Sperm competition accentuates selection on ejaculate attributes.

Pauline Vuarin (1, 2) , Yves Hingrat (3) , Loïc Lesobre (3) , Michel Saint Jalme (4) , Frédéric Lacroix (3) , Gabriele Sorci (2)

1 Emirates Center for Wildlife Propagation
2 BGS - Biogéosciences [UMR 6282]
3 Reneco International Wildlife Consultants LLC
4 CESCO - Centre d'Ecologie et des Sciences de la COnservation

Ejaculate attributes are important factors driving the probability of fertilizing eggs. When females mate with several males, competition between sperm to fertilize eggs should accentuate selection on ejaculate attributes. We tested this hypothesis in the North African houbara bustard ( Chlamydotis undulata undulata) by comparing the strength of selection acting on two ejaculate attributes when sperm from single males or sperm from different males were used for insemination. In agreement with the prediction, we found that selection on ejaculate attributes was stronger when sperm of different males competed for egg fertilization. These findings provide the first direct comparison of the strength of selection acting on ejaculate attributes under competitive and non-competitive fertilizations, confirming that sperm competition is a major selective force driving the evolution of ejaculate characteristics.

Mots clés: fertilization success; multiple mating; natural selection; sexual selection; sperm competition; fertilization success

Domaines: Reproduction sexuée

Pauline Vuarin, Yves Hingrat, Loïc Lesobre, Michel Saint Jalme, Frédéric Lacroix, et al.. Sperm competition accentuates selection on ejaculate attributes.. Biology Letters, 2019, 15 (3), pp.20180889. ⟨10.1098/rsbl.2018.0889⟩. ⟨hal-02078628⟩