Testis asymmetry and sperm length in Rhacophorus omeimontis

Theory predicts that the degree of testes asymmetry should be positively correlated with male body condition in species with directional testis asymmetry. We tested this prediction in Rhacophorus omeimontis, a species in which females mate with more than one male. Our results showed that the treefrogs did not exhibit the absence of directional asymmetry in testis size, but rather the occurrence of fluctuating asymmetry. Moreover, we also tested differences in body size, body mass, testis mass, testis asymmetry, and sperm size among initially paired, jointly paired, and unpaired males. We found that body size and mass, testis mass, testis asymmetry and sperm length did not differ among the three male types. Testis mass showed a positive relationship with soma mass, but the correlations between the extent of fluctuating testis asymmetry and sperm length, and between testis mass and sperm length were not significant. Our data suggest that testes size and sperm length do not play an important role in determining male mating success in the presence of sperm competition.