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 need an accessible version of this item please contact JSTOR User Support

The Mechanisms of Morph Determination in the Amphipod Jassa: Implications for the Evolution of Alternative Male Phenotypes

Josepha P. Kurdziel and L. Lacey Knowles
Proceedings: Biological Sciences
Vol. 269, No. 1502 (Sep. 7, 2002), pp. 1749-1754
Published by: Royal Society
Stable URL: http://www.jstor.org/stable/3067827
Page Count: 6
  • Read Online (Free)
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
The Mechanisms of Morph Determination in the Amphipod Jassa: Implications for the Evolution of Alternative Male Phenotypes
Preview not available

Abstract

The proximal basis for and the maintenance of alternative male reproductive strategies and tactics are generally not understood in most species, despite the occurrence of male polymorphism across many taxa. In the marine amphipod Jassa marmorata, males differ in morphology as well as behaviour. This dimorphism corresponds to two contrasting reproductive strategies: small sneaker males or 'minors', and large fighter males or 'majors'. This study uses quantitative genetic analyses in conjunction with experimental manipulations to assess the relative importance of genetic versus environmental factors in the determination and maintenance of these alternative mating strategies. Heritability analyses indicated the reproductive phenotypes do not reflect genetic differences between dimorphic males. By contrast, morph determination was significantly affected by diet quality. Majors essentially only developed on high-protein diets. Field studies also identified a strong correlation between seasonal shifts in the relative proportions of morphs and changes in food (i.e. phytoplankton) quantity and composition, corroborating that diet cues the switch between alternative reproductive tactics. Moreover, the comparison of major and minor growth trajectories identified a heterochronic shift in maturation times between morphs, indicating that ecological selective pressures, rather than just sexual selection, may be involved in the maintenance of this conditional strategy.

Page Thumbnails

  • Thumbnail: Page 
1749
    1749
  • Thumbnail: Page 
1750
    1750
  • Thumbnail: Page 
1751
    1751
  • Thumbnail: Page 
1752
    1752
  • Thumbnail: Page 
1753
    1753
  • Thumbnail: Page 
1754
    1754