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1.
Zootaxa ; 4624(3): zootaxa.4624.3.1, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31716208

RESUMO

An integrative taxonomic analysis of the Cyrtodactylus linnwayensis group of the Shan Plateau recovered two new populations from isolated karst habitats near Pinlaung Town, Shan State as a new species, C. pinlaungensis sp. nov. Cyrtodactylus pinlaungensis sp. nov. is most closely related to a clade comprising C. linnwayensis and C. ywanganensis from the western edge of the Shan Plateau approximately 90 km to the northwest. Cyrtodactylus pinlaungensis sp. nov. can be distinguished from all members of the C. linnwayensis group by a number of statistically different morphological characters, discrete color pattern differences, and its heavy tuberculation. It also bears an uncorrected pairwise sequence divergence of 5.0-7.6% from all other species combined based on the mitochondrial gene ND2 and its flanking tRNAs. The discovery of this new species on the Shan Plateau continues to underscore the fact that this region is rapidly emerging as a herpetological diversity hot-spot for Myanmar.


Assuntos
Lagartos , Animais , Ecossistema , Genes Mitocondriais , Mianmar , Filogenia
2.
Zootaxa ; 4656(3): zootaxa.4656.3.11, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31716818

RESUMO

A new species of Ansonia is described from the Shan Plateau of Myanmar based on an integrative taxonomic analysis that differentiates it from all other congeners. Molecular phylogenetic analyses based on the mitochondrial genes 12S and 16S rRNA and tRNA-val recover A. kyaiktiyoensis sp. nov. as the sister species to A. inthanon from Thailand but differs from it and other congeners by at least a 5.0% sequence divergence. It is further differentiated by the following combination of morphological characters: (1) maximum SVL 24 mm in males and females; (2) first finger shorter than second; (3) absence of interorbital and tarsal ridges; (4) presence of light-coloured interscapular spot; (5) presence of yellow rictal tubercle; (6) absence of wide, light-coloured patch below eye; (7) presence of large, discrete, bright-yellow submandibular spots along the underside of lower jaw; (8) iris yellow-gold; (9) presence of markings on the snout consisting of streaks below the eye to the lip, and on the canthus rostralis to the nostril; (10) dorsum grey-brown with orange-beige spots, a dark-brown X-shaped marking on the back surrounding the interscapular spot, and dark-coloured markings on rump; (11) fore- and hind limbs with orange-beige cross-bars; and (12) venter light-gray with yellow spotting, especially near flanks and underside of hind limbs. Ansonia kyaiktiyoensis sp. nov. is the westernmost known record for the genus and the only species west of the Salween Basin. Its discovery echoes the increasing number of herpetological discoveries being made in upland regions fringing the Ayeyarwady and Salween Basins.


Assuntos
Anuros , Bufonidae , Animais , Feminino , Masculino , Mianmar , Filogenia , RNA Ribossômico 16S , Tailândia
3.
Trends Parasitol ; 35(6): 399-408, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31053334

RESUMO

Global habitat fragmentation is associated with the emergence of infectious diseases of wildlife origins in human populations. Despite this well-accepted narrative, the underlying mechanisms driving this association remain unclear. We introduce a nuanced hypothesis, the 'coevolution effect'. The central concept is that the subdivision of host populations which occurs with habitat fragmentation causes localized coevolution of hosts, obligate parasites, and pathogens which act as 'coevolutionary engines' within each fragment, accelerating pathogen diversification, and increasing pathogen diversity across the landscape. When combined with a mechanism to exit a fragment (e.g., mosquitoes), pathogen variants will spill over into human communities. Through this combined ecoevolutionary approach we may be able to understand the fine-scale mechanisms that drive disease emergence in the Anthropocene.

4.
Evolution ; 73(6): 1151-1167, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31017301

RESUMO

A primary goal of biogeography is to understand how large-scale environmental processes, like climate change, affect diversification. One often-invoked but seldom tested process is the "species-pump" model, in which repeated bouts of cospeciation are driven by oscillating climate-induced habitat connectivity cycles. For example, over the past three million years, the landscape of the Philippine Islands has repeatedly coalesced and fragmented due to sea-level changes associated with glacial cycles. This repeated climate-driven vicariance has been proposed as a model of speciation across evolutionary lineages codistributed throughout the islands. This model predicts speciation times that are temporally clustered around the times when interglacial rises in sea level fragmented the islands. To test this prediction, we collected comparative genomic data from 16 pairs of insular gecko populations. We analyze these data in a full-likelihood, Bayesian model-choice framework to test for shared divergence times among the pairs. Our results provide support against the species-pump model prediction in favor of an alternative interpretation, namely that each pair of gecko populations diverged independently. These results suggest the repeated bouts of climate-driven landscape fragmentation have not been an important mechanism of speciation for gekkonid lizards across the Philippine Archipelago.

5.
PLoS One ; 14(3): e0214439, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30913266

RESUMO

Accurate species delimitation and description are necessary to guide effective conservation of imperiled species, and this synergy is maximized when multiple data sources are used to delimit species. We illustrate this point by examining Drymarchon couperi (Eastern Indigo Snake), a large, federally-protected species in North America that was recently divided into two species based on gene sequence data from three loci and heuristic morphological assessment. Here, we re-evaluate the two-species hypothesis for D. couperi by evaluating both population genetic and gene sequence data. Our analyses of 14 microsatellite markers revealed 6-8 genetic population clusters with significant admixture, particularly across the contact zone between the two hypothesized species. Phylogenetic analyses of gene sequence data with maximum-likelihood methods suggested discordance between mitochondrial and nuclear markers and provided phylogenetic support for one species rather than two. For these reasons, we place Drymarchon kolpobasileus into synonymy with D. couperi. We suggest inconsistent patterns between mitochondrial and nuclear DNA are driven by high dispersal of males relative to females. We advocate for species delimitation exercises that evaluate admixture and gene flow in addition to phylogenetic analyses, particularly when the latter reveal monophyletic lineages. This is particularly important for taxa, such as squamates, that exhibit strong sex-biased dispersal. Problems associated with over-delimitation of species richness can become particularly acute for threatened and endangered species, because of high costs to conservation when taxonomy demands protection of more individual species than are supported by accumulating data.


Assuntos
Distribuição Animal , Núcleo Celular/genética , Conservação dos Recursos Naturais , Espécies em Perigo de Extinção , Mitocôndrias/genética , Serpentes/classificação , Serpentes/genética , Animais , Feminino , Loci Gênicos/genética , Masculino , Repetições de Microssatélites/genética , Fatores Sexuais
6.
Syst Biol ; 68(3): 371-395, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30239868

RESUMO

A challenge to understanding biological diversification is accounting for community-scale processes that cause multiple, co-distributed lineages to co-speciate. Such processes predict non-independent, temporally clustered divergences across taxa. Approximate-likelihood Bayesian computation (ABC) approaches to inferring such patterns from comparative genetic data are very sensitive to prior assumptions and often biased toward estimating shared divergences. We introduce a full-likelihood Bayesian approach, ecoevolity, which takes full advantage of information in genomic data. By analytically integrating over gene trees, we are able to directly calculate the likelihood of the population history from genomic data, and efficiently sample the model-averaged posterior via Markov chain Monte Carlo algorithms. Using simulations, we find that the new method is much more accurate and precise at estimating the number and timing of divergence events across pairs of populations than existing approximate-likelihood methods. Our full Bayesian approach also requires several orders of magnitude less computational time than existing ABC approaches. We find that despite assuming unlinked characters (e.g., unlinked single-nucleotide polymorphisms), the new method performs better if this assumption is violated in order to retain the constant characters of whole linked loci. In fact, retaining constant characters allows the new method to robustly estimate the correct number of divergence events with high posterior probability in the face of character-acquisition biases, which commonly plague loci assembled from reduced-representation genomic libraries. We apply our method to genomic data from four pairs of insular populations of Gekko lizards from the Philippines that are not expected to have co-diverged. Despite all four pairs diverging very recently, our method strongly supports that they diverged independently, and these results are robust to very disparate prior assumptions.


Assuntos
Teorema de Bayes , Classificação/métodos , Genoma/genética , Filogeografia , Animais , Simulação por Computador , Genômica , Lagartos/classificação , Lagartos/genética , Filipinas , Filogenia
7.
F1000Res ; 8: 1854, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32025290

RESUMO

Many biologists are interested in teaching computing skills or using computing in the classroom, despite not being formally trained in these skills themselves. Thus biologists may find themselves researching how to teach these skills, and therefore many individuals are individually attempting to discover resources and methods to do so. Recent years have seen an expansion of new technologies to assist in delivering course content interactively. Educational research provides insights into how learners absorb and process information during interactive learning. In this review, we discuss the value of teaching foundational computing skills to biologists, and strategies and tools to do so. Additionally, we review the literature on teaching practices to support the development of these skills. We pay special attention to meeting the needs of diverse learners, and consider how different ways of delivering course content can be leveraged to provide a more inclusive classroom experience. Our goal is to enable biologists to teach computational skills and use computing in the classroom successfully.

8.
Am J Bot ; 102(1): 149-64, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25587157

RESUMO

UNLABELLED: • PREMISE OF THE STUDY: A recurrent explanation for phylogeographic discontinuities in the Baja California Peninsula and the Sonoran Desert Region has been the association of vicariant events with Pliocene and Pleistocene seaway breaks. Nevertheless, despite its relevance for plant dispersal, other explanations such as ecological and paleoclimatic factors have received little attention. Here, we analyzed the role of several of these factors to describe the phylogeographic patterns of the desert mistletoe, Phoradendron californicum.• METHODS: Using noncoding chloroplast regions, we assess the marginal probability of 19 a priori hypotheses related to geological and ecological factors to predict the cpDNA variation in P. californicum using a Bayesian coalescent framework. Complementarily, we used the macrofossil record and niche model projections on Last Glacial Maximum climatic conditions for hosts, mistletoe, and a bird specialist to interpret phylogeographic patterns.• KEY RESULTS: Genealogical reconstructions revealed five clades, which suggest a combination of cryptic divergence, long-distance seed dispersal, and isolating postdivergence events. Bayesian hypothesis test favored a series of Pliocene and Pleistocene geological events related to the formation of the Baja California Peninsula and seaways across the peninsula as the most supported explanation for this genealogical pattern. However, age estimates, niche projections, and fossil records show dynamic host-mistletoe interactions and evidence of host races, indicating that ecological and geological factors have been interacting during the formation and structuring of phylogeographic divergence.• CONCLUSIONS: Variation in cpDNA across the species range results from the interplay of vicariant events, past climatic oscillations, and more dynamic factors related to ecological processes at finer temporal and spatial scales.


Assuntos
DNA de Cloroplastos/genética , Phoradendron/genética , Teorema de Bayes , Clima , Ecossistema , Evolução Molecular , México , Dados de Sequência Molecular , Filogenia , Filogeografia , Análise de Sequência de DNA , Sudoeste dos Estados Unidos
9.
Evolution ; 68(12): 3607-17, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25213163

RESUMO

Establishing that a set of population-splitting events occurred at the same time can be a potentially persuasive argument that a common process affected the populations. Recently, Oaks et al. () assessed the ability of an approximate-Bayesian model-choice method (msBayes) to estimate such a pattern of simultaneous divergence across taxa, to which Hickerson et al. () responded. Both papers agree that the primary inference enabled by the method is very sensitive to prior assumptions and often erroneously supports shared divergences across taxa when prior uncertainty about divergence times is represented by a uniform distribution. However, the papers differ about the best explanation and solution for this problem. Oaks et al. () suggested the method's behavior was caused by the strong weight of uniformly distributed priors on divergence times leading to smaller marginal likelihoods (and thus smaller posterior probabilities) of models with more divergence-time parameters (Hypothesis 1); they proposed alternative prior probability distributions to avoid such strongly weighted posteriors. Hickerson et al. () suggested numerical-approximation error causes msBayes analyses to be biased toward models of clustered divergences because the method's rejection algorithm is unable to adequately sample the parameter space of richer models within reasonable computational limits when using broad uniform priors on divergence times (Hypothesis 2). As a potential solution, they proposed a model-averaging approach that uses narrow, empirically informed uniform priors. Here, we use analyses of simulated and empirical data to demonstrate that the approach of Hickerson et al. () does not mitigate the method's tendency to erroneously support models of highly clustered divergences, and is dangerous in the sense that the empirically derived uniform priors often exclude from consideration the true values of the divergence-time parameters. Our results also show that the tendency of msBayes analyses to support models of shared divergences is primarily due to Hypothesis 1, whereas Hypothesis 2 is an untenable explanation for the bias. Overall, this series of papers demonstrates that if our prior assumptions place too much weight in unlikely regions of parameter space such that the exact posterior supports the wrong model of evolutionary history, no amount of computation can rescue our inference. Fortunately, as predicted by fundamental principles of Bayesian model choice, more flexible distributions that accommodate prior uncertainty about parameters without placing excessive weight in vast regions of parameter space with low likelihood increase the method's robustness and power to detect temporal variation in divergences.


Assuntos
Evolução Biológica , Clima , Modelos Biológicos , Animais
10.
BMC Evol Biol ; 14: 150, 2014 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-24992937

RESUMO

BACKGROUND: To understand biological diversification, it is important to account for large-scale processes that affect the evolutionary history of groups of co-distributed populations of organisms. Such events predict temporally clustered divergences times, a pattern that can be estimated using genetic data from co-distributed species. I introduce a new approximate-Bayesian method for comparative phylogeographical model-choice that estimates the temporal distribution of divergences across taxa from multi-locus DNA sequence data. The model is an extension of that implemented in msBayes. RESULTS: By reparameterizing the model, introducing more flexible priors on demographic and divergence-time parameters, and implementing a non-parametric Dirichlet-process prior over divergence models, I improved the robustness, accuracy, and power of the method for estimating shared evolutionary history across taxa. CONCLUSIONS: The results demonstrate the improved performance of the new method is due to (1) more appropriate priors on divergence-time and demographic parameters that avoid prohibitively small marginal likelihoods for models with more divergence events, and (2) the Dirichlet-process providing a flexible prior on divergence histories that does not strongly disfavor models with intermediate numbers of divergence events. The new method yields more robust estimates of posterior uncertainty, and thus greatly reduces the tendency to incorrectly estimate models of shared evolutionary history with strong support.


Assuntos
Teorema de Bayes , Evolução Biológica , Modelos Genéticos , Filogeografia , Software
11.
Mol Phylogenet Evol ; 74: 29-37, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24486878

RESUMO

We utilize robust geographical genetic sampling, a multilocus dataset, a new synthesis of numerous fossil calibration points, a time-calibrated phylogeny, and the Dispersal-Extinction-Cladogenesis model to test the prediction that widespread Southeast Asian water monitor species initially diversified on the Asian mainland and subsequently invaded the island archipelagos of the Philippines, Sundaland, and Wallacea. Our results strongly contradict these expectations and instead infer an initial water monitor radiation of range-restricted but highly divergent evolutionary lineages (now recognized as endemic species) in one archipelago around 3.6 mya, followed by an out-of-the-Philippines reinvasion of the mainland (2.2 mya), resulting in a few, widespread species that now inhabit most the islands of the Sunda Shelf and the Southeast Asian mainland as far north as Myanmar, as well as an out-of-the-Philippines invasion of Sulawesi (2.1 mya). Our analyses both confirm the importance of island archipelagos as drivers of diversification for mainland biodiversity and emphasize the global evolutionary significance and conservation priority of the Philippines for understanding processes of diversification in island archipelagos.


Assuntos
Fósseis , Lagartos/genética , Filogenia , Animais , Ásia Sudeste , Biodiversidade , Calibragem
12.
Evolution ; 67(4): 991-1010, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23550751

RESUMO

Approximate Bayesian computation (ABC) is rapidly gaining popularity in population genetics. One example, msBayes, infers the distribution of divergence times among pairs of taxa, allowing phylogeographers to test hypotheses about historical causes of diversification in co-distributed groups of organisms. Using msBayes, we infer the distribution of divergence times among 22 pairs of populations of vertebrates distributed across the Philippine Archipelago. Our objective was to test whether sea-level oscillations during the Pleistocene caused diversification across the islands. To guide interpretation of our results, we perform a suite of simulation-based power analyses. Our empirical results strongly support a recent simultaneous divergence event for all 22 taxon pairs, consistent with the prediction of the Pleistocene-driven diversification hypothesis. However, our empirical estimates are sensitive to changes in prior distributions, and our simulations reveal low power of the method to detect random variation in divergence times and bias toward supporting clustered divergences. Our results demonstrate that analyses exploring power and prior sensitivity should accompany ABC model selection inferences. The problems we identify are potentially mitigable with uniform priors over divergence models (rather than classes of models) and more flexible prior distributions on demographic and divergence-time parameters.


Assuntos
Evolução Biológica , Clima , Modelos Biológicos , Animais , Especiação Genética , Fenômenos Geológicos , Ilhas , Filogenia
13.
Evolution ; 65(11): 3285-97, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22023592

RESUMO

True crocodiles (Crocodylus) are the most broadly distributed, ecologically diverse, and species-rich crocodylian genus, comprising about half of extant crocodylian diversity and exhibiting a circumtropical distribution. Crocodylus traditionally has been viewed as an ancient group of morphologically conserved species that originated in Africa prior to continental breakup. In this study, these long-held notions about the temporal and geographic origin of Crocodylus are tested using DNA sequence data of 10 loci from 76 individuals representing all 23 crocodylian species. I infer a time-calibrated species tree of all Crocodylia and estimate the spatial pattern of diversification within Crocodylus. For the first time, a fully resolved phylogenetic estimate of all Crocodylia is well-supported. The results overturn traditional views of the evolution of Crocodylus by demonstrating that the true crocodiles are not "living-fossils" that originated in Africa. Rather, Crocodylus originated from an ancestor in the tropics of the Late Miocene Indo-Pacific, and rapidly radiated and dispersed around the globe during a period marked by mass extinctions of fellow crocodylians. The findings also reveal more diversity within the genus than is recognized by current taxonomy.


Assuntos
Jacarés e Crocodilos/genética , Evolução Molecular , Filogenia , Animais , Sequência de Bases , Funções Verossimilhança , Modelos Genéticos , Dados de Sequência Molecular , Filogeografia , Análise de Sequência de DNA , Especificidade da Espécie
14.
Mol Phylogenet Evol ; 55(2): 699-710, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20132898

RESUMO

In the Philippines, Pleistocene sea level oscillations repeatedly connected and isolated neighboring islands. Hence, an understanding of the island platforms adjoined during periods of low sea level has led biologists to a suite of expectations that, taken together, represent a paradigm for the process of recent diversification in southeast Asia. We employ statistical tests of phylogenetic topology and population genetic analyses of widespread species of bent-toed geckos (Cyrtodactylus) to ascertain whether patterns of inter- and intra-specific diversity can be explained by a Pleistocene aggregate island model of diversification. Contrary to many classic studies of Philippine vertebrates, we find complex patterns that are only partially explained by past island connectivity. In particular, we determine that some populations inhabiting previously united island groups show substantial genetic divergence and are inferred to be polyphyletic. Additionally, greater genetic diversity is found within islands, than between them. Among the topological patterns inconsistent with the Pleistocene model, we note some similarities with other lineages, but no obviously shared causal mechanisms are apparent. Finally, we infer well-supported discordance between the gene trees inferred from mitochondrial and nuclear DNA sequences of two species, which we suspect is the result of incomplete lineage sorting. This study contributes to a nascent body of literature suggesting that the current paradigm for Philippine biogeography is an oversimplification requiring revision.


Assuntos
Evolução Molecular , Genética Populacional , Lagartos/genética , Filogenia , Animais , Teorema de Bayes , Núcleo Celular/genética , DNA Mitocondrial/genética , Geografia , Funções Verossimilhança , Lagartos/classificação , Modelos Genéticos , Filipinas , Alinhamento de Sequência , Análise de Sequência de DNA
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