Do Markers Linked to Disease Resistance Reflect Adaptive Genetic Diversity in a Salmonid Fish?

EPA Grant Number: F6D10901
Title: Do Markers Linked to Disease Resistance Reflect Adaptive Genetic Diversity in a Salmonid Fish?
Investigators: Tennessen, Jacob
Institution: Oregon State University
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2006 through August 1, 2009
Project Amount: $107,640
RFA: STAR Graduate Fellowships (2006) RFA Text |  Recipients Lists
Research Category: Fellowship - Conservation Genetics , Academic Fellowships , Biology/Life Sciences


Genetic markers linked to phenotypic traits, known as quantitative trait locus (QTL) markers, may be useful for estimating patterns of adaptive genetic variation and divergence in a species, which is important for wildlife management. I will test whether QTL markers linked to parasite resistance in a fish provide better information than neutral genetic markers with respect to adaptive population genetic patterns.


The fish parasite Ceratomyxa shasta occurs in some watersheds, but not all, in Oregon. Rainbow trout (Oncorhynchus mykiss) that co-exist with the parasite are largely resistant to it, while trout in other watersheds are susceptible. Susceptible fish have often been stocked unsuccessfully in watersheds containing the parasite. A cross between hatchery strains has identified QTL markers linked to parasite immunity. I will measure Fst, an indicator of genetic divergence, at QTL markers and neutral unlinked markers, between multiple populations. These will include both resistant and susceptible populations, as well as historically resistant populations where genes from susceptible stocked fish may have introgressed. I will also confirm that the QTL markers are linked to disease resistance in these populations by genotyping individual fish that have been experimentally shown to be resistant or susceptible.

Expected Results:

If natural selection for parasite resistance has affected the QTL markers, they should show higher Fst than unlinked neutral markers. This pattern should be especially pronounced in historically resistant populations where stocking and introgression has occurred, because natural selection will have purged harmful introduced alleles, while leaving neutral introduced alleles alone. The same QTL markers may be outliers in multiple population comparisons, and they should show a correlation with phenotype in these populations. If so, my results will suggest that QTL markers are more useful than neutral unlinked markers for detecting patterns of population structure under natural selection, which would be useful for conservation biologists who want to conserve adaptive genetic diversity.

Supplemental Keywords:

Oncorhynchus mykiss, Ceratomyxa shasta, conservation genetics, quantitative trait locus, Fst, immunity, rainbow trout, parasite, adaptive genetic variation,, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Genetics, Habitat, Ecology and Ecosystems, Biology, adaptive genetic variation, fish, animal responses, quantitative trait locus markers, genetic consequences, community genetic diversity, conservation biology, genetic markers

Progress and Final Reports:

  • 2007
  • 2008
  • Final