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Updated: Jul 6, 2026
09:34
Assessing Differences in Sperm Competitive Ability in Drosophila
Published on: August 22, 2013
Increased postcopulatory sexual selection reduces the intramale variation in sperm design
Simone Immler1, Sara Calhim, Tim R Birkhead
1Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S102TN, United Kingdom. s.immler@sheffield.ac.uk
Evolution; International Journal of Organic Evolution
|April 4, 2008
Summary
Sperm competition influences sperm design. In passerine birds, higher sperm competition risk correlates with less variation among a male
Area of Science:
- Evolutionary biology
- Sexual selection
- Animal reproduction
Background:
- Sperm competition is a key driver of sperm evolution.
- Inter- and intraspecific sperm design variation is linked to competition risk.
- Intramale sperm variation remains poorly understood.
Purpose of the Study:
- To investigate intramale variation in sperm design.
- To determine the influence of sperm competition risk on intramale variation in passerine birds.
Main Methods:
- Studied sperm design variation within individual male passerine birds.
- Analyzed the relationship between sperm competition risk and intramale variation.
Main Results:
- Found a negative association between sperm competition risk and intramale variation.
- This is the first evidence linking postcopulatory sexual selection to variation among sperm within a male.
Conclusions:
- Intramale sperm variation is shaped by postcopulatory sexual selection.
- Findings have implications for understanding male traits influenced by both pre- and postcopulatory sexual selection.
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