Data from: A genetic polymorphism underlying alternative reproductive tactics in Eurycea salamanders

Alternative reproductive tactics are discrete, intrasexual differences in
reproductive behavior within a population. In some cases,  these
complex phenotypes are determined by autosomal supergenes or sex
chromosomes—both of which exhibit reduced recombination and thus enable
the linked inheritance of co-adapted alleles from multiple loci. Most
alternative reproductive tactics in amphibians are plastic (and
reversible), environmentally determined, and lacking morphological
differentiation, but a striking exception is found in the two-lined
salamander (Eurycea bislineata) species complex. In some populations, two
distinct male phenotypes coexist: “searching” males have mental glands,
protruding premaxillary teeth, and elongate cirri used in terrestrial
courtship, while “guarding” males lack these traits and instead have
hypertrophied jaw musculature used in mate-guarding at aquatic nesting
sites. These tactics differ in many morphological and behavioral
phenotypes, but their proximate cause has not yet been described. Here, we
generated genome-wide SNP data from >130 Eurycea cf. wilderae
collected from Highlands Biological Station. We provide evidence for a XY
sex determination and for a Y-linked polymorphism underlying alternative
reproductive tactics in this population. We then develop and validate a
PCR-based genotyping assay and apply this to characterize the sex ratio
and relative frequency of tactics from a sample of larvae. Our results add
to the growing body of literature exploring the importance of supergenes
and sex chromosomes in complex intraspecific polymorphisms, and we
highlight opportunities for future work to continue exploring the genomic
architecture of these traits.