Intraspecific variation of testis size and sperm length in the yellow-pine chipmunk ( Tamias amoenus ): implications for sperm competition and reproductive success

摘要: Comparative analyses have found that relative testis size is a strong predictor of the prevalence sperm competition for many taxa, including mammals, yet underlying this pattern assumption intraspecific variation in related to individual fitness. Because ejaculate investment underlies interspecific patterns, it critical understand causes and consequences investment. We examined relationships between (testis length) reproductive success, body condition yellow-pine chipmunk (Tamias amoenus), small ground squirrel which occurs. genetic estimates male success from wild population chipmunks determined males with large testes had higher annual than testes. This result provides empirical support numerous comparative studies indicate associated intensity competition. In addition, good relatively larger poor condition, but there was no evidence length being dependent on condition. Finally, contrary predictions, invested more production (relatively heavy testes) produced shorter sperm, not longer less.