When there is very little migration within a population of living organisms, the distance between the birthplaces of individuals and the birthplaces of their parents is not much greater than the distance between neighbors. Under these conditions different types of genes may become locally more or less common than average by purely random chance. These random genetic changes are very different from the nonrandom genetic changes brought about by natural selection that lead to adaptive evolution. However, random changes in the genetic composition of local areas within a population can have a great impact on the specific evolutionary pathway along which a population is guided by natural selection. Therefore, to understand the types of evolutionary changes that may be brought about by natural selection, the importance of random changes must be determined. The investigators will study random genetic changes within natural populations of two plant species that are native to the tallgrass prairies of North America. The extent to which different local areas within each study population have different genetic compositions as a result of random changes will be measured. Migration distances of pollen grains and seeds will also be measured to see if the amount of random genetic change is consistent with present migration patterns. The information on how genetic variation is distributed among different local areas will also be useful in establishing management guidelines for the conservation of genetic diversity within the few remaining tracts of the once vast tallgrass prairie.
