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Sperm competition and the maintenance of polymorphism
1Department of Biology, Pennsylvania State University, University Park, PA 16802, USA. c92@psu.edu
Heredity
|April 5, 2002
Summary
Sperm competition in Drosophila is common, with outcomes depending on specific male pairings, not just individual male ability. This challenges simple genetic models and suggests complex interactions maintain genetic diversity.
Area of Science:
- Evolutionary Biology
- Genetics
- Animal Behavior
Background:
- Sperm competition occurs when sperm from multiple males are present in a female's reproductive tract.
- Field studies in Drosophila show a high frequency (80%) of females experiencing sperm competition, potentially underestimated due to paternity skew.
- Genetic variation in sperm competitive ability is significant, comparable to other fitness components.
Purpose of the Study:
- To investigate the patterns of genetic variation in sperm competition.
- To explore the implications of sperm competition for the maintenance of genetic polymorphism.
- To understand the factors influencing the outcome of sperm competition, including male-male and female-male interactions.
Main Methods:
- Analysis of genetic variation in sperm competitive ability.
- Examination of competitive success in pairwise male genotype trials.
- Investigation of female-male interactions influencing reproductive success.
Main Results:
- Sperm competitive ability varies greatly among males, similar to other fitness traits.
- The outcome of sperm competition is context-dependent, varying with the specific pair of competing male genotypes.
- Competitive success is not solely an intrinsic property of a male genotype but depends on interactions.
Conclusions:
- The context-dependent nature of sperm competition complicates simple genetic models and makes polymorphism maintenance more unexpected.
- Synergistic pleiotropy associated with competitive ability further highlights the complexity.
- Findings have implications for understanding the molecular basis of sperm competition and the evolutionary maintenance of genetic diversity in relevant genes.