Meeting Abstract
When two species successfully hybridize, there is potential for the hybrids to be isolated from the parental species, ecologically and/or reproductively, and to establish themselves as a new, hybrid species. Here, we re-visit a putative case of hybrid speciation among Dogface butterflies originally described in 1914 that has remained unexplored. The putative hybrids were described from a population in the San Bernardino mountains of Southern California, where the Southern Dogface (Zerene cesonia) and California Dogface (Zerene eurydice) have potential to come into contact. After successfully re-discovering the population with intermediate wing color patterns and the putative hybrid zone, we used a combination of comparative morphometrics of male genitalia and wing color patterns, population genomics, interspecific crosses and phenotypic plasticity experiments to test alternative hypotheses for the origin of the putative hybrid population with intermediate wing color patterns. Genomic and morphometrics showed little evidence of recent hybridization, yet laboratory crosses between the species yielded fertile F1. These findings suggest that although hybridization and gene flow may be possible, it occurs at a very low frequency for an extended period of time, and the intermediate population is not composed of recently generated intraspecific hybrids. Alternatively, by rearing butterflies in colder conditions we were able to generate intermediate wing patterns similar to those found in the putative hybrid zone. Collectively, our findings suggest that phenotypic plasticity, not hybridization, may be the major driver for the putative hybrids with intermediate wing color patterns.
