Genotyping-by-sequencing supports a genetic basis for alpine wing-reduction in a New Zealand stonefly

Wing polymorphism is a prominent feature of numerous insect groups, but the genomic basis for this diversity remains poorly understood. Wing reduction is a commonly observed trait in many species of stoneflies, particularly in cold or alpine environments. The widespread New Zealand stonefly Zelandoperla fenestrata species group ( Z. fenestrata, Z. tillyardi, Z. pennulata ) contains populations ranging from long-winged (macropterous) to vestigial-winged (micropterous), with the latter phenotype typically associated with high altitudes. The presence of flightless forms on numerous mountain ranges, separated by lowland fully winged populations, suggests wing reduction has occurred multiple times. We use Genotyping by Sequencing (GBS) to test for genetic differentiation between fully winged (n=62) and vestigial-winged (n=34) individuals, sampled from a sympatric population of distinct wing morphotypes, to test for a genetic basis for wing morphology. We found no population genetic differentiation between these two morphotypes across 6,843 SNP loci, however we did detect several outlier loci that strongly differentiated morphotypes across independent tests. This indicates small regions of the genome are likely to be highly differentiated between morphotypes, indicating a genetic basis for morphotype differentiation. These results provide a clear basis for ongoing genomic analysis to elucidate critical regulatory pathways for wing development in Pterygota.