Gene flow dynamics and population genetic structure in white oak species of northeastern Illinois.

摘要

The genus Quercus is composed of over 500 species of deciduous and evergreen species worldwide. Species in this genus are wind-pollinated and monoecious, with both male and female flowers occur on each individual. Because species in this genus are common and widespread, it is important to understand the population genetic structure and gene flow dynamics occurring in these species. For this reason, this thesis explores several aspects of Quercus population biology.; The data acquired for this thesis show that Quercus macrocarpa , bur oak, exhibits long-distance pollination, contributing to the genetic connectivity of 14 study populations. This long-distance gene flow resulted in low population differentiation, which implies this species should be resilient to the negative genetic effects of habitat fragmentation due to anthropogenic disturbance.; Other evidence of long-distance gene flow in Quercus macrocarpa comes from examination of contemporary gene flow in three populations. Paternity analysis of a of acorns from each of these sites revealed that over ∼50% of the acorns were sired by individuals located outside of the study sites. This is particularly interesting in the two isolated sites, since the closest individuals outside of these sites were over 200 meters away at Burnham Prairie and over 500 meters away at Goose Lake Prairie.; Because Quercus macrocarpa offspring are genetically diverse and trees do not rely on near-neighbors for their acorn crops, I devised a theoretical model regarding production of surplus ovules by each female flower as a mechanism to increase offspring diversity. This is based on the fact that oaks produce 5 ovules, all of which get fertilized, however only one develops into an acorn. My model predicts that an intermediate number of ovules results in maximum offspring diversity.; Additionally, Quercus microsatellite analysis was used for forensic analysis of leaves from Q. geminata in order to see if leaves from a murder suspect's car matched leaved found at the burial site of his putative victim. The Quercus primers used adequately amplified five years old evidence leaves, and proved to be sufficient in determining that the leaves from the suspect's car did not match the trees at the burial site.