Understanding a Serpentine - Nonserpentine Tree Species:
Ecological and Population Genetics of Quercus ilex

Serpentine soils exert particularly strong selective pressure. Serpentine endemics are thought to be poor competitors in non-serpentine environments, suggesting that genetic trade-offs along the evolutionary path toward serpentine tolerance render serpentine-adapted plant species or races relatively unfit in their ancestral habitats. Understanding the ecology and genetics of serpentine species is an excellent means of understanding how ecology may drive the formation of plant species.

This project utilizes AFLP data to (1) characterize the population genetic structure of Quercus ilex at a local scale and (2) identify molecular markers linked to genes that are adaptive in serpentine soils. The project is being undertaken in collaboration with Sara Branco, a graduate student at The Field Museum / University of Chicago, who is investigating the ecology of mycorrhizal fungi associated with this species, which grows in both serpentine and non-serpentine soils. The project offers the opportunity to investigate whether (and how) local adaptation to soil type can evolve in the face of widespread gene flow in this wind-pollinated species and thereby stands to significantly broaden our understanding of speciation, local adaptation, and the evolution of habitat diversity within forest trees. Moreover, the project forms a useful backdrop to Branco's work in fungal ecology in these communities. Ultimately, the interaction between above-ground and below-ground processes is essential to the fitness and distribution of oaks and their associates. The project we are pursuing in combination with Branco's dissertation research lays the groundwork for understanding the process of ecological divergence within a wide range of forest tree species.