Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

2006

Thesis Director

Scott Meiners

Thesis Committee Member

Eric Bollinger

Thesis Committee Member

Robert Fischer

Abstract

Tallgrass prairies have been drastically reduced to a few remnant areas that are both small and isolated. As a result, species within these areas may be exposed to a significant level of inbreeding depression and loss in genetic diversity, which can cause an overall loss of fitness in the population, increasing the chance of local extinction. In many cases, prairie restorations rely on seed collections from these small, isolated populations, which may lead to many of the same problems in the restored areas. This study specifically addressed the question: Does the dependence on seed collections from small, isolated remnants lead to loss of vigor in restored populations? To address the question, seed collections of five common prairie species were obtained from four remnant prairie populations (one large and three small). A common garden experiment was initiated in 2005, where up to 20 individuals per species per site from these populations were germinated in the greenhouse at Eastern Illinois University and transplanted into a prairie restoration site. Plants were monitored throughout the growing season for growth, vegetative reproduction, and flowering. All above ground biomass was harvested following senescence to assess total growth. Biomass varied significantly among collection sites in three of the five species (Dalea purpurea, Eryngium yuccifolium, and Parthenium integrifolium). However, these species did not show a consistent pattern with remnant size. Survival did not vary among collection sites for any of the species. These results suggest that plant performance is unpredictable based on remnant size and that the use of seed collections from several sites, even if a large contiguous site is available, as the best choice for restoration practice. This practice may assist restoration efforts in avoiding the loss of genetic fitness and produce healthy, viable restored populations.

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