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Assessing Differences in Sperm Competitive Ability in Drosophila
Published on: August 22, 2013
How multivariate ejaculate traits determine competitive fertilization success in Drosophila melanogaster
Stefan Lüpold1, Mollie K Manier, Kirstin S Berben
1Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA. sklupold@syr.edu
Current Biology : CB
|July 31, 2012
Summary
Sperm competition success in fruit flies depends on ejaculate traits and sperm interactions. Genetic variation in sperm quality influences paternity by affecting sperm displacement and storage within the female reproductive tract.
Area of Science:
- Evolutionary biology
- Reproductive biology
- Genetics
Background:
- Sperm competition occurs when females mate with multiple males.
- Ejaculate quality and sperm interactions influence sperm competition success.
- Few ejaculate traits beyond sperm number are understood in a multivariate context.
Purpose of the Study:
- To investigate genetic variation in sperm quality and performance traits.
- To examine how rival sperm interact and influence each other's performance.
- To determine the fitness consequences of sperm quality variation in sperm competition.
Main Methods:
- Used isogenic lines of Drosophila melanogaster with distinguishable sperm.
- Competed males from different lines to observe sperm interactions.
- Analyzed genetic variation in sperm quality and performance traits.
Main Results:
- Genetic variation exists for multiple sperm quality and performance traits.
- Rival sperm significantly influence each other's velocity.
- Slower and/or longer sperm are better at displacing rivals and resisting ejection.
- Offspring paternity is determined by the proportion of stored competing sperm.
Conclusions:
- Sperm quality variation has fitness consequences in sperm competition.
- Different ejaculate traits are important at different time points.
- Postcopulatory sexual selection plays a role in trait diversification and speciation.
