Reproductive phenology of three species of Pristimantis in an Andean cloud forest

Abstract

We studied the reproductive phenology of three coexisting Pristimantis species inhabiting an Andean tropical cloud forest in the Cordillera Oriental of Colombia. Populations were constituted mostly by juveniles, numerous adult males, and few reproductive adult females and, therefore, the operational sex ratio was greatly biased to males while the populational sex ratio was not. Mean snout-vent lengths (SVL) were larger in adult females than in males, as well as the minimum size of sexual maturity, which indicates that females became mature or adult at larger body sizes than males and explains the highly biased operational sex ratio. The testes histological analyses revealed the presence of sperm in almost all the collected males indicating that they are a permanent resource for reproduction in the three studied species. Males’ abdominal fat bodies showed no significant temporal variation nor a relationship with the rainy season. We observed three patterns of breeding activity: 1) Continuous reproductive activity in P. miyatai; 2) reproductive activity during the rainy seasons and juvenile recruitment in the following dry seasons in P. merostictus, and 3) reproductive activity mainly during the second semester of the year and juvenile recruitment in the following dry season (P. uisae). The analyses of reproductive activity and recruitment of juveniles revealed significant temporal overlap among Pristimantis species suggesting that reproductive phenology does not play a significant role in the temporal segregation of these anuran species. Nevertheless, the different breeding patterns could represent a strategy to reduce interspecific froglet overcrowding in the growing microhabitats thus facilitating coexistence among potentially competing taxa.