| Description |
Dispersal is the main process leading to gene flow in populations. Gene flow influences the spatial distribution of populations, individuals and genes. Natural populations are typically subdivided, or structured, in space and genetic composition in part due to limited dispersal. Understanding how genetic variation is partitioned and the factors that govern this process is a major goal of evolutionary biologists because the degree to which populations are structured affects rates of local adaptation, speciation and extinction. In my dissertation I examine how one life history trait, phoretic dispersal, influences gene flow and genetic differentiation in populations. Here I compare related and sympatric species that are ecologically very similar, but explicitly differ in dispersal behavior. Wing lice (Columbicola columbae) frequently engage in phoresis or "hitchhike" on the pigeon lousefly (Pseudolynchia canariensis), while body lice (Campanulotes compar) do not. In the first part of my dissertation I characterize the genetic makeup of wing and body lice populations on a local scale. I found that in a geographic area where flies occur, wing lice have significantly less population genetic structure than body lice. Next I identified geographic areas where flies are absent from pigeon populations. Finally, I compared patterns of genetic differentiation on a global scale for wing and body lice populations. I found that in areas without flies, wing lice and body lice have similar patterns of genetic differentiation. These findings strongly suggest that ongoing phoretic dispersal erodes population genetic structure and enhances population connectivity for wing lice. |
