Demography and selection shape transcriptomic divergence in field crickets

Area of Science:

• Evolutionary Biology
• Genomics
• Speciation Research

Background:

• Gene flow, demography, and selection can mimic genomic variation patterns, complicating speciation studies.
• Cryptic species Gryllus rubens and Gryllus texensis exhibit divergent mating behaviors, necessitating evolutionary history investigation.

Purpose of the Study:

• To disentangle the roles of gene flow, demography, and selection in the evolutionary history of Gryllus rubens and Gryllus texensis.
• To identify genetic footprints of selection within the inferred demographic context of these cricket species.

Main Methods:

• Transcriptomic variation analysis in Gryllus rubens and Gryllus texensis.
• Inference of demographic history, including gene flow and population bottlenecks.
• Screening for footprints of selection, considering demographic history and using FST-based outlier detection.

Main Results:

• Strong evidence for long-term bidirectional gene flow that ceased in the late Pleistocene.
• Identification of a population bottleneck in G. rubens, supporting a peripatric origin.
• Demographic history significantly shaped genetic differentiation (FST distribution); FST-based selection scans yielded many false positives.
• Alternative selection detection methods highlighted loci potentially controlling mating behavior variation.

Conclusions:

• Demography plays a crucial role in shaping genetic divergence patterns.
• Integrating demographic inference with selection analyses provides a more comprehensive understanding of speciation.
• Identified candidate genes may be key to understanding divergent mating behaviors in closely related species.