Meeting Abstract
The Mountain Pine Beetle (MPB) is an eruptive pest of various pine species native to western North America, reaching from northern Mexico to Canada along the Rocky Mountain and Sierra Nevada ranges. Current MPB ranges are expanding as a result of climate change and infestations cause extensive damage to susceptible forests. Applying genome-wide RAD sequencing to over 700 individuals from 37 populations, we are examining phylogeographic structure, gene flow, and adaptation across the range. Strong population structuring occurs between geographic regions with extensive admixing occurring in the sky island populations residing in the Great Basin. However results also suggest that there are distinct genetic boundaries between some geographically proximate regions. Experimental crossing experiments have previously found postzygotic isolation between geographically distant populations. Moreover crosses between the geographically close populations of Oregon and Idaho also showed a reduction in hybrid male fitness despite their proximity. Population structuring of the autosomes and sex chromosomes show that these populations are permeable to gene flow at autosomal sites but Y chromosome sites show clear disjunction between regions. Population structure suggests that separate genetic lineages occur across similar latitudes in the Rockies and Sierra Nevada. Leveraging a complementary QTL study of development time, a crucial trait in seasonal synchronization, we also discuss tests for parallel adaptation across lineages.
