Genomics Reveals Exceptional Phylogenetic Diversity Within a Narrow-Range Flightless Insect

Range-restricted upland taxa are prone to population bottlenecks and thus typically have low genetic diversity, making them particularly vulnerable to environmental change. In this study, we used a combination of genotyping-by-sequencing (10,419 SNPs) and mitochondrial COI sequencing to test for population genetic structure within the narrow-range flightless sub-alpine stonefly Zelandoperla maungatuaensis Foster. This species is restricted to only a handful of upland streams along a 4 km stretch of the isolated Maungatua range in southeast New Zealand. We identified striking genetic structure across the narrow range of Z. maungatuaensis, with three deeply divergent allopatric lineages detected. These distinct lineages likely diverged in the early-mid Pleistocene, apparently persisting in separate microrefugia throughout subsequent glacial cycles. Our results illustrate how secondary flight loss can facilitate insect diversification across fine spatial scales, and demonstrate that intraspecific phylogenetic diversity cannot necessarily be predicted from range-size alone. Additional demographic analyses are required to better understand the conservation status of these divergent Z. maungatuaensis lineages, and to assess their potential susceptibility to climate change and other anthropogenic impacts.