Mating patterns of Rana kukunoris from three populations along an altitudinal gradient on the Tibetan Plateau

Abstract

Large-male mating advantage and size-assortative mating are two different size-dependent mating patterns which deviate from random mating in frogs. These two pairing patterns may arise due to female choice, male-male competition, male choice, or a combination of these. Our study investigated the mating system of Rana kukunoris at three elevations on the Tibetan Plateau, southwestern China, throughout a breeding season. We compared body size between amplectant and non-amplectant males, and among amplectant pairs. For R. kukunoris, the results showed a large-male mating advantage at the two higher elevations and a size-assortative mating at the highest elevation. In addition to sexual selection, we found that the length of the breeding season, population density and operational sex ratio may influence mating patterns.