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Diversification and asymmetrical gene flow across time and space: lineage sorting and hybridization in polytypic barking frogs
Author(s) -
Streicher Jeffrey W.,
Devitt Thomas J.,
Goldberg Caren S.,
Malone John H.,
Blackmon Heath,
Fujita Matthew K.
Publication year - 2014
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.12814
Subject(s) - biology , coalescent theory , gene flow , introgression , evolutionary biology , lineage (genetic) , phylogenetic tree , reticulate evolution , hybrid zone , clade , genetics , genetic variation , gene
Young species complexes that are widespread across ecologically disparate regions offer important insights into the process of speciation because of their relevance to how local adaptation and gene flow influence diversification. We used mitochondrial DNA and up to 28 152 genomewide single nucleotide polymorphisms from polytypic barking frogs ( C raugastor augusti complex) to infer phylogenetic relationships and test for the signature of introgressive hybridization among diverging lineages. Our phylogenetic reconstructions suggest (i) a rapid P liocene– P leistocene radiation that produced at least nine distinct lineages and (ii) that geographic features of the arid C entral M exican P lateau contributed to two independent northward expansions. Despite clear lineage differentiation (many private alleles and high between‐lineage F ST scores), D ‐statistic tests, which differentiate introgression from ancestral polymorphism, allowed us to identify two putative instances of reticulate gene flow. Partitioned D ‐statistics provided evidence that these events occurred in the same direction between clades but at different points in time. After correcting for geographic distance, we found that lineages involved in hybrid gene flow interactions had higher levels of genetic variation than independently evolving lineages. These findings suggest that the nature of hybrid compatibility can be conserved overlong periods of evolutionary time and that hybridization between diverging lineages may contribute to standing levels of genetic variation.