Conclusion
Our study shows that using a population genomic approach to studying
sibling species can identify both species-level divergence as well as
fine-scale genetic structuring. Tracing the level of gene flow within
and between these species enables the detection of geographic isolation,
hybridization, and cryptic species to offer a more accurate depiction of
the current species dynamics. Radiation within the C. variipenniscomplex occurred despite the long-range dispersal capabilities of biting
midges as well as hybridization between sympatric species. Because of
this, we believe that behavioral and ecological isolation may have
shaped evolution within this group or is at least maintaining the
existing species boundaries. Significant geographic isolation was only
found between populations of C. occidentalis , but more work is
needed to determine if the lack of gene flow between California and the
other populations represents an incipient speciation event. Delimiting
the species in the C . variipennis complex will not only
aid in vector surveillance efforts, but continued study of the
speciation of closely related vector and non-vector species could
produce valuable evolutionary insights into vector competency.