How sexual selection can drive the evolution of costly sperm ornamentation

Stefan Lupold, Mollie K. Manier, Nalini Puniamoorthy, Christopher Schoff, William T. Starmer, Shannon H Buckley Luepold, John M. Belote, Scott S Pitnick

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Post-copulatory sexual selection (PSS), fuelled by female promiscuity, is credited with the rapid evolution of sperm quality traits across diverse taxa. Yet, our understanding of the adaptive significance of sperm ornaments and the cryptic female preferences driving their evolution is extremely limited. Here we review the evolutionary allometry of exaggerated sexual traits (for example, antlers, horns, tail feathers, mandibles and dewlaps), show that the giant sperm of some Drosophila species are possibly the most extreme ornaments in all of nature and demonstrate how their existence challenges theories explaining the intensity of sexual selection, mating-system evolution and the fundamental nature of sex differences. We also combine quantitative genetic analyses of interacting sex-specific traits in D. melanogaster with comparative analyses of the condition dependence of male and female reproductive potential across species with varying ornament size to reveal complex dynamics that may underlie sperm-length evolution. Our results suggest that producing few gigantic sperm evolved by (1) Fisherian runaway selection mediated by genetic correlations between sperm length, the female preference for long sperm and female mating frequency, and (2) longer sperm increasing the indirect benefits to females. Our results also suggest that the developmental integration of sperm quality and quantity renders post-copulatory sexual selection on ejaculates unlikely to treat male-male competition and female choice as discrete processes.

Original languageEnglish (US)
Pages (from-to)535-538
Number of pages4
JournalNature
Volume533
Issue number7604
DOIs
StatePublished - May 25 2016

ASJC Scopus subject areas

  • General
  • Medicine(all)

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