Correlated evolution of sexual dimorphism and male dimorphism in a clade of neotropical harvestmen

Bruno A. Buzatto*, Joseph L. Tomkins, Leigh W. Simmons, Glauco Machado

*Corresponding author for this work

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Secondary sexual traits increase male fitness, but may be maladaptive in females, generating intralocus sexual conflict that is ameliorated through sexual dimorphism. Sexual selection on males may also lead some males to avoid expenditure on secondary sexual traits and achieve copulations using alternative reproductive tactics (ARTs). Secondary sexual traits can increase or decrease fitness in males, depending on which ART they employ, generating intralocus tactical conflict that can be ameliorated through male dimorphism. Due to the evolutionary forces acting against intralocus sexual and tactical conflicts, male dimorphism could coevolve with sexual dimorphism, a hypothesis that we tested by investigating these dimorphisms across 48 harvestman species. Using three independently derived phylogenies, we consistently found that the evolution of sexual dimorphism was correlated with that of male dimorphism, and suggest that the major force behind this relationship is the similarity between selection against intralocus sexual conflict and selection against intralocus tactical conflict. We also found that transitions in male dimorphism were more likely in the presence of sexual dimorphism, indicating that if a sexually selected trait arises on an autosome and is expressed in both sexes, its suppression in females probably evolves earlier than its suppression in small males that adopt ARTs.

Original languageEnglish
Pages (from-to)1671-1686
Number of pages16
JournalEvolution
Volume68
Issue number6
DOIs
Publication statusPublished - Jun 2014
Externally publishedYes

Keywords

  • alternative phenotypes
  • coevolution
  • intralocus sexual conflict
  • intralocus tactical conflict
  • intrasexual dimorphism
  • Opiliones
  • Intralocus sexual conflict
  • Intrasexual dimorphism
  • Intralocus tactical conflict
  • Coevolution
  • Alternative phenotypes

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