students.This paper explores ways to promotediversification of ballroom dancing on college campus to provide a useful reference for popularization of ballroomdancing and P.E.curriculum reform in institutions of higher education.%高校体育教学的宗旨是提高学生的体质水平,培养大学生的体育习惯,促进大学生身心健康发展,培养学生的终身体育意识。交谊舞是一项健康的文化体育活动,也是一项国际性的社交活动。作为高校阳光体育活动推广和高校体育课程改革重点引入的运动项目,交谊舞是当代大学生身心发展的有效途径;是满足当代大学生实际体育需求的最好形式;是培养当代大学生终身体育意识的最佳方式。探索交谊舞在高校多元化的推广途径,为当前高校交谊舞的普及和高校体育课程的改革提供有益参考。

  7. Hydrological cycles and trends in the NW Argentine Andes since 1940

    Science.gov (United States)

    Castino, Fabiana; Bookhagen, Bodo; Strecker, Manfred

    2016-04-01

    Strong spatiotemporal variability characterizes the hydrometeorological pattern in the NW Argentine Andes, draining parts of the most populated and economically important areas of South America. During the summer monsoon season (DJF), the eastern flanks of the central Andes are characterized by deep convection, exposing them to extreme hydrometeorological events. These often result in floods and landslides with disastrous effects on the local populations. Here, we analyze river discharge to explore long-term hydrological variability in NW Argentine Andes and the linked climate controlling processes. We rely on 13 daily river discharge time series relevant to drainage basins spanning several size orders (102-104 km2) starting in 1914 and define different hydro-climate indices both for the mean and the extreme hydrological events. We apply quantile regression to investigate long-term trends and spectral analysis associated with cross-correlation with SST-based climate indices to identify links to large-scale climate variability modes. River discharge presents a pronounced and coherent variability signal in South America, particularly for wide drainage basins, such as the Amazon and Paraná/La Plata rivers, strongly associated to Pacific and Atlantic Oceans Sea Surface Temperature (SST) anomalies (i.e. ENSO, PDO, AMO). Our analysis evidences that in the NW Argentine Andes, mean discharge values are characterized by statistically significant, mostly positive, long-term trends since 1940, whereas the extreme events present a more non-unidirectional trend pattern. Also, coherent multi-annual to multi-decadal cycles characterizing the discharge pattern have been identified, suggesting that processes linked to SST anomaly-modes strongly control the hydrometeorology variability in the NW Argentina Andes.

  8. Episodic subgreenschist facies metamorphism in the Andes of Chile - is it a valid model?

    Science.gov (United States)

    Bevins, R. E.; Robinson, D.; Aguirre, L.; Vergara, M.

    2003-04-01

    The Central Andes of Chile are characterized by subgreenschist facies burial metamorphism that is reported as having developed in up to seven episodic cycles of some 40Myr duration. The main evidence in support of the model is reported as mineralogical breaks at major stratigraphic boundaries that are interpreted as documenting sharp breaks in metamorphic grade. Here we test this model by examination of the progressive secondary mineral development, reaction progress in mafic phyllosilicates, and topological variations of the low-grade assemblages in metabasites for Jurassic to Miocene sequences east of Santiago. The mafic phyllosilicates (smectite - mixed-layer chlorite/smectite - chlorite) show increasing reaction progress with stratigraphic age and there is a continuum across the main stratigraphic boundaries, such there is no offset or gap in the reaction progress at these boundaries. There are some differences in mineral assemblages between the various stratigraphic units, such as between prehnite+pumpellyite+/-laumonite or amphibole-bearing and non amphibole bearing rocks, from which contrasting subgreenschist facies can be recognised. However, consideration of the controls on mineral parageneses at subgreenschist facies conditions demonstrates that these different facies cannot be used solely as evidence of sharp breaks in metamorphic grade at unconformities, as has been reported in many previous publications for the Andes. The presently accepted model for the Central Andes, involving repeated cycles of episodic metamorphism developing in extensional basins, is, therefore, partly unfounded. Consideration of the overall tectonic evolution of this part of the Andes concurs that the burial metamorphism developed in extensional settings, but in only two events, namely in mid-late Cretaceous and Late Miocene times respectively. The results from this work suggest that the record of sharp metamorphic breaks and the episodic model of metamorphism reported for many

  9. Reconstructing web evolution and spider diversification in the molecular era.

    Science.gov (United States)

    Blackledge, Todd A; Scharff, Nikolaj; Coddington, Jonathan A; Szüts, Tamas; Wenzel, John W; Hayashi, Cheryl Y; Agnarsson, Ingi

    2009-03-31

    The evolutionary diversification of spiders is attributed to spectacular innovations in silk. Spiders are unique in synthesizing many different kinds of silk, and using silk for a variety of ecological functions throughout their lives, particularly to make prey-catching webs. Here, we construct a broad higher-level phylogeny of spiders combining molecular data with traditional morphological and behavioral characters. We use this phylogeny to test the hypothesis that the spider orb web evolved only once. We then examine spider diversification in relation to different web architectures and silk use. We find strong support for a single origin of orb webs, implying a major shift in the spinning of capture silk and repeated loss or transformation of orb webs. We show that abandonment of costly cribellate capture silk correlates with the 2 major diversification events in spiders (1). Replacement of cribellate silk by aqueous silk glue may explain the greater diversity of modern orb-weaving spiders (Araneoidea) compared with cribellate orb-weaving spiders (Deinopoidea) (2). Within the "RTA clade," which is the sister group to orb-weaving spiders and contains half of all spider diversity, >90% of species richness is associated with repeated loss of cribellate silk and abandonment of prey capture webs. Accompanying cribellum loss in both groups is a release from substrate-constrained webs, whether by aerially suspended webs, or by abandoning webs altogether. These behavioral shifts in silk and web production by spiders thus likely played a key role in the dramatic evolutionary success and ecological dominance of spiders as predators of insects.

  10. Origin and diversification of wings: Insights from a neopteran insect.

    Science.gov (United States)

    Medved, Victor; Marden, James H; Fescemyer, Howard W; Der, Joshua P; Liu, Jin; Mahfooz, Najmus; Popadić, Aleksandar

    2015-12-29

    Winged insects underwent an unparalleled evolutionary radiation, but mechanisms underlying the origin and diversification of wings in basal insects are sparsely known compared with more derived holometabolous insects. In the neopteran species Oncopeltus fasciatus, we manipulated wing specification genes and used RNA-seq to obtain both functional and genomic perspectives. Combined with previous studies, our results suggest the following key steps in wing origin and diversification. First, a set of dorsally derived outgrowths evolved along a number of body segments including the first thoracic segment (T1). Homeotic genes were subsequently co-opted to suppress growth of some dorsal flaps in the thorax and abdomen. In T1 this suppression was accomplished by Sex combs reduced, that when experimentally removed, results in an ectopic T1 flap similar to prothoracic winglets present in fossil hemipteroids and other early insects. Global gene-expression differences in ectopic T1 vs. T2/T3 wings suggest that the transition from flaps to wings required ventrally originating cells, homologous with those in ancestral arthropod gill flaps/epipods, to migrate dorsally and fuse with the dorsal flap tissue thereby bringing new functional gene networks; these presumably enabled the T2/T3 wing's increased size and functionality. Third, "fused" wings became both the wing blade and surrounding regions of the dorsal thorax cuticle, providing tissue for subsequent modifications including wing folding and the fit of folded wings. Finally, Ultrabithorax was co-opted to uncouple the morphology of T2 and T3 wings and to act as a general modifier of hindwings, which in turn governed the subsequent diversification of lineage-specific wing forms.

  11. Evolving Phytoplankton Stoichiometry Fueled Diversification of the Marine Biosphere

    Directory of Open Access Journals (Sweden)

    Antonietta Quigg

    2012-05-01

    Full Text Available The availability of nutrients and the quantity and quality of food at the base of food webs have largely been ignored in discussions of the Phanerozoic record of biodiversity. We examine the role of nutrient availability and phytoplankton stoichiometry (the relative proportions of inorganic nutrients to carbon in the diversification of the marine biosphere. Nutrient availability and phytoplankton stoichiometry played a critical role in the initial diversification of the marine biosphere during the Neoproterozoic. Initial biosphere expansion during this time resulted in the massive sequestration of nutrients into biomass which, along with the geologically slow input of nutrients from land, set the stage for severe nutrient limitation and relatively constant marine biodiversity during the rest of the Paleozoic. Given the slow nutrient inputs from land and low recycling rates, the growth of early-to-middle Paleozoic metazoans remained limited by their having to expend energy to first “burn off” (respire excess carbon in food before the associated nutrients could be utilized for growth and reproduction; the relative equilibrium in marine biodiversity during the Paleozoic therefore appears to be real. Limited nutrient availability and the consequent nutrient imbalance may have delayed the appearance of more advanced carnivores until the Permo-Carboniferous, when widespread orogeny, falling sea level, the spread of forests, greater weathering rates, enhanced ocean circulation, oxygenation, and upwelling all combined to increase nutrient availability. During the Meso-Cenozoic, rising oxygen levels, the continued nutrient input from land, and, especially, increasing rates of bioturbation, enhanced nutrient availability, increasing the nutrient content of phytoplankton that fueled the diversification of the Modern Fauna.

  12. Origins, Innovations, and Diversification of Suction Feeding in Vertebrates.

    Science.gov (United States)

    Wainwright, Peter C; McGee, Matthew D; Longo, Sarah J; Hernandez, L Patricia

    2015-07-01

    We review the origins, prominent innovations, and major patterns of diversification in suction feeding by vertebrates. Non-vertebrate chordates and larval lamprey suspension-feed by capturing small particles in pharyngeal mucous. In most of these lineages the gentle flows that transport particles are generated by buccal cilia, although larval lamprey and thaliacean urochordates have independently evolved a weak buccal pump to generate an oscillating flow of water that is powered by elastic recovery of the pharynx following compression by buccal muscles. The evolution of jaws and the hyoid facilitated powerful buccal expansion and high-performance suction feeding as found today throughout aquatic vertebrates. We highlight three major innovations in suction feeding. Most vertebrate suction feeders have mechanisms that occlude the corners of the open mouth during feeding. This produces a planar opening that is often nearly circular in shape. Both features contribute to efficient flow of water into the mouth and help direct the flow to the area directly in front of the mouth's aperture. Among several functions that have been identified for protrusion of the upper jaw, is an increase in the hydrodynamic forces that suction feeders exert on their prey. Protrusion of the upper jaw has evolved five times in ray-finned fishes, including in two of the most successful teleost radiations, cypriniforms and acanthomorphs, and is found in about 60% of living teleost species. Diversification of the mechanisms of suction feeding and of feeding behavior reveals that suction feeders with high capacity for suction rarely approach their prey rapidly, while slender-bodied predators with low capacity for suction show the full range of attack speeds. We hypothesize that a dominant axis of diversification among suction feeders involves a trade-off between the forces that are exerted on prey and the volume of water that is ingested.

  13. The Impact of Organismal Innovation on Functional and Ecological Diversification.

    Science.gov (United States)

    Wainwright, Peter C; Price, Samantha A

    2016-09-01

    Innovations in organismal functional morphology are thought to be a major force in shaping evolutionary patterns, with the potential to drive adaptive radiation and influence the evolutionary prospects for lineages. But the evolutionary consequences of innovation are diverse and usually do not result in adaptive radiation. What factors shape the macroevolutionary impact of innovations? We assert that little is known in general about the macroevolutionary outcomes associated with functional innovations and we discuss a framework for studying biological innovations in an evolutionary context. Innovations are novel functional mechanisms that enhance organismal performance. The ubiquity of trade-offs in functional systems means that enhanced performance on one axis often occurs at the expense of performance on another axis, such that many innovations result in an exchange of performance capabilities, rather than an expansion. Innovations may open up new resources for exploitation but their consequences for functional and ecological diversification depend heavily on the adaptive landscape around these novel resources. As an example of a broader program that we imagine, we survey five feeding innovations in labrid fishes, an exceptionally successful and ecologically diverse group of reef fishes, and explore their impact on the rate of evolution of jaw functional morphology. All of the innovations provide performance enhancements and result in changes in patterns of resource use, but most are not associated with subsequent functional diversification or substantial ecological diversification. Because selection acts on a specific performance enhancement and not on the evolutionary potential of an innovation, the enhancement of diversity may be highly serendipitous. The macroevolutionary potential of innovations depends critically on the interaction between the performance enhancement and the ecological opportunity that is exposed.

  14. Analysis of Advantages and Disadvantages in Diversification Strategy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Diversification Strategy, or called Multi-operatio ns Strategy, means the strategy taken by enterprises engaging two or more kinds of material or labor products for different economic uses in the same time. It is H.Igor Ansoff who was a great economics master famous with his Product-mark et Strategy theory announced in the 1950's. Coming out of practice of some others, we may draw a conclusion that it looks li ke each of enterprise expansions reduces operating-risk. But in fact, the enter prise probab...

  15. Continuous and Jump Betas: Implications for Portfolio Diversification

    Directory of Open Access Journals (Sweden)

    Vitali Alexeev

    2016-06-01

    Full Text Available Using high-frequency data, we decompose the time-varying beta for stocks into beta for continuous systematic risk and beta for discontinuous systematic risk. Estimated discontinuous betas for S&P500 constituents between 2003 and 2011 generally exceed the corresponding continuous betas. We demonstrate how continuous and discontinuous betas decrease with portfolio diversification. Using an equiweighted broad market index, we assess the speed of convergence of continuous and discontinuous betas in portfolios of stocks as the number of holdings increase. We show that discontinuous risk dissipates faster with fewer stocks in a portfolio compared to its continuous counterpart.

  16. The reinforcing influence of recommendations on global diversification

    CERN Document Server

    Zeng, An; Shang, Mingsheng; Zhang, Yi-Cheng

    2011-01-01

    Recommender systems are promising ways to filter the overabundant information in modern society. Their algorithms help individuals to explore decent items, but it is unclear how they allocate popularity among items. In this paper, we simulate successive recommendations and measure their influence on the dispersion of item popularity by Gini coefficient. Our result indicates that local diffusion and collaborative filtering reinforce the popularity of hot items, widening the popularity dispersion. On the other hand, the heat conduction algorithm increases the popularity of the niche items and generates smaller dispersion of item popularity. Simulations are compared to mean-field predictions. Our results suggest that recommender systems have reinforcing influence on global diversification.

  17. Screening for new accumulator plants in Andes Range mines

    Science.gov (United States)

    Bech, Jaume; Roca, Núria

    2016-04-01

    accumulated considerable concentrations of Cu and Zn. The species from the genus Bidens (Asteraceae) were able not only to accumulate high shoot As concentrations (> 1000 μg g-1 in B. cynapiifolia from Peru) but also considerable amounts of Pb (B. humilis from Chile). The highest Cu shoot concentrations were found in Mullinum spinosum (870 μg g-1) and in B. cynapiifolia (620 μg g-1). The shoot accumulation of Zn was highest in Baccharis amdatensis (>1900 μg g-1) and in Rumex crispus (1300 μg g-1) from the Ag mine in Ecuador (Bech et al., 2002). In the Peruvian Andes, B. triplinervia can be considered interesting for phytostabilization, due to its capacity to restrict the accumulation of elevated amounts of Pb and Zn in the shoots.

  18. The Largest Holocene Eruption of the Central Andes Found

    Science.gov (United States)

    Fernandez-Turiel, J.; Rodriguez-Gonzalez, A.; Saavedra, J.; Perez-Torrado, F.; Carracedo, J.; Osterrieth, M.; Carrizo, J.; Esteban, G.

    2013-12-01

    We present new data and interpretation about a major eruption -spreading ˜110 km3 ashes over 440.000 km2- long thought to have occurred around 4200 years ago in the Cerro Blanco Volcanic Complex (CBVC) in NW Argentina. This eruption may be the biggest during the past five millennia in the Central Volcanic Zone of the Andes, and possibly one of the largest Holocene eruptions in the world. The environmental effects of this voluminous eruption are still noticeable, as evidenced by the high content of arsenic and other trace elements in the groundwaters of the Chacopampean Plain. The recognition of this significant volcanic event may shed new light on interpretations of critical changes observed in the mid-Holocene paleontological and archaeological records, and offers researchers an excellent, extensive regional chronostratigraphic marker for reconstructing mid-Holocene geological history over a wide geographical area of South America. More than 100 ashes were sampled in Argentina, Chile and Uruguay during different field campaigns. Ash samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), grain size distributions laser diffraction, and geochemically by electron microprobe (EMPA) and laser ablation-HR-ICP-MS. New and published 14C ages were calibrated to calendar years BP. The age of the most recent CBVC eruption is 4407-4093 cal y BP, indirectly dated by 14C of associated organic sediment within the lower part of a proximal fall deposit of this event (26°53'16.05"S-67°44'48.68"W). This is the youngest record of a major volcanic event in the Southern Puna. This age is consistent with other radiocarbon dates of organic matter in palaeosols underlying or overlying distal ash fall deposits. Based on their products, all of rhyolitic composition, we have distinguished 8 main episodes during the evolution of the most recent CBVC eruption: 1) the eruption began with a white rhyolite lava dome extrusion; 2) followed by a Plinian

  19. Lake Andes National Wildlife Refuge Waterfowl Production Area District: Narrative report: January 1 through December 31, 1966

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR- Waterfowl Production Area District outlines Refuge accomplishments during the 1966 calendar year. The report begins...

  20. Fort Niobrara Easement Refuges: Lake Andes, Lake Arconge, Carr, Eagle Creek: May 1, 1942 to August 31, 1942

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report summarizes activities on Lake Andes NWR between May and August of 1942. Lake Arconge Refuge, Carr Refuge, and Eagle Creek Refuge are also...

  1. Fort Niobrara Easement Refuges: Lake Andes, Lake Arconge, Carr, Eagle Creek: Narrative report: Sept. to Dec. 1943

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report summarizes activities on Lake Andes, Lake Arconge, Carr, and Eagle Creek Refuges between September and December of 1943. Weather conditions,...

  2. Assessing adaptation – Climate change and indigenous livelihood in the Andes of Bolivia

    Directory of Open Access Journals (Sweden)

    Marolyn Vidaurre de la Riva

    2013-12-01

    Full Text Available Based on a case study of Charazani – Bolivia, this article outlines the understanding of adaptive strategies to cope with climate change and its impact on environmental and socioeconomic conditions that are affecting rural livelihoods. Mainly qualitative methods were used to collect and analyze data following the framework for vulnerability assessments of a socio-ecological system. Climate data reveals an increase of precipitation and temperature during the last decades. Furthermore the occurrence of extreme weather events, particularly drought, frost, hailstorms and consequently landslides and fire are increasing. Local testimonies highlight these events as the principle reasons for agricultural losses. This climatic variability and simultaneous social changes were identified as the drivers of vulnerability. Yet, several adaptive measures were identified at household, community and external levels in order to cope with such vulnerability; e.g. traditional techniques in agriculture and risk management. Gradually, farmers complement these activities with contemporary practices in agriculture, like intensification of land use, diversification of irrigation system and use of artificial fertilizers. As part of a recent trend community members are forced to search for new off-farm alternatives beyond agriculture for subsistence. Despite there is a correspondingly large array of possible adaptation measures that families are implementing, local testimonies point out, that farmers often do not have the capacity and neither the economical resources to mitigate the risk in agricultural production. Although several actions are already considered to promote further adaptive capacity, the current target is to improve existing livelihood strategies by reducing vulnerability to hazards induced by climate change.

  3. Genetic Diversification and Dispersal of Taro (Colocasia esculenta (L.) Schott).

    Science.gov (United States)

    Chaïr, H; Traore, R E; Duval, M F; Rivallan, R; Mukherjee, A; Aboagye, L M; Van Rensburg, W J; Andrianavalona, V; Pinheiro de Carvalho, M A A; Saborio, F; Sri Prana, M; Komolong, B; Lawac, F; Lebot, V

    2016-01-01

    Taro (Colocasia esculenta (L.) Schott) is widely distributed in tropical and sub-tropical areas. However, its origin, diversification and dispersal remain unclear. While taro genetic diversity has been documented at the country and regional levels in Asia and the Pacific, few reports are available from Americas and Africa where it has been introduced through human migrations. We used eleven microsatellite markers to investigate the diversity and diversification of taro accessions from nineteen countries in Asia, the Pacific, Africa and America. The highest genetic diversity and number of private alleles were observed in Asian accessions, mainly from India. While taro has been diversified in Asia and the Pacific mostly via sexual reproduction, clonal reproduction with mutation appeared predominant in African and American countries investigated. Bayesian clustering revealed a first genetic group of diploids from the Asia-Pacific region and to a second diploid-triploid group mainly from India. Admixed cultivars between the two genetic pools were also found. In West Africa, most cultivars were found to have originated from India. Only one multi-locus lineage was assigned to the Asian pool, while cultivars in Madagascar originated from India and Indonesia. The South African cultivars shared lineages with Japan. The Caribbean Islands cultivars were found to have originated from the Pacific, while in Costa Rica they were from India or admixed between Indian and Asian groups. Taro dispersal in the different areas of Africa and America is thus discussed in the light of available records of voyages and settlements.

  4. Ubiquity of Polynucleobacter necessarius subspecies asymbioticus results from ecological diversification.

    Science.gov (United States)

    Jezbera, Jan; Jezberová, Jitka; Brandt, Ulrike; Hahn, Martin W

    2011-04-01

    The subspecies Polynucleobacter necessarius asymbioticus (> 99% 16S rRNA similarity) has a cosmopolitan distribution and a ubiquitous occurrence in lentic freshwater habitats. We tested if the observed ubiquity of these free-living planktonic freshwater bacteria results from a euryoecious (generalist) adaptation of P. n. asymbioticus strains, or from ecological diversification within the subspecies. We developed a reverse line blot hybridization assay enabling the cultivation-independent detection of 13 groups within the subspecies in environmental samples. A set of 121 lentic freshwater habitats, spanning a broad variety of habitat types (e.g. pH levels ranging from 3.8 to 8.5) was investigated for the presence of these 13 P. n. asymbioticus groups. Statistical analyses of the reverse line blot hybridization detections revealed pronounced differences in habitat preferences of several of the groups. Their preferences differed regarding pH, conductivity, dissolved organic carbon and oxygen concentration of habitats. For some groups, differences in environmental preferences resulted even in complete niche separation between them. The revealed differences in habitat preferences suggest that the previously reported ubiquity of P. n. asymbioticus results from ecological diversification within the taxon and not from generalist adaptation of strains.

  5. A model for the evolutionary diversification of religions.

    Science.gov (United States)

    Doebeli, Michael; Ispolatov, Iaroslav

    2010-12-21

    We address the problem of cultural diversification by studying selection on cultural ideas that colonize human hosts and using diversification of religions as a conceptual example. In analogy to studying the evolution of pathogens or symbionts colonizing animal hosts, we use models for host-pathogen dynamics known from theoretical epidemiology. In these models, religious content colonizes individual humans. Rates of transmission of ideas between humans, i.e., transmission of cultural content, and rates of loss of ideas (loss of belief) are determined by the phenotype of the cultural content, and by interactions between hosts carrying different ideas. In particular, based on the notion that cultural non-conformism can be negative frequency-dependent (for example, religion can lead to oppression of lower classes and emergence of non-conformism and dissent once a religious belief has reached dominance), we assume that the rate of loss of belief increases as the number of humans colonized by a particular religious phenotype increases. This generates frequency-dependent selection on cultural content, and we use evolutionary theory to show that this frequency dependence can lead to the emergence of coexisting clusters of different cultural types. The different clusters correspond to different cultural traditions, and hence our model describes the emergence of distinct descendant cultures from a single ancestral culture in the absence of any geographical isolation.

  6. Genetic Diversification and Dispersal of Taro (Colocasia esculenta (L. Schott.

    Directory of Open Access Journals (Sweden)

    H Chaïr

    Full Text Available Taro (Colocasia esculenta (L. Schott is widely distributed in tropical and sub-tropical areas. However, its origin, diversification and dispersal remain unclear. While taro genetic diversity has been documented at the country and regional levels in Asia and the Pacific, few reports are available from Americas and Africa where it has been introduced through human migrations. We used eleven microsatellite markers to investigate the diversity and diversification of taro accessions from nineteen countries in Asia, the Pacific, Africa and America. The highest genetic diversity and number of private alleles were observed in Asian accessions, mainly from India. While taro has been diversified in Asia and the Pacific mostly via sexual reproduction, clonal reproduction with mutation appeared predominant in African and American countries investigated. Bayesian clustering revealed a first genetic group of diploids from the Asia-Pacific region and to a second diploid-triploid group mainly from India. Admixed cultivars between the two genetic pools were also found. In West Africa, most cultivars were found to have originated from India. Only one multi-locus lineage was assigned to the Asian pool, while cultivars in Madagascar originated from India and Indonesia. The South African cultivars shared lineages with Japan. The Caribbean Islands cultivars were found to have originated from the Pacific, while in Costa Rica they were from India or admixed between Indian and Asian groups. Taro dispersal in the different areas of Africa and America is thus discussed in the light of available records of voyages and settlements.

  7. A statistical design for testing apomictic diversification through linkage analysis.

    Science.gov (United States)

    Zeng, Yanru; Hou, Wei; Song, Shuang; Feng, Sisi; Shen, Lin; Xia, Guohua; Wu, Rongling

    2014-03-01

    The capacity of apomixis to generate maternal clones through seed reproduction has made it a useful characteristic for the fixation of heterosis in plant breeding. It has been observed that apomixis displays pronounced intra- and interspecific diversification, but the genetic mechanisms underlying this diversification remains elusive, obstructing the exploitation of this phenomenon in practical breeding programs. By capitalizing on molecular information in mapping populations, we describe and assess a statistical design that deploys linkage analysis to estimate and test the pattern and extent of apomictic differences at various levels from genotypes to species. The design is based on two reciprocal crosses between two individuals each chosen from a hermaphrodite or monoecious species. A multinomial distribution likelihood is constructed by combining marker information from two crosses. The EM algorithm is implemented to estimate the rate of apomixis and test its difference between two plant populations or species as the parents. The design is validated by computer simulation. A real data analysis of two reciprocal crosses between hickory (Carya cathayensis) and pecan (C. illinoensis) demonstrates the utilization and usefulness of the design in practice. The design provides a tool to address fundamental and applied questions related to the evolution and breeding of apomixis.

  8. Down-side Risk Metrics as Portfolio Diversification Strategies across the GFC

    NARCIS (Netherlands)

    D.E. Allen (David); M.J. McAleer (Michael); R.J. Powell (Robert); A.K. Singh (Abhay)

    2015-01-01

    textabstractThis paper features an analysis of the effectiveness of a range of portfolio diversification strategies, with a focus on down-side risk metrics, as a portfolio diversification strategy in a European market context. We apply these measures to a set of daily arithmetically compounded retur

  9. The Impact of Business Diversification on Performance of IDX Listed Firms

    Directory of Open Access Journals (Sweden)

    Ony Humarseno

    2013-07-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE This study analyzes the correlation between business diversification and performances in Indonesian listed companies from 2006-2011. In addition to observing business diversification impact on company’s performance in term of Return on Assets (ROA and Tobin’s Q, this research also observes the business diversification impact on the performances of different companies at different level. The result of this research indicates that diversification gives negative effect to ROA and Tobin’s Q, while for higher level of diversification, the effect on Tobin’s Q is relatively high. The negative effect of diversification on ROA is higher in the group of companies with higher ROA. The different results show that when using Tobin’s Q as a measure of companies’ performances, diversification gives negative impact to companies’ performance in the intermediate level.   Keywords: Diversification, companies’ performance, ROA, quantile regression, Tobin’s Q

  10. 7 CFR 4290.740 - Portfolio diversification (“overline” limitation).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Portfolio diversification (âoverlineâ limitation). 4290.740 Section 4290.740 Agriculture Regulations of the Department of Agriculture (Continued) RURAL... Enterprise for Rbic Financing § 4290.740 Portfolio diversification (“overline” limitation). (a) Without...

  11. 13 CFR 107.740 - Portfolio diversification (“overline” limitation).

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Portfolio diversification (âoverlineâ limitation). 107.740 Section 107.740 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION... Eligibility of A Small Business for Sbic Financing § 107.740 Portfolio diversification (“overline”...

  12. Phylogeny and tempo of diversification in the superradiation of spiny-rayed fishes.

    Science.gov (United States)

    Near, Thomas J; Dornburg, Alex; Eytan, Ron I; Keck, Benjamin P; Smith, W Leo; Kuhn, Kristen L; Moore, Jon A; Price, Samantha A; Burbrink, Frank T; Friedman, Matt; Wainwright, Peter C

    2013-07-30

    Spiny-rayed fishes, or acanthomorphs, comprise nearly one-third of all living vertebrates. Despite their dominant role in aquatic ecosystems, the evolutionary history and tempo of acanthomorph diversification is poorly understood. We investigate the pattern of lineage diversification in acanthomorphs by using a well-resolved time-calibrated phylogeny inferred from a nuclear gene supermatrix that includes 520 acanthomorph species and 37 fossil age constraints. This phylogeny provides resolution for what has been classically referred to as the "bush at the top" of the teleost tree, and indicates acanthomorphs originated in the Early Cretaceous. Paleontological evidence suggests acanthomorphs exhibit a pulse of morphological diversification following the end Cretaceous mass extinction; however, the role of this event on the accumulation of living acanthomorph diversity remains unclear. Lineage diversification rates through time exhibit no shifts associated with the end Cretaceous mass extinction, but there is a global decrease in lineage diversification rates 50 Ma that occurs during a period when morphological disparity among fossil acanthomorphs increases sharply. Analysis of clade-specific shifts in diversification rates reveal that the hyperdiversity of living acanthomorphs is highlighted by several rapidly radiating lineages including tunas, gobies, blennies, snailfishes, and Afro-American cichlids. These lineages with high diversification rates are not associated with a single habitat type, such as coral reefs, indicating there is no single explanation for the success of acanthomorphs, as exceptional bouts of diversification have occurred across a wide array of marine and freshwater habitats.

  13. Architecting product diversification - Formalizing variability dependencies in software product family engineering

    NARCIS (Netherlands)

    Jaring, M; Bosch, J; Ehrich, HD; Schewe, KD

    2004-01-01

    In a software product family context, software architects design architectures that support product diversification in both space (multiple contexts) and time (changing contexts). Product diversification is based on the concept of variability: a single architecture and a set of components support a

  14. Expressing product diversification - Categorizing and classifying variability in software product family engineering

    NARCIS (Netherlands)

    Jaring, M; Bosch, J

    2004-01-01

    In a software product family context, software architects design architectures that support product diversification in both space (multiple contexts) and time (changing contexts). Product diversification is based on the concept of variability: a single architecture and a set of components support a

  15. Diversification of tanagers, a species rich bird group, from lowlands to montane regions of South America

    DEFF Research Database (Denmark)

    Fjeldså, Jon; Rahbek, Carsten

    2006-01-01

    of intensive speciation throughout the evolutionary history of the group, and species richness patterns here seem largely to be driven by the rate of speciation, with further diversification from the highlands into adjacent lowlands. The diversification process in montane areas may be related to high...

  16. Create Better Diversified High-Conviction Equity Portfolios using the Portfolio Diversification Index

    NARCIS (Netherlands)

    D.P. Crezée (Dominiek); L.A.P. Swinkels (Laurens)

    2010-01-01

    textabstractWe investigate the construction of well-diversified high-conviction equity portfolios, building on Rudin and Morgan (2006) who introduced the Portfolio Diversification Index (PDI) as a new measure of portfolio diversification applied to long/short equity hedge funds in an in-sample perio

  17. Patterns of diversification in islands: A comparative study across three gecko genera in the Socotra Archipelago.

    Science.gov (United States)

    Garcia-Porta, Joan; Morales, Hernán E; Gómez-Díaz, Elena; Sindaco, Roberto; Carranza, Salvador

    2016-05-01

    In this study we used the complete fauna of geckos of the Socotra Archipelago to test whether the three gecko genera co-occurring in the islands (Pristurus, Hemidactylus and Haemodracon) produced similar outcomes of morphological and climatic diversification. To test this, we produced a time-calibrated tree of 346 geckos including all 16 endemic species of the archipelago and 26 potential close-relatives in the continent. Our dating estimates revealed that most of the diversity of geckos in the archipelago was the consequence of in situ diversification. However not all genera shared similar patterns of diversification. While in Hemidactylus and Haemodracon this involved great differences in body size and low levels of climatic diversification (mostly involving sympatric distributions), an opposite pattern appeared in Pristurus in which most of the diversification involved shifts in climatic envelopes (mostly involving allopatric and parapatric distributions) but almost no size differentiation. Consistently with this, Pristurus was the only genus in which rates of size diversification in islands were substantially lower than in the continent. This illustrates how different groups can greatly differ in their patterns of intra-island diversification and highlights the importance of taxon-dependent factors at determining different patterns of diversification in the same insular context.

  18. Divergence and diversification in North American Psoraleeae (Fabaceae due to climate change

    Directory of Open Access Journals (Sweden)

    Crandall Keith A

    2008-12-01

    Full Text Available Abstract Background Past studies in the legume family (Fabaceae have uncovered several evolutionary trends including differential mutation and diversification rates across varying taxonomic levels. The legume tribe Psoraleeae is shown herein to exemplify these trends at the generic and species levels. This group includes a sizable diversification within North America dated at approximately 6.3 million years ago with skewed species distribution to the most recently derived genus, Pediomelum, suggesting a diversification rate shift. We estimate divergence dates of North American (NAm Psoraleeae using Bayesian MCMC sampling in BEAST based on eight DNA regions (ITS, waxy, matK, trnD-trnT, trnL-trnF, trnK, trnS-trnG, and rpoB-trnC. We also test the hypothesis of a diversification rate shift within NAm Psoraleeae using topological and temporal methods. We investigate the impact of climate change on diversification in this group by (1 testing the hypothesis that a shift from mesic to xeric habitats acted as a key innovation and (2 investigating diversification rate shifts along geologic time, discussing the impact of Quaternary climate oscillations on diversification. Results NAm Psoraleeae represents a recent, rapid radiation with several genera originating during the Pleistocene, 1 to 2 million years ago. A shift in diversification rate is supported by both methods with a 2.67-fold increase suggested around 2 million years ago followed by a 8.73-fold decrease 440,000 years ago. The hypothesis that a climate regime shift from mesic to xeric habitats drove increased diversification in affected taxa was not supported. Timing of the diversification rate increase supports the hypothesis that glaciation-induced climate changes during the Quaternary influenced diversification of the group. Nonrandom spatial diversification also exists, with greater species richness in the American Southwest. Conclusion This study outlines NAm Psoraleeae as a model example

  19. Temporal patterns of diversification in Andean Eois, a species-rich clade of moths (Lepidoptera, Geometridae).

    Science.gov (United States)

    Strutzenberger, P; Fiedler, K

    2011-04-01

    The timing of the origin of present day Neotropical animal diversity is still a matter of debate. For a long time, a preponderance of glacial (i.e. Pleistocene) radiations has been proposed. However, recent data from molecular clock studies indicate a preglacial origin for most of the examined taxa. We performed a fossil-calibrated molecular dating analysis of the genus Eois, which is a major component of one of the world's most diverse assemblages of herbivorous insects. We found that diversification of Eois took place in the Miocene following a pattern best explained by density-dependent diversification. A strong slowdown of diversification towards the present was detected. Diversification of Eois does overlap with increased Andean uplift and diversification of the most commonly used host plant genus Piper. These findings match the patterns found for the majority of Neotropical tetrapods and for three other unrelated, ecologically different lepidopteran genera.

  20. Size, Diversification and Risk: Preliminary Evidence from Commercial Banks in Pakistan

    Directory of Open Access Journals (Sweden)

    Ayesha Afzal

    2012-12-01

    Full Text Available The aim of this paper is to provide some preliminary evidence on relation between size, diversification and risk in commercial banks of Pakistan. Using a panel of Pakistani banks, we investigated whether bigger banks are better diversified than smaller banks.The results suggested that larger banks were more diversified than their smaller counterparts mainly on account of their outreach and size of credit portfolio. On the risk side, based on accounting and market based risk measures, we explored if there is any impact of diversification on risk. We could not deduce significant result in favor of accounting risk measure of impaired lending signaling that banks find no incentive in diversification of credit books. The market based measures of VaR and Default indicator were significantly related to diversification signifying that market participants consider diversification as a relevant tool for risk mitigation. These findings have policy implications for regulators and risk management to ensure stability in financial system.

  1. Interseismic Rates From the CTO cGPS Andes and Nepal Networks

    Science.gov (United States)

    Genrich, J. F.; Galetzka, J.; Chowdhury, F.; Avouac, J.; Simons, M.; Barrientos, S. E.; Comte, D.; Norabuena, E. O.; Sapkota, S. N.

    2009-12-01

    To study crustal deformation at converging plate margins the Caltech Tectonics Observatory (CTO), together with partner institutions in the host countries, operates continuously observing GPS stations in the central Andes (northern Chile and southern Peru) and in Nepal. The currently 20-site Andes network was established in 2005 with 7 stations. Efforts are underway to provide data streaming links at near real time for the majority of sites. The Nepal network started with 10 sites in 2004 and has been expanded to 23 sites in the last couple of years. Dual frequency code and phase data from all sites are processed with the GAMIT/GLOBK processing package. Reliable interseismic velocities are now available for the majority of sites. Network metadata, rinex data files, processed time series and velocity estimates can be found online thru links at the CTO website: tectonics.caltech.edu.

  2. Illicit crops and armed conflict as constraints on biodiversity conservation in the Andes region.

    Science.gov (United States)

    Fjeldså, Jon; Alvarez, María D; Lazcano, Juan Mario; León, Blanca

    2005-05-01

    Coca, once grown for local consumption in the Andes, is now produced for external markets, often in areas with armed conflict. Internationally financed eradication campaigns force traffickers and growers to constantly relocate, making drug-related activities a principal cause of forest loss. The impact on biodiversity is known only in general terms, and this article presents the first regional analysis to identify areas of special concern, using bird data as proxy. The aim of conserving all species may be significantly constrained in the Santa Marta and Perijá mountains, Darién, some parts of the Central Andes in Colombia, and between the middle Marañón and middle Huallaga valleys in Peru. Solutions to the problem must address the root causes: international drug markets, long-lasting armed conflict, and lack of alternative income for the rural poor.

  3. Surface uplift in the Central Andes driven by growth of the Altiplano Puna Magma Body

    Science.gov (United States)

    Perkins, Jonathan P.; Ward, Kevin M.; de Silva, Shanaka L.; Zandt, George; Beck, Susan L.; Finnegan, Noah J.

    2016-10-01

    The Altiplano-Puna Magma Body (APMB) in the Central Andes is the largest imaged magma reservoir on Earth, and is located within the second highest orogenic plateau on Earth, the Altiplano-Puna. Although the APMB is a first-order geologic feature similar to the Sierra Nevada batholith, its role in the surface uplift history of the Central Andes remains uncertain. Here we show that a long-wavelength topographic dome overlies the seismically measured extent of the APMB, and gravity data suggest that the uplift is isostatically compensated. Isostatic modelling of the magmatic contribution to dome growth yields melt volumes comparable to those estimated from tomography, and suggests that the APMB growth rate exceeds the peak Cretaceous magmatic flare-up in the Sierran batholith. Our analysis reveals that magmatic addition may provide a contribution to surface uplift on par with lithospheric removal, and illustrates that surface topography may help constrain the magnitude of pluton-scale melt production.

  4. Climate change and water resources in arid mountains: an example from the Bolivian Andes.

    Science.gov (United States)

    Rangecroft, Sally; Harrison, Stephan; Anderson, Karen; Magrath, John; Castel, Ana Paola; Pacheco, Paula

    2013-11-01

    Climate change is projected to have a strongly negative effect on water supplies in the arid mountains of South America, significantly impacting millions of people. As one of the poorest countries in the region, Bolivia is particularly vulnerable to such changes due to its limited capacity to adapt. Water security is threatened further by glacial recession with Bolivian glaciers losing nearly half their ice mass over the past 50 years raising serious water management concerns. This review examines current trends in water availability and glacier melt in the Bolivian Andes, assesses the driving factors of reduced water availability and identifies key gaps in our knowledge of the Andean cryosphere. The lack of research regarding permafrost water sources in the Bolivian Andes is addressed, with focus on the potential contribution to mountain water supplies provided by rock glaciers.

  5. Approximate Bayesian Computation of diversification rates from molecular phylogenies : introducing a new efficient summary statistic, the nLTT

    NARCIS (Netherlands)

    Janzen, Thijs; Hoehna, Sebastian; Etienne, Rampal S.

    2015-01-01

    Molecular phylogenies form a potential source of information on rates of diversification, and the mechanisms that underlie diversification patterns. Diversification models have become increasingly complex over the past decade, and we have reached a point where the computation of the analytical likel

  6. 政府干预和内部人控制与企业多元化研究%Reseach on Government Intervention, Internal Control and Enterprises' Diversification

    Institute of Scientific and Technical Information of China (English)

    高燕燕; 黄国良

    2015-01-01

    Diversification should berestricted by enterprises' resources, which aims at making full use of remaining resources. Under the system background of"government intervention" coexisting with "internal control", government and the internal would influence the enterprises' diversification strategy by resources to realize their own interests. This paper gives a systematic review and summary of relevant literatures about the impact of government intervention and internal control on the enterprise resources and diversification. Then the paper proposes that it should bring government intervention, internal control as well as enterprise resources into the research frame of diversification to reflect the dynamic relationships among them; It should expand the research content to the degree of government and the internal influencing on diversification mode and how to regulate their behavior and diversification mode to promote enterprises' value;Moreover, it should improve the measuring method of resources as well as compare the change before and after the share splitting reform.%多元化作为企业剩余资源的配置活动要受到企业资源的制约。在“政府干预”和“内部人控制”并存的制度背景下,政府和内部人为实现自身的利益要求,有能力也有动力利用掌控的资源对国有企业的多元化战略施加影响。文章系统梳理和总结了政府干预、内部人控制对企业资源和多元化经营影响的相关文献,提出:研究框架上应突破单一视角的藩篱,将政府干预、内部人控制和企业资源同时纳入多元化的研究框架,反映它们之间的动态关系;研究内容上应在政府和内部人对多元化模式的影响程度以及如何规范他们的行为和企业多元化模式方面加以扩展;研究深度上应在资源的测度方法、股改前后政府和内部人影响多元化的动机、模式和效果是有所变化等方面加以深入。

  7. Predators shape distribution and promote diversification of morphological defenses in Leucorrhinia , Odonata

    Science.gov (United States)

    Petrin, Zlatko; Schilling, Emily Gaenzle; Loftin, Cyndy; Johansson, Frank

    2010-01-01

    Predators strongly influence species assemblages and shape morphological defenses of prey. Interestingly, adaptations that constitute effective defenses against one type of predator may render the prey susceptible to other types of predators. Hence, prey may evolve different strategies to escape predation, which may facilitate adaptive radiation of prey organisms. Larvae of different species in the dragonfly genus Leucorrhinia have various morphological defenses. We studied the distribution of these larvae in relation to the presence of predatory fish. In addition, we examined the variation in morphological defenses within species with respect to the occurrence of fish. We found that well-defended species, those with more and longer spines, were more closely associated with habitats inhabited by predatory fish and that species with weakly developed morphological defenses were more abundant in habitats without fish. The species predominantly connected to lakes with or without fish, respectively, were not restricted to a single clade in the phylogeny of the genus. Our data is suggestive of phenotypic plasticity in morphological defense in three of the studied species since these species showed longer spines in lakes with fish. We suggest that adaptive phenotypic plasticity may have broadened the range of habitats accessible to Leucorrhinia. It may have facilitated colonization of new habitats with different types of predators, and ultimately, speciation through adaptive radiation.

  8. Population diversification in a yeast metabolic program promotes anticipation of environmental shifts.

    Science.gov (United States)

    Venturelli, Ophelia S; Zuleta, Ignacio; Murray, Richard M; El-Samad, Hana

    2015-01-01

    Delineating the strategies by which cells contend with combinatorial changing environments is crucial for understanding cellular regulatory organization. When presented with two carbon sources, microorganisms first consume the carbon substrate that supports the highest growth rate (e.g., glucose) and then switch to the secondary carbon source (e.g., galactose), a paradigm known as the Monod model. Sequential sugar utilization has been attributed to transcriptional repression of the secondary metabolic pathway, followed by activation of this pathway upon depletion of the preferred carbon source. In this work, we demonstrate that although Saccharomyces cerevisiae cells consume glucose before galactose, the galactose regulatory pathway is activated in a fraction of the cell population hours before glucose is fully consumed. This early activation reduces the time required for the population to transition between the two metabolic programs and provides a fitness advantage that might be crucial in competitive environments.

  9. Population diversification in a yeast metabolic program promotes anticipation of environmental shifts.

    Directory of Open Access Journals (Sweden)

    Ophelia S Venturelli

    2015-01-01

    Full Text Available Delineating the strategies by which cells contend with combinatorial changing environments is crucial for understanding cellular regulatory organization. When presented with two carbon sources, microorganisms first consume the carbon substrate that supports the highest growth rate (e.g., glucose and then switch to the secondary carbon source (e.g., galactose, a paradigm known as the Monod model. Sequential sugar utilization has been attributed to transcriptional repression of the secondary metabolic pathway, followed by activation of this pathway upon depletion of the preferred carbon source. In this work, we demonstrate that although Saccharomyces cerevisiae cells consume glucose before galactose, the galactose regulatory pathway is activated in a fraction of the cell population hours before glucose is fully consumed. This early activation reduces the time required for the population to transition between the two metabolic programs and provides a fitness advantage that might be crucial in competitive environments.

  10. 78 FR 2934 - Promoting Diversification of Ownership in the Broadcasting Services

    Science.gov (United States)

    2013-01-15

    ... August 14, 2009, there were about 10,660 (96 percent) of 11,100 commercial radio stations in the United..., by commercial overnight courier, or by first-class or overnight U.S. Postal Service mail. All filings.... Any envelopes and boxes must be disposed of before entering the building. Commercial overnight...

  11. 76 FR 7719 - Promoting Diversification of Ownership in the Broadcasting Services

    Science.gov (United States)

    2011-02-11

    ... adopted at 73 FR 28361, May 16, 2008, are effective on March 14, 2011. FOR FURTHER INFORMATION CONTACT... Docket Nos. 01-235, 01-317, 00-244; FCC 07-217, 73 FR 28361, May 16, 2008. Synopsis As required by the... hours and burden costs published in the Federal Register on October 13, 2010, 75 FR 62816 have...

  12. 75 FR 27199 - Promoting Diversification of Ownership in the Broadcasting Services

    Science.gov (United States)

    2010-05-14

    ... Communications Commission published in the Federal Register of May 16, 2008 (73 FR 28361), a Report and Order... rules in 47 CFR 73.3555 and 73.5008 published at 73 FR 28361, May 16, 2008, related to steps the...'s Third Erratum, FCC 10-49, adopted March 29, 2010 and released March 29, 2010. In FR Doc....

  13. Climate-driven diversification in two widespread Galerida larks

    Directory of Open Access Journals (Sweden)

    Crochet Pierre-André

    2008-01-01

    Full Text Available Abstract Background The major impact of Plio-Pleistocene climatic oscillations on the current genetic structure of many species is widely recognised but their importance in driving speciation remains a matter of controversies. In addition, since most studies focused on Europe and North America, the influence of many other biogeographic barriers such as the Sahara remains poorly understood. In this paper, climate-driven diversification was investigated by using a comparative phylogeographic approach in combination with phenotypic data in two avian species groups distributed on both sides of the deserts belt of Africa and Asia. In particular, we tested whether: 1 vicariance diversification events are concomitant with past climatic events; and 2 current ecological factors (using climate and competition as proxies contribute to phenotypic divergence between allopatric populations. Results Mitochondrial and nuclear sequence data indicated that the crested and Thekla lark species groups diverged in the early Pliocene and that subsequent speciation events were congruent with major late Pliocene and Pleistocene climatic events. In particular, steep increase in aridity in Africa near 2.8 and 1.7 million years ago were coincident with two north-south vicariance speciation events mediated by the Sahara. Subsequent glacial cycles of the last million years seem to have shaped patterns of genetic variation within the two widespread species (G. cristata and G. theklae. The Sahara appears to have allowed dispersal from the tropical areas during climatic optima but to have isolated populations north and south of it during more arid phases. Phenotypic variation did not correlate with the history of populations, but was strongly influenced by current ecological conditions. In particular, our results suggested that (i desert-adapted plumage evolved at least three times and (ii variation in body size was mainly driven by interspecific competition, but the response

  14. Biogeography and diversification of Brassicales: A 103million year tale.

    Science.gov (United States)

    Cardinal-McTeague, Warren M; Sytsma, Kenneth J; Hall, Jocelyn C

    2016-06-01

    Brassicales is a diverse order perhaps most famous because it houses Brassicaceae and, its premier member, Arabidopsis thaliana. This widely distributed and species-rich lineage has been overlooked as a promising system to investigate patterns of disjunct distributions and diversification rates. We analyzed plastid and mitochondrial sequence data from five gene regions (>8000bp) across 151 taxa to: (1) produce a chronogram for major lineages in Brassicales, including Brassicaceae and Arabidopsis, based on greater taxon sampling across the order and previously overlooked fossil evidence, (2) examine biogeographical ancestral range estimations and disjunct distributions in BioGeoBEARS, and (3) determine where shifts in species diversification occur using BAMM. The evolution and radiation of the Brassicales began 103Mya and was linked to a series of inter-continental vicariant, long-distance dispersal, and land bridge migration events. North America appears to be a significant area for early stem lineages in the order. Shifts to Australia then African are evident at nodes near the core Brassicales, which diverged 68.5Mya (HPD=75.6-62.0). This estimated age combined with fossil evidence, indicates that some New World clades embedded amongst Old World relatives (e.g., New World capparoids) are the result of different long distance dispersal events, whereas others may be best explained by land bridge migration (e.g., Forchhammeria). Based on these analyses, the Brassicaceae crown group diverged in Europe/Northern Africa in the Eocene, circa 43.4Mya (HPD=46.6-40.3) and Arabidopsis separated from close congeners circa 10.4Mya. These ages fall between divergent dates that were previously published, suggesting we are slowly converging on a robust age estimate for the family. Three significant shifts in species diversification are observed in the order: (1) 58Mya at the crown of Capparaceae, Cleomaceae and Brassicaceae, (2) 38Mya at the crown of Resedaceae+Stixis clade, and

  15. Unexpectedly high beta-diversity of root-associated fungal communities in the Bolivian Andes

    DEFF Research Database (Denmark)

    Barnes, Christopher James; Maldonado Goyzueta, Carla Brenda; Frøslev, Tobias Guldberg;

    2016-01-01

    Bolivia is one of the most biologically diverse countries on the planet. Between the Andes and the Amazon drainage basin spans the Yungas, a vast forested region shown to be extremely species rich in macro-organisms. However, it remains unclear whether this high diversity is also reflected in mic...... root-associated fungal diversity in subtropical regions. This study sheds further light on the diversity and distribution of the world's "hidden biodiversity"....

  16. Cryptococcus gattii meningoencephalitis in an HIV-negative patient from the Peruvian Andes

    OpenAIRE

    Gutierrez, Ericson L.; Valqui,Willi; Vilchez,Luis; Evangelista,Lourdes; Crispin,Sarita; Tello,Mercedes; Ñavincopa,Marcos; Béjar,Vilma; Gonzáles,José; Alex G. Ortega-Loayza

    2010-01-01

    We report a case of an immunocompetent Peruvian patient from the Andes with a one-month history of meningoencephalitis. Cryptococcus gattii was identified from a cerebrospinal fluid culture through assimilation of D-proline and D-tryptophan as the single nitrogen source. Initially, the patient received intravenous antifungal therapy with amphotericin B. The patient was discharged 29 days after hospitalization and continued with oral fluconazole treatment for ten weeks. During this period, the...

  17. Active orogeny of the south-central Andes studied with GPS geodesy

    Directory of Open Access Journals (Sweden)

    E. Kendrick

    2006-12-01

    Full Text Available We present GPS measurements of the crustal velocity field in the southern Central Andes between the Santa Cruz corner and the Malargüe fold and thrust belt, and model this interseismic velocity field as the combination of an ephemeral, elastic signal associated with locking of the main plate boundary, and a steady and non-reversing component of displacement associated with localized backarc convergence and growth of the mountain belt. We find that this second component, i.e. the ongoing and permanent displacement of the forearc and the high Andes relative to the craton, can be modeled very well as a steady clockwise rotation of an Andean microplate about a pole located in southern Argentina. Near the Malargüe Basin, this microplate (or block is moving nearly parallel to the strike of the orogen, transporting material towards the bend in the central Andes. Farther north, in the southern limb of the Central Andes, the motion of this same crustal block is directed nearly perpendicular to the strike of the mountain belt. Our results suggest that permanent deformation rates in the backarc range from a maximum of ~ 6-7 mm/yr in the Bolivian Subandes to less than ~ 3 mm/yr in the Argentine Precordillera and Malargue fold and thrust belt. It is likely that most active backarc deformation is accruing in a narrow zone (~ 50 km wide associated with the backarc boundary (usually defined as the thrust front though at this stage it is impossible to distinguish whether specific backarc structures are actively accruing strain.

  18. Adenovirus Vectors Expressing Hantavirus Proteins Protect Hamsters against Lethal Challenge with Andes Virus ▿

    OpenAIRE

    2009-01-01

    Hantaviruses infect humans following aerosolization from rodent feces and urine, producing hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Due to the high rates of mortality and lack of therapies, vaccines are urgently needed. Nonreplicating adenovirus (Ad) vectors that express Andes hantavirus (ANDV) nucleocapsid protein (AdN) or glycoproteins (AdGN and AdGC) were constructed. Ad vectors were tested for their ability to protect Syrian hamsters from a lethal ANDV infe...

  19. La implantación de la viruela en los Andes, la historia de un holocausto

    Directory of Open Access Journals (Sweden)

    Uriel García Cáceres

    2003-03-01

    Full Text Available La historia de las epidemias de viruela en los Andes tiene el carácter tétrico del relato de un holocausto. Esta presentación está destinada a resaltar las etapas más importantes del proceso de la implantación de la viruela en las poblaciones andinas en general y, en particular, en el Perú, desde principio del siglo XVI hasta nuestros días.

  20. Foreland shortening and crustal balancing in the Andes at 30°S latitude

    Science.gov (United States)

    Allmendinger, R. W.; Figueroa, D.; Synder, D.; Beer, J.; Mpodozis, C.; Isaacks, B. L.

    1990-08-01

    Excellent surface exposures, known Benioff zone geometry, a dynamic morphology, and the availability of industry seismic reflection data all make the Andes at 30°S an excellent transect for investigating crustal-scale balanced sections. 150-170 km of horizontal shortening has occurred in three major belts located between the trench and the foreland. The thin-skinned, east-verging Precordillera of western Argentina accounts for 60-75% of the total shortening and formed mostly since major volcanism ceased at ˜10 Ma. Industry seismic reflection data show that the décollement of the Precordillera belt is located anomalously deep at ˜15 km. The belt is dominated by fault propagation folds and contains several prominent out-of-sequence thrust faults. Seismic stratigraphie analysis shows that Miocene strata in the Iglesia Valley, located between the Precordillera and the crest of the Andes, accumulated in a piggy-back basin. Onlap relations on the western side indicate that the High Cordillera was uplifted as a major fault bend fold over a buried ramp. Thrusting in the two western belts, both in the High Cordillera of Chile, formed during the waning stages of arc volcanism, 11-16 Ma. and account for 25-40% of the shortening. The observed shortening is probably greater than can be accounted for with reasonable crustal thicknesses, indicating the possibility of continental truncation or erosion along the plate margin or an anomalously thick root held down by the nearly flat subducted Nazca Plate. Our preferred crustal geometry puts the ramp between upper and lower crustal deformation west of the high topography, requiring crustal scale tectonic wedging to thicken the crust beneath the crest of the Andes. This non-unique model provides a simple explanation of the first order morphology of the Andes at this latitude.

  1. Late Quaternary deglacial history of the Mérida Andes, Venezuela

    Science.gov (United States)

    Stansell, Nathan D.; Abbott, Mark B.; Polissar, Pratigya J.; Wolfe, Alexander P.; Bezada, Maximiliano; Rull, Valentí

    2005-10-01

    Radiocarbon-dated sediment cores from seven lakes and two bogs spanning the Cordillera de Mérida in the Venezuelan Andes were used to identify and date the regional history of late Pleistocene and Holocene glacial activity. Coring sites were selected at different elevations across a pronounced rain shadow from southeast (wet) to northwest (dry). Sediment lithostratigraphy and magnetic susceptibility, in conjunction with AMS radiocarbon dates on macrofossils and charcoal, were used to constrain deglaciation. The local expression of the Last Glacial Maximum occurred between 22 750 and 19 960 cal. yr BP. On the wetter southeastern side of the Cordillera de Mérida, glaciers had significantly retreated by 15 700 cal. yr BP, followed by several minor glacial advances and retreats between 14 850 and 13 830 cal. yr BP. At least one major glacial readvance occurred between 13 830 and 10 000 cal. yrBP in the wetter southeastern sector of the region. The drier northwest side of the Cordillera de Mérida records initial glacial retreat by 14240cal.yrBP. Multiple sites on both sides of the Mérida Andes record a further phase of extensive deglaciation approximately 10000cal.yrBP. However, the north-northwest facing Mucubají catchment remained partially glaciated until ca. 6000cal.yrBP. Deglacial ages from the Venezuelan Andes are consistently younger than those reported from the Southern Hemisphere Andes, suggesting an inter-hemispheric deglacial lag in the northern tropics of the order of two thousand years.

  2. Desarrollo del programa de Doctorado en Ingeniería en la Universidad de los Andes

    Directory of Open Access Journals (Sweden)

    2009-05-01

    Full Text Available La Memoria, que la Revista de Ingeniería presenta en este número, recuenta el proceso de constitución del programa de doctorado en la Facultad de Ingeniería de la Universidad de los Andes, el cual cumple en 2009 una década de formación de profesionales a nivel doctoral.

  3. A plastic rheology phenomenological 201 . model that explains the Andes evolution in northern Argentina

    OpenAIRE

    Introcaso, Antonio; Giménez, Mario; Martínez, María Patricia; Ruiz, Francisco

    2012-01-01

    A plastic rheology, partially phenomenological model is presented to explain the isostatically compensated Andean relief formation. This model considers a combination of lithospheric heating with long period relaxation and successive crustal shortenings on a north section of Argentina located at 24°S latitude. The present size of the Andean root –related to the Andes construction– was obtained by inverting regionalized Bouguer anomalies, also consistent with geoi...

  4. Climate Change and Glacial Lake Outburst Floods in the Bolivian Andes

    OpenAIRE

    Joensen, Maria Louisa

    2015-01-01

    Climate change is causing many tropical glaciers to retreat, creating dangerous glacier lakes with risks of outbursts. Although it is a growing hazard in many countries, glacial lake outburst floods (GLOFs) have not been studied much in the Bolivian Andes. Through this literature review, the risks of GLOFs has been researched by looking into temperature, precipitation and glacier retreat trends in the Altiplano, Cordillera Real and Cordillera Apolobamba, as well as the vulnerability of mounta...

  5. Ethnic voting in the Andes: how ethnicity and ethnic attitudes shape presidential vote choice

    OpenAIRE

    Kelly, S. G. W.

    2016-01-01

    The rise of ethnic politics has been a prominent feature of Latin America’s recent history, particularly in the Andes where much of the population claim some indigenous descent. Prominent politicians use ethnicity to frame important aspects of their political projects and identities, survey data show an emerging ethnic voting gap in several countries, and political protests, debates, and media coverage periodically expose strong ethnic undercurrents. Yet existing scholarship has not examined ...

  6. The Irish potato famine pathogen Phytophthora infestans originated in central Mexico rather than the Andes.

    Science.gov (United States)

    Goss, Erica M; Tabima, Javier F; Cooke, David E L; Restrepo, Silvia; Fry, William E; Forbes, Gregory A; Fieland, Valerie J; Cardenas, Martha; Grünwald, Niklaus J

    2014-06-17

    Phytophthora infestans is a destructive plant pathogen best known for causing the disease that triggered the Irish potato famine and remains the most costly potato pathogen to manage worldwide. Identification of P. infestan's elusive center of origin is critical to understanding the mechanisms of repeated global emergence of this pathogen. There are two competing theories, placing the origin in either South America or in central Mexico, both of which are centers of diversity of Solanum host plants. To test these competing hypotheses, we conducted detailed phylogeographic and approximate Bayesian computation analyses, which are suitable approaches to unraveling complex demographic histories. Our analyses used microsatellite markers and sequences of four nuclear genes sampled from populations in the Andes, Mexico, and elsewhere. To infer the ancestral state, we included the closest known relatives Phytophthora phaseoli, Phytophthora mirabilis, and Phytophthora ipomoeae, as well as the interspecific hybrid Phytophthora andina. We did not find support for an Andean origin of P. infestans; rather, the sequence data suggest a Mexican origin. Our findings support the hypothesis that populations found in the Andes are descendants of the Mexican populations and reconcile previous findings of ancestral variation in the Andes. Although centers of origin are well documented as centers of evolution and diversity for numerous crop plants, the number of plant pathogens with a known geographic origin are limited. This work has important implications for our understanding of the coevolution of hosts and pathogens, as well as the harnessing of plant disease resistance to manage late blight.

  7. Potential of a Neutrino Detector in the ANDES Underground Laboratory for Geophysics and Astrophysics of Neutrinos

    CERN Document Server

    Machado, P A N; Nunokawa, H; Funchal, R Zukanovich

    2012-01-01

    The construction of the Agua Negra tunnels that will link Argentina and Chile under the Andes, the world longest mountain range, opens the possibility to build the first deep underground labo- ratory in the Southern Hemisphere. This laboratory has the acronym ANDES (Agua Negra Deep Experiment Site) and its overburden could be as large as \\sim 1.7 km of rock, or 4500 mwe, providing an excellent low background environment to study physics of rare events like the ones induced by neutrinos and/or dark matter. In this paper we investigate the physics potential of a few kiloton size liquid scintillator detector, which could be constructed in the ANDES laboratory as one of its possible scientific programs. In particular, we evaluate the impact of such a detector for the studies of geoneutrinos and galactic supernova neutrinos assuming a fiducial volume of 3 kilotons as a reference size. We emphasize the complementary roles of such a detector to the ones in the Northern Hemisphere neutrino facilities through some adv...

  8. Miocene orographic uplift forces rapid hydrological change in the southern central Andes

    Science.gov (United States)

    Rohrmann, Alexander; Sachse, Dirk; Mulch, Andreas; Pingel, Heiko; Tofelde, Stefanie; Alonso, Ricardo N.; Strecker, Manfred R.

    2016-10-01

    Rainfall in the central Andes associated with the South American Monsoon and the South American Low-Level Jet results from orographic effects on atmospheric circulation exerted by the Andean Plateau and the Eastern Cordillera. However, despite its importance for South American climate, no reliable records exist that allow decoding the evolution of thresholds and interactions between Andean topography and atmospheric circulation, especially regarding the onset of humid conditions in the inherently dry southern central Andes. Here, we employ multi-proxy isotope data of lipid biomarkers, pedogenic carbonates and volcanic glass from the Eastern Cordillera of NW Argentina and present the first long-term evapotranspiration record. We find that regional eco-hydrology and vegetation changes are associated with initiation of moisture transport via the South American Low-Level Jet at 7.6 Ma, and subsequent lateral growth of the orogen at 6.5 Ma. Our results highlight that topographically induced changes in atmospheric circulation patterns, not global climate change, were responsible for late Miocene environmental change in this part of the southern hemisphere. This suggests that mountain building over time fundamentally controlled habitat evolution along the central Andes.

  9. Grenvillian remnants in the Northern Andes: Rodinian and Phanerozoic paleogeographic perspectives

    Science.gov (United States)

    Cardona, A.; Chew, D.; Valencia, V. A.; Bayona, G.; Mišković, A.; Ibañez-Mejía, M.

    2010-01-01

    Grenvillian crust is encountered in several basement inliers in the northern Andes of Colombia, Ecuador and Peru and is also represented as a major detrital or inherited component within Neoproterozoic to Paleozoic sedimentary and magmatic rocks. This review of the tectonic and geochronological record of the Grenvillian belt in the northern Andes suggests that these crustal segments probably formed on an active continental margin in which associated arc and back-arc magmatism evolved from ca. 1.25 to 1.16 Ga, possibly extending to as young as 1.08 Ga. The lithostratigraphic and tectonic history of the Grenvillian belt in the northern Andes differs from that of the Sunsas belt on the southwest Amazonian Craton and from the Grenvillian belt of Eastern Laurentia. It is considered that this belt, along with similar terranes of Grenvillian age in Middle America and Mexico define a separate composite orogen which formed on the northwestern margin of the Amazonian Craton. Microcontinent accretion and interaction with the Sveconorwegian province on Baltica is a feasible tectonic scenario, in line with recent paleogeographic reconstructions of the Rodinian supercontinent. Although Phanerozoic tectonics may have redistributed some of these terranes, they are still viewed as para-autocthonous domains that remained in proximity to the margin of Amazonia. Paleogeographic data derived from Phanerozoic rocks suggest that some of the Colombian Grenvillian fragments were connected to northernmost Peru and Ecuador until the Mesozoic, whereas the Mexican terranes where attached to the Colombian margin until Pangea fragmentation in Late Triassic times.

  10. A palaeoequatorial ornithischian and new constraints on early dinosaur diversification.

    Science.gov (United States)

    Barrett, Paul M; Butler, Richard J; Mundil, Roland; Scheyer, Torsten M; Irmis, Randall B; Sánchez-Villagra, Marcelo R

    2014-09-22

    Current characterizations of early dinosaur evolution are incomplete: existing palaeobiological and phylogenetic scenarios are based on a fossil record dominated by saurischians and the implications of the early ornithischian record are often overlooked. Moreover, the timings of deep phylogenetic divergences within Dinosauria are poorly constrained owing to the absence of a rigorous chronostratigraphical framework for key Late Triassic-Early Jurassic localities. A new dinosaur from the earliest Jurassic of the Venezuelan Andes is the first basal ornithischian recovered from terrestrial deposits directly associated with a precise radioisotopic date and the first-named dinosaur from northern South America. It expands the early palaeogeographical range of Ornithischia to palaeoequatorial regions, an area sometimes thought to be devoid of early dinosaur taxa, and offers insights into early dinosaur growth rates, the evolution of sociality and the rapid tempo of the global dinosaur radiation following the end-Triassic mass extinction, helping to underscore the importance of the ornithischian record in broad-scale discussions of early dinosaur history.

  11. Tectonic and climate driven fluctuations in the stratigraphic base level of a Cenozoic continental coal basin, northwestern Andes

    Science.gov (United States)

    Silva Tamayo, J. C.; Sierra, G. M.; Correa, L. G.

    2008-12-01

    amalgamation and promoted both, high preservation of geomorphic elements and high diversity of sedimentary facies. This resulted in the most symmetric stratigraphic cycles of the entire Amagá Formation. The final stage of evolution of the Amagá Basin was related to the early stage of development of the late Miocene northwestern Andes tholeitic volcanism (from ˜10 to ˜8 Ma). The extensive thrusting and folding associated to this volcanism reduced the subsidence rates along the basin and thus the accommodation space. This permitted the development of highly aggradational braided rivers and promoted channels amalgamation. Little preservation of low energy facies, poor preservation of the geomorphic elements and a complete obliteration of important swamp deposits (coal beds) within the basin are reflected by the most asymmetric stratigraphic cycles of the whole formation. The presence of greenish/reddish flood plain deposits and Alfisols suggests a dry climate during this depositional stage. The presence of channel sandstones with high contents of volcanic rock fragments supports a dry climate, and suggests an incipient phase of the Combia tholeiitic magmatism present during deposition of the Amagá Formation. The subsequent eastward migration of the NW Andes magmatic arc (after ˜8 Ma) may have produced basin inversion and suppressed deposition along the Amagá Basin.

  12. ATG8 Expansion: A Driver of Selective Autophagy Diversification?

    Science.gov (United States)

    Kellner, Ronny; De la Concepcion, Juan Carlos; Maqbool, Abbas; Kamoun, Sophien; Dagdas, Yasin F

    2017-03-01

    Selective autophagy is a conserved homeostatic pathway that involves engulfment of specific cargo molecules into specialized organelles called autophagosomes. The ubiquitin-like protein ATG8 is a central player of the autophagy network that decorates autophagosomes and binds to numerous cargo receptors. Although highly conserved across eukaryotes, ATG8 diversified from a single protein in algae to multiple isoforms in higher plants. We present a phylogenetic overview of 376 ATG8 proteins across the green plant lineage that revealed family-specific ATG8 clades. Because these clades differ in fixed amino acid polymorphisms, they provide a mechanistic framework to test whether distinct ATG8 clades are functionally specialized. We propose that ATG8 expansion may have contributed to the diversification of selective autophagy pathways in plants.

  13. Origin and Diversification of Dung Beetles in Madagascar

    DEFF Research Database (Denmark)

    Miraldo, Andreia; Wirta, Helena; Hanski, Ilkka

    2011-01-01

    Madagascar has a rich fauna of dung beetles (Scarabaeinae and Aphodiinae) withalmost 300 species described to date. Like most other taxa in Madagascar, dung beetles exhibit an exceptionally high level of endemism (96% of the species). Here,we review the current knowledge of the origin...... and diversification of Malagasy dung beetles. Based on molecular phylogenies, the extant dung beetles originate from eight colonizations, of which four have given rise to extensive radiations. These radiations have occurred in wet forests, while the few extant species in the less successfulradiations occur in open...... and semi-open habitats. We discuss the likely mechanisms of speciation and the ecological characteristics of the extant communities, emphasizing the role of adaptation along environmental gradients and allopatric speciation in generating the exceptionally high beta diversity in Malagasy dung beetles...

  14. Higher Education Student Body Diversification as Glocal Practice

    Directory of Open Access Journals (Sweden)

    José Gerardo Alvarado

    2012-07-01

    Full Text Available Georg Simmel's assertion that strangeness organizes nearness and remoteness helps to understand how the social category of First Generation College Student (FGCS, first in the family to attend college is used at a public university in the United States southwest. Membership Categorization Analysis (MCA is applied to ethnographic data. Difference categories and devices morph into those of distance in an interaction where a recruitment convention substitutes for a handshake between a boy and some adults in the hallway of a student center. These changes imbricate with those found in the analysis of a student-persistence sequence of an educational marketing recruitment DVD. As evidence of glocal practice or the global impact of local contact gestures of student body diversification or massification policies directed at FGCSs (and others, they appear to coincide with distribution and recognition social justice projects that are inviting us to reach out across distances, short and long.

  15. Biogenetically inspired synthesis and skeletal diversification of indole alkaloids

    Science.gov (United States)

    Mizoguchi, Haruki; Oikawa, Hideaki; Oguri, Hiroki

    2014-01-01

    To access architecturally complex natural products, chemists usually devise a customized synthetic strategy for constructing a single target skeleton. In contrast, biosynthetic assembly lines often employ divergent intramolecular cyclizations of a polyunsaturated common intermediate to produce diverse arrays of scaffolds. With the aim of integrating such biogenetic strategies, we show the development of an artificial divergent assembly line generating unprecedented numbers of scaffold variations of terpenoid indole alkaloids. This approach not only allows practical access to multipotent intermediates, but also enables systematic diversification of skeletal, stereochemical and functional group properties without structural simplification of naturally occurring alkaloids. Three distinct modes of [4+2] cyclizations and two types of redox-mediated annulations provided divergent access to five skeletally distinct scaffolds involving iboga-, aspidosperma-, andranginine- and ngouniensine-type skeletons and a non-natural variant within six to nine steps from tryptamine. The efficiency of our approach was demonstrated by successful total syntheses of (±)-vincadifformine, (±)-andranginine and (-)-catharanthine.

  16. Diversification in toxicology: man and environment. EUROTOX proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, J.P. [Intercantonal Office for the Control of Medicines (IOCM), Bern (Switzerland); Autrup, J.L.; Autrup, H. [eds.] [Aarhus Univ. (Denmark). Steno Inst. of Public Health

    1998-12-31

    This volume contains the main papers presented at the 1997 EUROTOX Congress, Aaarhus, Denmark, 24-28 June 1997. Diversification in toxicology is not seen as splitting into subfields, but as the application of basic science to such diverse areas as man and his environment. The pressing issues which have been dealt with not only include reproductive effects of environmental chemicals (`xenoestrogens`), but also receptor-mediated toxic responses, new frontiers in human and ecological toxicology, chemoprevention of cancer and molecular approaches in toxicological research. The practical and ethical facets of toxicology, e.g. ecotoxicological risk assessment, biomarkers of exposure, complex chemical mixtures as well as animal welfare and the ethics of animal experimentation, are also treated. (orig.)

  17. Reduce, reuse, and recycle: developmental evolution of trait diversification.

    Science.gov (United States)

    Preston, Jill C; Hileman, Lena C; Cubas, Pilar

    2011-03-01

    A major focus of evolutionary developmental (evo-devo) studies is to determine the genetic basis of variation in organismal form and function, both of which are fundamental to biological diversification. Pioneering work on metazoan and flowering plant systems has revealed conserved sets of genes that underlie the bauplan of organisms derived from a common ancestor. However, the extent to which variation in the developmental genetic toolkit mirrors variation at the phenotypic level is an active area of research. Here we explore evidence from the angiosperm evo-devo literature supporting the frugal use of genes and genetic pathways in the evolution of developmental patterning. In particular, these examples highlight the importance of genetic pleiotropy in different developmental modules, thus reducing the number of genes required in growth and development, and the reuse of particular genes in the parallel evolution of ecologically important traits.

  18. Impacts of diversification of cytochrome P450 on plant metabolism.

    Science.gov (United States)

    Mizutani, Masaharu

    2012-01-01

    Cytochrome P450 monooxygenases (P450s) catalyze a wide variety of monooxygenation reactions in primary and secondary metabolism in plants. The share of P450 genes in each plant genome is estimated to be up to 1%. This implies that the diversification of P450 has made a significant contribution to the ability to acquire the emergence of new metabolic pathways during land plant evolution. The P450 families conserved universally in land plants contribute to their chemical defense mechanisms. Several P450s are involved in the biosynthesis and catabolism of plant hormones. Species-specific P450 families are essential for the biosynthetic pathways of phytochemicals such as terpenoids and alkaloids. Genome wide analysis of the gene clusters including P450 genes will provide a clue to defining the metabolic roles of orphan P450s. Metabolic engineering with plant P450s is an important technology for large-scale production of valuable phytochemicals such as medicines.

  19. A six-parameter space to describe galaxy diversification

    CERN Document Server

    Fraix-Burnet, Didier; Chattopadhyay, Asis Kumar; Davoust, Emmanuel; Thuillard, Marc

    2012-01-01

    Galaxy diversification proceeds by transforming events like accretion, interaction or mergers. These explain the formation and evolution of galaxies that can now be described with many observables. Multivariate analyses are the obvious tools to tackle the datasets and understand the differences between different kinds of objects. However, depending on the method used, redundancies, incompatibilities or subjective choices of the parameters can void the usefulness of such analyses. The behaviour of the available parameters should be analysed before an objective reduction of dimensionality and subsequent clustering analyses can be undertaken, especially in an evolutionary context. We study a sample of 424 early-type galaxies described by 25 parameters, ten of which are Lick indices, to identify the most structuring parameters and determine an evolutionary classification of these objects. Four independent statistical methods are used to investigate the discriminant properties of the observables and the partitioni...

  20. International portfolio diversification: United States and south Asian equity markets

    Directory of Open Access Journals (Sweden)

    Mushtaq Rizwan

    2014-01-01

    Full Text Available This paper explores the dynamic liaison between US and three developing South Asian equity markets in short and long term. To gauge the long-term relationship, we applied Johansen co-integration procedure as all the representative indices are found to be non-stationary at level. The findings illustrate that the US equity market index exhibits a reasonably different movement over time in contrast to the three developing equity markets under consideration. However, the Granger-causality test divulge that the direction of causality scamper from US equity market to the three South Asian markets. It further indicates that within the three developing equity markets the direction of causality emanates from Bombay stock market to Karachi and Colombo. Overall, the results of the study suggest that the American investors can get higher returns through international diversification into developing equity markets, while the US stock market would also be a gainful upshot for South Asian investors.

  1. Cryptococcus gattii meningoencephalitis in an HIV-negative patient from the Peruvian Andes Meningoencefalite causada por Cryptococcus gattii em um paciente HIV-negativo procedente dos Andes Peruanos

    Directory of Open Access Journals (Sweden)

    Ericson L. Gutierrez

    2010-08-01

    Full Text Available We report a case of an immunocompetent Peruvian patient from the Andes with a one-month history of meningoencephalitis. Cryptococcus gattii was identified from a cerebrospinal fluid culture through assimilation of D-proline and D-tryptophan as the single nitrogen source. Initially, the patient received intravenous antifungal therapy with amphotericin B. The patient was discharged 29 days after hospitalization and continued with oral fluconazole treatment for ten weeks. During this period, the patient showed clinical improvement with slight right-side residual weakness. Through this case report, we confirm the existence of this microorganism as an infectious agent in Peru.Nós reportamos o caso de um paciente peruano immunocompetente proveniente dos Andes com história de um mês com meningoencefalite. Foi identificado o Cryptococcus gattii na cultura de liquido cerebrospinal através da assimilação de D-prolina e D-tryptofano como fonte única de nitrogênio. Inicialmente, o paciente recebeu tratamento antifúngico intravenoso com amfotericina B. O paciente foi liberado 29 dias depois da hospitalização, seguindo tratamento oral durante 10 semanas com fluconazol. Durante este período, o paciente apresentou melhoria clinica e uma leve fraqueza residual direita. Com o reporte do caso, nós confirmamos a existência desse microorganismo como agente infeccioso em nosso país.

  2. Conservation and diversification of Msx protein in metazoan evolution.

    Science.gov (United States)

    Takahashi, Hirokazu; Kamiya, Akiko; Ishiguro, Akira; Suzuki, Atsushi C; Saitou, Naruya; Toyoda, Atsushi; Aruga, Jun

    2008-01-01

    Msx (/msh) family genes encode homeodomain (HD) proteins that control ontogeny in many animal species. We compared the structures of Msx genes from a wide range of Metazoa (Porifera, Cnidaria, Nematoda, Arthropoda, Tardigrada, Platyhelminthes, Mollusca, Brachiopoda, Annelida, Echiura, Echinodermata, Hemichordata, and Chordata) to gain an understanding of the role of these genes in phylogeny. Exon-intron boundary analysis suggested that the position of the intron located N-terminally to the HDs was widely conserved in all the genes examined, including those of cnidarians. Amino acid (aa) sequence comparison revealed 3 new evolutionarily conserved domains, as well as very strong conservation of the HDs. Two of the three domains were associated with Groucho-like protein binding in both a vertebrate and a cnidarian Msx homolog, suggesting that the interaction between Groucho-like proteins and Msx proteins was established in eumetazoan ancestors. Pairwise comparison among the collected HDs and their C-flanking aa sequences revealed that the degree of sequence conservation varied depending on the animal taxa from which the sequences were derived. Highly conserved Msx genes were identified in the Vertebrata, Cephalochordata, Hemichordata, Echinodermata, Mollusca, Brachiopoda, and Anthozoa. The wide distribution of the conserved sequences in the animal phylogenetic tree suggested that metazoan ancestors had already acquired a set of conserved domains of the current Msx family genes. Interestingly, although strongly conserved sequences were recovered from the Vertebrata, Cephalochordata, and Anthozoa, the sequences from the Urochordata and Hydrozoa showed weak conservation. Because the Vertebrata-Cephalochordata-Urochordata and Anthozoa-Hydrozoa represent sister groups in the Chordata and Cnidaria, respectively, Msx sequence diversification may have occurred differentially in the course of evolution. We speculate that selective loss of the conserved domains in Msx family

  3. Geographical diversification of growth-defense strategies in an invasive plant

    Institute of Scientific and Technical Information of China (English)

    Xiao-Yun PAN; Xin JIA; Dong-Jing FU; Bo LI

    2013-01-01

    Interactions between herbivore pressure and resource availability may result in growth-defense trade-offs in plants (resource availability hypothesis),which promote the potential for ecological diversification and have recently been proposed as a new mechanism of plant invasion (resource-enemy release hypothesis).In the present study,we tested this idea by comparing patterns of maximum growth rate and antiherbivore defense capacity against Agasicles hygrophila (a specialist phytophagous insect on Alternanthera philoxeroides) among six morphs of A.philoxeroides from both native (Argentina) and introduced (US and China) ranges.The results revealed that herbivore resistance consistently exhibited a significant trade-off against the growth rate of A.philoxeroides.Compared with native morphs in Argentina,introduced morphs generally exhibited a higher growth rate and lower defense.The results demonstrate that the combination of flea beetle pressure and resource availability facilitates geographical divergence of A.philoxeroides,and that release from natural specialists and increased resource availability may interact to contribute to its successful invasion.

  4. A climate for speciation: rapid spatial diversification within the Sorex cinereus complex of shrews

    Science.gov (United States)

    Hope, Andrew G.; Speer, Kelly A.; Demboski, John R.; Talbot, Sandra L.; Cook, Joseph A.

    2012-01-01

    The cyclic climate regime of the late Quaternary caused dramatic environmental change at high latitudes. Although these events may have been brief in periodicity from an evolutionary standpoint, multiple episodes of allopatry and divergence have been implicated in rapid radiations of a number of organisms. Shrews of the Sorex cinereus complex have long challenged taxonomists due to similar morphology and parapatric geographic ranges. Here, multi-locus phylogenetic and demographic assessments using a coalescent framework were combined to investigate spatiotemporal evolution of 13 nominal species with a widespread distribution throughout North America and across Beringia into Siberia. For these species, we first test a hypothesis of recent differentiation in response to Pleistocene climate versus more ancient divergence that would coincide with pre-Pleistocene perturbations. We then investigate the processes driving diversification over multiple continents. Our genetic analyses highlight novel diversity within these morphologically conserved mammals and clarify relationships between geographic distribution and evolutionary history. Demography within and among species indicates both regional stability and rapid expansion. Ancestral ecological differentiation coincident with early cladogenesis within the complex enabled alternating and repeated episodes of allopatry and expansion where successive glacial and interglacial phases each promoted divergence. The Sorex cinereus complex constitutes a valuable model for future comparative assessments of evolution in response to cyclic environmental change.

  5. Diversity Dynamics in Nymphalidae Butterflies: Effect of Phylogenetic Uncertainty on Diversification Rate Shift Estimates

    Science.gov (United States)

    Peña, Carlos; Espeland, Marianne

    2015-01-01

    The species rich butterfly family Nymphalidae has been used to study evolutionary interactions between plants and insects. Theories of insect-hostplant dynamics predict accelerated diversification due to key innovations. In evolutionary biology, analysis of maximum credibility trees in the software MEDUSA (modelling evolutionary diversity using stepwise AIC) is a popular method for estimation of shifts in diversification rates. We investigated whether phylogenetic uncertainty can produce different results by extending the method across a random sample of trees from the posterior distribution of a Bayesian run. Using the MultiMEDUSA approach, we found that phylogenetic uncertainty greatly affects diversification rate estimates. Different trees produced diversification rates ranging from high values to almost zero for the same clade, and both significant rate increase and decrease in some clades. Only four out of 18 significant shifts found on the maximum clade credibility tree were consistent across most of the sampled trees. Among these, we found accelerated diversification for Ithomiini butterflies. We used the binary speciation and extinction model (BiSSE) and found that a hostplant shift to Solanaceae is correlated with increased net diversification rates in Ithomiini, congruent with the diffuse cospeciation hypothesis. Our results show that taking phylogenetic uncertainty into account when estimating net diversification rate shifts is of great importance, as very different results can be obtained when using the maximum clade credibility tree and other trees from the posterior distribution. PMID:25830910

  6. Niche evolution and diversification in a Neotropical radiation of birds (Aves: Furnariidae).

    Science.gov (United States)

    Seeholzer, Glenn F; Claramunt, Santiago; Brumfield, Robb T

    2017-03-01

    Rapid diversification may be caused by ecological adaptive radiation via niche divergence. In this model, speciation is coupled with niche divergence and lineage diversification is predicted to be correlated with rates of niche evolution. Studies of the role of niche evolution in diversification have generally focused on ecomorphological diversification but climatic-niche evolution may also be important. We tested these alternatives using a phylogeny of 298 species of ovenbirds (Aves: Furnariidae). We found that within Furnariidae, variation in species richness and diversification rates of subclades were best predicted by rate of climatic-niche evolution than ecomorphological evolution. Although both are clearly important, univariate regression and multivariate model averaging more consistently supported the climatic-niche as the best predictor of lineage diversification. Our study adds to the growing body of evidence, suggesting that climatic-niche divergence may be an important driver of rapid diversification in addition to ecomorphological evolution. However, this pattern may depend on the phylogenetic scale at which rate heterogeneity is examined.

  7. Patterns of host plant utilization and diversification in the brush-footed butterflies.

    Science.gov (United States)

    Hamm, Christopher A; Fordyce, James A

    2015-03-01

    Herbivorous insects represent one of the most successful animal radiations known. They occupy a wide range of niches, feed on a great variety of plants, and are species rich; yet the factors that influence their diversification are poorly understood. Host breadth is often cited as a major factor influencing diversification, and, according to the Oscillation Hypothesis, shifts from generalist to specialist feeding states increase the diversification rate for a clade. We explored the relationship between host breadth and diversification within the Nymphalidae (Lepidoptera) and explicitly tested predictions of the Oscillation Hypothesis. We found strong evidence of diversification rate heterogeneity, but no difference in host breadth between clades with a higher diversification rate compared to their sisters. We also found some clades exhibited phylogenetic nonindependence in host breadth and these clades had lower host plant turnover than expected by chance, suggesting host breadth is evolutionarily constrained. Finally, we found that transitions among host breadth categories varied, but the likelihood of reductions in host breadth was greater than that of increases. Our results indicate host breadth is decoupled from diversification rate within the Nymphalidae, and that constraints on diet breadth might play an important role in the evolution of herbivorous insects.

  8. Ecological opportunities, habitat, and past climatic fluctuations influenced the diversification of modern turtles.

    Science.gov (United States)

    Rodrigues, João Fabrício Mota; Diniz-Filho, José Alexandre Felizola

    2016-08-01

    Habitat may be viewed as an important life history component potentially related to diversification patterns. However, differences in diversification rates between aquatic and terrestrial realms are still poorly explored. Testudines is a group distributed worldwide that lives in aquatic and terrestrial environments, but until now no-one has evaluated the diversification history of the group as a whole. We aim here to investigate the diversification history of turtles and to test if habitat influenced speciation rate in these animals. We reconstructed the phylogeny of the modern species of chelonians and estimated node divergence dates using molecular markers and a Bayesian approach. Then, we used Bayesian Analyses of Macroevolutionary Mixtures to evaluate the diversification history of turtles and evaluate the effect of habitat on this pattern. Our reconstructed phylogeny covered 300 species (87% of the total diversity of the group). We found that the emydid subfamily Deirochelyinae, which forms the turtle hotspot in south-eastern United States, had an increase in its speciation rate, and that Galapagos tortoises had similar increases. Current speciation rates are lower in terrestrial turtles, contradicting studies supporting the idea terrestrial animals diversify more than aquatic species. Our results suggest that habitat, ecological opportunities, island invasions, and climatic factors are important drivers of diversification in modern turtles and reinforce the importance of habitat as a diversification driver.

  9. Into and out of the tropics: global diversification patterns in a hyperdiverse clade of ectomycorrhizal fungi.

    Science.gov (United States)

    Looney, Brian P; Ryberg, Martin; Hampe, Felix; Sánchez-García, Marisol; Matheny, P Brandon

    2016-01-01

    Ectomycorrhizal (ECM) fungi, symbiotic mutualists of many dominant tree and shrub species, exhibit a biogeographic pattern counter to the established latitudinal diversity gradient of most macroflora and fauna. However, an evolutionary basis for this pattern has not been explicitly tested in a diverse lineage. In this study, we reconstructed a mega-phylogeny of a cosmopolitan and hyperdiverse genus of ECM fungi, Russula, sampling from annotated collections and utilizing publically available sequences deposited in GenBank. Metadata from molecular operational taxonomic unit cluster sets were examined to infer the distribution and plant association of the genus. This allowed us to test for differences in patterns of diversification between tropical and extratropical taxa, as well as how their associations with different plant lineages may be a driver of diversification. Results show that Russula is most species-rich at temperate latitudes and ancestral state reconstruction shows that the genus initially diversified in temperate areas. Migration into and out of the tropics characterizes the early evolution of the genus, and these transitions have been frequent since this time. We propose the 'generalized diversification rate' hypothesis to explain the reversed latitudinal diversity gradient pattern in Russula as we detect a higher net diversification rate in extratropical lineages. Patterns of diversification with plant associates support host switching and host expansion as driving diversification, with a higher diversification rate in lineages associated with Pinaceae and frequent transitions to association with angiosperms.

  10. Exploring Diversification as A Management Strategy in Substance Use Disorder Treatment Organizations.

    Science.gov (United States)

    Fields, Dail; Riesenmy, Kelly; Roman, Paul M

    2015-10-01

    Implementation of the Affordable Care Act (ACA) creates both environmental uncertainties and opportunities for substance use disorder (SUD) treatment providers. One managerial response to uncertainties and emergent opportunities is strategic diversification of various dimensions of organizational activity. This paper explored organizational outcomes related to diversification of funding sources, services offered, and referral sources in a national sample of 590 SUD treatment organizations. Funding diversification was related to higher average levels of census, organization size, and recent expansion of operations. Service diversification was related to higher average levels of use of medication-assisted treatment (MAT), organization size, and expansion. Referral source diversification was related only to greater average use of MAT. Overall, strategic diversification in the three areas explored was related to positive organizational outcomes. Considering alternative strategies of diversification may help position SUD treatment centers to deliver more innovative treatments such as MAT as well as enhance capacity to satisfy current unmet treatment needs of individuals with behavioral health coverage provided under the ACA.

  11. Phylogenetic diversification patterns and divergence times in ground beetles (Coleoptera: Carabidae: Harpalinae

    Directory of Open Access Journals (Sweden)

    Ober Karen A

    2010-08-01

    Full Text Available Abstract Background Harpalinae is a species rich clade of carabid beetles with many unusual morphological forms and ecological interactions. How this diversity evolved has been difficult to reconstruct, perhaps because harpalines underwent a rapid burst of diversification early in their evolutionary history. Here we investigate the tempo of evolution in harpalines using molecular divergence dating techniques and explore the rates of lineage accumulation in harpalines and their sister group. Results According to molecular divergence date estimates, harpalines originated in the mid Cretaceous but did not diversify extensively until the late Cretaceous or early Paleogene about 32 million years after their origin. In a relatively small window of time, harpalines underwent rapid speciation. Harpalines have a relative high net diversification rate and increased cladogenesis in some regions of the clade. We did not see a significant decrease in diversification rate through time in the MCCR test, but a model of diversification with two shift points to lower diversification rates fit the harpaline lineage accumulation through time the best. Conclusions Our results indicate harpalines are significantly more diverse and have higher diversification than their sistergroup. Instead of an immediate burst of explosive diversification, harpalines may have had a long "fuse" before major lineages diversified during the early Paleogene when other taxa such as mammals, birds, and some flowering plants were also rapidly diversifying.

  12. Diversity dynamics in Nymphalidae butterflies: effect of phylogenetic uncertainty on diversification rate shift estimates.

    Science.gov (United States)

    Peña, Carlos; Espeland, Marianne

    2015-01-01

    The species rich butterfly family Nymphalidae has been used to study evolutionary interactions between plants and insects. Theories of insect-hostplant dynamics predict accelerated diversification due to key innovations. In evolutionary biology, analysis of maximum credibility trees in the software MEDUSA (modelling evolutionary diversity using stepwise AIC) is a popular method for estimation of shifts in diversification rates. We investigated whether phylogenetic uncertainty can produce different results by extending the method across a random sample of trees from the posterior distribution of a Bayesian run. Using the MultiMEDUSA approach, we found that phylogenetic uncertainty greatly affects diversification rate estimates. Different trees produced diversification rates ranging from high values to almost zero for the same clade, and both significant rate increase and decrease in some clades. Only four out of 18 significant shifts found on the maximum clade credibility tree were consistent across most of the sampled trees. Among these, we found accelerated diversification for Ithomiini butterflies. We used the binary speciation and extinction model (BiSSE) and found that a hostplant shift to Solanaceae is correlated with increased net diversification rates in Ithomiini, congruent with the diffuse cospeciation hypothesis. Our results show that taking phylogenetic uncertainty into account when estimating net diversification rate shifts is of great importance, as very different results can be obtained when using the maximum clade credibility tree and other trees from the posterior distribution.

  13. Diversity dynamics in Nymphalidae butterflies: effect of phylogenetic uncertainty on diversification rate shift estimates.

    Directory of Open Access Journals (Sweden)

    Carlos Peña

    Full Text Available The species rich butterfly family Nymphalidae has been used to study evolutionary interactions between plants and insects. Theories of insect-hostplant dynamics predict accelerated diversification due to key innovations. In evolutionary biology, analysis of maximum credibility trees in the software MEDUSA (modelling evolutionary diversity using stepwise AIC is a popular method for estimation of shifts in diversification rates. We investigated whether phylogenetic uncertainty can produce different results by extending the method across a random sample of trees from the posterior distribution of a Bayesian run. Using the MultiMEDUSA approach, we found that phylogenetic uncertainty greatly affects diversification rate estimates. Different trees produced diversification rates ranging from high values to almost zero for the same clade, and both significant rate increase and decrease in some clades. Only four out of 18 significant shifts found on the maximum clade credibility tree were consistent across most of the sampled trees. Among these, we found accelerated diversification for Ithomiini butterflies. We used the binary speciation and extinction model (BiSSE and found that a hostplant shift to Solanaceae is correlated with increased net diversification rates in Ithomiini, congruent with the diffuse cospeciation hypothesis. Our results show that taking phylogenetic uncertainty into account when estimating net diversification rate shifts is of great importance, as very different results can be obtained when using the maximum clade credibility tree and other trees from the posterior distribution.

  14. Migraciones en la puna: su relación con el uso de los recursos naturales del departamento Los Andes Migraciones en la puna: su relación con el uso de los recursos naturales del departamento Los Andes

    Directory of Open Access Journals (Sweden)

    Francisco R. Barbarán

    2009-12-01

    Full Text Available From an historic and demographic perspective, as well as the use of natural resources, we analyzed the relationship between human migrations and the economic activities of Los Andes Department, West of the Salta Province, in NW Argentina. Using the residual method, we calculated migratory balances between Argentinean population censuses carried out in 1947,1960, 1970, 1980 and 2001. The migratory balances were negative for all the periods studied. When the train started to run through Ramal C-14, the workers who built it have to find jobs somewhere else. At the same time, the railway made easier for the natives, to find better economicopportunities out of the Puna. The close of mine La Casualidad by the end of the 70’s, the low creation of jobs by the remaining mining operations, focused in to hire qualified technicians no available in Los Andes and the privatization of the railway in early 90’s, were important factors of emigration. Despite of cattle rising as the main economic activity in rural areas, it is practiced without any technology of management. The overgrazing caused for that reason, has reduced almost to the half the quantity of sheep by inhabitant between 1947 and 2001. That is why the local people have to press more on the wildlife, trading illegally with vicuña (Vicugna vicugna fiber. Despite of a touristic development plan, a law promoting sheep rising and a census of vicuña population carried out by the provincial government, these recent actions should be part of a development project of regional scale, oriented to the sustainable use of the natural resources of Los Andes Department. That project would create jobs and discourage emigration.Desde una perspectiva histórica, demográfica y del uso de los recursos naturales, analizamos la relación existente entre las migraciones humanas y las actividades económicas en el departamento Los Andes, ubicado al W de la provincia de Salta, en el Noroeste Argentino. Usando el m

  15. Facing unprecedented drying of the Central Andes? Precipitation variability over the period AD 1000-2100

    Science.gov (United States)

    Neukom, Raphael; Rohrer, Mario; Calanca, Pierluigi; Salzmann, Nadine; Huggel, Christian; Acuña, Delia; Christie, Duncan A.; Morales, Mariano S.

    2015-08-01

    Projected future trends in water availability are associated with large uncertainties in many regions of the globe. In mountain areas with complex topography, climate models have often limited capabilities to adequately simulate the precipitation variability on small spatial scales. Also, their validation is hampered by typically very low station density. In the Central Andes of South America, a semi-arid high-mountain region with strong seasonality, zonal wind in the upper troposphere is a good proxy for interannual precipitation variability. Here, we combine instrumental measurements, reanalysis and paleoclimate data, and a 57-member ensemble of CMIP5 model simulations to assess changes in Central Andes precipitation over the period AD 1000-2100. This new database allows us to put future projections of precipitation into a previously missing multi-centennial and pre-industrial context. Our results confirm the relationship between regional summer precipitation and 200 hPa zonal wind in the Central Andes, with stronger Westerly winds leading to decreased precipitation. The period of instrumental coverage (1965-2010) is slightly dryer compared to pre-industrial times as represented by control simulations, simulations from the past Millennium, ice core data from Quelccaya ice cap and a tree-ring based precipitation reconstruction. The model ensemble identifies a clear reduction in precipitation already in the early 21st century: the 10 year running mean model uncertainty range (ensemble 16-84% spread) is continuously above the pre-industrial mean after AD 2023 (AD 2028) until the end of the 21st century in the RCP2.6 (RCP8.5) emission scenario. Average precipitation over AD 2071-2100 is outside the range of natural pre-industrial variability in 47 of the 57 model simulations for both emission scenarios. The ensemble median fraction of dry years (defined by the 5th percentile in pre-industrial conditions) is projected to increase by a factor of 4 until 2071-2100 in

  16. Sr and Nd isotopic and trace element compositions of Quaternary volcanic centers of the Southern Andes

    Science.gov (United States)

    Futa, K.; Stern, C.R.

    1988-01-01

    Isotopic compositions of samples from six Quaternary volcanoes located in the northern and southern extremities of the Southern Volcanic Zone (SVZ, 33-46??S) of the Andes and from four centers in the Austral Volcanic Zone (AVZ, 49-54??S) range for 87Sr 86Sr from 0.70280 to 0.70591 and for 143Nd 144Nd from 0.51314 to 0.51255. The ranges are significantly greater than previously reported from the southern Andes but are different from the isotopic compositions of volcanoes in the central and northern Andes. Basalts and basaltic andesites from three centers just north of the Chile Rise-Trench triple junction have 87Sr 86Sr, 143Nd 144Nd, La Yb, Ba La, and Hf Lu that lie within the relatively restricted ranges of the basic magmas erupted from the volcanic centers as far north as 35??S in the SVZ of the Andes. The trace element and Sr and Nd isotopic characteristics of these magmas may be explained by source region contamination of subarc asthenosphere, with contaminants derived from subducted pelagic sediments and seawater-altered basalts by dehydration of subducted oceanic lithosphere. In the northern extremity of the SVZ between 33?? and 34??S, basaltic andesites and andesites have higher 87Sr 86Sr, Rb Cs, and Hf Lu, and lower 143Nd 144Nd than basalts and basaltic andesites erupted farther south in the SVZ, which suggests involvement of components derived from the continental crust. In the AVZ, the most primitive sample, high-Mg andesite from the southernmost volcanic center in the Andes (54??S) has Sr and Nd isotopic compositions and K Rb and Ba La similar to MORB. The high La Yb of this sample suggests formation by small degrees of partial melting of subducted MORB with garnet as a residue. Samples from centers farther north in the AVZ show a regionally regular northward increase in SiO2, K2O, Rb, Ba, Ba La, and 87Sr 86Sr and decrease in MgO, Sr, K Rb, Rb Cs, and 143Nd 144Nd, suggesting increasingly greater degrees of fractional crystallization and associated intra

  17. Global diversification of a tropical plant growth form: environmental correlates and historical contingencies in climbing palms.

    Science.gov (United States)

    Couvreur, Thomas L P; Kissling, W Daniel; Condamine, Fabien L; Svenning, Jens-Christian; Rowe, Nick P; Baker, William J

    2014-01-01

    Tropical rain forests (TRF) are the most diverse terrestrial biome on Earth, but the diversification dynamics of their constituent growth forms remain largely unexplored. Climbing plants contribute significantly to species diversity and ecosystem processes in TRF. We investigate the broad-scale patterns and drivers of species richness as well as the diversification history of climbing and non-climbing palms (Arecaceae). We quantify to what extent macroecological diversity patterns are related to contemporary climate, forest canopy height, and paleoclimatic changes. We test whether diversification rates are higher for climbing than non-climbing palms and estimate the origin of the climbing habit. Climbers account for 22% of global palm species diversity, mostly concentrated in Southeast Asia. Global variation in climbing palm species richness can be partly explained by past and present-day climate and rain forest canopy height, but regional differences in residual species richness after accounting for current and past differences in environment suggest a strong role of historical contingencies in climbing palm diversification. Climbing palms show a higher net diversification rate than non-climbers. Diversification analyses of palms detected a diversification rate increase along the branches leading to the most species-rich clade of climbers. Ancestral character reconstructions revealed that the climbing habit originated between early Eocene and Miocene. These results imply that changes from non-climbing to climbing habits may have played an important role in palm diversification, resulting in the origin of one fifth of all palm species. We suggest that, in addition to current climate and paleoclimatic changes after the late Neogene, present-day diversity of climbing palms can be explained by morpho-anatomical innovations, the biogeographic history of Southeast Asia, and/or ecological opportunities due to the diversification of high-stature dipterocarps in Asian TRFs.

  18. Global diversification of a tropical plant growth form: environmental correlates and historical contingencies in climbing palms

    Directory of Open Access Journals (Sweden)

    Thomas L. P. Couvreur

    2015-01-01

    Full Text Available Tropical rain forests (TRF are the most diverse terrestrial biome on Earth, but the diversification dynamics of their constituent growth forms remain largely unexplored. Climbing plants contribute significantly to species diversity and ecosystem processes in TRF. We investigate the broad-scale patterns and drivers of species richness as well as the diversification history of climbing and non-climbing palms (Arecaceae. We quantify to what extent macroecological diversity patterns are related to contemporary climate, forest canopy height and paleoclimatic changes. We test whether diversification rates are higher for climbing than non-climbing palms and estimate the origin of the climbing habit. Climbers account for 22% of global palm species diversity mostly concentrated in Southeast Asia. Global variation in climbing palm species richness can be partly explained by past and present-day climate and rain forest canopy height, but regional differences in residual species richness after accounting for current and past differences in environment suggest a strong role of historical contingencies in climbing palm diversification. Climbing palms show a higher net diversification rate than non-climbers. Diversification analysis of palms detected a diversification rate increase along the branches leading to the most species-rich clade of climbers. Ancestral character reconstructions revealed that the climbing habit originated between early Eocene and Miocene. These results imply that changes from non-climbing to climbing habit may have played an important role in palm diversification, resulting in the origin of one fifth of all palm species. We suggest that, in addition to current climate and paleoclimatic changes after the late Neogene, present-day diversity of climbing palms can be explained by morpho-anatomical innovations, the biogeographic history of Southeast Asia, and/or ecological opportunities due to the diversification of high

  19. Developing services for climate impact and adaptation baseline information and methodologies for the Andes

    Science.gov (United States)

    Huggel, C.

    2012-04-01

    Impacts of climate change are observed and projected across a range of ecosystems and economic sectors, and mountain regions thereby rank among the hotspots of climate change. The Andes are considered particularly vulnerable to climate change, not only due to fragile ecosystems but also due to the high vulnerability of the population. Natural resources such as water systems play a critical role and are observed and projected to be seriously affected. Adaptation to climate change impacts is therefore crucial to contain the negative effects on the population. Adaptation projects require information on the climate and affected socio-environmental systems. There is, however, generally a lack of methodological guidelines how to generate the necessary scientific information and how to communicate to implementing governmental and non-governmental institutions. This is particularly important in view of the international funds for adaptation such as the Green Climate Fund established and set into process at the UNFCCC Conferences of the Parties in Cancun 2010 and Durban 2011. To facilitate this process international and regional organizations (World Bank and Andean Community) and a consortium of research institutions have joined forces to develop and define comprehensive methodologies for baseline and climate change impact assessments for the Andes, with an application potential to other mountain regions (AndesPlus project). Considered are the climatological baseline of a region, and the assessment of trends based on ground meteorological stations, reanalysis data, and satellite information. A challenge is the scarcity of climate information in the Andes, and the complex climatology of the mountain terrain. A climate data platform has been developed for the southern Peruvian Andes and is a key element for climate data service and exchange. Water resources are among the key livelihood components for the Andean population, and local and national economy, in particular for

  20. The Importance of Localized Related Variety for International Diversification of Corporate Technology

    DEFF Research Database (Denmark)

    Dettmann, Eva; Lacasa, Iciar Dominguez; Günther, Jutta;

    2016-01-01

    The importance of localized related variety for international diversification of corporate technology, Regional Studies. Internationalization of research and development has increased substantially in recent years. This paper analyses the determinants of spatial distribution of foreign technologi......The importance of localized related variety for international diversification of corporate technology, Regional Studies. Internationalization of research and development has increased substantially in recent years. This paper analyses the determinants of spatial distribution of foreign...... technological activities. The estimations show that this is the case in regions characterized by a high overall technological strength. This suggests that related variety facilitates technological diversifications of foreign corporations in regions at the top of the geographic hierarchy...

  1. THE EFFECT OF COMPANY DIVERSIFICATION TOWARDS EARNING MANAGEMENT MODERATED BY MANAGERIAL OWNERSHIP

    Directory of Open Access Journals (Sweden)

    Ratih Kusumaningtyas

    2015-09-01

    Full Text Available This study aims to examine the effect of diversification towards earnings management moderated by managerial ownership. The sample in this research is 48 manufacturing companies listed in Indonesian Stock Exchange period 2009- 2013. Purposive sampling was utilized as a sampling technique in this study. This research used moderating regression analysis to examine the proposed of hypothesis. The result found that diversification has significant positive effect on earnings management. Managerial ownership also has significant positive effect in moderating the relationship between corporate diversification with earnings management. While the three control variables such as company size (size, the company’s growth (growth and leverage have no significant effect on earnings management.

  2. Recent trends in human migrations: the case of the Venezuelan Andes.

    Science.gov (United States)

    Suarez, M M; Torrealba, R

    1982-01-01

    Changes in world capitalism caused prices of traditional raw materials to fall and new energy demands to arise at the end of the 19th and beginning of the 20th century. The Andean countries witnessed the fall in the value of their exports and began to receive large flows of foreign investment in mining and industry. Consequently, urban economies were strengthened and demographic patterns were changed. This led to the internal migrations and to a process of social change. These consequences are summarized from relevant studies focusing on Ecuador, Colombia, and Venezuela. Since the 1960s a compendium of information has become available which highlights the causes of the migration, migration patterns, the composition of migratory movements, and the mechanisms that the migrant uses to establish himself/herself in the city. Preston (1969) distinguished 2 migratory patterns in Ecuador: rural to urban, with migratory flows from the rural areas to urban centers and new industrial cities that experienced development and high demand for unskilled labor at comparatively high wages: and rural to rural, based on the movement of population from depressed rural areas to other areas in which programs for colonization or commercial agriculture have been promoted. In a study of Colombia, McGreevey (1968) identifies the lack of cultivatable land, rural violence in certain departments, and other economic and family causes as the principal factors that induced migrations to the cities. The study emphasizes that the predominant model of movement relates to "fill in" migration. The spatial mobility of the Venezuelan Andean population was initially outlined in a voluminous report on economic and social problems of the region (1954). The study indicates that during the intercensal period 1941-50 cities grew much more rapidly than rural "municipos" and that the drive to find employment and earn a living were the most important motives in the movement of peasants to the cities. All of the

  3. Assembling the history of the Parareptilia: phylogeny, diversification, and a new definition of the clade

    Directory of Open Access Journals (Sweden)

    L. A. Tsuji

    2009-02-01

    Full Text Available In the present study, the historical development of Parareptilia as a phylogenetically valid clade is summarized, and for the first time a modern phylogenetic definition of both Parareptilia as well as Eureptilia is presented, which will facilitate the study of problems of early amniote classification. Furthermore, a preliminary study of the rates of diversification in parareptiles is performed on the basis of topological information on species diversity. While acknowledging that the bias of the fossil record also needs to be considered for a more definitive statement on parareptile diversification, our results show that a significant increase in diversification rate could be recorded only among Triassic procolophonoids, making it difficult to interpret evolutionary novelties such as herbivory or impedance-matching hearing as being key innovations that might have driven diversification. doi:10.1002/mmng.200800011

  4. Acquisition versus greenfield foreign entry : diversification mode choice in Central and Eastern Europe

    NARCIS (Netherlands)

    Dikova, Desislava; Witteloostuijn, Adriaan van

    2005-01-01

    Departing from the traditional transaction cost approach in diversification mode literature, this study investigates the influence of experimental organizational learning on the choice between acquisition and a greenfield investment. We provide empirical support that prior experience with acquisitio

  5. A description of data sets to determine the innovative diversification capacity of farm households.

    Science.gov (United States)

    Mc Fadden, Terence

    2016-09-01

    This data represents research activities carried out in Co. Offaly and Co. Mayo, Ireland, to identify farm household innovative diversification behavior and policy/institutional actor capacity roles in support. The data sets are overlain with household and agency data from the two study areas to describe levels of innovative diversification capacity by individual socio-economic farm household profile. The data sets summarize the public policy discussions on rural innovation and diversification and policy actor response requirements, and incorporate both qualitative and quantitative data set combinations. The data are used to assess policy/institutional actors' roles and farm households' capacity for innovation at the farm household/institution interface in support of sustainable rural business innovations on-farm and diversification.

  6. Robust Approach to Analysis of International Diversification Benefits between US, UK and Emerging Stock Markets

    Directory of Open Access Journals (Sweden)

    Ozlem Yorulmaz

    Full Text Available As is known skewness and outliers are frequently observed in return series, overlooking both concepts during the statistical analysis may cause misleading interpretations. In this paper similar movements of stock markets through the returns of developed and emerging stock markets are recognized and appealing portfolio diversification benefits are identified for investors of USA, UK and Turkey. Different from the previous studies, modified robust principal component analysis which considers skewness and outliers effects was used to investigate the best portfolio diversification. Sixteen stock markets are represented with five components according to findings obtained from analysis. Hence Egyptian, Hungarian, Polish, Thai and Indonesian stock markets provide appealing portfolio diversification opportunities for investors of Turkey. And for the investors of USA and UK, selected emerging markets except Mexican and Turkish offer good diversification benefit.

  7. Related Diversification, Unrelated Diversification and Regional Economic Development--Evidences from Panel Data on China's 282 Prefecture-level City%相关多样化、无关多样化与地区经济发展——基于中国282个地级市面板数据的实证研究

    Institute of Scientific and Technical Information of China (English)

    孙晓华; 柴玲玲

    2012-01-01

    经济全球化背景下,面对经济快速增长的内在要求和急剧变化的外部市场环境.如何调整产业结构以实现经济持续稳定发展是各地区面临的重要问题。本文以产业多样化影响地区经济发展的理论机制为基础.利用熵指标法将产业多样化分解为相关和无关两部分.以中国2003--2009年地级市面板数据为样本,从经济增长和经济稳定两个维度检验了相关与无关多样化对地区经济发展的影响.发现相关多样化对地区经济增长与经济稳定都存在显著的促进作用.无关多样化不利于经济增长但有助于提高经济稳定性。为进一步考察不同宏观经济形势下多样化在经济稳定功能方面的差异,以全球经济危机为分界点进行了分阶段回归,结果显示:当外部市场状况良好时,相关多样化的稳定效应较为明显.当遭遇外部经济冲击时.相关多样化的稳定作用被削弱甚至逆转,而无关多样化则始终发挥着经济稳定器的功能。%In the context of economic globalization, faced with the inherent requirements of rapid economic growth and dramatic changes in the external market environment, how to adjust the industrial structure in order to achieve sustained and stable economic development is the important issue faced by each region. This article is based on the theoretical mechanisms of the impact of industrial diversification on regional economic development, and by using the entropy index method, industrial diversification is decomposed into related and unrelated to the two parts, also taking China's prefecture-level city panel data from 2003 to 2009 as samples, the impact of related and unrelated diversification on regional economic development is examined from economic growth and economic stability in two dimensions, and the results show related diversification has a significant promoting role in regional economic growth and economic

  8. Control tectónico de la red de drenaje de los Andes del norte argentino Tectonic control of the drainage in the Andes of northern Argentina

    Directory of Open Access Journals (Sweden)

    R. Mon

    2005-09-01

    Full Text Available Los ríos transversales que drenan la vertiente oriental de los Andes del norte argentino muestran bruscos desvíos hacia cursos longitudinales, inmediatamente al oeste de la traza de grandes cabalgamientos o de los bordes de láminas levantadas por fallas ubicadas en el lado opuesto de ellos. Los ríos desviados colectan otros ríos transversales antes de emerger en la dirección opuesta y de atravesar el frente montañoso. El desvío de los ríos se interpreta como la respuesta al levantamiento progresivo y al crecimiento lateral de cinturones fallados o de anticlinales propagados a lo largo de fallas ciegas. La mayor parte de los ríos de la región fueron desviados, pocos de ellos mantuvieron sus cursos a través de las estructuras en desarrollo. La reorganización del drenaje por el desarrollo de una topografía controlada estructuralmente influyó en la ubicación y en la concentración de los desagües de los ríos en el frente montañoso. Este segmento de los Andes, que se extiende a lo largo de más de 600 km, tiene sólo tres desagües representados por los ríos troncales Bermejo, Juramento y Salí-Dulce. El drenaje evolucionó desde el levantamiento de la Puna (12- 15 Ma, después de la regresión marina final. El desvío de los ríos puede haber empezado después del levantamiento de la Cordillera Oriental (10 Ma y prosiguió con el levantamiento de nuevas montañas hacia el este. El levantamiento de las cadenas montañosas avanzó de oeste a este. Los cinturones más orientales del Sistema Subandino y de las Sierras Pampeanas septentrionales se levantaron después de los 3 Ma. El levantamiento rápido de los obstáculos tectónicos puede explicar la tendencia al desvío de los ríos de esta región.Transverse rivers draining the eastern flank of the Andes of north Argentina show abrupt diversions to axial courses immediately west of the trace of big thrusts, or the borders of plates uplifted by faults located along the opposite

  9. Detecting Hidden Diversification Shifts in Models of Trait-Dependent Speciation and Extinction.

    Science.gov (United States)

    Beaulieu, Jeremy M; O'Meara, Brian C

    2016-07-01

    The distribution of diversity can vary considerably from clade to clade. Attempts to understand these patterns often employ state-dependent speciation and extinction models to determine whether the evolution of a particular novel trait has increased speciation rates and/or decreased extinction rates. It is still unclear, however, whether these models are uncovering important drivers of diversification, or whether they are simply pointing to more complex patterns involving many unmeasured and co-distributed factors. Here we describe an extension to the popular state-dependent speciation and extinction models that specifically accounts for the presence of unmeasured factors that could impact diversification rates estimated for the states of any observed trait, addressing at least one major criticism of BiSSE (Binary State Speciation and Extinction) methods. Specifically, our model, which we refer to as HiSSE (Hidden State Speciation and Extinction), assumes that related to each observed state in the model are "hidden" states that exhibit potentially distinct diversification dynamics and transition rates than the observed states in isolation. We also demonstrate how our model can be used as character-independent diversification models that allow for a complex diversification process that is independent of the evolution of a character. Under rigorous simulation tests and when applied to empirical data, we find that HiSSE performs reasonably well, and can at least detect net diversification rate differences between observed and hidden states and detect when diversification rate differences do not correlate with the observed states. We discuss the remaining issues with state-dependent speciation and extinction models in general, and the important ways in which HiSSE provides a more nuanced understanding of trait-dependent diversification.

  10. Global diversification of a tropical plant growth form: environmental correlates and historical contingencies in climbing palms

    OpenAIRE

    Couvreur, Thomas L.P.; W. Daniel Kissling; Fabien L. Condamine; Jens-Christian eSvenning; Rowe, Nick P.; Baker, William J.

    2015-01-01

    Tropical rain forests (TRF) are the most diverse terrestrial biome on Earth, but the diversification dynamics of their constituent growth forms remain largely unexplored. Climbing plants contribute significantly to species diversity and ecosystem processes in TRF. We investigate the broad-scale patterns and drivers of species richness as well as the diversification history of climbing and non-climbing palms (Arecaceae). We quantify to what extent macroecological diversity patterns are related...

  11. Limits to international diversification in oil and gas -domestic vs foreign asset control

    OpenAIRE

    2010-01-01

    We provide evidence that international diversification in the oil and gas sector comes at an important cost; lower control over foreign oilfield assets (and therefore reduced control over oilfield cash-flows). This work examines the factors that drive companies to diversify despite the loss of control over oilfields. Detailed worldwide data for 293 companies owning 6633 field stakes enable us to demonstrate that diversification increases with firm size but results in lower asset control - wit...

  12. Deep global evolutionary radiation in birds: diversification and trait evolution in the cosmopolitan bird family Rallidae.

    Science.gov (United States)

    Garcia-R, Juan C; Gibb, Gillian C; Trewick, Steve A

    2014-12-01

    Sufficient breadth of taxon sampling in major organisms groups is important to identify more realistic biological diversification processes that reveal the degree of historical biogeographic signal and net diversification retained in the current lineage distribution. We examine the mechanisms driving diversity in one of the major avian clades with an exceptional large-scale radiation, the family Rallidae, using the most complete species-level (∼70%) time calibrated hypothesis of evolutionary relationships produced to date. We find that Rallidae exhibit a pattern of diversification involving episodes of range expansion and regional speciation that results in most clades represented in all habitable continents. Our results suggest that several features may have played an important role on the diversification rates in Rallidae. Lineage accumulation is nearly constant and morphology (frontal shield and body size), innovate (flightlessness), habitat (forest) and distribution (insular) traits are possibly associated with increasing diversification rates along with spatial and ecological processes during the Miocene and Pliocene. Diversification and the global retention of lineage diversity have occurred in multiple lineages in Rallidae due to their dispersal ability and exploitation of ecological opportunities.

  13. Livelihood Capital and Livelihood Diversification for Different Farmers in Yuanjiang Dry- Hot River Valley

    Institute of Scientific and Technical Information of China (English)

    Wenjuan ZHAO; Shilong YANG; Xiao WANG

    2016-01-01

    Under the analytical framework of sustainable livelihoods,we establish the evaluation indicator system for farmers’ livelihood capital,to evaluate the current livelihood capital and livelihood diversification for different farmers in the Dai nationality region of Xinping County in the Yuanjiang dry-hot river valley area,and discuss the relationship between livelihood capital and livelihood diversification. Studies have shown that the mode dominated by agriculture,supplemented by non-agricultural activities,combined with breeding,is the commonly used livelihood strategy for farmers in this region. As farmers change from pure agriculture to non-agriculture,their total livelihood capital and nonagricultural livelihood diversification index will increase,while agricultural livelihood diversification index will decrease. In the meantime,their livelihood activities gradually shift from agricultural to non-agricultural ones,which is mainly reflected in the combination of both agricultural and non-agricultural activities. Regression analysis on livelihood capital and livelihood diversification shows that natural and physical capital is the basis of realizing agricultural livelihood diversification. Farmers with rich natural and physical capital will prefer agricultural livelihood strategies. While financial and human capital is the driving force for farmers’ transition from pure agriculture to non-agriculture.

  14. An Appraisal of the practice of corporate diversification in selected Nigerian banks

    Directory of Open Access Journals (Sweden)

    Olu Ojo

    2011-07-01

    Full Text Available This research investigates the diversification-performance relationship in Nigerian banking industry. Empirical evidences emerging from previous studies from developed countries about the effect of diversification on performance in the banking industry have so far yielded mixed results. There is a major gap in the relevant literature on developing countries which this research filled by studying Nigerian banks and providing empirical evidence on diversification-performance relationship. Survey research design was adopted with the application of probability sampling technique in selecting our case study companies and respondents. Primary data were collected through questionnaire while secondary data were garnered from the annual report and accounts of the banks under study. Data were analyzed through descriptive statistics while correlation and ANOVA were used to test our hypotheses. It was discovered that diversification impacts corporate performance of these banks positively and recommends that these banks should engage in geographical diversification in addition to other forms of diversification they are currently involved in for maximum performance.

  15. Dioecy does not consistently accelerate or slow lineage diversification across multiple genera of angiosperms.

    Science.gov (United States)

    Sabath, Niv; Goldberg, Emma E; Glick, Lior; Einhorn, Moshe; Ashman, Tia-Lynn; Ming, Ray; Otto, Sarah P; Vamosi, Jana C; Mayrose, Itay

    2016-02-01

    Dioecy, the sexual system in which male and female organs are found in separate individuals, allows greater specialization for sex-specific functions and can be advantageous under various ecological and environmental conditions. However, dioecy is rare among flowering plants. Previous studies identified contradictory trends regarding the relative diversification rates of dioecious lineages vs their nondioecious counterparts, depending on the methods and data used. We gathered detailed species-level data for dozens of genera that contain both dioecious and nondioecious species. We then applied a probabilistic approach that accounts for differential speciation, extinction, and transition rates between states to examine whether there is an association between dioecy and lineage diversification. We found a bimodal distribution, whereby dioecious lineages exhibited higher diversification in certain genera but lower diversification in others. Additional analyses did not uncover an ecological or life history trait that could explain a context-dependent effect of dioecy on diversification. Furthermore, in-depth simulations of neutral characters demonstrated that such bimodality is also found when simulating neutral characters across the observed trees. Our analyses suggest that - at least for these genera with the currently available data - dioecy neither consistently places a strong brake on diversification nor is a strong driver.

  16. Adaptive radiation versus 'radiation' and 'explosive diversification': why conceptual distinctions are fundamental to understanding evolution.

    Science.gov (United States)

    Givnish, Thomas J

    2015-07-01

    Adaptive radiation is the rise of a diversity of ecological roles and role-specific adaptations within a lineage. Recently, some researchers have begun to use 'adaptive radiation' or 'radiation' as synonymous with 'explosive species diversification'. This essay aims to clarify distinctions between these concepts, and the related ideas of geographic speciation, sexual selection, key innovations, key landscapes and ecological keys. Several examples are given to demonstrate that adaptive radiation and explosive diversification are not the same phenomenon, and that focusing on explosive diversification and the analysis of phylogenetic topology ignores much of the rich biology associated with adaptive radiation, and risks generating confusion about the nature of the evolutionary forces driving species diversification. Some 'radiations' involve bursts of geographic speciation or sexual selection, rather than adaptive diversification; some adaptive radiations have little or no effect on speciation, or even a negative effect. Many classic examples of 'adaptive radiation' appear to involve effects driven partly by geographic speciation, species' dispersal abilities, and the nature of extrinsic dispersal barriers; partly by sexual selection; and partly by adaptive radiation in the classical sense, including the origin of traits and invasion of adaptive zones that result in decreased diversification rates but add to overall diversity.

  17. Elevated Extinction Rates as a Trigger for Diversification Rate Shifts: Early Amniotes as a Case Study.

    Science.gov (United States)

    Brocklehurst, Neil; Ruta, Marcello; Müller, Johannes; Fröbisch, Jörg

    2015-11-23

    Tree shape analyses are frequently used to infer the location of shifts in diversification rate within the Tree of Life. Many studies have supported a causal relationship between shifts and temporally coincident events such as the evolution of "key innovations". However, the evidence for such relationships is circumstantial. We investigated patterns of diversification during the early evolution of Amniota from the Carboniferous to the Triassic, subjecting a new supertree to analyses of tree balance in order to infer the timing and location of diversification shifts. We investigated how uneven origination and extinction rates drive diversification shifts, and use two case studies (herbivory and an aquatic lifestyle) to examine whether shifts tend to be contemporaneous with evolutionary novelties. Shifts within amniotes tend to occur during periods of elevated extinction, with mass extinctions coinciding with numerous and larger shifts. Diversification shifts occurring in clades that possess evolutionary innovations do not coincide temporally with the appearance of those innovations, but are instead deferred to periods of high extinction rate. We suggest such innovations did not cause increases in the rate of cladogenesis, but allowed clades to survive extinction events. We highlight the importance of examining general patterns of diversification before interpreting specific shifts.

  18. A Robust Semi-Parametric Test for Detecting Trait-Dependent Diversification.

    Science.gov (United States)

    Rabosky, Daniel L; Huang, Huateng

    2016-03-01

    Rates of species diversification vary widely across the tree of life and there is considerable interest in identifying organismal traits that correlate with rates of speciation and extinction. However, it has been challenging to develop methodological frameworks for testing hypotheses about trait-dependent diversification that are robust to phylogenetic pseudoreplication and to directionally biased rates of character change. We describe a semi-parametric test for trait-dependent diversification that explicitly requires replicated associations between character states and diversification rates to detect effects. To use the method, diversification rates are reconstructed across a phylogenetic tree with no consideration of character states. A test statistic is then computed to measure the association between species-level traits and the corresponding diversification rate estimates at the tips of the tree. The empirical value of the test statistic is compared to a null distribution that is generated by structured permutations of evolutionary rates across the phylogeny. The test is applicable to binary discrete characters as well as continuous-valued traits and can accommodate extremely sparse sampling of character states at the tips of the tree. We apply the test to several empirical data sets and demonstrate that the method has acceptable Type I error rates.

  19. Temperate radiations and dying embers of a tropical past: the diversification of Viburnum.

    Science.gov (United States)

    Spriggs, Elizabeth L; Clement, Wendy L; Sweeney, Patrick W; Madriñán, Santiago; Edwards, Erika J; Donoghue, Michael J

    2015-07-01

    We used a near-complete phylogeny for the angiosperm clade Viburnum to assess lineage diversification rates, and to examine possible morphological and ecological factors driving radiations. Maximum-likelihood and Bayesian approaches identified shifts in diversification rate and possible links to character evolution. We inferred the ancestral environment for Viburnum and changes in diversification dynamics associated with subsequent biome shifts. Viburnum probably diversified in tropical forests of Southeast Asia in the Eocene, with three subsequent radiations in temperate clades during the Miocene. Four traits (purple fruits, extrafloral nectaries, bud scales and toothed leaves) were statistically associated with higher rates of diversification. However, we argue that these traits are unlikely to be driving diversification directly. Instead, two radiations were associated with the occupation of mountainous regions and a third with repeated shifts between colder and warmer temperate forests. Early-branching depauperate lineages imply that the rare lowland tropical species are 'dying embers' of once more diverse lineages; net diversification rates in Viburnum likely decreased in these tropical environments after the Oligocene. We suggest that 'taxon pulse' dynamics might characterize other temperate plant lineages.

  20. Old lineages in a new ecosystem: diversification of arcellinid amoebae (Amoebozoa and peatland mosses.

    Directory of Open Access Journals (Sweden)

    Omar Fiz-Palacios

    Full Text Available Arcellinid testate amoebae (Amoebozoa form a group of free-living microbial eukaryotes with one of the oldest fossil records known, yet several aspects of their evolutionary history remain poorly understood. Arcellinids occur in a range of terrestrial, freshwater and even brackish habitats; however, many arcellinid morphospecies such as Hyalosphenia papilio are particularly abundant in Sphagnum-dominated peatlands, a relatively new ecosystem that appeared during the diversification of Sphagnum species in the Miocene (5-20 Myr ago. Here, we reconstruct divergence times in arcellinid testate amoebae after selecting several fossils for clock calibrations and then infer whether or not arcellinids followed a pattern of diversification that parallels the pattern described for Sphagnum. We found that the diversification of core arcellinids occurred during the Phanerozoic, which is congruent with most arcellinid fossils but not with the oldest known amoebozoan fossil (i.e. at ca. 662 or ca. 750 Myr. Overall, Sphagnum and the Hyalospheniidae exhibit different patterns of diversification. However, an extensive molecular phylogenetic analysis of distinct clades within H. papilio species complex demonstrated a correlation between the recent diversification of H. papilio, the recent diversification of Sphagnum mosses, and the establishment of peatlands.