Mode of sexual selection determined by resource abundance in two sand goby populations

Elisabet Forsgren*, Charlotta Kvarnemo, Kai Lindström

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

120 Citations (Scopus)

Abstract

We used field observations and experiments to show that sexual selection in two populations of sand gobies, Pomatoschistus minutus (Pisces, Gobiidae), was affected by differences in resource availability. Male sand gobies rely on empty mussel shells for nest building and spawning. The two populations differed considerably in nest-site abundance and sexual-selection regimes. In one population nest sites were scarce, leading to stronger male-male competition over nests, a higher nest site colonization rate and reduced potential for female choice compared with the other population that had a surplus of nests. In the high-competition population, males were larger than females, perhaps as a response to selection, whereas the other population was not sexually size dimorphic. The results from the field were confirmed in a pool experiment that demonstrated the effect of nest abundance on nest occupancy and male reproductive success. Larger males were more successful in obtaining nest sites in both high and low nest availability treatments. Larger males were also favored by females as mating partners, but only in the treatment with surplus nest sites. Nest shortage was associated with an increased potential for intrasexual selection (measured as the coefficient of variation), whereas the potential for intersexual selection was increased when nests were common. In conclusion, nest-site abundance can influence the relative contribution of intrasexual competition and mate choice in a population. Hence, resource availability can contribute to within-species variation in mating patterns.

Original languageEnglish
Pages (from-to)646-654
Number of pages9
JournalEvolution
Volume50
Issue number2
DOIs
Publication statusPublished - Apr 1996
Externally publishedYes
MoE publication typeA1 Journal article-refereed

Keywords

  • Gobiidae
  • Nest site
  • Pomatoschistus minutus
  • Population differences
  • Resource abundance
  • Sexual selection

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