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Grantee Research Project Results

Grantee Research Project Results

Plant Population Genetics in the Great Basin (U.S.A.): Outbreeding Depression and Implications for Restoration

EPA Grant Number: F5D10641
Title: Plant Population Genetics in the Great Basin (U.S.A.): Outbreeding Depression and Implications for Restoration
Investigators: Kramer, Andrea T.
Institution: University of Illinois at Chicago
EPA Project Officer: Jones, Brandon
Project Period: August 22, 2005 through August 22, 2008
Project Amount: $107,878
RFA: STAR Graduate Fellowships (2005)
Research Category: Academic Fellowships



The objective of this research is to test the potential effects of genetic changes imposed by restoration activities, with particular emphasis on the potential for outbreeding depression, in two perennial forbs (Penstemon pachyphyllus and P. rostriflorus) commonly found in the Great Basin region of the western United States.

This research addresses the effects of genetic changes on plant populations resulting from restoration practices. Using two perennial forb species (Penstemon) found throughout the Great Basin (U.S.A.), I ask whether outbreeding depression (a decrease in offspring fitness as parents are increasingly genetically different) may negatively affect the success of a restoration. For this, I will use hand pollinations to cross plants from different populations, assessing the fitness of offspring when grown at the original parental sites as well as in a common garden over two generations.


To determine the effects of mixing populations at scales relevant to ecological restoration, hand pollinations will be performed among six study populations for each study species. Study populations are separated by 5 to 500 km, and preliminary work has revealed local adaptation among populations. By experimentally crossing parental populations over five spatial scales, the effect of crossing distance on outbreeding depression in resulting progeny can be quantified. Progeny produced from experimental manipulations will be used to test for outbreeding depression via two potential mechanisms. First, outbreeding depression via a dilution mechanism will be tested using a reciprocal transplant study. Second, outbreeding depression via a hybrid breakdown mechanism will be tested using a multiple generation common garden study.

Expected Results:

It is hypothesized that outbreeding depression via a dilution mechanism will occur in progeny of crossed, locally adapted populations, resulting in progeny demonstrating relative fitness declines in the first generation when grown in either parental environment. Additionally, it is hypothesized that outbreeding depression via a hybrid breakdown mechanism will occur in progeny of crossed, genetically distinct populations, resulting in decreased relative fitness in the second generation of progeny due to recombination of coadapted gene complexes. Results of this study will be informed by the use of microsatellite loci, currently being employed to determine levels of population differentiation (FST) and degree of inbreeding (FIS) in original study populations. This will increase the power of the proposed study to provide direction for effective restoration genetic practices in this region.

Supplemental Keywords:

Penstemon pachyphyllus, Penstemon rostriflorus, restoration genetics, outbreeding depression, dilution mechanism, reciprocal transplant study, hybrid breakdown mechanism, common garden, Great Basin, microsatellite DNA, ecological restoration, plant population genetics, local adaptation, population differentiation, hand pollination,, Scientific Discipline, ENVIRONMENTAL MANAGEMENT, Water, Ecosystem Protection/Environmental Exposure & Risk, Genetics, Restoration, Resources Management, Aquatic Ecosystem Restoration, population dynamics, conservation, species interactions, plant diversity, ecological variation, restoration strategies, environmental rehabilitation

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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