Biology subjects

Stull, G. W.

Publications and source records attributed to Stull, G. W..

10 recordsLinked to original sources

bioRxiv2025

Longevity in plants impacts phylogenetic and population dynamics

Many long-lived plant species exhibit notable patterns in phylogenies, such as short molecular branch lengths and high gene-tree conflict. However, it is not clear what biological properties of long-lived plant species or concomitant processes acting within these lineages generate these patterns. To explore this mystery, we implemented an agent-based model and conducted simulations to investigate how longevity affects molecular evolution and population dynamics. Through these simulations, we demonstrated that the patterns exhibited in empirical datasets for long-lived species can be explained by their lifespan and overlapping generations. We also show that somatic mutations can exacerbate these patterns, although evidence for substantive rates in empirical systems high enough to impact phylogenetic patterns is scarce. We discuss several empirical datasets containing life history shifts that exhibit diverse phylogenomic patterns. The variation produced through different parameterizations of our simulations reflects the diversity of patterns found in empirical datasets. Our results have broad implications for phylogenomic patterns and population genetics in general, as well as for specifically explaining patterns of evolution in long-lived lineages.

evolutionary biology↗

bioRxiv2025

PlastidHub: an integrated analysis platform for plastid phylogenomics and comparative genomics

The plastome (plastid genome) represents an indispensable molecular data source for studying plant phylogeny and evolution. Although plastome size is much smaller than that of nuclear genome, accurate and efficient annotation and of use plastome sequences are not simple tasks. Therefore, a streamlined phylogenomic pipeline from plastome annotation to phylogenetic reconstruction and comparative genomics would greatly facilitate research using this important organellar genome. Here we develop PlastidHub, a new web application that primarily uses novel tools to analyze plastome sequences. In comparison with existing tools, new functionalities in PlastidHub include: (1) standardization of quadripartite structure; (2) improvement of annotation flexibility and consistency; (3) quantitative assessment of annotation completeness; (4) diverse extraction modes for canonical and specialized sequences; (5) intelligent screening of molecular markers for biodiversity studies; (6) visual comparison of structural variations and annotation completeness at the gene-level. PlastidHub has the following features: cloud-based web applications that do not require users to install, update, or maintain tools; detailed help documents including user guides, test examples, a static pop-up prompt box, and dynamic pop-up warning prompts when entering unreasonable parameter values; batch processing functionalities for all tools; intermediate result documents for secondary use; and easy-to-operate task flows between file upload and download. Interrelated task-based user interface design is the most important feature of PlastidHub. Give that PlastidHub is easy to use without specialized computational skills or resources, this new platform should become widely used among botanists and evolutionary biologists, improving and expediting research employing the plastome. PlastidHub is available at https://www.plastidhub.cn.

plant biology↗

bioRxiv2023

Rapid in-situ diversification rates in Rhamnaceae explain the parallel evolution of high diversity in temperate biomes from global to local scales

O_LIThe macroevolutionary processes that have shaped biodiversity across the temperate realm remain poorly understood and may have resulted from evolutionary dynamics related to diversification rates, dispersal rates, and colonization times, closely coupled with Cenozoic climate change. C_LIO_LIWe integrated phylogenomic, environmental ordination, and macroevolutionary analyses for the cosmopolitan angiosperm family Rhamnaceae to disentangle the evolutionary processes that have contributed to high species diversity within and across temperate biomes. C_LIO_LIOur results show independent colonization of environmentally similar but geographically separated temperate regions mainly during the Oligocene, consistent with the global expansion of temperate biomes. High global, regional, and local temperate diversity was the result of high in-situ diversification rates, rather than high immigration rates or accumulation time, except for Southern China, which was colonized much earlier than other regions. The relatively common lineage dispersals out of temperate hotspots highlights strong source-sink dynamics across the cosmopolitan distribution of Rhamnaceae. C_LIO_LIThe proliferation of temperate environments since the Oligocene may have provided the ecological opportunity for rapid in-situ diversification of Rhamnaceae across the temperate realm. Our study illustrates the importance of high in-situ diversification rates for the establishment of modern temperate biomes and biodiversity hotspots across spatial scales. C_LI

evolutionary biology↗

bioRxiv2023

Genome duplications, genomic conflict, and rapid phenotypic evolution characterize the Cretaceous radiation of Fagales

O_LIFlowering plant lineages display remarkable diversity in life history and morphological form. However our understanding of how this phenotypic diversity or disparity, arises and what, if any, relation there is to processes such as gene and genome duplication remains unlcear. C_LIO_LIHere we investigate the relationship between phenotypic and genomic evolution in the angiosperm order Fagales, a lineage of woody plants that has been a dominant component of temperate and subtropical forests since the Late Cretaceous. To this end, we examine newly generated trait and transcriptomic datasets spanning the phylogenetic breadth of the order, including most extant genera as well as a rich diversity of Cretaceous fossil representatives. C_LIO_LIOur phylogenomic analyses resolved the location of an ancient polyploidization event in Juglandaceae and identified hotspots of gene-duplication and genomic conflict across the order. Examinations of phenotypic evolution (including morphospace occupancy and rate shifts) show that the morphospace occupied by Fagales was filled by the early Cenozoic and rates of evolution were highest during the early radiation of the Fagales crown and its major families. Many instances of phenotypic rates also correspond to hotspots of gene duplication. C_LIO_LIOur results show that Fagales conform to an "early burst" model of phenotypic diversification, with morphospace being filled early in the groups evolutionary history. Our study is consistent with others showing a decoupling of species diversification with other biological processes (e.g., phenotypic and genomic evolution), underscoring the complexity of understanding the major drivers of plant evolution over broad timescales. C_LI

evolutionary biology↗

bioRxiv2023

Phylogenomic Analyses Reveal Widespread Gene Flow During the Early Radiation of Oaks and Relatives (Fagaceae: Quercoideae)

AO_SCPLOWBSTRACTC_SCPLOWOaks (Quercus), one of the most species-rich and ecologically dominant woody plant clades in the Northern Hemisphere, are well known for their propensity to hybridize and form syngameons, complexes where alleles are readily exchanged among closely related species. While hybridization has been extensively studied towards the tips of the oak phylogeny, the extent, timeline, and evolutionary scenarios of hybridization during the early radiation of oaks and related genera (Quercoideae) remain poorly known. Using an expansive new dataset of nuclear and chloroplast sequences (including up to 431 spp.), we conducted a multifaceted phylogenomic investigation of Quercus aimed at characterizing gene-tree and cytonuclear (chloroplast-nuclear) discordance and identifying ancient reticulation in the early evolution of the group. We document extensive nuclear gene-tree and cytonuclear discordance at deep nodes in Quercus and Quercoideae, with Quercus recovered as non-monophyletic in the chloroplast phylogeny. Analyses recovered clear signatures of gene flow against a backdrop of incomplete lineage sorting, with gene flow most prevalent among major lineages of Quercus and Quercoideae during their initial radiation, dated to the early-middle Eocene. Ancestral reconstructions including fossil data suggest that the ancestors of Castanea+Castanopsis, Lithocarpus, and the Old World oak clade co-occurred in North America and Eurasia, while the ancestors of Chrysolepis, Notholithocarpus, and the New World oak clade co-occurred in North America, offering ample opportunity for hybridization in each region. Following this initial phase of radiation and reticulation, we detected multiple niche shifts in Quercus and other Quercoideae genera that likely facilitated their expansion into new habitats arising from post-Eocene climatic changes. Our study shows that hybridization--perhaps in the form of ancient syngameons similar to those seen today--has been a common and important process throughout the evolutionary history of oaks and their close relatives.

evolutionary biology↗

bioRxiv2022

Two shifts in evolutionary lability underlie independent gains and losses of root-nodule symbiosis in a single clade of plants

Root nodule symbiosis (RNS) allows plants to access atmospheric nitrogen converted into usable forms through a mutualistic relationship with soil bacteria. RNS is a complex trait requiring coordination from both the plant host and the bacterial symbiont, and pinpointing the evolutionary origins of root nodules is critical for understanding the genetic basis of RNS. This endeavor is complicated by data limitations and the intermittent presence of RNS in a single clade of ca. 30,000 species of flowering plants, i.e., the nitrogen-fixing clade (NFC). We developed the most extensive de novo phylogeny for all major lineages of the NFC and an enhanced root nodule trait database to reconstruct the evolution of RNS. Through identification of the evolutionary pathway to RNS gain, we show that shifts among heterogeneous evolutionary rates can explain how a complex trait such as RNS can arise many times across a large phylogeny. Our analysis identifies a two-step process in which an ancestral precursor state gave rise to a more labile state from which RNS was quickly gained at specific points in the NFC. Our rigorous reconstruction of ancestral states illustrates how a two-step pathway could have led to multiple independent gains and losses of RNS, contrary to recent hypotheses invoking just a single gain and numerous losses. RNS may be an example of multi-level convergent evolution, thus requiring a broader phylogenetic and genetic scope for genome-phenome mapping to elucidate mechanisms enabling fully functional RNS.

evolutionary biology↗

bioRxiv2021

Gene duplications and genomic conflict underlie major pulses of phenotypic evolution in gymnosperms

Inferring the intrinsic and extrinsic drivers of species diversification and phenotypic disparity across the Tree of Life is a major challenge in evolutionary biology. In green plants, polyploidy (or whole-genome duplication, WGD) is known to play a major role in microevolution and speciation1, but the extent to which WGD has shaped macroevolutionary patterns of diversification and phenotypic innovation across plant phylogeny remains an open question. Here we examine the relationship of various facets of genomic evolution--including gene and genome duplication, genome size, and chromosome number--with macroevolutionary patterns of phenotypic innovation, species diversification, and climatic occupancy in gymnosperms. We show that genomic changes, such as WGD and genome-size shifts, underlie the origins of most major extant gymnosperm clades, and notably our results support an ancestral WGD in the gymnosperm lineage. Spikes of gene duplication typically coincide with major spikes of phenotypic innovation, while increased rates of phenotypic evolution are typically found at nodes with high gene-tree conflict, representing historic population-level dynamics during speciation. Most shifts in gymnosperm diversification since the rise of angiosperms are decoupled from putative WGDs and instead are associated with increased rates of climatic occupancy evolution, particularly in cooler and/or more arid climatic conditions, suggesting that ecological opportunity, especially in the later Cenozoic, and environmental heterogeneity have driven a resurgence of gymnosperm diversification. Our study provides critical insight on the processes underlying diversification and phenotypic evolution in gymnosperms, with important broader implications for the major drivers of both micro- and macroevolution in plants.

evolutionary biology↗

bioRxiv2020

Phylogenomic conflict coincides with rapid morphological innovation

Evolutionary biologists have long been fascinated with the episodes of rapid phenotypic innovation that underlie the emergence of major lineages. Although our understanding of the environmental and ecological contexts of such episodes has steadily increased, it has remained unclear how population processes contribute to emergent macroevolutionary patterns. One insight gleaned from phylogenomics is that phylogenomic conflict, frequently caused by population-level processes, is often rampant during the origin of major lineages. With the understanding that phylogenomic conflict is often driven by complex population processes, we hypothesized that there may be a direct correspondence between areas of high conflict and elevated rates of phenotypic innovation if both patterns result from the same processes. We evaluated this hypothesis in six clades spanning vertebrates and plants. We found that the most conflict-rich regions of these six clades also tended to experience the highest rates of phenotypic innovation, suggesting that population processes shaping both phenotypic and genomic evolution may leave signatures at deep timescales. Closer examination of the biological significance of phylogenomic conflict may yield improved connections between micro- and macroevolution and increase our understanding of the processes that shape the origin of major lineages across the Tree of Life.

evolutionary biology↗

bioRxiv2019

Characterizing gene tree conflict in plastome-inferred phylogenies

Premise of the studyEvolutionary relationships among plants have been inferred primarily using chloroplast data. To date, no study has comprehensively examined the plastome for gene tree conflict.\n\nMethodsUsing a broad sampling of angiosperm plastomes, we characterized gene tree conflict among plastid genes at various time scales and explore correlates to conflict (e.g., evolutionary rate, gene length, molecule type).\n\nKey resultsWe uncover notable gene tree conflict against a backdrop of largely uninformative genes. We find gene length is the strongest correlate to concordance, and that nucleotides outperform amino acids. Of the most commonly used markers, matK greatly outperforms rbcL; however, the rarely used gene rpoC2 is the top-performing gene in every analysis. We find that rpoC2 reconstructs angiosperm phylogeny as well as the entire concatenated set of protein-coding chloroplast genes.\n\nConclusionsOur results suggest that longer genes are superior for phylogeny reconstruction. The alleviation of some conflict through the use of nucleotides suggests that systematic error is likely the root of most of the observed conflict, but further research on biological conflict within plastome is warranted given the documented cases of heteroplasmic recombination. We suggest rpoC2 as a useful marker for reconstructing angiosperm phylogeny, reducing the effort and expense of assembling and analyzing entire plastomes.

evolutionary biology↗

bioRxiv2017

Missing the point (estimate): Bayesian and likelihood phylogenetic reconstructions of morphological characters produce generally concordant inferences. A comment on Puttick et al.

Puttick et al. [1] performed a simulation study to compare accuracy among methods of inferring phylogeny from discrete morphological characters. They report that a Bayesian implementation of the Mk model [2] was most accurate (but with low resolution), while a maximum likelihood (ML) implementation of the same model was least accurate. They conclude by strongly advocating that Bayesian implementations of the Mk model should be the default method of analysis for such data. While we appreciate the authors attempt to investigate the accuracy of alternative methods of analysis, their conclusion is based on an inappropriate comparison of the ML point estimate, which does not consider confidence, with the Bayesian consensus, which incorporates estimation credibility into the summary tree. Using simulation, we demonstrate that ML and Bayesian estimates are concordant when confidence and credibility are comparably reflected in summary trees, a result expected from statistical theory. We therefore disagree with the conclusions of PEA and consider their prescription of any default method to be poorly founded. Instead, we recommend caution and thoughtful consideration of the model or method being applied to a morphological dataset.

evolutionary biology↗