Female polymorphism, frequency dependence, and rapid evolutionary dynamics in natural populations

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Population Genetics

Background:

• Rapid evolutionary change is documented in natural populations, often linked to environmental shifts and interspecific interactions like predation.
• Intraspecific interactions, particularly antagonistic male-female mating, are increasingly recognized but lack robust evidence for driving rapid evolutionary dynamics due to data limitations.

Purpose of the Study:

• To investigate whether male-female mating interactions can cause rapid evolutionary change in morph frequencies within natural populations.
• To explore the role of sexual conflict and mating harassment in driving evolutionary dynamics and maintaining polymorphism.

Main Methods:

• Utilized field data from a color-polymorphic damselfly species.
• Employed computer simulations to model evolutionary dynamics.
• Analyzed frequency- and density-dependent effects of male mating harassment on female fecundity.

Main Results:

• Demonstrated that male-female mating interactions lead to rapid evolutionary shifts in morph frequencies between damselfly generations.
• Identified sexual conflict, specifically male mating harassment, as the driver of these changes, negatively impacting morph fecundities.
• Showed that frequency-dependent processes maintain female polymorphism within most populations, contrary to expectations of enhanced population divergence.

Conclusions:

• Sexual conflict, mediated by male mating harassment, can induce rapid evolutionary change in natural populations.
• These findings challenge traditional views of sexual conflict promoting population divergence, aligning instead with models of female genetic clustering under harassment.
• The study highlights the significant role of intraspecific interactions in shaping evolutionary trajectories and maintaining genetic diversity.