Spatial and genetic structure of the lodgepole x jack pine hybrid zone in Canada

Abstract

In north-central Alberta, lodgepole (Pinus contorta Dougl. ex Loud. var. latifolia) and jack pine (Pinus banksiana Lamb) form a stable mosaic hybrid zone, which remains poorly defined. I characterized the genetic composition of the hybrid zone using samples collected from British Columbia to Ontario, and the previously un-sampled Yukon Territory and Northwest Territories, typed at 29 discriminating SNPs. I found differences in genomic clines between the northern and southern historical pine contact zones at specific loci, which could indicate important adaptive differences between the naïve northern and attacked southern hybrid zones during future mountain pine beetle range expansions. Understanding the exogenous processes influencing pine distributions in the hybrid zone is relevant to preventing pine mortality from future mountain pine beetle expansions. To characterize the spatial structure of the hybrid zone, I used logistic regression to create statistically accurate predictive models for pine species composition from a combination of geographic and environmental variables. I found that location, elevation and moisture indices are important predictors for species class. The hybrid zone takes the form of a mosaic across the entire distribution, which extends north and east of current estimates. I suggest that current species ranges be updated.