Greater opportunities for sexual selection in male than in female obligate brood parasitic birds

Matthew I.M. Louder, Mark E. Hauber, Amber N.A. Louder, Jeffrey P. Hoover, Wendy M. Schelsky

Research output: Contribution to journalArticle

Abstract

Females are expected to have evolved to be more discriminatory in mate choice than males as a result of greater reproductive investment into larger gametes (eggs vs. sperm). In turn, males are predicted to be more promiscuous than females, showing both a larger variance in the number of mates and a greater increase in reproductive success with more mates, yielding more intense sexual selection on males vs. females (Bateman's Paradigm). However, sex differences in costly parental care strategies can either reinforce or counteract the initial asymmetry in reproductive investment, which may be one cause for some studies failing to conform with predictions of Bateman's Paradigm. For example, in many bird species with small female-biased initial investment but extensive biparental care, both sexes should be subject to similar strengths of sexual selection because males and females are similarly restricted in their ability to pursue additional mates. Unlike 99% of avian species, however, obligate brood parasitic birds lack any parental care in either sex, predicting a conformation to Bateman's Paradigm. Here we use microsatellite genotyping to demonstrate that in brood parasitic brown-headed cowbirds (Molothrus ater), per capita annual reproductive success increases with the number of mates in males, but not in females. Furthermore, also as predicted, the variance of the number of mates and offspring is greater in males than in females. Thus, contrary to previous findings in this species, our results conform to predictions of the Bateman's Paradigm for taxa without parental care.

Original languageEnglish (US)
Pages (from-to)1310-1315
Number of pages6
JournalJournal of Evolutionary Biology
Volume32
Issue number11
DOIs
StatePublished - Nov 1 2019

Fingerprint

sexual selection
bird
parental care
birds
Molothrus ater
reproductive success
prediction
gender
mate choice
gamete
mating behavior
gender differences
sperm
genotyping
germ cells
asymmetry
spermatozoa
microsatellite repeats
egg

Keywords

  • Bateman's gradient
  • anisogamy
  • brood parasitism
  • parental investment

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

Cite this

Greater opportunities for sexual selection in male than in female obligate brood parasitic birds. / Louder, Matthew I.M.; Hauber, Mark E.; Louder, Amber N.A.; Hoover, Jeffrey P.; Schelsky, Wendy M.

In: Journal of Evolutionary Biology, Vol. 32, No. 11, 01.11.2019, p. 1310-1315.

Research output: Contribution to journalArticle

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