Biology subjects

Rader, J. A.

Publications and source records attributed to Rader, J. A..

10 recordsLinked to original sources

bioRxiv2026

Negative allometry of egg size among 29 species of drosophilid flies

The body size of adults and immature stages are fundamental animal traits that influence animal physiology, ecology, and range distribution. While the importance of egg size has been acknowledged as a proxy of parental investment in animals, little work has addressed the tempo and mode of evolution of egg size and shape. Here, we present a comparative study of this trait using a phylogeny based on genome-wide markers together with measurements of egg size and adult body size from 29 drosophilid species. Our analyses revisit the allometric relationship between egg size and body size and show that egg size scales negatively with respect to adult size, even after accounting for shared evolutionary history. In other words, larger species tend to produce proportionally smaller eggs. We also detect a moderate phylogenetic signal in both egg size and egg shape, indicating that closely related species resemble each other in these traits. Model comparisons show that the evolution of egg morphology in drosophilids is best described by gradual divergence through time driven by stochastic evolutionary change. This pattern contrasts with findings from other animal groups, including birds, cephalopods, and reptiles, where alternative evolutionary models better explain trait evolution. Together, these results suggest that the evolutionary dynamics shaping egg morphology in drosophilids differ from those operating in other major lineages and underscore the importance of comparative analyses of early developmental traits across taxa.

evolutionary biology↗

bioRxiv2026

An ancient gene duplication is implicated in virulence in the human pathogen, Histoplasma

Histoplasma spp. is a dimorphic fungal primary pathogen that infects people worldwide and frequently affects immunosuppressed patients. Previous studies have identified the AMY1 gene product, the -amylase Amy1p, as essential for -glucan production and virulence in Histoplasma capsulatum. We identified two new genes (AMY2 and AMY3) in the Histoplasma genome that encode putative -amylases and made mutants using CRISPR/Cas9 technology, followed by evaluation of their role in -glucan biosynthesis and virulence. We also searched for AMY gene copies in 19 fungal genomes with the goals of identifying orthologs for AMY2 and AMY3, and establishing how many AMY copies existed across different fungi. We found that the number and type of -amylases vary depending on the fungal species; that all -amylases related to Histoplasma Amy1p belong to the GH13_5 subfamily, and all orthologs related to Histoplasmas Amy2p and Amy3p belong to the GH13_1 subfamily. We performed phylogenetic analyses of the three paralogs and revealed that the Histoplasma AMY duplications are ancient. We further established Amy2 is an ortholog of Aspergillus niger AgtA, and Aspergillus nidulans AmyD, and that it is partially involved in Histoplasma -glucan biosynthesis and virulence, while Amy3p is an ortholog of Aspergillus flavus Amy1, and it is dispensable for -glucan biosynthesis and virulence.

microbiology↗

bioRxiv2026

Body size, wing area, and wing loading follow a pattern of trait conservatism in Drosophila

Wing loading is a metric of flight performance that captures the relationship between body mass and wing area and reflects how much weight each unit of wing surface supports during flight. Comparative studies have documented substantial differences in wing loading among individuals and across species. However, no study has evaluated the extent of this variation when species are reared under identical, controlled conditions. Here, we address that gap by measuring wing loading in 30 species of drosophilids raised in a common lab environment. We applied comparative phylogenetic methods to assess the extent to which the evolution of body mass, wing area, and wing loading is structured by shared ancestry. We find that wing area and body mass exhibit moderate phylogenetic signal, but wing loading does not. In addition, all three traits are best explained by a model of evolution in which most trait divergence occurs during speciation events. More conservative analyses provide no support for adaptive peaks in wing loading within drosophilids. Together, our results indicate that the evolutionary dynamics of wing loading in Drosophila differ from those described in birds and bats, and raise the question of whether similar patterns characterize other insect lineages.

evolutionary biology↗

bioRxiv2025

Flight feathers evolve fastest near the tip of the wing

Form-function relationships are foundational to evolutionary biology, but we are only beginning to understand the mechanisms that link biomechanical function to morphological evolution. In bird wings, the pace of morphological evolution follows a gradient of aerodynamic force production along the wing, with the fastest rates experienced at the wingtip. We examined how this gradient has manifested in the evolution of the individual flight feathers that comprise the wing surface. Specifically, we studied whether the flight feathers show a pattern of allometric scaling with respect to avian body size, and if the allometric pattern varies along the wing. We also asked whether the pace of evolution of the primary flight feathers follows the same gradient pattern as the overall wing morphology, and if there is modularity within the feather series. We measured the lengths of each of the primary flight feathers from 509 wings representing 514 bird species and calculated morphological disparity and evolutionary rate for each feather in the primary sequence. We found that evolutionary rate and disparity increase significantly toward the wingtip. We also found evidence for modularity within the feather sequence, but we were unable to positively delineate those modules. Our study provides further evidence that the mechanical sensitivity of morphological traits predicts their evolution, with highly sensitive features biased toward higher rates, and that it scales across multiple levels of anatomical organization.

evolutionary biology↗

bioRxiv2025

Sex differentiation, divergence, and introgression in the leishmaniasis vector Lutzomyia longipalpis

An estimated one billion people are at risk of acquiring the disease leishmaniasis annually. This disease, among others, is transmitted to humans via sandfly vectors of the family Psychodidae. In the Neotropics, Lutzomyia longipalpis is one of the most common vectors of leishmaniasis, but little is known about its genetics and population structure, hampering control efforts. We generated sex-specific genome assemblies of Lu. longipalpis from Colombia, and examined population genomics of this species. We found that sex accounts for [~]11% of genome-wide variation, primarily driven by differentiation between the sexes in an XY sex chromosome. Analyses of transposable elements indicate that the size difference in the sex chromosome is driven by more transposable elements in the male chromosome. Further, we examined population genomics and structure across the South American continent. We identified significant genetic divergence between Colombian and Brazilian sandflies and population structure within Lu. longipalpis sensu lato samples collected from the same sites in Brazil. These results strongly suggest the presence of multiple, sympatric species within a cryptic species complex, concordant with other published phenotypic evidence. SIGNIFICANCELeishmaniasis has emerged as an important public health issue. Transmission occurs exclusively through Phlebotomine sandflies of the genera Lutzomyia and Phlebotomus, yet our ability to prevent its spread is constrained by limited knowledge of the biological and ecological factors that make these insects effective vectors. In this manuscript, we leverage whole-genome sequencing to investigate the evolutionary forces shaping genetic diversity in Lutzomyia longipalpis, a key vector of leishmaniasis.

genomics↗

bioRxiv2024

Temperature affects conspecific and heterospecific mating rates in Drosophila

Behavioral mating choices and mating success are important factors in the development of reproductive isolation during speciation. Environmental conditions, especially temperature, can affect these key traits. Environmental conditions can vary across, and frequently delimit species geographic ranges. Pairing suboptimal conditions with relative rarity of conspecifics at range margins may set the stage for hybridization. Despite the importance of mating behaviors as a reproductive barrier, a general understanding of the interaction between behavioral choices and the environment is lacking, in part because systematic studies are rare. With this report, we begin to bridge that gap by providing evidence that temperature has a significant - but not consistent influence on mating choices and success, and thus on reproductive isolation in Drosophila. We studied mating propensity and success at four different temperatures among 14 Drosophila species in non-choice conspecific mating trials and in heterospecific trials among two Drosophila species triads that are known to regularly hybridize in the wild. We show that mating frequency varies significantly across a 10{degrees}C range (from 18{o}C to 28{o}C), both in 1:1 mating trials and in high-density en-masse trials, but that the effect of temperature is highly species-specific. We also show that mating frequency is consistently low and that temperature has a moderate effect in some heterospecific crosses. As conspecific mating propensity decreases outside of the optimal thermal range, while heterospecific matings remain constant, the proportion of heterospecific matings at suboptimal temperatures is relatively high. This result indicates that temperature can modulate behavioral choices that impose reproductive barriers and influence the rate of hybridization. More broadly, our results demonstrate that to truly understand how mating choice and reproductive isolation occur in nature, they need to be studied in an environmental context.

animal behavior and cognition↗

bioRxiv2023

PhyloMatcher: a tool for resolving conflicts in taxonomic nomenclature

SummaryLarge-scale comparative studies rely on the application of both phylogenetic trees and phenotypic data, both of which come from a variety of sources, but due to the changing nature of phylogenetic classification over time, many taxon names in comparative datasets do not match the nomenclature in phylogenetic trees. Manual curation of taxonomic synonyms in large comparative datasets can be daunting. To address this issue, we introduce PhyloMatcher, a tool which allows for programmatic querying of two commonly used taxonomic databases to find associated synonyms with given target species names. Availability and implementationPhyloMatcher is easily installed as a Python package with pip, or as a standalone GUI application. PhyloMatcher source code and documentation are freely available at https://github.com/Lswhiteh/PhyloMatcher, the GUI application can be downloaded from the Releases page. ContactLswhiteh@unc.edu Supplemental InformationWe provide documentation for PhyloMatcher, including walkthrough instructions for the GUI application on the Releases page of https://github.com/Lswhiteh/PhyloMatcher.

bioinformatics↗

bioRxiv2022

Isotopic niches do not follow the expectations of niche conservatism in the bird genus Cinclodes

Phenotypic traits are expected to be more similar among closely related species than among species that diverged long ago (all else being equal). This pattern, known as phylogenetic niche conservatism, also applies to traits that are important to determine the niche of species. To test this hypothesis on ecological niches, we analyzed isotopic data from 254 museum study skins from 12 of the 16 species of the bird genus Cinclodes and measured stable isotope ratios for four different elements: Carbon, Nitrogen, Hydrogen and Oxygen. We find that all traits, measured individually, or as a composite measurement, lack any phylogenetic signal, which in turn suggests a high level of lability in ecological niches. We compared these metrics to the measurements of morphological traits in the same genus and found that isotopic niches are uniquely evolutionarily labile compared to other traits. Our results suggest that, in Cinclodes, the realized niche evolves much faster than expected by the constraints of phylogenetic history and poses the question of whether this is a general pattern across the tree of life.

evolutionary biology↗

bioRxiv2022

Morphological evolution of bird wings follows a mechanical sensitivity gradient determined by the aerodynamics of flapping flight

The physical principles that govern the function of biological structures also mediate their evolution, but the evolutionary drivers of morphological traits within complex structures can be difficult to predict. We used morphological traits measured from 1096 3-dimensional bird wing scans from 178 species to test how two frameworks for relating morphology to evolution interact. We examined whether the modular organization of the wing into handwing and armwing regions, or the relationship between trait morphology and functional output (i.e. mechanical sensitivity, driven here by flapping flight aerodynamics) dominate evolutionary rate ({sigma}2) and mode. Our results support discretization of the armwing and handwing as morphological modules, but morphological disparity and{sigma} 2 varied continuously with the mechanical sensitivity gradient and were not modular. Thus, mechanical sensitivity should be considered an independent driver of evolutionary dynamics, distinct from morphological modularity. TeaserMechanical sensitivity drives wing shape evolution in birds and may be fundamental to the evolution of biomechanical systems.

evolutionary biology↗

bioRxiv2022

How Turkey vultures tune their airspeed to environmental and behavioral factors

Animals must tune their physical performance to changing environmental conditions, and the breadth of environmental tolerance may contribute to delineating the species geographic range. A common environmental challenge that flying animals face is the reduction of air density at high elevation and a reduction in the effectiveness of lift production that accompanies it. Turkey vultures (Cathartes aura) inhabit a >3000 m elevation range, and fly considerably higher, necessitating that they compensate for air density differences through behavior, physiology, or biomechanics. We predicted that birds flying at high elevation would demonstrate higher median flight speeds while maintaining similar glide angles. We used 3-dimensional videography to track Turkey vultures flying at three elevations and found a negative relationship between median airspeed and air density that matched our prediction. Additionally, neither the ratio of horizontal speed to sinking speed nor flapping behavior varied with air density. These results were robust to varying flight behavior (climbing vs. level flight). Finally, we derived a glide polar from the free-flying vultures and showed that they are proficient at tuning their flight speed to minimize their cost of transport during straight-line flight, but transition to a minimum power strategy during gliding turns.

zoology↗