Summary: Climate change has led to distributional changes for many species. While most species undergo a range shift or a contraction, the mountain pine beetle (MPB; Dendroctonus ponderosae) in Canada have expanded their range. These bark-beetles were historically found within British Columbia but recently spread and established in Alberta as winter temperatures have become warmer. Using whole-genome sequence data from 160 MPB, along with past molecular studies, we examined the genomic impact of this type of expansion in MPB. We characterize the spread of MPB as a pushed expansion as genetic variation is retained within the expansion range, and the first example of this expansion to be studied in wild populations. We then used these genomes to look for evidence of adaptation in expansion range MPB. These analyses were coupled with a GWAS on larvae that either survived or perished from extreme cold temperatures. We found 52 genes common between all analyses, suggesting that expansion did not impact the ability of MPB to rapidly adapt to conditions in its expansion range..