QUANTITATIVE GENETICS OF SEXUAL SELECTION IN THE FIELD CRICKET, GRYLLUS INTEGER

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Genetics

Background:

• Sexual selection theories propose heritable variation in female mating preferences and male traits.
• A positive genetic correlation between preference and trait is often predicted.

Purpose of the Study:

• To investigate heritable variation in female phonotactic preferences for male calling song stimulus level in Texas field crickets (Gryllus integer).
• To assess genetic effects on female choosiness and male calling song characteristics.
• To determine the genetic correlation between female preference and male trait.

Main Methods:

• Quantitative genetic analysis of female phonotactic responses to male calling song stimulus levels.
• Estimation of additive genetic effects on female preferences and male song traits (pulses per trill).
• Calculation of the genetic correlation between female preference and male song trait in a field population.

Main Results:

• Significant heritable genetic variation was found for female preferences for male calling song stimulus level (34% of variation).
• Significant additive genetic variation was observed for the number of pulses per trill in male songs (39% of variation).
• A significant positive genetic correlation (0.51 ± 0.17) was estimated between female preference and male song trait.

Conclusions:

• Heritable variation exists for female preferences and male traits in Gryllus integer, supporting sexual selection theory.
• The number of pulses per trill in male songs is under stabilizing sexual selection.
• The findings suggest a genetic basis for the co-evolution of female preference and male traits in this species.