The evolution of sexual size dimorphism in the house finch. III. Developmental basis

Alexander V. Badyaev, Linda A. Whittingham, Geoffrey E. Hill

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

Sexual size dimorphism of adults proximately results from a combination of sexually dimorphic growth patterns and selection on growing individuals. Yet, most studies of the evolution of dimorphism have focused on correlates of only adult morphologies. Here we examined the ontogeny of sexual size dimorphism in an isolated population of the house finch (Carpodacus mexicanus). Sexes differed in growth rates and growth duration; in most traits, females grew faster than males, but males grew for a longer period. Sexual dimorphism in bill traits (bill length, width, depth) and in body traits (wing, tarsus, and tail length; mass) developed during different periods of ontogeny. Growth of bill traits was most different between sexes during the juvenile period (after leaving the nest), whereas growth of body traits was most sexually dimorphic during the first few days after hatching. Postgrowth selection on juveniles strongly influenced sexual dimorphism in all traits; in some traits, this selection canceled or reversed dimorphism patterns produced by growth differences between sexes. The net result was that adult sexual dimorphism, to a large degree, was an outcome of selection for survival during juvenile stages. We suggest that previously documented fast and extensive divergence of house finch populations in sexual size dimorphism may be partially produced by distinct environmental conditions during growth in these populations.

Original languageEnglish (US)
Pages (from-to)176-189
Number of pages14
JournalEvolution
Volume55
Issue number1
DOIs
StatePublished - 2001
Externally publishedYes

Keywords

  • Growth
  • House finch
  • Molecular sex identification
  • Sexual size dimorphism
  • Viability selection

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Agricultural and Biological Sciences(all)

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