The Forest ecosystem genomics Research: supporTing Transatlantic Cooperation project (FoResTTraC) sponsored a workshop in August 2010 to evaluate the potential for using a landscape genomics approach for studying plant adaptation to the environment and the potential of local populations for coping with changing climate. This paper summarizes our discussions and articulates a vision of how we believe forest trees offer an unparalleled opportunity to address fundamental biological questions, as well as the application of landscape genomic methods complement traditional forest genetic approaches to provide critical information needed for natural resource management. In this paper, we will cover four topics. First, we begin by defining landscape genomics and briefly reviewing the unique situation for tree species in the application of this approach toward understanding plant adaptation to the environment. Second, we review traditional approaches in forest genetics for studying local adaptation and identifying loci underlying locally adapted phenotypes. Third, we present existing and emerging methods available for landscape genomic analyses. Finally, we briefly touch on how these approaches can aid in understanding practical topics such as management of tree populations facing climate change.
Ecologically interacting species may have phylogeographic histories that are shaped both by features of their abiotic landscape, and by biotic constraints imposed by their co-association. The Baja California peninsula provides an excellent opportunity to examine the influence of abiotic vs. biotic factors on patterns of diversity in plant-insect species. This is because past climatic and geological changes impacted the genetic structure of plants quite differently to that of co-distributed free-living animals (e.g., herpetofauna and small mammals). Thus, ‘plant-like’ patterns should be discernible in host-specific insect herbivores. Here we investigate the population history of a monophagous bark beetle, Araptus attenuatus, and consider drivers of phylogeographic patterns in light of previous work on its host plant, Euphorbia lomelii. Based on mitochondrial and nuclear markers, we found that the evolutionary history of A. attenuatus exhibits similarities to host plant that are attributable to both biotic and abiotic processes. Southward range expansion and recent colonization of continental Sonora peninsula appear to be unique to this taxon pair, and likely reflect influences of the host plant. On the other hand, abiotic factors with landscape-level influences on suites of co-distributed taxa, such as Plio- and Pleistocene-aged marine incursions in the region, also left genetic signatures in beetle populations. Superimposed on these similarities, bark beetle-specific patterns and processes were also evident. Taken together, this work illustrates that the evolutionary history of species-specific insect herbivores may represent a mosaic of influences, including, but not limited to, those imposed by the host plant.