Meeting Abstract

27.6  Friday, Jan. 4  Disentangling sperm speed from sperm length HUMPHRIES, S.**; EVANS, J.P.; SIMMONS, L.W.; University of Sheffield; University of Western Australia; University of Western Australia s.humphries@sheffield.ac.uk

Sperm competition is a form of post-copulatory sexual selection that has implications across a wide range of biology. Sperm length is often used as a proxy for sperm competitive ability, and is often assumed to be linked directly to swimming speed. Here we use hydrodynamic theory to explain the inconsistent patterns of length-velocity relationships for sperm recorded in the literature. We show that no single measure of length is capable of predicting swimming speed but that the use of a simple ratio of tail to head length is all that is required to do so. Furthermore, we show that knowledge of how head and tail lengths scale together allows prediction of differences in swimming speed both within and between species. This should allow future studies to determine the link between sperm morphology, sperm function and sperm competition.