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.

Sex Roles Are Not Always Reversed When the Potential Reproductive Rate Is Higher in Females

Noboru Okuda
The American Naturalist
Vol. 153, No. 5 (May 1999), pp. 540-548
DOI: 10.1086/303196
Stable URL: http://www.jstor.org/stable/10.1086/303196
Page Count: 9
  • Read Online (Free)
  • Download ($19.00)
  • 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.
Sex Roles Are Not Always Reversed When the Potential Reproductive
Rate Is Higher in Females
Preview not available

Abstract

abstract: Sex roles were examined in a cardinalfish, Apogon notatus, in which males alone mouthbrood the eggs received from a single female. Before spawning, a male and female formed a pair, within which the female is more active in courtship and attacks against conspecifics. Females had a higher potential for reproduction and on average produced more than twice as many clutches as those mouthbrooded by a male in a season by changing mates after spawning. Animals in which mating competition is more intense among females and, ultimately, sexual selection is more strongly acting on females are defined as sex‐role reversed. Sex‐role reversal is expected where the operational sex ratio (OSR) is female biased. In A. notatus, however, the OSR was male biased throughout the breeding season. This was due primarily to a higher mortality in females. The theory predicts that sexual selection operates more strongly on the sex toward which the OSR is biased. The facts that the variance in reproductive success was greater in males and the males developed a sexual trait suggest that sexual selection is acting more strongly on males than on females. Accordingly, this fish is not sex‐role reversed.

Page Thumbnails

  • Thumbnail: Page 
1
    1
  • Thumbnail: Page 
2
    2
  • Thumbnail: Page 
3
    3
  • Thumbnail: Page 
4
    4
  • Thumbnail: Page 
5
    5
  • Thumbnail: Page 
6
    6
  • Thumbnail: Page 
7
    7
  • Thumbnail: Page 
8
    8
  • Thumbnail: Page 
9
    9