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.

Chaoborus Predation and Life-History Evolution in Daphnia pulex: Temporal Pattern of Population Diversity, Fitness, and Mean Life History

Ken Spitze
Evolution
Vol. 45, No. 1 (Feb., 1991), pp. 82-92
DOI: 10.2307/2409484
Stable URL: http://www.jstor.org/stable/2409484
Page Count: 11
  • 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.
Chaoborus Predation and Life-History Evolution in Daphnia pulex: Temporal Pattern of Population Diversity, Fitness, and Mean Life History
Preview not available

Abstract

The effect of predation by the aquatic dipteran larva Chaoborus americanus on genetic diversity and life-history evolution in the cladoceran Daphnia pulex was investigated in large replicate laboratory populations. Instantaneous daily loss rates of clonal diversity and genetic variance for fitness indicate that 93-99% of initial genetic diversity can be removed from populations during the 8-12 generations of clonal reproduction that occur each year in natural populations. In the absence of predation, the principal evolved changes in mean population life history were smaller immature body size and increased and earlier fecundity. In the presence of size-selective Chaoborus predation, populations evolved toward larger body size and increased and earlier reproduction. The difference between these two trajectories is an estimate of the direct additive effect of Chaoborus predation. This effect was manifested as evolution toward larger body size with a trend toward earlier and increased reproduction.

Page Thumbnails

  • Thumbnail: Page 
82
    82
  • Thumbnail: Page 
83
    83
  • Thumbnail: Page 
84
    84
  • Thumbnail: Page 
85
    85
  • Thumbnail: Page 
86
    86
  • Thumbnail: Page 
87
    87
  • Thumbnail: Page 
88
    88
  • Thumbnail: Page 
89
    89
  • Thumbnail: Page 
90
    90
  • Thumbnail: Page 
91
    91
  • Thumbnail: Page 
92
    92