Understanding the causes and consequences of biological diversity remains the unifying goal of ecology and evolutionary biology. One promising avenue to understand the causes and consequences of genetic diversity within populations is to consider correlations between that genetic diversity and species diversity of the community in which it resides. Both genetic and species diversity can respond to locality characteristics, or each level can influence and be influenced by the other. First, I investigate how area connectivity and gene flow affects the population genetic diversity pattern in the California vole (Microtus californicus). I show that migration across the landscape produces an identical genetic pattern at the local and regional spatial scales in this small mammal (Chapter 1). Next, I explored two ways in which genetic and species diversity influence each other. In one approach, I examine the effects of a species-rich competitor community on the genotypic diversity of a focal community when genetic diversity allows for differential strength of competition with different species. Using computer simulations, I show that species diversity of competitors can act as an important promoter of genotypic diversity within species (Chapter 2). Next, moving to a riparian community in northern Utah, I demonstrate that the genetic diversity of a foundation tree correlates positively with the species diversity of understory plants, including forbs, grasses, and vines (Chapter 3). Finally, I show that both genetic diversity and species richness across the globe show a similar pattern: genetic markers in over 70 vertebrate species show a significant trend of higher diversity at low latitudes than at higher latitudes (Chapter 4). By taking a broad approach to understanding the causes and consequences of intraspecific genetic diversity, with a particular focus on links to species diversity patterns, my dissertation finds general principles that operate across systems. The two levels of diversity can influence each other by creating spatially-varied selection regimes, but gene flow and mutation are two processes operating on the genetic level whose power to scale up to influence species-level patterns is highly contextual.
Adams RI. 2011. Ecological and evolutionary connections between genetic and species diversity. PhD Dissertation, Department of Biology, Stanford University.
Year Published: 2011