Evolutionary and Ecological Processes in Conservation and Preservation of Plant Adaptive Potential

Abstract

Anthropogenetic disturbances, such as habitat loss and fragmentation, overexploitation, and climate change have diminished population sizes of many species, increasing risks of population extirpation or species extinction. Consequently, conservation of genetic variability, to preserve and maintain rare species’ evolutionary potential and avoid within-population inbreeding, is a major goal of conservation biology. For plants, various approaches and guidelines have been developed to preserve species’ genetic diversity ex situ (“off-site”). However, effective methods to guide conservation and management decisions without relying on the availability of genetic data or knowledge about population size and population genetic structure are lacking. With the first two chapters of my dissertation, I aimed to complement existing ex situ strategies by investigating surrogates for estimating genetic variation to optimize conservation of rare species’ evolutionary potential when access to genetic data is limited. My results demonstrated that guiding population sampling using environmental and geographic distances, as opposed to randomly selecting source populations, can increase genetic diversity and differentiation captured in simulated ex situ collections. Likewise, my research showed that for species with largely heritable seed traits, morphological variation estimated from contemporary seed collections can be used as a proxy for standing genetic variation and help inform sampling efforts aiming to optimize genetic diversity preserved ex situ. Although strategies targeted to conserve rare species’ evolutionary potential where genetic data may be lacking are needed, the increasing affordability of next-generation sequencing technologies is increasing access to genomic data for rare species. With my third chapter, I investigated whether inferring rare species’ evolutionary history from genomic data may help inform conservation practices. My results demonstrated that teasing apart spatial and temporal effects of stochastic and deterministic processes on population genetic structure may be used to estimate past and contemporary changes in populations’ evolutionary potential, as well as to evaluate risks and benefits of genetic rescue as a management strategy. Overall, my PhD research establishes tools and approaches to preserve genetic variation for rare species using different types of data. As world’s biodiversity continue to decline, tool development to accommodate species-specific data availability for preservation of genetic variation is crucial.