Mass-specific metabolic rate and sperm competition determine sperm size in marsupial mammals.

ABSTRACT: Two complementary hypotheses have been proposed to explain variation in sperm size. The first proposes that post-copulatory sexual selection favors an increase in sperm size because it enhances sperm swimming speed, which is an important determinant of fertilization success in competitive contexts. The second hypothesis proposes that mass-specific metabolic rate acts as a constraint, because large animals with low mass-specific metabolic rates will not be able to process resources at the rates needed to produce large sperm. This constraint is expected to be particularly pronounced among mammals, given that this group contains some of the largest species on Earth. We tested these hypotheses among marsupials, a group in which mass-specific metabolic rates are roughly 30% lower than those of

SUBMITTER: Tourmente M 

PROVIDER: S-EPMC3120838 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature