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- Title
Is decreased germination fraction associated with risk of sibling competition?
- Authors
Evans, Ann S.; Hyatt, Laura A.
- Abstract
Seed dormancy is hypothesized to be a risk-spreading strategy that maximizes plant fitness. By spreading germination time of offspring among years, plants may not only vary the environment to which their offspring are exposed, but may also reduce potential fitness losses dueto sib competition. The sibling competition hypothesis predicts thatlarge families whose offspring are more likely to experience siblingcompetition should stagger germination over several seasons (i.e. have greater dormancy) to a greater extent than small families. This should be observed as a lower initial probability of germination for seeds from large families than those from small families. We examined the relationship between family size and germination behavior in the desert mustard Lesquerella fendleri. In a single population in centralNew Mexico, USA, we estimated family size and germination fraction of 189 randomly selected maternal plants. Although a median test was not supportive, the randomization test showed marginal support for thesibling competition hypothesis. An additional study of twelve large and twelve small families in each of three other populations also showed a trend (significant in one population) for larger families to have lower germination fractions than small families. These results suggest a degree of support for the hypothesis, given that so many selective forces interact to generate patterns of seed dormancy. Thus, we have not ruled out the hypothesis that large families reduce the likelihood of sib competition in good years by producing seed crops with initially low germination. Sibling competition as well as environmental heterogeneity may have influenced the evolution of seed dormancy in this system.
- Subjects
RISK assessment; REPRODUCTION; PREDATION; EVOLUTIONARY theories; BOTANY; ECOLOGY
- Publication
Oikos, 1998, Vol 83, Issue 1, p29
- ISSN
0030-1299
- Publication type
Article