Genomic-wide sequencing reveals remarkable connection between widely disjunct populations of the internationally threatened bog buck moth

Rare, threatened species often suffer from habitat fragmentation, which leads to smaller populations vulnerable to negative impacts including inbreeding depression and collapse of metapopulation dynamics. Therefore, understanding the population structure and relationships of each population of a threatened species is critical for prioritising habitat conservation and reintroduction efforts. The bog buck moth (Hemileuca sp.) is a lineage previously recognised as several populations of conservation concern in New York state and the Province of Ontario. Recent genomic research discovered that bog buck moth from New York was a highly divergent, distinct entity compared to the group's diversity across North America. Nevertheless, the Canadian populations have not been evaluated and are geographically disjunct from the nearest New York population by ~170 km. As New York populations are in sharp decline, confirming that the relatively robust Ontario populations are conspecific, and understanding their relationship to New York populations, is a conservation priority. We integrated genomic data from an Ontario population into a broader dataset containing populations from across the range of the species group. Bog buck moth populations from Ontario and New York were identified as reciprocally monophyletic conspecifics, and other ecologically similar populations of Hemileuca from the western Great Lakes region are confirmed to be a different, widespread species. These results corroborate the restricted range of the bog buck moth and suggest that Ontario and New York populations have not been in recent contact. Therefore, reintroduction efforts must be developed in the context of this population structure.