Biology subjects

Braun, E. L.

Publications and source records attributed to Braun, E. L..

13 recordsLinked to original sources

bioRxiv2026

UVfinder: a tool to extract bryophyte sex-linked gene copies from the GoFlag408 probe set

PremiseTarget enrichment sequencing using probe sets like GoFlag 408 has revolutionized phylogenetics, yet recent genomic data indicate that some probes may be sex-linked, potentially introducing topological conflict but also allowing studies of sex-specific evolutionary processes. To test for sex-linkage across the bryophytes, we developed UVfinder, a pipeline designed to identify sex-linked GoFlag loci across published moss genomes and enable sex-aware downstream analyses. Methods and ResultsApplying UVfinder to 50 dioicous moss genomes,we identified 93 probes that exhibit sex-linkage in one or more lineages. Our results provide genomic evidence for neo-sex chromosome formation via autosome-sex chromosome fusion and gene translocation. By comparing species trees derived from sex-linked versus autosomal loci in Hypnales and Dicranidae, we demonstrate that sex-linked loci harbor phylogenetic information that is distinct from that in autosomes. We also discovered a pervasive female sampling bias perhaps reflecting a preference among collectors for plants with sporophytes. ConclusionsOur findings highlight the dynamism in sex linkage across bryophytes and suggest that sex-aware phylogenomics can be used to reconstruct ancestral karyotypes and potentially resolve topological conflict. We also expect that UVfinder will facilitate study of sex specific evolutionary processes, particularly with improved genome assemblies and increased sampling in males.

bioinformatics↗

bioRxiv2026

Recombination and incomplete lineage sorting resolve the enigma of lysozyme evolution

Lysozyme has long been a model for understanding enzyme structure, function, and evolution. Early studies revealed a conflict between organismal phylogeny and the distribution of three functionally important amino acid residues in galliform birds. Lysozymes differing at all three amino acids appear functionally equivalent, but intermediates exhibit reduced stability and have not been observed in nature. However, the phylogeny suggests two independent occurrences of the three mutations, requiring two separate transitions through low fitness intermediates. We reexamined this apparent paradox using phylogenomic methods, accounting for incomplete lineage sorting and intralocus recombination. The lysozyme locus tree conflicts with an estimated species tree, but the conflict involves a short branch in coalescent units, consistent with incomplete lineage sorting. We also found evidence for recombination, with different parts of the lysozyme locus supporting alternative relationships. The three amino acids are encoded by exons located in different recombination-defined segments with different evolutionary histories. These results support a model where ancestral polymorphism, coupled with recombination between independently arising mutations, allowed rapid transitions between peaks in the fitness landscape without fixation of deleterious intermediates. Our findings resolve this long-standing question in lysozyme evolution and highlight the importance of considering complex genealogical processes such as incomplete lineage sorting and recombination when reconstructing ancestral proteins and interpreting apparent cases of molecular convergence.

evolutionary biology↗

bioRxiv2025

The phylogenetic position of the extinct Hawaiian honeyeaters: Overcoming the limitations of antique DNA

Mohoidae, the Hawaiian honeyeaters, are a group of extinct birds that once inhabited the Hawaiian Islands. Their genetic data are only available from historical museum specimens, so it is based on highly fragmented and damaged DNA. Poor sequence recovery in these "antique" samples can bias phylogenetic inference which often results in exceptionally long terminal branches in the phylogeny. These long branches can distort estimates of phylogeny, an artifact known as long branch attraction. However, the best way to analyze this data is unclear because these long branches are typically artifactual, reflecting DNA quality. We investigated the position of Mohoidae within the superfamily Bombycilloidea using published alignments of ultraconserved elements (UCEs) and re-assembled UCEs from raw sequencing reads. The uncertainty involves two monotypic families (Hypocoliidae and Hylocitreidae). Re-aligning UCEs using a smaller taxon set closely related to Mohoidae, along with edge trimming and re-assembly, eliminated the long branches of Mohoidae and Hypocoliidae (also represented by an antique sample). The sister relationship of these two families in previous studies appears to be artifactual; our new analyses yielded congruent topologies that placed Mohoidae as sister to a clade comprising Hypocoliidae and Hylocitreidae. We also found that different assemblers (SPAdes vs Trinity) yielded sequences with conflicts towards the ends of the UCEs, especially for the antique samples, although this did not alter the topology. Finally, combining the UCEs with legacy data allowed us to produce a strongly supported complete phylogeny of Bombycilloidea the included all extant species as well as the extinct Mohoidae.

evolutionary biology↗

bioRxiv2025

Efficient Inference of Macrophylogenies: Insights from the Avian Tree of Life

The exponential growth of molecular sequence data over the past decade has enabled the construction of numerous clade-specific phylogenies encompassing hundreds or thousands of taxa. These independent studies often include overlapping data, presenting a unique opportunity to build macrophylogenies (phylogenies sampling > 1,000 taxa) for entire classes across the Tree of Life. However, the inference of large trees remains constrained by logistical, computational, and methodological challenges. The Avian Tree of Life provides an ideal model for evaluating strategies to robustly infer macrophylogenies from intersecting datasets derived from smaller studies. In this study, we leveraged a comprehensive resource of sequence capture datasets to evaluate the phylogenetic accuracy and computational costs of four methodological approaches: (1) supermatrix approaches using concatenation, including the "fast" maximum likelihood (ML) methods, (2) filtering datasets to reduce heterogeneity, (3) supertree estimation based on published phylogenomic trees, and (4) a "divide-and-conquer" strategy, wherein smaller ML trees were estimated and subsequently combined using a supertree approach. Additionally, we examined the impact of these methods on divergence time estimation using a dataset that includes newly vetted fossil calibrations for the Avian Tree of Life. Our findings highlight that recently developed fast tree search approaches offer a reasonable compromise between computational efficiency and phylogenetic accuracy, facilitating inference of macrophylogenies.

evolutionary biology↗

bioRxiv2024

Testing the mettle of METAL: A comparison of phylogenomic methods using a challenging but well-resolved phylogeny

The evolutionary histories of different genomic regions typically differ from each other and from the underlying species phylogeny. This makes species tree estimation challenging. Here, we examine the performance of phylogenomic methods using a well-resolved phylogeny that nevertheless contains many difficult nodes, the species tree of living birds. We compared trees generated by maximum likelihood (ML) analysis of concatenated data, gene tree summary methods, and SVDquartets. We also conduct the first empirical test of a "new" method called METAL (Metric algorithm for Estimation of Trees based on Aggregation of Loci), which is based on evolutionary distances calculated using concatenated data. We conducted this test using a novel dataset comprising more than 4,000 ultraconserved element (UCE) loci from almost all bird families and two existing UCE and intron datasets sampled from almost all avian orders. We identified "reliable clades" very likely to be present in the true avian species tree and used them to assess method performance. ML analyses of concatenated data recovered almost all reliable clades with less data and greater robustness to missing data than other methods. METAL recovered many reliable clades, but only performed well with the largest datasets. Gene tree summary methods (weighted ASTRAL and weighted ASTRID) performed well; they required less data than METAL but more data than ML concatenation. SVDquartets exhibited the worst performance of the methods tested. In addition to the methodological insights, this study provides a novel estimate of avian phylogeny with almost 99% of the currently recognized avian families. Only one of the 181 reliable clades we examined was consistently resolved differently by ML concatenation versus other methods, suggesting that it may be possible to achieve consensus on the deep phylogeny of extant birds.

evolutionary biology↗

bioRxiv2022

Molecular early burst associated with the diversification of birds at the K-Pg boundary

Complex patterns of genome and life-history evolution associated with the end-Cretaceous (K- Pg) mass extinction event limit our understanding of the early evolutionary history of crown group birds [1-9]. Here, we assess molecular heterogeneity across living birds using a technique enabling inferred sequence substitution models to transition across the history of a clade [10]. Our approach identifies distinct and contrasting regimes of molecular evolution across exons, introns, untranslated regions, and mitochondrial genomes. Up to fifteen shifts in the mode of avian molecular evolution map to rapidly diversifying clades near the Cretaceous-Palaeogene boundary, demonstrating a burst of genomic disparity early in the evolutionary history of crown birds [11-13]. Using simulation and machine learning techniques, we show that shifts in developmental mode [14] or adult body mass [4] best explain transitions in the mode of nucleotide substitution. These patterns are related, in turn, to macroevolutionary shifts in the allometric scaling relationship between basal metabolic rate and body mass [15, 16]. In agreement with theoretical predictions, this scaling relationship appears to have weakened across the end-Cretaceous transition. Overall, our study provides evidence that the Chicxulub bolide impact [17] triggered integrated patterns of evolution across avian genomes, physiology, and life history that structured the evolutionary potential of modern birds.

evolutionary biology↗

bioRxiv2022

Reconciling GenBank names with standardized avian taxonomies to improve linkage between phylogeny and phenotype

Biodiversity research has advanced by testing expectations of ecological and evolutionary hypotheses through the linking of large-scale genetic, distributional, and trait datasets. The rise of molecular systematics over the past 30 years has resulted in a wealth of DNA sequence data from around the globe, facilitating biodiversity research. However, advances in molecular systematics also have created taxonomic instability, as new estimates of evolutionary relationships and interpretations of species limits have led to widespread scientific name changes. Taxonomic instability, or "splits, lumps, and shuffles", present logistical challenges to large-scale biodiversity research because species or populations may be listed under different names in different data sources, or because different species or populations may be listed under previous names. Consequently, distributional and trait data are often difficult to link directly to DNA sequence data without extensive and time consuming curation. Here, we present RANT: Reconciliation of Avian NCBI Taxonomy. RANT applies taxonomic reconciliation to standardize all avian names in use in NCBI GenBank, a primary source of genetic data, to a widely-used and regularly-updated avian taxonomy: eBird/Clements. Of 14,341 avian species or subspecies names used by GenBank, 11,031 names directly matched an eBird/Clements name, which were linked to over 6 million nucleotide sequences. For the remaining unique avian names in GenBank, we used Avibases taxonomic concepts, taxonomic descriptions in Cornells Birds of the World, and DNA sequence metadata to identify corresponding eBird/Clements names. Reconciled names were linked to over 600,000 nucleotide sequences, approximately 9% of all avian sequences on GenBank. Nearly 10% of eBird/Clements names had nucleotide sequences listed under two or more GenBank names. Our avian GenBank naming reconciliation is open source and available at GitHub, where it can be updated to correspond with future annual eBird/Clements taxonomic updates. LAY SUMMARY- 23% of avian names on GenBank do not match eBird/Clements, a widely-used standardized avian taxonomy - 600,000 nucleotide sequences on GenBank are associated with names that do not match eBird/Clements - 10% of eBird/Clements names have nucleotide sequences listed under multiple GenBank names - We provide an open source taxonomic reconciliation to mitigate difficulties associated with non-standardized name use for GenBank data

zoology↗

bioRxiv2021

Historical specimens and the limits of subspecies phylogenomics in the New World quails (Odontophoridae)

As phylogenomics focuses on comprehensive taxon sampling at the species and population/subspecies levels, incorporating genomic data from historical specimens has become increasingly common. While historical samples can fill critical gaps in our understanding of the evolutionary history of diverse groups, they also introduce additional sources of phylogenomic uncertainty, making it difficult to discern novel evolutionary relationships from artifacts caused by sample quality issues. These problems highlight the need for improved strategies to disentangle artifactual patterns from true biological signal as historical specimens become more prevalent in phylogenomic datasets. Here, we tested the limits of historical specimen-driven phylogenomics to resolve subspecies-level relationships within a highly polytypic family, the New World quails (Odontophoridae), using thousands of ultraconserved elements (UCEs). We found that relationships at and above the species-level were well-resolved and highly supported across all analyses, with the exception of discordant relationships within the two most polytypic genera which included many historical specimens. We examined the causes of discordance and found that inferring phylogenies from subsets of taxa resolved the disagreements, suggesting that analyzing subclades can help remove artifactual causes of discordance in datasets that include historical samples. At the subspecies-level, we found well-resolved geographic structure within the two most polytypic genera, including the most polytypic species in this family, Northern Bobwhites (Colinus virginianus), demonstrating that variable sites within UCEs are capable of resolving phylogenetic structure below the species level. Our results highlight the importance of complete taxonomic sampling for resolving relationships among polytypic species, often through the inclusion of historical specimens, and we propose an integrative strategy for understanding and addressing the uncertainty that historical samples sometimes introduce to phylogenetic analyses.

evolutionary biology↗

bioRxiv2021

Categorical edge-based analyses of phylogenomic data reveal conflicting signals for difficult relationships in the avian tree

Phylogenetic analyses fail to yield a satisfactory resolution of some relationships in the tree of life even with genome-scale datasets, so the failure is unlikely to reflect limitations in the amount of data. Gene tree conflicts are particularly notable in studies focused on these contentious nodes, and taxon sampling, different analytical methods, and/or data type effects can further confound analyses. Although many efforts have been made to incorporate biological conflicts, few studies have curated individual genes for their efficiency in phylogenomic studies. Here, we conduct an edge-based analysis of Neoavian evolution, examining the phylogenetic efficacy of two recent phylogenomic bird datasets and three datatypes (ultraconserved elements [UCEs], introns, and coding regions). We assess the potential causes for biases in signal-resolution for three difficult nodes: the earliest divergence of Neoaves, the position of the enigmatic Hoatzin (Opisthocomus hoazin), and the position of owls (Strigiformes). We observed extensive conflict among genes for all data types and datasets even after meticulous curation. Edge-based analyses (EBA) increased congruence and provided information about the impact of data type, GC content variation (GCCV), and outlier genes on each of nodes we examined. First, outlier gene signals appeared to drive different patterns of support for the relationships among the earliest diverging Neoaves. Second, the placement of Hoatzin was highly variable, although our EBA did reveal a previously unappreciated data type effect with an impact on its position. It also revealed that the resolution with the most support here was Hoatzin + shorebirds. Finally, GCCV, rather than data type (i.e., coding vs non-coding)per se, was correlated with a signal that supports monophyly of owls + Accipitriformes (hawks, eagles, and New World vultures). Eliminating high GCCV loci increased the signal for owls + mousebirds. Categorical EBA was able to reveal the nature of each edge and provide a way to highlight especially problematic branches that warrant a further examination. The current study increases our understanding about the contentious parts of the avian tree, which show even greater conflicts than appreciated previously.

evolutionary biology↗

bioRxiv2020

TAPER: Pinpointing errors in multiple sequence alignments despite varying rates of evolution

AO_SCPLOWBSTRACTC_SCPLOWErroneous data can creep into sequence datasets for reasons ranging from contamination to annotation and alignment mistakes. These errors can reduce the accuracy of downstream analyses such as tree inference and will diminish the confidence of the community in the results even when they do not impact the analysis. As datasets keep getting larger, it has become difficult to visually check for errors, and thus, automatic error detection methods are needed more than ever before. Alignment masking methods, which are widely used, completely remove entire aligned sites. Therefore, they may reduce signal as much as or more than they reduce the noise. An alternative is designing targeted methods that look for errors in small species-specific stretches of the alignment by detecting outliers. Crucially, such a method should attempt to distinguish the real heterogeneity, which includes signal, from errors. This type of error filtering is surprisingly under-explored. In this paper, we introduce TAPER, an automatic algorithm that looks for small stretches of error in sequence alignments. Our results show that TAPER removes very little data yet finds much of the error and cleans up the alignments.

bioinformatics↗

bioRxiv2020

Complete vertebrate mitogenomes reveal widespread gene duplications and repeats

Modern sequencing technologies should make the assembly of the relatively small mitochondrial genomes an easy undertaking. However, few tools exist that address mitochondrial assembly directly. As part of the Vertebrate Genomes Project (VGP) we have developed mitoVGP, a fully automated pipeline for similarity-based identification of mitochondrial reads and de novo assembly of mitochondrial genomes that incorporates both long (>10 kbp, PacBio or Nanopore) and short (100-300 bp, Illumina) reads. Our pipeline led to successful complete mitogenome assemblies of 100 vertebrate species of the VGP. We have observed that tissue type and library size selection have considerable impact on mitogenome sequencing and assembly. Comparing our assemblies to purportedly complete reference mitogenomes based on short-read sequencing, we have identified errors, missing sequences, and incomplete genes in those references, particularly in repeat regions. Our assemblies have also identified novel gene region duplications, shedding new light on mitochondrial genome evolution and organization.

genomics↗

bioRxiv2020

Protein evolution is structure dependent and non-homogeneous across the tree of life

MotivationProtein sequence evolution is a complex process that varies among-sites within proteins and across the tree of life. Comparisons of evolutionary rate matrices for specific taxa ( clade-specific models) have the potential to reveal this variation and provide information about the underlying reasons for those changes. To study changes in patterns of protein sequence evolution we estimated and compared clade-specific models in a way that acknowledged variation within proteins due to structure. ResultsClade-specific model fit was able to correctly classify proteins from four specific groups (vertebrates, plants, oomycetes, and yeasts) more than 70% of the time. This was true whether we used mixture models that incorporate relative solvent accessibility or simple models that treat sites as homogeneous. Thus, protein evolution is non-homogeneous over the tree of life. However, a small number of dimensions could explain the differences among models (for mixture models ~50% of the variance reflected relative solvent accessibility and ~25% reflected clade). Relaxed purifying selection in taxa with lower long-term effective population sizes appears to explain much of the among clade variance. Relaxed selection on solvent-exposed sites was correlated with changes in amino acid side-chain volume; other differences among models were more complex. Beyond the information they reveal about protein evolution, our clade-specific models also represent tools for phylogenomic inference. AvailabilityModel files are available from https://github.com/ebraun68/clade_specific_prot_models. Contactebraun68@ufl.edu Supplementary informationSupplementary data are appended to this preprint.

evolutionary biology↗

bioRxiv2018

Why do phylogenomic analyses of early animal evolution continue to disagree? Sites in different structural environments yield different answers

Phylogenomics has revolutionized the study of evolutionary relationships. However, genome-scale data have not been able to resolve all relationships in the tree of life. This could reflect the poor-fit of the models used to analyze heterogeneous datasets; that heterogeneity is likely to have many explanations. However, it seems reasonable to hypothesize that the different patterns of selection on proteins based on their structures might represent a source of heterogeneity. To test that hypothesis, we developed an efficient pipeline to divide phylogenomic datasets that comprise proteins into subsets based on secondary structure and relative solvent accessibility. We then tested whether amino acids in different structural environments had different signals for the deepest branches in the metazoan tree of life. Sites located in different structural environments did support distinct tree topologies. The most striking difference in phylogenetic signal reflected relative solvent accessibility; analyses of sites on the surface of proteins yielded a tree that placed ctenophores sister to all other animals whereas sites buried inside proteins yielded a tree with a sponge-ctenophore clade. These differences in phylogenetic signal were not ameliorated when we repeated our analyses using the site-heterogeneous CAT model, a mixture model that is often used for analyses of protein datasets. In fact, analyses using the CAT model actually resulted in rearrangements that are unlikely to represent evolutionary history. These results provide striking evidence that it will be necessary to achieve a better understanding the constraints due to protein structure to improve phylogenetic estimation.

evolutionary biology↗