Repeated alpine flight loss within the widespread New Zealand stonefly Nesoperla fulvescens

Flight loss is a common feature of upland insect assemblages, with recent studies detecting parallel wing reduction events across independent alpine lineages. However, the geographic scale over which such repeated evolution can operate remains unclear. In this study, we use genotyping-by-sequencing to assess the genomic relationships among vestigial-winged and full-winged populations of the widespread New Zealand stonefly Nesoperla fulvescens, to test for repeated wing loss events over small spatial scales. Biogeographic analyses indicate that alpine wing loss in this widespread species is restricted to a single, narrow mountain range. Intriguingly, our coalescent analyses indicate that upland vestigial-winged N. fulvescens populations are not sister to one another, suggesting wings have been lost independently in disjunct populations of this species, over a <30 km scale. Our results suggest that selection against flight above the alpine treeline can drive rapid and repeated adaptation even across narrow spatial scales. We propose that such repetitive processes may represent a far more pervasive feature of alpine insect adaptation than is currently recognised.