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70 results for “divergence time estimation”
Data from: Fossils matter: improved estimates of divergence times in Pinus reveal older diversification
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Data from: Bayesian divergence-time estimation with genome-wide SNP data of sea catfishes (Ariidae) supports Miocene closure of the Panamanian isthmus
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The implications of lineage-specific rates for divergence time estimation
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Data from: A jungle tale: molecular phylogeny and divergence time estimates of the Desmopsis - Stenanona clade (Annonaceae) in Mesoamerica
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Data from: The past sure is tense: on interpreting phylogenetic divergence time estimates
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Divergence time estimation of genus Tribolium by extensive sampling of highly conserved orthologs
<p><i>Tribolium castaneum</i>, the red flour beetle, is among the most well-studied eukaryotic genetic model organisms. <i>Tribolium</i> often serves as a comparative bridge from highly derived <i>Drosophila</i> traits to other organisms. Simultaneously, as a member of the most diverse order of metazoans, Coleoptera, <i>Tribolium</i> informs us about innovations that accompany hyper diversity. However, understanding the tempo and mode of evolutionary innovation requires well-resolved, time-calibrated phylogenies, which are not available for <i>Tribolium</i>. The most recent effort to understand <i>Tribolium</i>phylogenetics used two mitochondrial and three nuclear markers. The study concluded that the genus may be paraphyletic and reported a broad range for divergence time estimates. Here we employ recent advances in Bayesian methods to estimate the relationships and divergence times among <i>Tribolium castaneum</i>, <i>T. brevicornis</i>, <i>T. confusum</i>, <i>T. freemani</i>, and <i>Gnatocerus cornutus </i>using 1368 orthologs conserved across all five species and an independent substitution rate estimate. We find that the most basal split within <i>Tribolium</i> occurred ~86 Mya [95% HPD 85.90–87.04 Mya] and that the most recent split was between <i>T. freemani</i> and <i>T. castaneum</i> at ~14 Mya [95% HPD 13.55-14.00]. Our results are consistent with broader phylogenetic analyses of insects and suggest that Cenozoic climate changes played a role in the <i>Tribolium </i>diversification.</p>
Data from: Robustness to divergence time underestimation when inferring species trees from estimated gene trees
To infer species trees from gene trees estimated from phylogenomic data sets, tractable methods are needed that can handle dozens to hundreds of loci. We examine several computationally efficient approaches—MP-EST, STAR, STEAC, STELLS, and STEM—for inferring species trees from gene trees estimated using maximum likelihood (ML) and Bayesian approaches. Among the methods examined, we found that topology-based methods often performed better using ML gene trees and methods employing coalescent times typically performed better using Bayesian gene trees, with MP-EST, STAR, STEAC, and STELLS outperforming STEM under most conditions. We examine why the STEM tree (also called GLASS or Maximum Tree) is less accurate on estimated gene trees by comparing estimated and true coalescence times, performing species tree inference using simulations, and analyzing a great ape data set keeping track of false positive and false negative rates for inferred clades. We find that although true coalescence times are more ancient than speciation times under the multispecies coalescent model, estimated coalescence times are often more recent than speciation times. This underestimation can lead to increased bias and lack of resolution with increased sampling (either alleles or loci) when gene trees are estimated with ML. The problem appears to be less severe using Bayesian gene-tree estimates.
Data from: Bayesian estimation of species divergence times using correlated quantitative characters
Discrete morphological data have been widely used to study species evolution, but the use of quantitative (or continuous) morphological characters is less common. Here, we implement a Bayesian method to estimate species divergence times using quantitative characters. Quantitative character evolution is modelled using Brownian diffusion with character correlation and character variation within populations. Through simulations, we demonstrate that ignoring the population variation (or population "noise") and the correlation among characters leads to biased estimates of divergence times and rate, especially if the correlation and population noise are high. We apply our new method to the analysis of quantitative characters (cranium landmarks) and molecular data from carnivoran mammals. Our results show that time estimates are affected by whether the correlations and population noise are accounted for or ignored in the analysis. The estimates are also affected by the type of data analysed, with analyses of morphological characters only, molecular data only, or a combination of both; showing noticeable differences among the time estimates. Rate variation of morphological characters among the carnivoran species appears to be very high, with Bayesian model selection indicating that the independent-rates model fits the morphological data better than the autocorrelated-rates model. We suggest that using morphological continuous characters, together with molecular data, can bring a new perspective to the study of species evolution. Our new model is implemented in the MCMCtree computer program for Bayesian inference of divergence times.
Data from: Using phylogenomic data to explore the effects of relaxed clocks and calibration strategies on divergence time estimation: primates as a test case
Primates have long been a test case for the development of phylogenetic methods for divergence time estimation. Despite a large number of studies, however, the timing of origination of crown Primates relative to the K-Pg boundary and the timing of diversification of the main crown groups remain controversial. Here we analysed a dataset of 372 taxa (367 Primates and 5 outgroups, 3.4 million aligned base pairs) that includes nine primate genomes. We systematically explore the effect of different interpretations of fossil calibrations and molecular clock models on primate divergence time estimates. We find that even small differences in the construction of fossil calibrations can have a noticeable impact on estimated divergence times, especially for the oldest nodes in the tree. Notably, choice of molecular rate model (auto-correlated or independently distributed rates) has an especially strong effect on estimated times, with the independent rates model producing considerably more ancient age estimates for the deeper nodes in the phylogeny. We implement thermodynamic integration, combined with Gaussian quadrature, in the program MCMCTree, and use it to calculate Bayes factors for clock models. Bayesian model selection indicates that the auto-correlated rates model fits the primate data substantially better, and we conclude that time estimates under this model should be preferred. We show that for eight core nodes in the phylogeny, uncertainty in time estimates is close to the theoretical limit imposed by fossil uncertainties. Thus, these estimates are unlikely to be improved by collecting additional molecular sequence data. All analyses place the origin of Primates close to the K-Pg boundary, either in the Cretaceous or straddling the boundary into the Palaeogene.
Estimating uncertainty in divergence times among three-spined stickleback clades using the multispecies coalescent
<p>Incomplete lineage sorting (ILS) can lead to biased divergence time estimates. To explore if and how ILS has influenced the results of a recent study of worldwide phylogeny of three-spined sticklebacks (Gasterosteus aculeatus), we estimated divergence times among major clades by applying both a concatenation approach and the multispecies coalescent (MSC) model to single-nucleotide polymorphisms. To further test the influence of different calibration strategies, we applied different calibrations to the root and to younger nodes in addition to the ones used in the original study. Both the updated calibrations and the application of the MSC model influenced divergence time estimates, sometimes significantly. The new divergence time estimates were more ancient than in the previous study for older nodes, whereas the estimates of younger nodes were not strongly affected by the re-analyses. However, given the applied MSC method employs a simple substitution model and cannot account for changes in population size, we suggest that different analytical approaches and calibration strategies should be used in order to explore uncertainty in divergence time estimates. This study provides a valuable reference timeline for the ages of worldwide three-spined stickleback populations and emphasizes the need to embrace, rather than obscure, uncertainties around divergence time estimates.</p>
FIGURE 2. Penaeini ultrametric tree. Below a in Molecular phylogeny and divergence time estimates of Penaeid Shrimp Lineages (Decapoda: Penaeidae)
FIGURE 2. Penaeini ultrametric tree. Below a geological time-scale is shown.
Data from: Divergence time estimation using fossils as terminal taxa and the origins of Lissamphibia
Were molecular data available for extinct taxa, questions regarding the origins of many groups could be settled in short order. As this is not the case, various strategies have been proposed to combine paleontological and neontological datasets. The use of fossil dates as node age calibrations for divergence time estimation from molecular phylogenies is commonplace. In addition, simulations suggest that the addition of morphological data from extinct taxa may improve phylogenetic estimation when combined with molecular data for extant species, and a few studies have combined morphological and molecular data to estimate combined-evidence phylogenies containing both fossil and extant taxa. However, to date, few if any studies have attempted to infer divergence time estimates using phylogenies containing both extinct and living taxa, sampled for both molecular and morphological data. Here, I infer both the phylogeny and time of origin for Lissamphibia using Bayesian methods, based on a dataset containing morphological data for extinct taxa, molecular data for a number of extant species, and molecular and morphological data for a subset of extant taxa. The results suggest that Lissamphibia is monophyletic, nested within Lepospondyli, and originated in the late Carboniferous at the earliest. This research illustrates potential pitfalls for the use of fossils as post-hoc age constraints on internal nodes, and highlights the importance of explicit phylogenetic analysis of extinct taxa. These results suggest that the application of fossils as minima or maxima on molecular phylogenies should be supplemented or supplanted by combined-evidence analyses whenever possible.
Figure 4 from: Del Latte L, Bortolin F, Rota-Stabelli O, Fusco G, Bonato L (2015) Molecular-based estimate of species number, phylogenetic relationships and divergence times for the genus Stenotaenia (Chilopoda, Geophilomorpha) in the Italian region. In: Tuf IH, Tajovský K (Eds) Proceedings of the 16th International Congress of Myriapodology, Olomouc, Czech Republic. ZooKeys 510: 31-47. https://doi.org/10.3897/zookeys.510.8808
Figure 4 - Dated phylogeny. Estimates of divergence time, calculated using 28S sequences and two priors (age of the root and substitution rate) in the package BEAST v1.7.2 (see text). 95% High Posterior Density intervals are represented by coloured bars for the most robust nodes, emphasized by a circle. Greek letters refer to the species tentatively recognised (see Fig. 1). The tree has the same topology of the concatenated ML tree of Fig. 3, but for the position of Tuoba sydneyensis and the relationships within the group formed by species β, ε, γ and the specimen from Iran. The specimen from Volpago (species δ) is absent because its 28S sequence was not obtained. Time scale is different in the two intervals 0–100 and 100–200 Ma.
Figure 3 from: Del Latte L, Bortolin F, Rota-Stabelli O, Fusco G, Bonato L (2015) Molecular-based estimate of species number, phylogenetic relationships and divergence times for the genus Stenotaenia (Chilopoda, Geophilomorpha) in the Italian region. In: Tuf IH, Tajovský K (Eds) Proceedings of the 16th International Congress of Myriapodology, Olomouc, Czech Republic. ZooKeys 510: 31-47. https://doi.org/10.3897/zookeys.510.8808
Figure 3 - Maximum likelihood phylogeny. ML tree obtained from concatenated COI and 28S sequences, by the GTR+I+G model, and manually rooted. The following support values are indicated at the nodes (only for those present in the topology obtained from the concatenated sequences): ML bootstrap for the analysis of concatenated genes (upper left); Bayesian posterior probabilities (upper right, in italics); ML bootstrap for the analysis of COI sequences (lower left); ML bootstrap for the analysis of 28S sequences (lower right). Bootstrap values < 50% and posterior probabilities < 0.50 are not shown. Circles indicate ingroup nodes that are highly supported in the tree based on concatenated sequences. Terminal node groupings indicated by Greek letters refer to the species tentatively recognized (see text and Fig. 1). The specimen from Volpago (species δ) is absent because its 28S sequence was not obtained.
Figure 1 from: Del Latte L, Bortolin F, Rota-Stabelli O, Fusco G, Bonato L (2015) Molecular-based estimate of species number, phylogenetic relationships and divergence times for the genus Stenotaenia (Chilopoda, Geophilomorpha) in the Italian region. In: Tuf IH, Tajovský K (Eds) Proceedings of the 16th International Congress of Myriapodology, Olomouc, Czech Republic. ZooKeys 510: 31-47. https://doi.org/10.3897/zookeys.510.8808
Figure 1 - Sampling localities of Stenotaenia in the Italian region. Greek letters refer to the species tentatively recognized after the analyses (see text).
The implications of interrelated assumptions on estimates of divergence times and rates of diversification
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Data from: Robustness to divergence time underestimation when inferring species trees from estimated gene trees
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Data from: Treating fossils as terminal taxa in divergence time estimation reveals ancient vicariance patterns in the palpimanoid spiders
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Data from: The impact of fossil stratigraphic ranges on tip‐calibration, and the accuracy and precision of divergence time estimates
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Data from: Divergence time estimation using fossils as terminal taxa and the origins of Lissamphibia
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