Data from: Genomic and morphological evidence support contemporary three-way interspecific hybridization in ranid frogs

Hybridization is increasingly understood as common throughout and beyond
the speciation process, rather than an anomaly. Sympatric taxa are
expected to exhibit strong reproductive isolation, and while hybridization
may occur, it often results in inviable offspring. We investigated
hybridization among three ranid frogs (Rana areolata, R. palustris, and R.
sphenocephala) in eastern Oklahoma, where their distributions and breeding
phenology overlap. Using micro-CT scans of cranial morphology, genomic SNP
data, and phenological records, we confirmed two putative hybrids
collected in the field — remarkable given the phylogenetic distance
between these non-sister taxa. Genomic data show split ancestry from
parental populations, representing one R. areolata × R. palustris and one
R. areolata × R. sphenocephala. Cranial morphology indicates hybrids
exhibit intermediate phenotypes, and our assessment identified a third
likely hybrid, a specimen collected two decades earlier from the same
area. Both genetically confirmed hybrids were R. areolata backcrosses, but
minimal introgression throughout the dataset suggests hybrid fitness may
be lower than that of parental populations. Hybridization appears
facilitated by overlapping breeding strategies and ecological factors
leading to misdirected amplexus. This study provides the first
documentation of natural hybridization in R. areolata, a species of
conservation concern throughout its range. Our findings emphasize the
utility of high-resolution morphological data (micro-CT) in complementing
genomic approaches for hybrid diagnosis and suggest cranial morphology may
be an effective method for hybrid identification in similar systems.
Understanding this atypical three-species hybridization has important
implications for conservation, as hybrid fitness and introgression can
influence population dynamics and genetic integrity.