1,938 research outputs found

    Niche evolution and diversification in a Neotropical radiation of birds (Aves: Furnariidae)

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    © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution. 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

    Mitochondrial genomes and thousands of ultraconserved elements resolve the taxonomy and historical biogeography of the Euphonia and Chlorophonia finches (Passeriformes: Fringillidae)

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    © 2020 American Ornithological Society. Relationships of the Neotropical finches in the genera Euphonia and Chlorophonia (Fringillidae: Euphoniinae) have been clarified by recent molecular studies, but species-level relationships within this group have not been thoroughly addressed. In this study, we sampled specimens representing every recognized species of these genera, in addition to 2 outgroup taxa, and used target enrichment to sequence thousands of ultraconserved element (UCE) loci, as well as mitochondrial DNA reconstructed from off-target reads, from each specimen to infer these relationships. We constructed both concatenation and coalescent-based estimates of phylogeny from this dataset using matrices of varying levels of completeness, and we generated a time-scaled ultrametric tree using a recently published fossil-based external calibration. We found uniformly strong support for a monophyletic subfamily Euphoniinae and genus Chlorophonia, but a paraphyletic Euphonia across UCEs and mitochondrial genomes. Otherwise, our inferred relationships were largely concordant with previous studies. Our time-tree indicated a stem divergence time of 13.8 million years ago for this lineage, followed by a relatively young crown age of only 7.1 myr. Reconstructions of biogeographic history based on this tree suggest a South American origin for crown Euphoniinae, possibly resulting from a transoceanic dispersal event from the Eastern Hemisphere, followed by 2 dispersal events into the Caribbean and as many as 6 invasions of North America coinciding with recent estimates of the age at which the Isthmus of Panama had completely formed. We recommend splitting Euphonia and resurrecting the genus Cyanophonia for the 3 blue-hooded species more closely related to Chlorophonia. Based on our results, we suspect that there is undescribed species-level diversity in at least one, possibly many, widespread and phenotypically diverse species

    Phylogeography of the Variable Antshrike (Thamnophilus caerulescens), a South American passerine distributed along multiple environmental gradients

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    © 2020 Elsevier Inc. The Neotropics show a wealth of distributional patterns shared by many co-distributed species. A distinctive pattern is the so-called “circum-Amazonian distribution,” which is observed in species that do not occur in Amazonia but rather along a belt of forested habitats spanning south and east of Amazonia, the Andean foothills, and often into the Venezuelan Coastal Range and the Tepuis. Although this pattern is widespread across animals and plants, its underlying biogeographic mechanisms remain poorly understood. The Variable Antshrike (Thamnophilus caerulescens) is a sexually dimorphic suboscine passerine that exhibits extreme plumage variation and occurs along the southern portion of the circum-Amazonian belt. We describe broad-scale phylogeographic patterns of T. caerulescens and assess its demographic history using DNA sequences from the mitochondrion and ultraconserved elements (UCEs). We identified three genomic clusters: a) northern Atlantic Forest; b) southeastern Cerrado and central-southern Atlantic Forest, and c) Chaco and Andes. Our results were consistent with Pleistocene divergence followed by gene flow, mainly between the latter two clusters. There were no genetic signatures of rapid population expansions or bottlenecks. The population from the northern Atlantic Forest was the most genetically divergent group within the species. The demographic history of T. caerulescens was probably affected by series of humid and dry periods throughout the Quaternary that generated subtle population expansions and contractions allowing the intermittent connection of habitats along the circum-Amazonian belt. Recognizing the dynamic history of climate-mediated forest expansions, contractions, and connections during the South American Pleistocene is central toward a mechanistic understanding of circum-Amazonian distributions

    Corrigendum to “Phylogeography of the Variable Antshrike (Thamnophilus caerulescens), a South American passerine distributed along multiple environmental gradients” [Mol. Phylogenet. Evol. 148 (2020) 106810](S1055790320300828)(10.1016/j.ympev.2020.106810)

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    © 2020 Elsevier Inc. The authors regret: (a) The information of Table 2 has incorrect values in column 6. The following table has the correct values. (b) Also, there is a minor typo in the section ‘Data accessibility’, in the word: ‘alignmentsare’. The correct words are: ‘alignments are’. The authors would like to apologize for any inconvenience caused

    Similarity thresholds used in DNA sequence assembly from short reads can reduce the comparability of population histories across species

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    Comparing inferences among datasets generated using short read sequencing may provide insight into the concerted impacts of divergence, gene flow and selection across organisms, but comparisons are complicated by biases introduced during dataset assembly. Sequence similarity thresholds allow the de novo assembly of short reads into clusters of alleles representing different loci, but the resulting datasets are sensitive to both the similarity threshold used and to the variation naturally present in the organism under study. Thresholds that require high sequence similarity among reads for assembly (stringent thresholds) as well as highly variable species may result in datasets in which divergent alleles are lost or divided into separate loci (‘over-splitting’), whereas liberal thresholds increase the risk of paralogous loci being combined into a single locus (‘under-splitting’). Comparisons among datasets or species are therefore potentially biased if different similarity thresholds are applied or if the species differ in levels of within-lineage genetic variation. We examine the impact of a range of similarity thresholds on assembly of empirical short read datasets from populations of four different non-model bird lineages (species or species pairs) with different levels of genetic divergence. We find that, in all species, stringent similarity thresholds result in fewer alleles per locus than more liberal thresholds, which appears to be the result of high levels of over-splitting. The frequency of putative under-splitting, conversely, is low at all thresholds. Inferred genetic distances between individuals, gene tree depths, and estimates of the ancestral mutation-scaled effective population size (θ) differ depending upon the similarity threshold applied. Relative differences in inferences across species differ even when the same threshold is applied, but may be dramatically different when datasets assembled under different thresholds are compared. These differences not only complicate comparisons across species, but also preclude the application of standard mutation rates for parameter calibration. We suggest some best practices for assembling short read data to maximize comparability, such as using more liberal thresholds and examining the impact of different thresholds on each dataset

    Positive association between population genetic differentiation and speciation rates in New World birds

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    An implicit assumption of speciation biology is that population differentiation is an important stage of evolutionary diversification, but its significance as a rate-limiting control on phylogenetic speciation dynamics remains largely untested. If population differentiation within a species is related to its speciation rate over evolutionary time, the causes of differentiation could also be driving dynamics of organismal diversity across time and space. Alternatively, geographic variants might be short-lived entities with rates of formation that are unlinked to speciation rates, in which case the causes of differentiation would have only ephemeral impacts. By pairing population genetics datasets from173 NewWorld bird species (\u3e17,000 individuals) with phylogenetic estimates of speciation rate, we show that the population differentiation rates within species are positively correlated with their speciation rates over long timescales. Although population differentiation rate explains relatively little of the variation in speciation rate among lineages, the positive relationship between differentiation rate and speciation rate is robust to species-delimitation schemes and to alternative measures of both rates. Population differentiation occurs at least three times faster than speciation, which suggests that most populations are ephemeral. Speciation and population differentiation rates are more tightly linked in tropical species than in temperate species, consistent with a history of more stable diversification dynamics through time in the Tropics. Overall, our results suggest that the processes responsible for population differentiation are tied to those that underlie broad-scale patterns of diversity
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