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

Spatiotemporal Patterns of Sperm Storage and Last-Male Sperm Precedence in Birds

J. V. Briskie
Functional Ecology
Vol. 10, No. 3 (Jun., 1996), pp. 375-383
DOI: 10.2307/2390286
Stable URL: http://www.jstor.org/stable/2390286
Page Count: 9
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
Spatiotemporal Patterns of Sperm Storage and Last-Male Sperm Precedence in Birds
Preview not available

Abstract

1. In birds, females store sperm in specialized sperm storage tubules (SSTs) located at the junction of the uterus and vagina. To determine the proximate mechanism by which the last male to copulate sires a disproportionate share of the subsequent offspring, the patterns of sperm storage over the breeding season and across the uterovaginal junction (UVJ) in the Yellow-headed Blackbird Xanthocephalus xanthocephalus, were examined. 2. SSTs at the vaginal end of the UVJ matured and began storing sperm earlier than SSTs in the uterine region. Vaginal-end SSTs also stored a greater number of sperm (per SST and overall) and were more likely to store sperm in multiple layers than uterine-end SSTs. 3. Depletion of sperm from SSTs during the laying period was rapid, but uterine-end SSTs appeared to lose more sperm overall than did SSTs at the vaginal end of the UVJ. 4. The spatial and temporal pattern of sperm storage in Blackbirds suggests a new proximate mechanism for last-male sperm precedence in birds. Unlike previous hypotheses, the SST maturation hypothesis requires neither sperm stratification nor sperm displacement to account for last male precedence. Instead, it is suggested that precedence arises through the storage of last-male sperm in the uterine-end SSTs. As uterine-end SSTs lie closest to the infundibulum (site of fertilization), sperm stored in this region obtain an advantage over sperm from vaginal-end SSTs in the race to fertilize an egg. 5. This new mechanism suggests that females may be able to control the paternity of their offspring through the sequential maturation of their SSTs. By following the simple rule-copulate last with the male you want as a sire-each female could ensure that sperm from this male would be placed in the best position to successfully fertilize her eggs.

Page Thumbnails

  • Thumbnail: Page 
375
    375
  • Thumbnail: Page 
376
    376
  • Thumbnail: Page 
377
    377
  • Thumbnail: Page 
378
    378
  • Thumbnail: Page 
379
    379
  • Thumbnail: Page 
380
    380
  • Thumbnail: Page 
381
    381
  • Thumbnail: Page 
382
    382
  • Thumbnail: Page 
383
    383