Mating patterns and post-mating isolation in three cryptic species of the Engystomops petersi species complex

Determining the extent of reproductive isolation in cryptic species with dynamic geographic ranges can give us important insights into the processes that generate and maintain genetic divergence in the absence of severe geographic barriers. We studied mating patterns, propensity to crossbreed in nature and subsequent fertilization rates, as well as survival and development of hybrid F1 offspring for three species of the E. petersi species complex in Yasuní National Park, Ecuador. We found at least two species in five out of seven locations sampled, and 14.3% of the wild pairs genotyped were heterospecific crosses. We also found reduced fertilization rates in hybrid crosses between E. petersi females and E. “magnus” males, and between E. “magnus” females and E. “selva” males but not in the opposite hybrid crosses, suggesting asymmetric reproductive isolation for these species. Larval development time decreased in F1 hybrid crosses compared to conspecific F1s, but we did not find any redu...