Selection Along Ecological Gradients: Genome-Wide Assessment of Introgression and Adaptive mRNA Loci

Bradley T. Martin, Marlis R. Douglas, Tyler K. Chafin, John S. Placyk, Jr., Roger D. Birkhead, Christopher A. Phillips, Michael E. Douglas

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Introgressive hybridization can have evolutionary consequences (e.g., increased adaptive potential) or impact demographic parameters (e.g., outbreeding depression). Importantly, introgression can occur differentially across the genome. Statistical identification of introgression in natural populations has been limited, but with advances in sequencing technologies such studies are now feasible. To assess introgression and selection in three Terrapene taxa inhabiting the southeastern United States we screened thousands of genome-wide Single-Nucleotide-Polymorphisms (SNPs) in 392 individuals. Population structure was assessed using ADMIXTURE, and individuals with mixed ancestry were statistically evaluated for introgression using HyDe, followed by classification into hybrid generations using NewHybrids. Finally, loci were aligned to the Terrapene transcriptome to infer genomic clines indicative of loci under selection. Across four discrete populations, 157 individuals were statistically corroborated as admixed (P<0.05). Introgressed individuals were primarily assigned to the F2 and backcross generations, and admixture patterns generally reflected spatial clines. Ten unique loci under selection aligned to the transcriptome, with the majority seemingly associated with temperature tolerance and anoxia. These data illuminate genome-wide selection gradients and gene flow of three Terrapene taxa inhabiting the southeastern U.S. Furthermore, having a better understanding of the dynamics of introgression occurring in the region will help facilitate effective conservation management strategies
Original languageEnglish (US)
Title of host publicationAmerican Fisheries Society & The Wildlife Society 2019 Joint Annual Conference, Sept. 27-Oct. 4, 2019, Reno, NV
StatePublished - 2019


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