Minimal prezygotic isolation between ecologically divergent sibling species

Area of Science:

• Evolutionary biology
• Speciation research
• Animal behavior

Background:

• Mating signal divergence is a key factor in speciation.
• Sibling cricket species Gryllus saxatilis and Gryllus navajo exhibit ecological and dispersal differences.
• Previous studies indicated potential gene flow between these species.

Purpose of the Study:

• To quantify genetic divergence between G. saxatilis and G. navajo using RAD-seq data.
• To assess the degree of prezygotic reproductive isolation by analyzing male mating songs and female song preference.
• To investigate the role of female behavior in admixed populations.

Main Methods:

• Restriction site associated DNA sequencing (RAD-seq) for genetic analysis.
• Acoustic analysis to quantify differences in male cricket songs.
• Playback experiments to test female preference for conspecific and heterospecific songs.

Main Results:

• Genetically distinct populations and intermediate admixed populations were identified.
• Male mating songs were statistically different, but the magnitude of difference was small.
• Females from pure populations showed no song preference, while females from admixed populations preferred G. navajo song.

Conclusions:

• Prezygotic reproductive isolation between G. saxatilis and G. navajo is minimal.
• Female song preference in admixed populations may play a role in maintaining species boundaries.
• The findings contribute to understanding the speciation process in closely related species.