scholarly journals Phylogenetic non-independence in rates of trait evolution

Author(s):  
Manabu Sakamoto ◽  
Chris Venditti

Statistical non-independence of species’ biological traits is recognized in most traits under selection. Yet, whether or not the evolutionary rates of such biological traits are statistically non-independent remains to be tested. Here we test the hypothesis that phenotypic evolutionary rates are non-independent, i.e. contain phylogenetic signal, using empirical rates of evolution in three separate traits: body mass in mammals; beak shape in birds; and bite force in amniotes. Specifically, we test whether rates are non-independent throughout the evolutionary history of each tree. We find evidence for phylogenetic signal in evolutionary rates in all three case studies. While phylogenetic signal diminishes deeper in time, this is reflective of statistical power owing to small sample and effect sizes. When effect size is large, e.g., owing to the presence of fossil tips, we detect high phylogenetic signals even in deeper time slices. Thus, we recommend that rates be treated as being non-independent throughout the evolutionary history of the group of organisms under study, and any summaries or analyses of rates through time – including associations of rates with traits – need account for the undesired effects of shared ancestry.

2018 ◽  
Vol 14 (10) ◽  
pp. 20180502 ◽  
Author(s):  
Manabu Sakamoto ◽  
Chris Venditti

Statistical non-independence of species’ biological traits is recognized in most traits under selection. Yet, whether or not the evolutionary rates of such biological traits are statistically non-independent remains to be tested. Here, we test the hypothesis that phenotypic evolutionary rates are non-independent, i.e. contain phylogenetic signal, using empirical rates of evolution in three separate traits: body mass in mammals, beak shape in birds and bite force in amniotes. Specifically, we test if evolutionary rates are phylogenetically interdependent. We find evidence for phylogenetic signal in evolutionary rates in all three case studies. While phylogenetic signal diminishes deeper in time, this is reflective of statistical power owing to small sample and effect sizes. When effect size is large, e.g. owing to the presence of fossil tips, we detect high phylogenetic signals even in deeper time slices. Thus, we recommend that rates be treated as being non-independent throughout the evolutionary history of the group of organisms under study, and any summaries or analyses of rates through time—including associations of rates with traits—need to account for the undesired effects of shared ancestry.


BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Tiago R. Simões ◽  
Michael W. Caldwell ◽  
Stephanie E. Pierce

Abstract Background The vast majority of all life that ever existed on earth is now extinct and several aspects of their evolutionary history can only be assessed by using morphological data from the fossil record. Sphenodontian reptiles are a classic example, having an evolutionary history of at least 230 million years, but currently represented by a single living species (Sphenodon punctatus). Hence, it is imperative to improve the development and implementation of probabilistic models to estimate evolutionary trees from morphological data (e.g., morphological clocks), which has direct benefits to understanding relationships and evolutionary patterns for both fossil and living species. However, the impact of model choice on morphology-only datasets has been poorly explored. Results Here, we investigate the impact of a wide array of model choices on the inference of evolutionary trees and macroevolutionary parameters (divergence times and evolutionary rates) using a new data matrix on sphenodontian reptiles. Specifically, we tested different clock models, clock partitioning, taxon sampling strategies, sampling for ancestors, and variations on the fossilized birth-death (FBD) tree model parameters through time. We find a strong impact on divergence times and background evolutionary rates when applying widely utilized approaches, such as allowing for ancestors in the tree and the inappropriate assumption of diversification parameters being constant through time. We compare those results with previous studies on the impact of model choice to molecular data analysis and provide suggestions for improving the implementation of morphological clocks. Optimal model combinations find the radiation of most major lineages of sphenodontians to be in the Triassic and a gradual but continuous drop in morphological rates of evolution across distinct regions of the phenotype throughout the history of the group. Conclusions We provide a new hypothesis of sphenodontian classification, along with detailed macroevolutionary patterns in the evolutionary history of the group. Importantly, we provide suggestions to avoid overestimated divergence times and biased parameter estimates using morphological clocks. Partitioning relaxed clocks offers methodological limitations, but those can be at least partially circumvented to reveal a detailed assessment of rates of evolution across the phenotype and tests of evolutionary mosaicism.


2019 ◽  
Author(s):  
Marko J. Spasojevic ◽  
Sören Weber1

Stable carbon (C) and nitrogen (N) isotopes in plants are important indicators of plant water use efficiency and N acquisition strategies. While often regarded as being under environmental control, there is growing evidence that evolutionary history may also shape variation in stable isotope ratios (δ13C and δ15N) among plant species. Here we examined patterns of foliar δ13C and δ15N in alpine tundra for 59 species in 20 plant families. To assess the importance of environmental controls and evolutionary history, we examined if average δ13C and δ15N predictably differed among habitat types, if individual species exhibited intraspecific trait variation (ITV) in δ13C and δ15N, and if there were a significant phylogenetic signal in δ13C and δ15N. We found that variation among habitat types in both δ13C and δ15N mirrored well-known patterns of water and nitrogen limitation. Conversely, we also found that 40% of species exhibited no ITV in δ13C and 35% of species exhibited no ITV in δ15N, suggesting that some species are under stronger evolutionary control. However, we only found a modest signal of phylogenetic conservatism in δ13C and no phylogenetic signal in δ15N suggesting that shared ancestry is a weaker driver of tundra wide variation in stable isotopes. Together, our results suggest that both evolutionary history and local environmental conditions play a role in determining variation in δ13C and δ15N and that considering both factors can help with interpreting isotope patterns in nature and with predicting which species may be able to respond to rapidly changing environmental conditions.


Science ◽  
2021 ◽  
Vol 373 (6556) ◽  
pp. 792-796 ◽  
Author(s):  
Paul K. Strother ◽  
Clinton Foster

Molecular time trees indicating that embryophytes originated around 500 million years ago (Ma) during the Cambrian are at odds with the record of fossil plants, which first appear in the mid-Silurian almost 80 million years later. This time gap has been attributed to a missing fossil plant record, but that attribution belies the case for fossil spores. Here, we describe a Tremadocian (Early Ordovician, about 480 Ma) assemblage with elements of both Cambrian and younger embryophyte spores that provides a new level of evolutionary continuity between embryophytes and their algal ancestors. This finding suggests that the molecular phylogenetic signal retains a latent evolutionary history of the acquisition of the embryophytic developmental genome, a history that perhaps began during Ediacaran-Cambrian time but was not completed until the mid-Silurian (about 430 Ma).


2018 ◽  
Author(s):  
Gang Li ◽  
Henrique V. Figueiro ◽  
Eduardo Eizirik ◽  
William J. Murphy

Current phylogenomic approaches implicitly assume that the predominant phylogenetic signal within a genome reflects the true evolutionary history of organisms, without assessing the confounding effects of gene flow that result in a mosaic of phylogenetic signals that interact with recombinational variation. Here we tested the validity of this assumption with a recombination-aware analysis of whole genome sequences from 27 species of the cat family. We found that the prevailing phylogenetic signal within the autosomes is not always representative of speciation history, due to ancient hybridization throughout felid evolution. Instead, phylogenetic signal was concentrated within large, conserved X-chromosome recombination deserts that exhibited recurrent patterns of strong genetic differentiation and selective sweeps across mammalian orders. By contrast, regions of high recombination were enriched for signatures of ancient gene flow, and these sequences inflated crown-lineage divergence times by ~40%. We conclude that standard phylogenomic approaches to infer the Tree of Life may be highly misleading without considering the genomic partitioning of phylogenetic signal relative to recombination rate, and its interplay with historical hybridization.


Author(s):  
A. I. Kavaleuskaya ◽  
T. V. Ramanouskaya

The highly conserved MTG gene family includes three homologs in vertebrates (MTG8, MTGR1, MTG16) encoding transcriptional corepressors, which are important in haemopoiesis, neurogenesis and epithelial stem cell differentiation. These genes are of particular interest because they are involved in translocations, associated with different types of cancer. Looking at how this gene family evolved might provide insights into history of its structural and functional diversification. We have performed a phylogenetic analysis of MTG nucleotide and protein sequences to examine the evolutionary events. The domain organization of MTG gene products was clarified, the mechanism of appearance of the first MTG gene was revealed and the ancestor taxon was determined. Also the mechanism of MTG gene family emergence was established. In addition, analysis of the rates of evolution acting on individual domains was made, and conservative positions within each gene of MTG family were determined.


Paleobiology ◽  
10.1666/14006 ◽  
2014 ◽  
Vol 40 (4) ◽  
pp. 675-692 ◽  
Author(s):  
Paul G. Harnik ◽  
Paul C. Fitzgerald ◽  
Jonathan L. Payne ◽  
Sandra J. Carlson

Determining which biological traits affect taxonomic durations is critical for explaining macroevolutionary patterns. Two approaches are commonly used to investigate the associations between traits and durations and/or extinction and origination rates: analyses of taxonomic occurrence patterns in the fossil record and comparative phylogenetic analyses, predominantly of extant taxa. By capitalizing upon the empirical record of past extinctions, paleontological data avoid some of the limitations of existing methods for inferring extinction and origination rates from molecular phylogenies. However, most paleontological studies of extinction selectivity have ignored phylogenetic relationships because there is a dearth of phylogenetic hypotheses for diverse non-vertebrate higher taxa in the fossil record. This omission inflates the degrees of freedom in statistical analyses and leaves open the possibility that observed associations are indirect, reflecting shared evolutionary history rather than the direct influence of particular traits on durations. Here we investigate global patterns of extinction selectivity in Devonian terebratulide brachiopods and compare the results of taxonomic vs. phylogenetic approaches. Regression models that assume independence among taxa provide support for a positive association between geographic range size and genus duration but do not indicate an association between body size and genus duration. Brownian motion models of trait evolution identify significant similarities in body size, range size, and duration among closely related terebratulide genera. We use phylogenetic regression to account for shared evolutionary history and find support for a significant positive association between range size and duration among terebratulides that is also phylogenetically structured. The estimated range size–duration relationship is moderately weaker in the phylogenetic analysis due to the down-weighting of closely related genera that were both broadly distributed and long lived; however, this change in slope is not statistically significant. These results provide evidence for the phylogenetic conservatism of organismal and emergent traits, yet also the general phylogenetic independence of the relationship between range size and duration.


2017 ◽  
Author(s):  
Roman Sloutsky ◽  
Kristen M. Naegle

AbstractEvolutionary reconstruction algorithms produce models of the evolutionary history of proteins: the order of duplications and speciations that led to extant homologous proteins observed across species. Although they are regularly used to gain insight into protein function, these models are estimates of an unknowable truth according to the underlying assumptions inherent in each algorithm, its objective function, and the input sequences supplied for reconstruction. In practice, the generated models are highly sensitive to the sequence inputs. In this work, we asked whether we could identify stronger phylogenetic signal by capitalizing on the variance introduced by perturbing the input to evolutionary reconstruction to explore a rich space of possible models that could explain protein evolution. We subsampled from available protein orthologs, “same” proteins across multiple extant species, and produced an ensemble of topologies representing the duplication history which produced related proteins (paralogs) for simulated protein families and in a real protein family – the LacI transcription factor family. We found that two very important phenomena arise from this approach. First, the reproducibility of an all-sequence, single-alignment reconstruction, measured by comparing topologies inferred from 90% subsamples, directly correlates with the accuracy of that single-alignment reconstruction, producing a measurable value for something that has been traditionally unknowable. Second, if we take a large ensemble of trees inferred from 50% subsamples and cast the ensemble into a form that represents the distribution of pairwise leaf distances observed across the ensemble, then trees that capture the most frequently observed relationships are also the most accurate. We propose a new methodology, ASPEN, a meta-algorithm that finds and ranks the trees that are most consistent with observations across the ensemble. Top-ranked ASPEN trees are significantly more accurate than the single-alignment tree produced from all available sequences. Importantly, our findings suggest that the true tree is currently inaccessible for most real protein families. Instead, applications that rely on evolutionary models should integrate across many trees that are equally likely to represent the true evolutionary history of a protein family.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Dario Karmeinski ◽  
Karen Meusemann ◽  
Jessica A. Goodheart ◽  
Michael Schroedl ◽  
Alexander Martynov ◽  
...  

Abstract Background The soft-bodied cladobranch sea slugs represent roughly half of the biodiversity of marine nudibranch molluscs on the planet. Despite their global distribution from shallow waters to the deep sea, from tropical into polar seas, and their important role in marine ecosystems and for humans (as targets for drug discovery), the evolutionary history of cladobranch sea slugs is not yet fully understood. Results To enlarge the current knowledge on the phylogenetic relationships, we generated new transcriptome data for 19 species of cladobranch sea slugs and two additional outgroup taxa (Berthella plumula and Polycera quadrilineata). We complemented our taxon sampling with previously published transcriptome data, resulting in a final data set covering 56 species from all but one accepted cladobranch superfamilies. We assembled all transcriptomes using six different assemblers, selecting those assemblies that provided the largest amount of potentially phylogenetically informative sites. Quality-driven compilation of data sets resulted in four different supermatrices: two with full coverage of genes per species (446 and 335 single-copy protein-coding genes, respectively) and two with a less stringent coverage (667 genes with 98.9% partition coverage and 1767 genes with 86% partition coverage, respectively). We used these supermatrices to infer statistically robust maximum-likelihood trees. All analyses, irrespective of the data set, indicate maximal statistical support for all major splits and phylogenetic relationships at the family level. Besides the questionable position of Noumeaella rubrofasciata, rendering the Facelinidae as polyphyletic, the only notable discordance between the inferred trees is the position of Embletonia pulchra. Extensive testing using Four-cluster Likelihood Mapping, Approximately Unbiased tests, and Quartet Scores revealed that its position is not due to any informative phylogenetic signal, but caused by confounding signal. Conclusions Our data matrices and the inferred trees can serve as a solid foundation for future work on the taxonomy and evolutionary history of Cladobranchia. The placement of E. pulchra, however, proves challenging, even with large data sets and various optimization strategies. Moreover, quartet mapping results show that confounding signal present in the data is sufficient to explain the inferred position of E. pulchra, again leaving its phylogenetic position as an enigma.


Author(s):  
Amanda Patsis ◽  
Rick P. Overson ◽  
Krissa A. Skogen ◽  
Norman J. Wickett ◽  
Matthew G. Johnson ◽  
...  

Oenothera sect. Pachylophus has proven to be a valuable system in which to study plant-insect coevolution and the drivers of variation in floral morphology and scent. Current species circumscriptions based on morphological characteristics suggest that the section consists of five species, one of which is subdivided into five subspecies. Previous attempts to understand species (and subspecies) relationships at amolecular level have been largely unsuccessful due to high levels of incomplete lineage sorting and limited phylogenetic signal from slowly evolving gene regions. In the present study, target enrichment was used to sequence 322 conserved protein-coding nuclear genes from 50 individuals spanning the geographic range of Oenothera sect. Pachylophus, with species trees inferred using concatenation and coalescentbasedmethods. Our findings concur with previous research in suggesting that O. psammophila and O. harringtonii are nested within a paraphyleticOenothera cespitosa. By contrast, our results show clearly that the two annual species (O. cavernae and O. brandegeei) did not arise from the O. cespitosa lineage, but rather from a common ancestor of Oenothera sect. Pachylophus. Budding speciation as a result of edaphic specializationappears to best explain the evolution of the narrow endemic species O. harringtonii and O. psammophila. Complete understanding of possible introgression among subspecies of O. cespitosa will require broader sampling across the full geographical and ecological ranges of these taxa.


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