Etterson Lab
Plant ecological & evolutionary genetics
Dr. Julie R. Etterson
Associate Professor
University of Minnesota Duluth
Department of Biology153B Swenson Science Building
Duluth, MN 55812-3003
Email: jetterso@d.umn.edu
Office Phone: (218) 726-8110
Lab Phone: (218) 726-7408Fax: (218) 726-8142
2000 PhD, University of Minnestoa, Dept. Ecol. Evol. and Behavior
1994 BS, University of Minnesota, Biology
1986 BIS, School for International Training, International Studies
Research Summary
Our lab uses the tools of ecological genetics to understand factors that influence the persistence of native plant populations in response to anthropogenic changes in the environment including climate change, competition with invasive species, inbreeding due to small population size, introduction of nonnative genotypes during habitat restoration, and increased intensity of deer herbivory. Our goal is to examine how natural plant populations change phenotypically and genetically in response to these agents of selection. We use quantitative genetics to understand the underlying genetic architecture of traits and to attain insight into the potential for ongoing adaptive evolution in response to a changing environment. Using this approach, we can also predict the limits to natural selection to further molding of populations. Molecular techniques are used in our lab to quantify the extent of divergence among populations, the degree of inbreeding within populations, and as tools to distinguish between local and nonlocal genotypes of plants that were introduced for restoration purposes. 
Plant response to climate change
Climate change is expected to alter patterns of natural selection across species’ ranges and pose strong evolutionary challenges to native plant populations. The magnitude of evolutionary response that will occur in any given population depends critically upon the genetic architecture of traits that are the targets of selection. My reserach attempts to quantify the evolutionary potential of populations to novel conditions due to global warming employing a quantitative genetic approach.
Polyploidy and evolutionary potential
It is often assumed that polyploids possess greater evolutionary potential than their diploid progenitors because: 1) organisms with many gene copies harbor greater genetic diversity which is the fundamental substrate of evolutionary change, 2) genetic redundancy creates opportunities for duplicated genes to diverge and acquire new functions without compromising the original function, and 3) gene duplication increases the number of gene interactions, some combinations of which may enhance fitness. Thus, polyploidy may allow organisms to evolve faster or in novel directions compared to their diploid progenitors. Although this is a provocative idea and a compelling hypothesis, it has never been explicitly tested. I am testing this hypothesis in a polyploid goldenrod species. Solidago altissima.
I am interested in the role that both ecological and evolutionary dynamics play in the persistence of native plant populations that are experiencing invasion. Specifically, I am interested in how evolutionary and ecological dynamics interact to determine the fate of populations. I have recently initiated reserach into an invasive species that only occurs in the Duluth area in North America, Campanula cerviarcia. This species was first collected in this region in 1943 but was not correctly identified until 2003. I have begun to study the demographics and quantitative genetics of the invasive populations in this region. My graduate student, Ada Tse, is also studying genetic variation in Tanectum vulgare in response to simulated insect damage by biocontrol agents.
Parental effects
This collaboration with Dr. Laura Galloway at the University of Virginia examines the extent to which offspring phenotype is influenced by genetic inheritance and by environmental factors. Specifically, we are interested in effects of the parental environment that are transmitted from maternal or paternal parent to offspring.
Inbreeding Depression
Campanulastrum americana is an insect-pollinated self-compatible protandrous herb. Thus, inbreeding is most likely to occur as a result of pollinator movement among flowers of the same plant that are in different gender phases. However, Laura Galloway and I found that multilocus outcrossing rate was 94 % and did not differ significantly from unity. This result was unexpected since previous work demonstrated that pollinators frequently move from male- to female-phase flowers on the same plant.C. americana is also an autotetraploid species. Theory predicts that inbreeding depression should be lower in polyploids relative to diploids. In a greenhouse study, we found that inbreeding depression was not significant for most seed and germination characters. However, all later life traits except flowering date differed between inbred and outcrossed individuals resulting in a 26% reduction in cumulative fitness for inbred plants. Limited early- and moderate later-life inbreeding depression suggest it is buffered by the higher levels of heterozygosity found in an autotetraploid. A three-year field study confirmed the strong impact of inbreeding on mortality rates and fecundity.
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©2009 Julie Etterson
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