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Published on: August 22, 2019
Sexual selection and speciation in field crickets
1Department of Biological Sciences, Brock University, St. Catharines, ON, Canada L2S 3A1. dave.gray@uleth.ca
Summary
Sexual selection may drive speciation more often than thought. In field crickets (Gryllus texensis), genetic links between male song and female preference, without trait changes, support this speciation model.
Area of Science:
- Evolutionary biology
- Speciation research
- Animal behavior
Background:
- Sexual selection is increasingly recognized as a driver of speciation.
- Empirical evidence simultaneously testing key predictions of sexual selection-driven speciation is scarce.
- Distinguishing between speciation mechanisms requires evaluating multiple factors, including genetic variation and trait evolution.
Purpose of the Study:
- To empirically test predictions of sexual selection as a mechanism for speciation.
- To investigate the role of male song (pulse rate) and female phonotaxis in the speciation of field crickets.
- To contrast sexual selection-driven speciation with other models using the cryptic sister species Gryllus texensis and Gryllus rubens.
Main Methods:
- Collected data on male pulse rates and female phonotactic responses in Gryllus texensis.
- Assessed genetic variation in male song traits and female song preferences.
- Examined genetic correlations between male traits and female preferences.
- Investigated character displacement in song, song recognition, species-level discrimination, and preference.
Main Results:
- Significant genetic variation was found in male song (pulse rate) and female phonotactic responses.
- A significant genetic correlation exists between the male song trait and female preference.
- No evidence of character displacement was observed in male song, female song recognition, species-level song discrimination, or female song preference.
- Previous findings indicate a lack of hybrid inviability between the sister species.
Conclusions:
- The findings support divergent sexual selection as a primary driver of speciation between Gryllus texensis and Gryllus rubens.
- The genetic link between male song and female preference, coupled with the absence of character displacement, is consistent with sexual selection driving reproductive isolation.
- This study provides empirical support for theoretical models suggesting sexual selection can cause speciation under broad conditions.
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