Patterns of environmentally associated genomic and epigenomic variation in two common bumble bee species

Understanding how species occupy heterogeneous environments is major question in ecology and evolution and will be especially pertinent in understanding species responses to future climate conditions. From a molecular perspective, understanding how species cope with the various challenges associated with environmental heterogeneity requires a broad ‘omics approach. Here I present work looking at environmental adaptation across the genome and methylome of two common North American bumble bee species, Bombus vancouverensis and Bombus vosnesenskii. These species provide a juxtaposition between two species with similar ranges but differing degrees of population structure with B. vancouverensis having a higher amount of population structure than B. vosnesenskii. We first construct de novo reference genomes using a hybrid assembly approach for each species to facilitate whole genome and whole methylome sequencing experiments. Assemblies were highly complete with BUSCO scores of 98.4% and 98.2% for B. vancouverensis and B. vosnesenskii respectively using the orthoDB v. 10 hymenopteran dataset. The results of the whole genome dataset confirm previous findings regarding the population structure of each species. Environment association analysis (EAA) indicated that B. vancouverensis has a stronger signal of signal of local adaptation with several genomic regions with strong environmental associations, whereas few loci have a putatively adaptive signal in B. vosnesenskii. Analysis of the whole methylome data reveals there are differentially methylated variants associated with environmental variation.