Data from: 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 reduction in larval survival or early metamorph survival. Our results show evidence of post-mating isolation for at least two hybrid crosses of the cryptic species we studied. The general decrease in fertilization rates in heterospecific crosses suggests that sexual selection and reinforcement might have not only contributed to the pattern of call variation and behavioral isolation we see between species today, but they may also contribute to further signal divergence and behavioral evolution, especially in locations where hybridization is common and fertilization success is diminished.针对地理分布动态变化的隐存种（cryptic species），解析其生殖隔离程度，可帮助我们深入理解在缺乏强烈地理屏障的情况下，物种如何产生并维持遗传分化的相关过程。我们以厄瓜多尔亚苏尼国家公园内的E. petersi物种复合体（E. petersi species complex）中的3个物种为研究对象，对其交配模式、野外杂交倾向、后续受精率，以及杂交F1子代的存活与发育情况展开了研究。本次共采样7个位点，其中5个位点至少存在2个物种；经基因分型的野生交配对中，有14.3%为异种交配（heterospecific crosses）。研究还发现，当E. petersi雌体与E. “magnus”雄体、E. “magnus”雌体与E. “selva”雄体进行杂交时，受精率均出现下降；但反向杂交并未出现该现象，这表明这些物种间存在不对称生殖隔离（asymmetric reproductive isolation）。与同种F1子代相比，杂交F1子代的幼虫发育时长有所缩短，但未观察到幼虫存活率或早期变态个体存活率出现下降。本研究结果为本次所研究的隐存种中至少2组杂交组合存在交配后生殖隔离（post-mating isolation）提供了证据支持。异种交配中普遍存在的受精率下降现象表明，性选择与生殖强化不仅可能促成了当前物种间观察到的鸣声变异与行为隔离模式，还可能进一步推动信号分化与行为演化——在杂交频发且受精成功率降低的区域，这一效应尤为显著。