Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Ecological Causes of Sexual Dimorphism

Montgomery Slatkin
Evolution
Vol. 38, No. 3 (May, 1984), pp. 622-630
DOI: 10.2307/2408711
Stable URL: http://www.jstor.org/stable/2408711
Page Count: 9
  • Read Online (Free)
  • Download ($4.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Ecological Causes of Sexual Dimorphism
Preview not available

Abstract

There are several ecological mechanisms that could account for the origin of sexual dimorphism in a dioecious species that is initially monomorphic. Ecological conditions could favor different characteristics in each sex as a consequence of different ecological or social roles (dimorphic niche). ecological conditions could favor two distinct types of individuals of either sex (bimodal niche), or ecological conditions could favor dimorphism through competition in a manner analogous to ecological character displacement (competitive displacement). A model of a quantitative character evolving under each of these assumptions is introduced and analyzed. If there is a unique equilibrium of the population, as in the case of a dimorphic niche or competitive displacement, the extent of genetic correlation between the sexes does not affect the likelihood of a species evolving a sexual dimorphism. The ecological forces alone will determine whether or not a dimorphism can evolve. If there there are several stable equilibria, as is true for the bimodal niche, then the genetic correlations among the sexes in the trait of interest will determine which equilibrium is reached. In that case, the conditions under which dimorphism will evolve in a species that is initially nearly monomorphic are restrictive.

Page Thumbnails

  • Thumbnail: Page 
622
    622
  • Thumbnail: Page 
623
    623
  • Thumbnail: Page 
624
    624
  • Thumbnail: Page 
625
    625
  • Thumbnail: Page 
626
    626
  • Thumbnail: Page 
627
    627
  • Thumbnail: Page 
628
    628
  • Thumbnail: Page 
629
    629
  • Thumbnail: Page 
630
    630