Attractive males release fewer sperm

Attractive males release fewer sperm per mating to maximise their chances of producing offspring across a range of females, according to a new paper on the evolution of ejaculation strategies. The findings by researchers at UCL and the University of Oxford suggest that, paradoxically, matings with attractive males may be less fertile than those with unattractive ones. In a paper to be published in the journal American Naturalist, the team mathematically modelled a range of male ejaculation strategies to look for the optimum 'sperm load? per mating, and how this might vary depending on mating patterns. Previous studies have shown that in animals such as the domestic fowl, and fish such as the Arctic charr, males with privileged access to females produce ejaculates of lower fertilising quality than subordinate males. Sam Tazzyman, from UCL CoMPLEX (Centre for Mathematics and Physics in the Life Sciences and Experimental Biology), said: 'In some species, females mate with many different males. Each male's sperm competes with that of other males in a process known as 'sperm competition'. Since males have finite resources to allocate to breeding, they allocate them carefully to each mating to maximise their number of offspring.