Eggspot number and sexual selection in the cichlid fish Astatotilapia burtoni

PLoS One. 2012;7(8):e43695. doi: 10.1371/journal.pone.0043695. Epub 2012 Aug 24.

Abstract

Sexual selection on male coloration is one of the main mechanisms proposed to explain the explosive speciation rates in East African cichlid fish. True eggspots are color patterns characteristic of the most species-rich lineage of cichlids, the Haplochromini, and have been suggested to be causally related to the speciation processes. Eggspots are thought to have originated by sensory exploitation and subsequently gained several roles in sexual advertisement. However, for most of these functions the evidence is equivocal. In addition, the genetic architecture of this trait still is largely unknown. We conducted bidirectional selective breeding experiments for eggspot numbers in the model cichlid, Astatotilapia burtoni. After two generations, low lines responded significantly, whereas the high lines did not. Body size was both phenotypically and genotypically correlated with eggspot number and showed correlated response to selection. Males with higher numbers of eggspots were found to sire larger offspring. Despite the potential to act as honest indicators of fitness, the behavioral experiments showed no evidence of a role in either intra- or inter-sexual selection. Visual-based female preference was instead explained by courtship intensity. The evolution of this trait has been interpreted in light of adaptive theories of sexual selection, however the present and published results suggest the influence of non-adaptive factors such as sensory exploitation, environmental constraints and sexual antagonism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Communication*
  • Animals
  • Biological Evolution
  • Body Size / genetics
  • Cichlids / genetics
  • Cichlids / physiology*
  • Competitive Behavior / physiology
  • Female
  • Male
  • Mating Preference, Animal / physiology*
  • Phenotype

Grants and funding

FH is supported by the Brazilian National Counsel of Technological and Scientific Development (CNPq)/German Academic Exchange Program (DAAD) cooperation program (GDE 290049/2007-5). AM is funded by the Deutsche Forschungsgemeinschaft and the University of Konstanz. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.