Biology subjects

McDaniels, C. X.

Publications and source records attributed to McDaniels, C. X..

3 recordsLinked to original sources

bioRxiv2026

Mapping frog genomic diversity on a continental scale

Genetic variation is a key component of population resilience and thus an essential tool for wildlife management. For most species, however, we lack information about their current range-wide genomic diversity and how historical and contemporary factors have shaped those patterns. To address these gaps, we built new georeferenced genomic datasets for 2,481 individuals from 46 frog species to develop a genomic diversity atlas representing 43% of species native to the United States and Canada. We identified geographic "hotspots" of high genomic diversity and "coldspots" of low genomic diversity across species and analyzed potential explanations for these patterns. Our results show that several species have their lowest diversity at northern latitudes, at range edges, or within fragmented populations, suggesting areas in need of careful monitoring. More than half (56.8%) of species exhibited a latitudinal gradient in genomic diversity, but we found little evidence for an association between genomic diversity and human disturbance. Furthermore, discordant latitudinal patterns among species suggest that a combination of factors, including range center-edge dynamics and range fragmentation, interact to produce variable diversity patterns. Our study provides a general framework for mapping range-wide genomic diversity of multiple species to support genetically informed biodiversity conservation.

evolutionary biology↗

bioRxiv2026

The Tangled History and Taxonomy of an Iconic Chorus Frog Complex Clarified using Genomic Analyses

Species represent a fundamental unit of biodiversity in evolutionary biology, but the nature of the speciation continuum and inadequate sampling of organisms with broad distributions provide substantial challenges to species delimitation. The Pacific Treefrog complex (Pseudacris regilla sensu lato) is an iconic but systematically poorly understood group of chorus frogs inhabiting a vast portion of western North America. Current studies tentatively recognize three species in this complex (P. hypochondriaca, P. regilla, P. sierra), but disagreement remains among morphological, mitochondrial, and nuclear genetic data. In this study, we used thorough geographic sampling and thousands of nuclear loci, along with an integrative, multi-method approach to clarify the phylogenetic relationships and divergence history of P. regilla s.l. lineages and recommend a new taxonomic arrangement for the group. Pseudacris regilla and P. sierra fall firmly within the "gray zone" of speciation, composing a combined "north" lineage. Based on the degree of congruence in inferences from our analyses and evidence for isolating mechanisms, we propose a two species taxonomy for this complex, recognizing the "north" lineage as P. regilla and retaining P. hypochondriaca as a species. Our study shows how extensive geographic sampling, high-throughput sequencing, and multiple analytical approaches can resolve systematic uncertainties in challenging species complexes.

evolutionary biology↗

bioRxiv2025

Caudata macrogenetics: Species range size predicts intraspecific genetic variation in global salamanders

AimGenetic diversity contains valuable information about ecological and evolutionary aspects of species. Intraspecific genetic variation is shaped by species natural history traits and by characteristics of geography and climate within their ranges. Amphibians are of ecological and conservation interest because of their global distribution, deep history, trait diversity, and roles within ecological communities. Here, we studied genetic variation within salamanders to investigate predictors of nucleotide diversity and spatial patterns of genetic differentiation. LocationGlobal. Time PeriodPresent. Major Taxa StudiedSalamanders. MethodsWe repurposed mitochondrial DNA sequences and ecological data from open-access databases for 220 salamander species. We calculated nucleotide diversity ({pi}) and tested for isolation by distance (IBD) and isolation by environment (IBE). We analyzed these three variables with random forest and phylogenetic comparative methods using 28 predictors expected to be associated with genetic variation. ResultsWe recovered 8,108 Cytb sequences with their associated geographic coordinates, of which 7,007 sequences were manually curated by us. Range size, lineage age, and sample size were important predictors of genetic variation. We found higher diversity in regions including the Neotropics and central-eastern Europe. The absence of phylogenetic signal in {pi}, IBD, and IBE suggests that genetic variation is shaped by local ecological and geographical factors rather than by shared ancestry. Main ConclusionsOur finding of range size as an important predictor aligns with theoretical expectations that species with larger ranges tend to harbor more genetic diversity. Furthermore, lineage age being an important predictor is in line with the clade-age hypothesis, in which species with longer divergence times have higher genetic diversity because they have had more time to accumulate genetic variation. Our results underscore the importance of integrating spatial data into macrogenetic studies, providing valuable information for future studies and conservation strategies targeting regions with high or low genetic diversity.

evolutionary biology↗