Unravelling anisogamy: egg size and ejaculate size mediate selection on morphology in free-swimming sperm.

ABSTRACT: Gamete dimorphism (anisogamy) defines the sexes in most multicellular organisms. Theoretical explanations for its maintenance usually emphasize the size-related selection pressures of sperm competition and zygote survival, assuming that fertilization of all eggs precludes selection for phenotypes that enhance fertility. In external fertilizers, however, fertilization is often incomplete due to sperm limitation, and the risk of polyspermy weakens the advantage of high sperm numbers that is predicted to limit sperm size, allowing alternative selection pressures to target free-swimming sperm. We asked whether egg size and ejaculate size mediate selection on the free-swimming sperm of Galeolaria caespitosa, a marine tubeworm with external fertilization, by comparing relationships between sperm

SUBMITTER: Monro K 

PROVIDER: S-EPMC4947887 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature