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The frequency of multiple paternity predicts variation in testes size among island populations of house mice
Author(s) -
FIRMAN R. C.,
SIMMONS L. W.
Publication year - 2008
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2008.01612.x
Subject(s) - sperm competition , biology , sperm , intraspecific competition , house mice , sexual selection , competition (biology) , population , mating system , mating , zoology , evolutionary biology , mate choice , female sperm storage , ecology , genetics , demography , sociology
Polyandry generates selection on males through sperm competition, which has broad implications for the evolution of ejaculates and male reproductive anatomy. Comparative analyses across species and competitive mating trials within species have suggested that sperm competition can influence the evolution of testes size, sperm production and sperm form and function. Surprisingly, the intraspecific approach of comparing among population variation for investigating the selective potential of sperm competition has rarely been explored. We sampled seven island populations of house mice and determined the frequency of multiple paternity within each population. Applying the frequency of multiple paternity as an index of the risk of sperm competition, we looked for selective responses in male reproductive traits. We found that the risk of sperm competition predicted testes size across the seven island populations of house mice. However, variation in sperm traits was not explained by sperm competition risk. We discuss these findings in relation to sperm competition theory, and other intrinsic and extrinsic factors that might influence ejaculate quality.