An ABBA-BABA Test for Introgression Using Retroposon Insertion Data

Mapping Intimacies ◽

10.1101/709477 ◽

2019 ◽

Cited By ~ 2

Author(s):

Mark S. Springer ◽

John Gatesy

Keyword(s):

Dna Sequences ◽

Incomplete Lineage Sorting ◽

Species Tree ◽

Data Sets ◽

Lineage Sorting ◽

Sequence Alignments ◽

Data Set ◽

Short Branch ◽

Phylogenetic Methods ◽

Branch Lengths

AbstractDNA sequence alignments provide the majority of data for inferring phylogenetic relationships with both concatenation and coalescence methods. However, DNA sequences are susceptible to extensive homoplasy, especially for deep divergences in the Tree of Life. Retroposon insertions have emerged as a powerful alternative to sequences for deciphering evolutionary relationships because these data are nearly homoplasy-free. In addition, retroposon insertions satisfy the ‘no intralocus recombination’ assumption of summary coalescence methods because they are singular events and better approximate neutrality relative to DNA sequences commonly applied in phylogenomic work. Retroposons have traditionally been analyzed with phylogenetic methods that ignore incomplete lineage sorting (ILS). Here, we analyze three retroposon data sets for mammals (Placentalia, Laurasiatheria, Balaenopteroidea) with two different ILS-aware methods. The first approach constructs a species tree from retroposon bipartitions with ASTRAL, and the second is a modification of SVD-Quartets. We also develop a χ2 Quartet-Asymmetry Test to detect hybridization using retroposon data. Both coalescence methods recovered the same topology for each of the three data sets. The ASTRAL species tree for Laurasiatheria has consecutive short branch lengths that are consistent with an anomaly zone situation. For the Balaenopteroidea data set, which includes rorquals (Balaenopteridae) and gray whale (Eschrichtiidae), both coalescence methods recovered a topology that supports the paraphyly of Balaenopteridae. Application of the χ2 Quartet-Asymmetry Test to this data set detected 16 different quartets of species for which historical hybridization may be inferred, but significant asymmetry was not detected in the placental root and Laurasiatheria analyses.

ILS-Aware Analysis of Low-Homoplasy Retroelement Insertions: Inference of Species Trees and Introgression Using Quartets

Journal of Heredity ◽

10.1093/jhered/esz076 ◽

2019 ◽

Vol 111 (2) ◽

pp. 147-168 ◽

Cited By ~ 5

Author(s):

Mark S Springer ◽

Erin K Molloy ◽

Daniel B Sloan ◽

Mark P Simmons ◽

John Gatesy

Keyword(s):

Dna Sequences ◽

Species Tree ◽

Data Sets ◽

Species Trees ◽

Split Decomposition ◽

Sequence Alignments ◽

Data Set ◽

Short Branch ◽

Network Methods ◽

Branch Lengths

Abstract DNA sequence alignments have provided the majority of data for inferring phylogenetic relationships with both concatenation and coalescent methods. However, DNA sequences are susceptible to extensive homoplasy, especially for deep divergences in the Tree of Life. Retroelement insertions have emerged as a powerful alternative to sequences for deciphering evolutionary relationships because these data are nearly homoplasy-free. In addition, retroelement insertions satisfy the “no intralocus-recombination” assumption of summary coalescent methods because they are singular events and better approximate neutrality relative to DNA loci commonly sampled in phylogenomic studies. Retroelements have traditionally been analyzed with parsimony, distance, and network methods. Here, we analyze retroelement data sets for vertebrate clades (Placentalia, Laurasiatheria, Balaenopteroidea, Palaeognathae) with 2 ILS-aware methods that operate by extracting, weighting, and then assembling unrooted quartets into a species tree. The first approach constructs a species tree from retroelement bipartitions with ASTRAL, and the second method is based on split-decomposition with parsimony. We also develop a Quartet-Asymmetry test to detect hybridization using retroelements. Both ILS-aware methods recovered the same species-tree topology for each data set. The ASTRAL species trees for Laurasiatheria have consecutive short branch lengths in the anomaly zone whereas Palaeognathae is outside of this zone. For the Balaenopteroidea data set, which includes rorquals (Balaenopteridae) and gray whale (Eschrichtiidae), both ILS-aware methods resolved balaeonopterids as paraphyletic. Application of the Quartet-Asymmetry test to this data set detected 19 different quartets of species for which historical introgression may be inferred. Evidence for introgression was not detected in the other data sets.

ILS-Aware Analyses of Retroelement Insertions in the Anomaly Zone

10.1101/2020.09.29.319038 ◽

2020 ◽

Author(s):

Erin K. Molloy ◽

John Gatesy ◽

Mark S. Springer

Keyword(s):

Dna Sequences ◽

Incomplete Lineage Sorting ◽

Species Tree ◽

Species Trees ◽

Lineage Sorting ◽

Short Branch ◽

Multispecies Coalescent ◽

Branch Lengths ◽

Tree Estimation ◽

Infinite Sites Model

AbstractA major shortcoming of concatenation methods for species tree estimation is their failure to account for incomplete lineage sorting (ILS). Coalescence methods explicitly address this problem, but make various assumptions that, if violated, can result in worse performance than concatenation. Given the challenges of analyzing DNA sequences with both concatenation and coalescence methods, retroelement insertions have emerged as powerful phylogenomic markers for species tree estimation. We show that two recently proposed methods, SDPquartets and ASTRAL_BP, are statistically consistent estimators of the species tree under the multispecies coalescent model, with retroelement insertions following a neutral infinite sites model of mutation. The accuracy of these and other methods for inferring species trees with retroelements has not been assessed in simulation studies. We simulate retroelements for four different species trees, including three with short branch lengths in the anomaly zone, and assess the performance of eight different methods for recovering the correct species tree. We also examine whether ASTRAL_BP recovers accurate internal branch lengths for internodes of various lengths (in coalescent units). Our results indicate that two recently proposed ILS-aware methods, ASTRAL_BP and SDPquartets, as well as the newly proposed ASTRID_BP, always recover the correct species tree on data sets with large numbers of retroelements even when there are extremely short species-tree branches in the anomaly zone. Dollo parsimony performed almost as well as these ILS-aware methods. By contrast, unordered parsimony, polymorphism parsimony, and MDC recovered the correct species tree in the case of a pectinate tree with four ingroup taxa in the anomaly zone, but failed to recover the correct tree in more complex anomaly-zone situations with additional lineages impacted by extensive incomplete lineage sorting. Camin-Sokal parsimony always reconstructed an incorrect tree in the anomaly zone. ASTRAL_BP accurately estimated branch lengths when internal branches were very short as in anomaly zone situations, but branch lengths were upwardly biased by more than 35% when species tree branches were longer. We derive a mathematical correction for these distortions, assuming the expected number of new retroelement insertions per generation is constant across the species tree. We also show that short branches do not need to be corrected even when this assumption does not hold; therefore, the branch lengths estimates produced by ASTRAL_BP may provide insight into whether an estimated species tree is in the anomaly zone.

Disentangling Sources of Gene Tree Discordance in Phylogenomic Data Sets: Testing Ancient Hybridizations in Amaranthaceae s.l

Systematic Biology ◽

10.1093/sysbio/syaa066 ◽

2020 ◽

Cited By ~ 1

Author(s):

Diego F Morales-Briones ◽

Gudrun Kadereit ◽

Delphine T Tefarikis ◽

Michael J Moore ◽

Stephen A Smith ◽

...

Keyword(s):

Network Inference ◽

Incomplete Lineage Sorting ◽

Gene Tree ◽

Phylogenetic Network ◽

Species Tree ◽

Data Sets ◽

Species Trees ◽

Lineage Sorting ◽

Data Set ◽

Gene Tree Discordance

Abstract Gene tree discordance in large genomic data sets can be caused by evolutionary processes such as incomplete lineage sorting and hybridization, as well as model violation, and errors in data processing, orthology inference, and gene tree estimation. Species tree methods that identify and accommodate all sources of conflict are not available, but a combination of multiple approaches can help tease apart alternative sources of conflict. Here, using a phylotranscriptomic analysis in combination with reference genomes, we test a hypothesis of ancient hybridization events within the plant family Amaranthaceae s.l. that was previously supported by morphological, ecological, and Sanger-based molecular data. The data set included seven genomes and 88 transcriptomes, 17 generated for this study. We examined gene-tree discordance using coalescent-based species trees and network inference, gene tree discordance analyses, site pattern tests of introgression, topology tests, synteny analyses, and simulations. We found that a combination of processes might have generated the high levels of gene tree discordance in the backbone of Amaranthaceae s.l. Furthermore, we found evidence that three consecutive short internal branches produce anomalous trees contributing to the discordance. Overall, our results suggest that Amaranthaceae s.l. might be a product of an ancient and rapid lineage diversification, and remains, and probably will remain, unresolved. This work highlights the potential problems of identifiability associated with the sources of gene tree discordance including, in particular, phylogenetic network methods. Our results also demonstrate the importance of thoroughly testing for multiple sources of conflict in phylogenomic analyses, especially in the context of ancient, rapid radiations. We provide several recommendations for exploring conflicting signals in such situations. [Amaranthaceae; gene tree discordance; hybridization; incomplete lineage sorting; phylogenomics; species network; species tree; transcriptomics.]

Partitioned Gene-Tree Analyses and Gene-Based Topology Testing Help Resolve Incongruence in a Phylogenomic Study of Host-Specialist Bees (Apidae: Eucerinae)

Molecular Biology and Evolution ◽

10.1093/molbev/msaa277 ◽

2020 ◽

Author(s):

Felipe V Freitas ◽

Michael G Branstetter ◽

Terry Griswold ◽

Eduardo A B Almeida

Keyword(s):

Incomplete Lineage Sorting ◽

Gene Tree ◽

Species Tree ◽

Data Sets ◽

Gene Trees ◽

Lineage Sorting ◽

Data Set ◽

Analytical Strategy ◽

Analytical Approaches ◽

Phylogenomic Study

Abstract Incongruence among phylogenetic results has become a common occurrence in analyses of genome-scale data sets. Incongruence originates from uncertainty in underlying evolutionary processes (e.g., incomplete lineage sorting) and from difficulties in determining the best analytical approaches for each situation. To overcome these difficulties, more studies are needed that identify incongruences and demonstrate practical ways to confidently resolve them. Here, we present results of a phylogenomic study based on the analysis 197 taxa and 2,526 ultraconserved element (UCE) loci. We investigate evolutionary relationships of Eucerinae, a diverse subfamily of apid bees (relatives of honey bees and bumble bees) with >1,200 species. We sampled representatives of all tribes within the group and >80% of genera, including two mysterious South American genera, Chilimalopsis and Teratognatha. Initial analysis of the UCE data revealed two conflicting hypotheses for relationships among tribes. To resolve the incongruence, we tested concatenation and species tree approaches and used a variety of additional strategies including locus filtering, partitioned gene-trees searches, and gene-based topological tests. We show that within-locus partitioning improves gene tree and subsequent species-tree estimation, and that this approach, confidently resolves the incongruence observed in our data set. After exploring our proposed analytical strategy on eucerine bees, we validated its efficacy to resolve hard phylogenetic problems by implementing it on a published UCE data set of Adephaga (Insecta: Coleoptera). Our results provide a robust phylogenetic hypothesis for Eucerinae and demonstrate a practical strategy for resolving incongruence in other phylogenomic data sets.

Detecting destabilizing species in the phylogenetic backbone of Potentilla (Rosaceae) using low-copy nuclear markers

AoB Plants ◽

10.1093/aobpla/plaa017 ◽

2020 ◽

Vol 12 (3) ◽

Cited By ~ 1

Author(s):

Nannie L Persson ◽

Ingrid Toresen ◽

Heidi Lie Andersen ◽

Jenny E E Smedmark ◽

Torsten Eriksson

Keyword(s):

Incomplete Lineage Sorting ◽

Gene Tree ◽

Data Sets ◽

Gene Trees ◽

Lineage Sorting ◽

Nuclear Markers ◽

Data Set ◽

Multispecies Coalescent ◽

Single Marker ◽

Named Groups

Abstract The genus Potentilla (Rosaceae) has been subjected to several phylogenetic studies, but resolving its evolutionary history has proven challenging. Previous analyses recovered six, informally named, groups: the Argentea, Ivesioid, Fragarioides, Reptans, Alba and Anserina clades, but the relationships among some of these clades differ between data sets. The Reptans clade, which includes the type species of Potentilla, has been noticed to shift position between plastid and nuclear ribosomal data sets. We studied this incongruence by analysing four low-copy nuclear markers, in addition to chloroplast and nuclear ribosomal data, with a set of Bayesian phylogenetic and Multispecies Coalescent (MSC) analyses. A selective taxon removal strategy demonstrated that the included representatives from the Fragarioides clade, P. dickinsii and P. fragarioides, were the main sources of the instability seen in the trees. The Fragarioides species showed different relationships in each gene tree, and were only supported as a monophyletic group in a single marker when the Reptans clade was excluded from the analysis. The incongruences could not be explained by allopolyploidy, but rather by homoploid hybridization, incomplete lineage sorting or taxon sampling effects. When P. dickinsii and P. fragarioides were removed from the data set, a fully resolved, supported backbone phylogeny of Potentilla was obtained in the MSC analysis. Additionally, indications of autopolyploid origins of the Reptans and Ivesioid clades were discovered in the low-copy gene trees.

Terraces in Gene Tree Reconciliation-Based Species Tree Inference

10.1101/2020.04.17.047092 ◽

2020 ◽

Author(s):

Michael J. Sanderson ◽

Michelle M. McMahon ◽

Mike Steel

Keyword(s):

Incomplete Lineage Sorting ◽

Gene Tree ◽

Solution Space ◽

Species Tree ◽

Gene Trees ◽

Species Trees ◽

Lineage Sorting ◽

Data Set ◽

Tree Reconciliation ◽

The Impact

AbstractTerraces in phylogenetic tree space are sets of trees with identical optimality scores for a given data set, arising from missing data. These were first described for multilocus phylogenetic data sets in the context of maximum parsimony inference and maximum likelihood inference under certain model assumptions. Here we show how the mathematical properties that lead to terraces extend to gene tree - species tree problems in which the gene trees are incomplete. Inference of species trees from either sets of gene family trees subject to duplication and loss, or allele trees subject to incomplete lineage sorting, can exhibit terraces in their solution space. First, we show conditions that lead to a new kind of terrace, which stems from subtree operations that appear in reconciliation problems for incomplete trees. Then we characterize when terraces of both types can occur when the optimality criterion for tree search is based on duplication, loss or deep coalescence scores. Finally, we examine the impact of assumptions about the causes of losses: whether they are due to imperfect sampling or true evolutionary deletion.

Divergence estimation in the presence of incomplete lineage sorting and migration

10.1101/174342 ◽

2017 ◽

Author(s):

Graham Jones

Keyword(s):

Incomplete Lineage Sorting ◽

Simulated Data ◽

Species Tree ◽

Lineage Sorting ◽

Data Set ◽

Migration Rates ◽

Isolation With Migration ◽

Multispecies Coalescent ◽

Tree Inference ◽

And Migration

AbstractThis paper focuses on the problem of estimating a species tree from multilocus data in the presence of incomplete lineage sorting and migration. We develop a mathematical model similar to IMa2 (Hey 2010) for the relevant evolutionary processes which allows both the the population size parameters and the migration rates between pairs of species tree branches to be integrated out. We then describe a BEAST2 package DENIM which based on this model, and which uses an approximation to sample from the posterior. The approximation is based on the assumption that migrations are rare, and it only samples from certain regions of the posterior which seem likely given this assumption. The method breaks down if there is a lot of migration. Using simulations, Leaché et al 2014 showed migration causes problems for species tree inference using the multispecies coalescent when migration is present but ignored. We re-analyze this simulated data to explore DENIM’s performance, and demonstrate substantial improvements over *BEAST. We also re-analyze an empirical data set. [isolation-with-migration; incomplete lineage sorting; multispecies coalescent; species tree; phylogenetic analysis; Bayesian; Markov chain Monte Carlo]

Gene tree discord, simplex plots, and statistical tests under the coalescent

10.1101/2020.02.13.948083 ◽

2020 ◽

Cited By ~ 1

Author(s):

Elizabeth S. Allman ◽

Jonathan D. Mitchell ◽

John A. Rhodes

Keyword(s):

Incomplete Lineage Sorting ◽

Statistical Tests ◽

Gene Tree ◽

Complex Model ◽

Species Tree ◽

Data Sets ◽

Gene Trees ◽

Lineage Sorting ◽

Multispecies Coalescent ◽

Tree Inference

AbstractA simple graphical device, the simplex plot of quartet concordance factors, is introduced to aid in the exploration of a collection of gene trees on a common set of taxa. A single plot summarizes all gene tree discord, and allows for visual comparison to the expected discord from the multispecies coalescent model (MSC) of incomplete lineage sorting on a species tree. A formal statistical procedure is described that can quantify the deviation from expectation for each subset of four taxa, suggesting when the data is not in accord with the MSC, and thus either gene tree inference error is substantial or a more complex model such as that on a network may be required. If the collection of gene trees appears to be in accord with the MSC, the plots may reveal when substantial incomplete lineage sorting is present and coalescent based species tree inference is preferred over concatenation approaches. Applications to both simulated and empirical multilocus data sets illustrate the insights provided.

Consistency and identifiability of the polymorphism-aware phylogenetic models

10.1101/718320 ◽

2019 ◽

Author(s):

Rui Borges ◽

Carolin Kosiol

Keyword(s):

Incomplete Lineage Sorting ◽

Simulated Data ◽

Population Level ◽

Species Tree ◽

Population Variation ◽

Necessary Condition ◽

Lineage Sorting ◽

Data Set ◽

Genome Wide ◽

Phylogenetic Models

AbstractPolymorphism-aware phylogenetic models (PoMo) constitute an alternative approach for species tree estimation from genome-wide data. PoMo builds on the standard substitution models of DNA evolution but expands the classic alphabet of the four nucleotide bases to include polymorphic states. By doing so, PoMo accounts for ancestral and current intra-population variation, while also accommodating population-level processes ruling the substitution process (e.g. genetic drift, mutations, allelic selection). PoMo has shown to be a valuable tool in several phylogenetic applications but a proof of statistical consistency (and identifiability, a necessary condition for consistency) is lacking. Here, we prove that PoMo is identifiable and, using this result, we further show that the maximum a posteriori (MAP) tree estimator of PoMo is a consistent estimator of the species tree. We complement our theoretical results with a simulated data set mimicking the diversity observed in natural populations exhibiting incomplete lineage sorting. We implemented PoMo in a Bayesian framework and show that the MAP tree easily recovers the true tree for typical numbers of sites that are sampled in genome-wide analyses.

A comparative study of SVDquartets and other coalescent-based species tree estimation methods

10.1101/022855 ◽

2015 ◽

Author(s):

Jed Chou ◽

Ashu Gupta ◽

Shashank Yaduvanshi ◽

Ruth Davidson ◽

Mike Nute ◽

...

Keyword(s):

Incomplete Lineage Sorting ◽

Estimation Error ◽

Species Tree ◽

Estimation Methods ◽

Gene Trees ◽

Lineage Sorting ◽

Sequence Alignments ◽

Tree Estimation ◽

Combine Gene ◽

High Support

Background: Species tree estimation is challenging in the presence of incomplete lineage sorting (ILS), which can make gene trees different from the species tree. Because ILS is expected to occur and the standard concatenation approach can return incorrect trees with high support in the presence of ILS, “coalescent-based” summary methods (which first estimate gene trees and then combine gene trees into a species tree) have been developed that have theoretical guarantees of robustness to arbitrarily high amounts of ILS. Some studies have suggested that summary methods should only be used on “c-genes” (i.e., recombination-free loci) that can be extremely short (sometimes fewer than 100 sites). However, gene trees estimated on short alignments can have high estimation error, and summary methods tend to have high error on short c-genes. To address this problem, Chifman and Kubatko introduced SVDquartets, a new coalescent-based method. SVDquartets takes multi-locus unlinked single-site data, infers the quartet trees for all subsets of four species, and then combines the set of quartet trees into a species tree using a quartet amalgamation heuristic. Yet, the relative accuracy of SVDquartets to leading coalescent-based methods has not been assessed. Results: We compared SVDquartets to two leading coalescent-based methods (ASTRAL-2 and NJst), and to concatenation using maximum likelihood. We used a collection of simulated datasets, varying ILS levels, numbers of taxa, and number of sites per locus. Although SVDquartets was sometimes more accurate than ASTRAL-2 and NJst, most often the best results were obtained using ASTRAL-2, even on the shortest gene sequence alignments we explored (with only 10 sites per locus). Finally, concatenation was the most accurate of all methods under low ILS conditions. Conclusions: ASTRAL-2 generally had the best accuracy under higher ILS conditions, and concatenation had the best accuracy under the lowest ILS conditions. However, SVDquartets was competitive with the best methods under conditions with low ILS and small numbers of sites per locus. The good performance under many conditions of ASTRAL-2 in comparison to SVDquartets is surprising given the known vulnerability of ASTRAL-2 and similar methods to short gene sequences.