Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Geography

Supervisor

Yates, Adam G.

2nd Supervisor

Brua, Robert B.

Affiliation

Environment and Climate Change Canada

Co-Supervisor

Abstract

My study investigated the amount of variation associated with region and stream scales in the metabolomes of northern crayfish (Faxonius virilis), collected from seven streams distributed across three ecoregions in Western Canada. Additionally, my study measured metabolomes of crayfish from the same seven streams after experiencing a common laboratory environment to separate the effects of environmental and genetic variation. Region and stream scales were found to be poor predictors of metabolomic variation among crayfish sampled in the field but exhibited increased predictive ability among crayfish exposed to the common environment, indicating crayfish from separate populations responded differently to the common environment. Furthermore, variation among the crayfish metabolomes did not decrease in the common environment, indicating the important influence of genetic variation. These findings show unstressed populations of the northern crayfish display similar metabolomes despite experiencing differing environmental conditions. Reference conditions derived for metabolomic-based bioassessment may thus be applicable across regions.

Summary for Lay Audience

Bioassessment uses biological responses to evaluate the health of an ecosystem. Stream bioassessment will benefit from the ability of metabolomics (the study of all small molecules in an organism) to detect sub-lethal organism stress through changes in the metabolite profile (i.e., the metabolome). However, for the metabolome to be integrated into bioassessment programs, the amount of natural variation among and within populations must be established, creating a baseline to which potentially stressed populations can be compared. For instance, the metabolome of an organism may be affected by its surrounding environment, such as the climate, topography, and geology characteristics described by different ecoregions. However, the metabolomes of a species taken from several different ecoregions may also vary because the different populations are genetically different. My study determined the amount of variation in the metabolome of the northern crayfish (Faxonius virilis) that could be attributed to the ecoregion or stream of origin and whether environment or genetics was the more important source of variation. I collected northern crayfish from seven streams distributed across three ecoregions in Western Canada and compared their metabolomes. As well, I kept crayfish from the same seven streams under similar environmental conditions in the laboratory for 16 days. I found that the ecoregion and stream that the crayfish originated from were poor predictors of the crayfish’s metabolome among crayfish sampled directly from the streams. In contrast, ecoregion and stream of origin were better predictors of the metabolome among crayfish that had experienced the common environment, indicating crayfish of separate origins responded differently to the common environment. Furthermore, variation among the crayfish metabolomes did not decrease in the common environment, indicating that genetic variation was an important influence on the crayfish metabolome. These findings show that unstressed populations of the northern crayfish display similar metabolomes despite experiencing differing environmental conditions. The consistency in the northern crayfish metabolome across several ecoregions suggests that a single crayfish metabolome baseline could be used in bioassessment programs across the sampled ecoregions.

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