Dr. Janet L. Gehring Assistant Professor of Biology Bradley University
	Silene latifolia (female)		Silene latifolia (male)

My research is broadly concerned with how genetics and ecology interact to determine the evolutionary responses of plants to their environments. My research interests are focused on three areas within this broad field of study: 1) evolution of life-history traits, 2) evolutionary ecology of plant reproduction, especially the evolution and maintenance of breeding systems and sexual dimorphism, and 3) spatial patterns of genetic variation, both within-populations and over larger spatial scales. The questions addressed in my research program require field or greenhouse observations, often complimented by laboratory studies utilizing genetic markers. Currently my research is centered on two projects: sexual dimorphism in the dioecious Silene latifolia and the population genetics and evolutionary ecology of reproduction in Gentiana puberulenta.

Silene latifolia project
Most plants are bisexual and have both male and female function within the same individual, usually within the same flower. In about 7.6% of plant species, there are separate male and female individuals (dioecy). Although uncommon, dioecy has evolved independently in many plant families. Following separation of male and female function into distinct individuals, there is likely to be divergent selection resulting from differences in how males and female attain reproductive success. That is, reproduction becomes specialized (as it is in most animals). For example, females may be selected to maximize resource capture, since female reproductive success is often thought to be limited by resource availability. In another example, male-male competition for pollinators may cause selection for large flowers or floral displays, since male reproductive success is often thought to be limited by access to mates. Presently, we are documenting how the sexually dimorphic traits of S. latifolia (such as the intersexual difference in flower size seen in the photographs at the top of this page) are genetically correlated, both between traits and between sexes. We hypothesize that genes controlling flower size and number may affect the degree of sexual dimorphism in many other phenotypic traits of S. latifolia.

Gentiana puberulenta project
The once extensive North American tallgrass prairie has undergone severe habitat destruction and fragmentation because of its suitability for agriculture. The transformation of the tallgrass prairie into a relatively few, small remnants means that typical prairie species such as Gentianapuberulenta are found primarily in small, isolated populations surrounded by many square miles of row crops. These small isolated populations may experience 1) loss of genetic variation due to genetic drift, 2) higher rates of inbreeding, concomitantly decreasing heterozygosity and increasing inbreeding depression, and 3) absence of gene flow between populations. In collaboration with several Bradley undergraduates, my research lab is addressing the following questions regarding G. puberulenta. 1) Is percent seed germination low because of inbreeding depression and/or limited within-population genetic variation? 2) Is within-population genetic variation correlated with population size and/or remnant size? 3) Do spatial patterns of genetic structure vary among differently shaped prairie remnants? 4) Is G. puberulenta self-compatible? 5) Can G. puberulenta hybridize with Gentianaalba in restored prairies?

Research Experience for Undergraduates (REU)
My REU students in both 1999 and 2000 focused on identifying genetic markers in G. puberulenta that would allow us to study its population genetics. In 1999, Nichole French (below right) resolved and identified several polymorphic protein isozymes. In 2000, Felice Kelly (below left) successfully established a DNA extraction procedure and was moderately successful in using coffee microsatellite primers with Gentianapuberulenta.