DISSERTATION RESEARCH: Does genetic similarity of trees explain beta diversity of soil microbes and the strength of negative plant-soil feedbacks in a tropical tree population?

Adult trees in tropical forests prevent their offspring from sprouting nearby. This parent-offspring interaction can explain high species diversity in tropical forests. The genetic foundation for this negative interaction will be investigated. The genetic diversity of mature trees, seedlings, and bacteria and fungi in the soil will be assessed. The mechanisms by which pathogen-resistant genes influence reproduction and maintain diversity will be examined. Efforts in conservation and in tropical reforestation will be aided by this information. The project will strengthen the scientific workforce by training a graduate student in genetic techniques.

This study will be among the first to incorporate a genetic mechanism into the classical Janzen-Connell hypothesis of seedling survival and diversity maintenance in tropical forests. New evidence has shown that negative plant-soil feedbacks between tropical trees and their pathogens are genotype-specific (i.e., trees within a population respond differently to the same soil microbiome). Whether plant-soil feedbacks in tropical tree communities are genetically controlled will be determined for tree-seedling genetic similarity, for tree-tree genetic similarity, and for microbial community - tree community genetic similarity. Analyses of the genetics will complement experiments on the conditions in which pathogen-resistant genes affect population dynamics. The degree of similarities will elucidate the biological and spatial scales at which the interactions are effective. Training in genetic and metagenomics techniques and bioinformatics will provide research experience for the student.