Social dominance explains within-ejaculate variation in sperm design in a passerine bird

Alfonso Luis Rojas Mora, Magali Meniri, Sabrina Ciprietti & Fabrice Helfenstein

Abstract Comparative studies suggest that sperm competition exerts stabilizing selection towards an optimal sperm design e.g., the relative size and covariation of different sperm sections or a quantitative measure of sperm shape - that maximizes male fertility, which results in reduced levels of within-male variation in sperm morphology. Yet, these studies also reveal substantial amounts of unexplained within-ejaculate variance, and the factors presiding to the maintenance of such within-male variation in sperm design at the population level still remain to be identified. Sperm competition models predict that males should progressively invest more resources in their germline as their mating costs increase, i.e., the soma/germline allocation trade-off hypothesis. When access to fertile females is determined by social dominance, the soma/germline allocation trade-off hypothesis predicts that dominant males should invest less in the control of spermatogenesis. Hence, dominance should positively correlate with within-male variance in sperm design.
Keywords sperm size, sperm design, within-ejaculate variation, social hierarchy
Citation Luis Rojas Mora, A., Meniri, M., Ciprietti, S., & Helfenstein, F. (2017). Social dominance explains within-ejaculate variation in sperm design in a passerine bird. BMC Evolutionary Biology, 17, 66-76.
Type Journal article (English)
Date of appearance 4-3-2017
Journal BMC Evolutionary Biology
Volume 17
Pages 66-76
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