9220906 Dudash Inbreeding depression has been the subject of considerable attention for over 100 years. Although many researchers have quantified how progeny generated by self-matings perform poorly relative to progeny generated from matings between two different individuals, few empirical studies have focused on the differences in inbreeding depression in populations that differ in their natural outcrossing rates. The main goal of the proposed research is to determine the underlying genetic basis of the expression of inbreeding depression in two closely related native species from northern California, the self-pollinating Mimulas micranthus and the insect dependent (thus outcrossing) M. guttatus. The objectives are three-fold. First, to quantify the degree of inbreeding depression in terms of both male and female function in two populations of both the selfing and outcrossing species. The effects of inbreeding on female reproductive function are well documented, but he effects on male function, such as pollen production are largely unknown. Second, the genetic basis of inbreeding depression will be quantified by two greenhouse breeding experiments. Third, among-family level variation in inbreeding depression will be quantified in the outcrossing M. guttatus as a function of the observed floral variation. This two-species comparison will examine the relationship between the mating system and the genetic basis of the observed inbreeding depression, thus providing baseline information on the genetics driving changes in mating systems in natural plant populations. The results generated from the research on these two related species will provide insights into preserving both crop gene pool diversity and rare species genetic diversity.***
