Year of Award
Master of Science (MS)
Organismal Biology and Ecology
Department or School/College
Division of Biological Sciences
Winsor H. Lowe, Fred W. Allendorf
Michael K. Schwartz
amphibians, Bufo boreas, chytridiomycosis, genetic variation
University of Montana
Amphibians are more threatened than any other vertebrate group, with 41% of species experiencing declines. The causes of most declines are not well understood, though many declines have been linked to the emerging infectious disease chytridiomycosis. Additionally, amphibians are physiologically constrained to moist habitats and considered poor dispersers; thus, they may suffer genetic consequences of population isolation. To address threats to the persistence of boreal toads (Bufo boreas) in Glacier National Park, USA, I genotyped 551 individuals at 11 microsatellite loci and used spatially independent (STRUCTURE) and spatially explicit (GENELAND) Bayesian methods to describe population genetic structure and identify barriers to gene flow. I found evidence of hierarchical population structure: individuals were splint into high and low elevation groups, and 2 secondary groups were detected within the high elevation group. These results indicate that elevation strongly influences genetic structure. Genetic variation was high, but allelic richness declined with increasing elevation. I tested a subset of the samples for Batrachochytrium dendrobatidis (Bd), the fungal pathogen which causes chytridiomycosis. Thirty-seven of 109 toads tested positive for Bd. Infection prevalence was not correlated with elevation, but—surprisingly—increased with individual heterozygosity. This finding suggests that dispersal may be facilitating the spread of disease because heterozygosity is highest where dispersal and gene flow are greatest.
Addis, Brett Rebekah, "Genetic structure and disease prevalence of boreal toads (Bufo boreas) in Glacier National Park" (2012). Graduate Student Theses, Dissertations, & Professional Papers. 485.
© Copyright 2012 Brett Rebekah Addis