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Sex-specific spawning behavior and its consequences in an external fertilizer
1Department of Biological Science, Florida State University, Tallahassee, Florida 32306-1100, USA. levitan@bio.fsu.edu
The American Naturalist
|June 7, 2005
Summary
Sexual selection in external fertilizers can drive behavioral differences, not just physical ones. Spawning timing impacts fertilization success, with optimal intervals depending on sperm competition and environmental factors.
Area of Science:
- Marine Biology
- Evolutionary Biology
- Behavioral Ecology
Background:
- Identifying sexual selection targets in externally fertilizing species is challenging due to a lack of sexual dimorphism.
- Sex differences in spawning behavior, specifically males spawning before females, are observed in these taxa.
Purpose of the Study:
- To investigate the consequences of spawning order and time intervals between male and female spawning on fertilization success.
- To determine how these factors influence paternity share in externally fertilizing species.
Main Methods:
- Two field experiments were conducted using sea urchins.
- Experiment 1: Controlled release of female eggs and male sperm via syringes.
- Experiment 2: In situ induction of male spawning at varying intervals within a natural population.
Main Results:
- Spawning after females incurs a cost for males, particularly during sperm competition.
- The optimal time interval between male and female spawning is influenced by sperm competition levels, spatial separation, and water flow.
- Fertilization success and paternity share were measured to assess these impacts.
Conclusions:
- Sex differences in spawning timing among marine invertebrates can be explained by the costs and benefits of asynchronous spawning.
- Sexual selection in external fertilizers may lead to behavioral adaptations rather than morphological changes.