Find research datasets worth reusing

opencc-zeroJan 2022View details →

Data from: How to date a crocodile – estimation of neosuchian clade ages and a comparison of four time-scaling methods

Clade ages within the crocodylomorph clade Neosuchia have long been debated. Molecular and morphological studies have yielded remarkably divergent results. Despite recent advances, there has been no comprehensive relative comparison of the major time calibration methods available to estimate clade ages based on morphological data. We used four methods (cal3, Extended Hedman [EH], smoothed Ghost-Lineage-Analysis [sGLA] and the Fossilised Birth-Death model [FBD]) to date clade ages derived from a published crocodylomorph supertree and a new neosuchian phylogeny. All time-scaling methods applied here agree on the origination of Neosuchia during the Late Triassic/Early Jurassic, and the presence of the major extant eusuchian groups (Crocodyloidea, Gavialoidea, Alligatoroidea, and Caimaininae) by the end of the Late Cretaceous. The number of distinct lineages present before the K/Pg boundary is less certain, with support for two competing scenarios in which Crocodylinae, Tomistominae and Diplocynodontinae either: 1) diverged from other eusuchian lineages before the K/Pg boundary; or 2) evolved during a 'burst' of diversification after the K/Pg event. Cal3 and FBD are identified as the most suitable methods for time-scaling phylogenetic trees dominated by fossil taxa. Extended Hedman estimates are substantially older than the others, with larger standard deviations and a strong vulnerability to taxon sampling and topological changes. sGLA has similar problems and cannot be recommended either. We conclude that a detailed understanding of phylogenetic relationships, tree reconstruction methods, and good taxonomic coverage (in particular the inclusion of the oldest taxon in each clade) is essential when evaluating the results of such dating analyses.

opencc-zeroApr 2022View details →

The impact of molecular data on the phylogenetic position of the putative oldest crown crocodilian and the age of the clade

The use of molecular data for living groups is vital for interpreting fossils, especially when morphology-only analyses retrieve problematic phylogenies for living forms. These topological discrepancies impact on the inferred phylogenetic position of many fossil taxa. In Crocodylia, morphology-based phylogenetic inferences differ fundamentally in placing Gavialis basal to all other living forms, whereas molecular data consistently unite it with crocodylids. The Cenomanian Portugalosuchus azenhae was recently described as the oldest crown crocodilian, with affinities to Gavialis, based on morphology-only analyses, thus representing a potentially important new molecular clock calibration. Here we performed analyses incorporating DNA data into these morphological datasets, using scaffold and supermatrix (total evidence) approaches, in order to evaluate the position of basal crocodylians including Portugalosuchus. Our analyses incorporating DNA data robustly recovered Portugalosuchus outside Crocodylia (as well as thoracosaurs, planocraniids and Borealosuchus spp.), questioning the status of Portugalosuchus a crown crocodilian and any future use as a node calibration in molecular clock studies. Finally, we discuss how, with the increasing size of phylogenomic datasets, the molecular scaffold might be an efficient (though imperfect) approximation of more rigorous but demanding supermatrix analyses.

publicMar 2022View details →

Data from: How to date a crocodile – estimation of neosuchian clade ages and a comparison of four time-scaling methods

Open the record for dataset details and reuse information.

publicApr 2022View details →

The impact of molecular data on the phylogenetic position of the putative oldest crown crocodilian and the age of the clade

Open the record for dataset details and reuse information.

opencc-zeroDec 2015View details →

Data from: Bayesian phylogenetic estimation of clade ages supports trans-atlantic dispersal of cichlid fishes

Divergence-time estimation based on molecular phylogenies and the fossil record has provided insights into fundamental questions of evolutionary biology. In Bayesian node dating, phylogenies are commonly time calibrated through the specification of calibration densities on nodes representing clades with known fossil occurrences. Unfortunately, the optimal shape of these calibration densities is usually unknown and they are therefore often chosen arbitrarily, which directly impacts the reliability of the resulting age estimates. As possible solutions to this problem, two non-exclusive alternative approaches have recently been developed, the "fossilized birth-death" model and "total-evidence dating". While these approaches have been shown to perform well under certain conditions, they require including all (or a random subset) of the fossils of each clade in the analysis, rather than just relying on the oldest fossils of clades. In addition, both approaches assume that fossil records of different clades in the phylogeny are all the product of the same underlying fossil sampling rate, even though this rate has been shown to differ strongly between higher-level taxa. We here develop a flexible new approach to Bayesian age estimation that combines advantages of node dating and the fossilized birth-death model. In our new approach, calibration densities are defined on the basis of first fossil occurrences and sampling rate estimates that can be specified separately for all clades. We verify our approach with a large number of simulated datasets, and compare its performance to that of the fossilized birth-death model. We find that our approach produces reliable age estimates that are robust to model violation, on par with the fossilized birth-death model. By applying our approach to a large dataset including sequence data from over 1000 species of teleost fishes as well as 147 carefully selected fossil constraints, we recover a timeline of teleost diversification that is incompatible with previously assumed vicariant divergences of freshwater fishes. Our results instead provide strong evidence for trans-oceanic dispersal of cichlids and other groups of teleost fishes.

opencc-zeroDec 2013View details →

Data from: Methods for the quantitative comparison of molecular estimates of clade age and the fossil record

Approaches quantifying relative congruence, or incongruence, of molecular divergence estimates and the fossil record have been limited. Previously proposed methods are largely node specific, assessing incongruence at particular nodes for which both fossil data and molecular divergence estimates are available. These existing metrics, and other methods that quantify incongruence across topologies including entirely extinct clades, have so far not taken into account uncertainty surrounding both the divergence estimates and the ages of fossils. They have also treated molecular divergence estimates younger than previously assessed fossil minimum estimates of clade age as if they were the same as cases in which they were older. However, these cases are not the same. Recovered divergence dates younger than compared oldest known occurrences require prior hypotheses regarding the phylogenetic position of the compared fossil record and standard assumptions about the relative timing of morphological and molecular change to be incorrect. Older molecular dates, by contrast, are consistent with an incomplete fossil record and do not require prior assessments of the fossil record to be unreliable in some way. Here, we compare previous approaches and introduce two new descriptive metrics. Both metrics explicitly incorporate information on uncertainty by utilizing the 95% confidence intervals on estimated divergence dates and data on stratigraphic uncertainty concerning the age of the compared fossils. Metric scores are maximized when these ranges are overlapping. MDI (minimum divergence incongruence) discriminates between situations where molecular estimates are younger or older than known fossils reporting both absolute fit values and a number score for incompatible nodes. DIG range (divergence implied gap range) allows quantification of the minimum increase in implied missing fossil record induced by enforcing a given set of molecular-based estimates. These metrics are used together to describe the relationship between time trees and a set of fossil data, which we recommend be phylogenetically vetted and referred on the basis of apomorphy. Differences from previously proposed metrics and the utility of MDI and DIG range are illustrated in three empirical case studies from angiosperms, ostracods, and birds. These case studies also illustrate the ways in which MDI and DIG range may be used to assess time trees resultant from analyses varying in calibration regime, divergence dating approach or molecular sequence data analyzed.

opencc-zeroDec 2013View details →

Data from: Clock model makes a large difference to age estimates of long-stemmed clades with no internal calibration: a test using Australian grasstrees

Background: Estimating divergence times in phylogenies using a molecular clock depends on accurate modeling of nucleotide substitution rates in DNA sequences. Rate heterogeneity among lineages is likely to affect estimates, especially in lineages with long stems and short crowns ("broom" clades) and no internal calibration. We evaluate the performance of the random local clocks model (RLC) and the more routinely employed uncorrelated lognormal relaxed clock model (UCLN) in situations in which a significant rate shift occurs on the stem branch of a broom clade. We compare the results of simulations to empirical results from analyses of a real rate-heterogeneous taxon – Australian grass trees (Xanthorrhoea) – whose substitution rate is slower than in its sister groups, as determined by relative rate tests. Results: In the simulated datasets, the RLC model performed much better than UCLN: RLC correctly estimated the age of the crown node of slow-rate broom clades, whereas UCLN estimates were consistently too young. Similarly, in the Xanthorrhoea dataset, UCLN returned significantly younger crown ages than RLC (mean estimates respectively 3-6 Ma versus 25-35 Ma). In both real and simulated datasets, Bayes Factor tests strongly favored the RLC model over the UCLN model. Conclusions: The choice of an unsuitable molecular clock model can strongly bias divergence time estimates. In particular, for data predicted to have more rate variation among than within clades, dating with RLC is much more likely to be accurate than with UCLN. The choice of clocks should be informed by the biology of the study group (e.g., life-form) or assessed with relative rate tests and post-hoc model comparisons.

opencc-zeroOct 2023View details →

All about being old and shooting hairs: Clade age and urticating hair explain the patterns of diversification in tarantulas

The extreme asymmetry of species richness distribution across the tree of life has always intrigued evolutionary biologists. Two competing explanations have been proposed to explain this pattern—the clade age hypothesis and diversification rate variation. While these two scenarios may not be mutually exclusive, to what extent time and diversification rates interact to explain species richness patterns remains understudied. Here, we investigate the relative influence of these two scenarios using tarantulas (Family: Theraphosidae) as a model. Tarantulas represent a speciose group of spiders found worldwide but exceptionally diverse in South America. These spiders show two distinct patterns of microhabitat use (ground-dwelling or arboreal) and defence strategies (presence or absence of urticating hairs). Using various trait-independent and dependent diversification models, we test the clade age hypothesis, the role of microhabitat, antipredator defence strategy and geography in influencing diversification rates. Our results suggest that clade age is the primary predictor of species richness distribution across the tarantula subfamilies. However, the presence of urticating hair probably disrupted this pattern in some clades by increasing the net diversification rates, not by increasing the speciation rate but by reducing the extinction rate.

zenodo32/100

text-fig. 57. Diagrams showing the relations between age rank and clade rank and the SRC for pectinate components of the cladogram figured in Text-figure 55 and the total cladogram. Names of the diagrams refer to the terminal taxa to which the pectinate components lead. in The interrelationships and evolution of basal theropod dinosaurs

text-fig. 57. Diagrams showing the relations between age rank and clade rank and the SRC for pectinate components of the cladogram figured in Text-figure 55 and the total cladogram. Names of the diagrams refer to the terminal taxa to which the pectinate components lead.

opennotspecifiedMay 2003View details →

zenodo32/100

FIG UR E 3 (a) Dated phylogeny of the genus Theodoxus constructed in BEAST based on COI, 16S and ATPα. Node labels denote divergence times in millions of years ago (Ma); node bars indicate the 95% credibility interval around these dates. Small squares at nodes indicate significant support of divergence events found with BEAST and other phylogenetic analyses (see Figures S2.1 and S2.2), as explained through the key. Where MOTUs (A–R) show conspecifics among a number of morphospecies, species names are given in order of their year of description. Morphospecies, incorporated from GenBank, where determination was potentially dubious are highlighted by an asterisk. Clades (C) and subclades (SC) are demarcated by dashed lines between MOTUs. (b) LTT plots indicating the build‐up of lineages in Theodoxus over geological time. Dashed lines surrounding the solid LTT lines indicate the 95% confidence intervals. Where intra‐ and interspecific diversity diverge, interspecific diversity is highlighted in blue and intraspecific diversity in red. Transitions in geological ages are highlighted by narrow grey lines, while the grey bar marks the period of pronounced glacial cycles (last 900 kyr) [Colour figure can be viewed at wileyonlinelibrary.com] in Contributions of biogeographical functions to species accumulation may change over time in refugial regions

FIG UR E 3 (a) Dated phylogeny of the genus Theodoxus constructed in BEAST based on COI, 16S and ATPα. Node labels denote divergence times in millions of years ago (Ma); node bars indicate the 95% credibility interval around these dates. Small squares at nodes indicate significant support of divergence events found with BEAST and other phylogenetic analyses (see Figures S2.1 and S2.2), as explained through the key. Where MOTUs (A–R) show conspecifics among a number of morphospecies, species names are given in order of their year of description. Morphospecies, incorporated from GenBank, where determination was potentially dubious are highlighted by an asterisk. Clades (C) and subclades (SC) are demarcated by dashed lines between MOTUs. (b) LTT plots indicating the build‐up of lineages in Theodoxus over geological time. Dashed lines surrounding the solid LTT lines indicate the 95% confidence intervals. Where intra‐ and interspecific diversity diverge, interspecific diversity is highlighted in blue and intraspecific diversity in red. Transitions in geological ages are highlighted by narrow grey lines, while the grey bar marks the period of pronounced glacial cycles (last 900 kyr) [Colour figure can be viewed at wileyonlinelibrary.com]

opennotspecifiedMay 2019View details →

publicJul 2014View details →

Data from: Methods for the quantitative comparison of molecular estimates of clade age and the fossil record

Open the record for dataset details and reuse information.

publicAug 2016View details →

Data from: Bayesian phylogenetic estimation of clade ages supports trans-atlantic dispersal of cichlid fishes

Open the record for dataset details and reuse information.

publicDec 2014View details →

Data from: Clock model makes a large difference to age estimates of long-stemmed clades with no internal calibration: a test using Australian grasstrees

Open the record for dataset details and reuse information.

publicOct 2023View details →

All about being old and shooting hairs: Clade age and urticating hair explain the patterns of diversification in tarantulas

Open the record for dataset details and reuse information.

opencc-zeroDec 2012View details →

Data from: An expansion of age constraints for microbial clades that lack a conventional fossil record using phylogenomic dating

Most microbial taxa lack a conventional microfossil or biomarker record, and so we currently have little information regarding how old most microbial clades and their associated traits are. Building on the previously published oxygen age constraint, two new age constraints are proposed based on the ability of microbial clades to metabolize chitin and aromatic compounds derived from lignin. Using the archaeal domain of life as a test case, phylogenetic analyses, along with published metabolic and genetic data, showed that members of the Halobacteriales and Thermococcales are able to metabolize chitin. Ancestral state reconstruction combined with phylogenetic analysis of the genes underlying chitin degradation predicted that the ancestors of these two groups were also likely able to metabolize chitin or chitin-related compounds. These two clades were therefore assigned a maximum age of 1.0 Ga (when chitin likely first appeared). Similar analyses also predicted that the ancestor to the Sulfolobus solfataricus-Sulfolobus islandicus clade was able to metabolize phenol using catechol dioxygenase, so this clade was assigned a maximum age of 475 Ma. Inferred ages of archaeal clades using relaxed molecular clocks with the new age constraints were consistent with those inferred with the oxygen age constraints. This work expands our current toolkit to include Paleoproterozoic, Neoproterozoic, and Paleozoic age constraints, and should aid in our ability to phylogenetically reconstruct the antiquity of a wide array of microbial clades and their associated morphological and biogeochemical traits, spanning deep geologic time. Such hypotheses-although built upon evolutionary inferences-are fundamentally testable.

publicSep 2016View details →

Data from: Uncovering higher-taxon diversification dynamics from clade age and species-richness data

Open the record for dataset details and reuse information.

publicSep 2013View details →

Data from: An expansion of age constraints for microbial clades that lack a conventional fossil record using phylogenomic dating

Open the record for dataset details and reuse information.