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Updated: Oct 30, 2025
09:34
Assessing Differences in Sperm Competitive Ability in Drosophila
Published on: August 22, 2013
14.8K
Sexual selection towards a protamine expression ratio optimum in two rodent groups?
Lena Arévalo1,2, Maximiliano Tourmente1,3,4, María Varea-Sánchez1
1Reproductive Ecology and Biology Group, Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (CSIC), Madrid, 28006, Spain.
Summary
Sperm competition influences reproductive gene evolution differently in mice and voles, affecting sperm protamine ratios and head shape. Both groups show a common evolutionary trend towards balancing protamine expression.
Area of Science:
- Evolutionary biology
- Reproductive biology
- Genetics
Background:
- Post-copulatory sexual selection is a key driver of reproductive gene evolution.
- Detecting direct evolutionary impacts is challenging due to diverse reproductive systems.
- Sperm competition, indicated by relative testes mass, is a significant factor.
Purpose of the Study:
- To investigate the effect of relative testes mass on protamine genotype and sperm head phenotype.
- To compare these effects in two distinct rodent groups: mice and voles.
- To understand the evolutionary patterns of protamine expression under sexual selection.
Main Methods:
- Comparative analysis of protamine genotype (protamine 1/protamine 2 ratio) and sperm head phenotype.
- Utilizing relative testes mass as a proxy for sperm competition.
- Examining data across different species within mice and voles.
Main Results:
- In mice, increased testes mass correlated positively with protamine ratios and sperm head area.
- In voles, larger testes correlated with decreasing protamine ratios, but still trending towards a 1:1 ratio, and negatively with sperm head area.
- Distinct patterns of protamine selection and sperm head adaptation were observed between mice and voles.
Conclusions:
- Protamines play varied roles in sperm head adaptation between mice and voles.
- Despite group-specific differences, sexual selection via sperm competition drives a common evolutionary trajectory towards protamine expression equilibrium in both rodents.
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