Characterizing the physical and genetic structure of the lodgepole pine × jack pine hybrid zone: mosaic structure and differential introgression

TLDR: It is found the distribution of the pine classes is explained by environmental variables, and these distributions differ from classic distribution maps, and range limits should be redefined.

Abstract: Understanding the physical and genetic structure of hybrid zones can illuminate factors affecting their formation and stability In north-central Alberta, lodgepole pine (Pinus contorta Dougl ex Loud var latifolia) and jack pine (Pinus banksiana Lamb) form a complex and poorly defined hybrid zone Better knowledge of this zone is relevant, given the recent host expansion of mountain pine beetle into jack pine We characterized the zone by genotyping 1998 lodgepole, jack pine, and hybrids from British Columbia, Alberta, Saskatchewan, Ontario, and Minnesota at 11 microsatellites Using Bayesian algorithms, we calculated genetic ancestry and used this to model the relationship between species occurrence and environment In addition, we analyzed the ancestry of hybrids to calculate the genetic contribution of lodgepole and jack pine Finally, we measured the amount of gene flow between the pure species We found the distribution of the pine classes is explained by environmental variables, and these distributions differ from classic distribution maps Hybrid ancestry was biased toward lodgepole pine; however, gene flow between the two species was equal The results of this study suggest that the hybrid zone is complex and influenced by environmental constraints As a result of this analysis, range limits should be redefined