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Chafin, T. K.

Publications and source records attributed to Chafin, T. K..

2 recordsLinked to original sources

FGTpartitioner: Parsimonious delimitation of ancestry breakpoints in large genome-wide SNP datasets

O_LIPartitioning large (e.g. chromosomal) alignments into ancestry blocks is a common step in phylogenomic analyses. However, current solutions require complicated analytical assumptions, or are difficult to implement due to excessive runtimes and unintuitive documentation. Additionally, most methods require haplotype phasing, which is often intractable for non-model studies.\nC_LIO_LIHere, I present an efficient and rapid solution for partitioning large genome alignments into ancestry blocks, which better accommodates non-model diploid organisms in that phasing information is not required a priori.\nC_LIO_LIFGTpartitioner processes a full-chromosome alignment orders of magnitude faster than alternative solutions, while recovering identical results, both via algorithmic improvements and the use of native parallelization.\nC_LIO_LIFGTpartitioner provides a means for simple and rapid block delimitation in genome-wide datasets as a pretext for phylogenomic analysis. It thus widens the potential uses for researchers studying phylogenetic processes across large, non-model genomes. Complete code and documentation for FGTpartitioner are available as an open-source repository on GitHub: https://github.com/tkchafin/FGTpartitioner\nC_LI

bioinformatics

Hybridization drives genetic erosion in sympatric desert fishes of western North America

Many species have evolved or currently coexist in sympatry due to differential adaptation in a heterogeneous environment. However, anthropogenic habitat modifications can either disrupt reproductive barriers or obscure environmental conditions which underlie fitness gradients. In this study, we evaluated the potential for an anthropogenically-mediated shift in reproductive boundaries that separate two historically sympatric fish species (Gila cypha and G. robusta) endemic to the Colorado River Basin using ddRAD sequencing of 368 individuals. We first examined the integrity of reproductive isolation while in sympatry and allopatry, then characterized hybrid ancestries using genealogical assignment tests. We tested for localized erosion of reproductive isolation by comparing site-wise genomic clines against global patterns and identified a breakdown in the drainage-wide pattern of selection against interspecific heterozygotes. This, in turn, allowed for the formation of a hybrid swarm in one tributary, and asymmetric introgression where species co-occur. We also detected a weak but significant relationship between genetic purity and degree of consumptive water removal, suggesting a role for anthropogenic habitat modifications in undermining species boundaries. In addition, results from basin-wide genomic clines suggested that hybrids and parental forms are adaptively non-equivalent. If so, then a failure to manage for hybridization will exacerbate the long-term extinction risk in parental populations. These results reinforce the role of anthropogenic habitat modification in promoting interspecific introgression in sympatric species by relaxing divergent selection. This, in turn, underscores a broader role for hybridization in decreasing global biodiversity within rapidly deteriorating environments.

evolutionary biology