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Polyandry and postcopulatory sexual selection in a wild population.
1Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA.
Molecular Ecology
|November 19, 2015
Summary
Female swordtail crickets exhibit strong postcopulatory sexual selection, mating with multiple males but only utilizing sperm from a fraction, with skewed paternity among successful sires.
Area of Science:
- Evolutionary Biology
- Behavioral Ecology
- Genetics
Background:
- Postcopulatory sexual selection, including sperm competition and cryptic female choice, can significantly influence evolution.
- Polyandry (females mating with multiple males) is common, yet natural mating rates and the strength of postcopulatory selection are understudied.
- Microsatellite analysis offers a powerful tool to assess mating patterns and paternity in natural populations.
Purpose of the Study:
- To estimate the number of mates and sires in wild Hawaiian swordtail crickets (Laupala cerasina).
- To compare natural mating rates and paternity with observations from a semi-natural enclosure.
- To quantify the strength of postcopulatory sexual selection by examining sperm utilization and paternity skew.
Main Methods:
- Utilized microsatellite genotyping to determine the number of unique sires contributing to offspring.
- Observed and recorded mating behaviors in a semi-natural enclosure.
- Compared sperm store diversity with observed mating frequencies and paternity outcomes.
Main Results:
- Wild females mated with an average of 3.6 males but utilized sperm from only 58% of them.
- Paternity was significantly skewed among males that successfully sired offspring.
- Similar patterns of reduced sperm utilization and skewed paternity were observed in the semi-natural enclosure.
Conclusions:
- Postcopulatory sexual selection is a strong force in Laupala cerasina.
- Females exercise cryptic female choice, limiting sperm use from a subset of their mates.
- Significant paternity skew indicates intense competition among males post-mating.
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