Date of Award
Honors College Thesis
Biological Sciences BS
Jacob F. Schaefer, Ph.D
Sabine Heinhorst, Ph.D.
Understanding the mechanisms driving habitat preference throughout an organism’s life opens doors to the further understanding of the origins of diversity. Two species of minnow, Fundulus notatus and Fundulus olivaceus, are ideal for ecological research on habitat preference. Ordinarily, F. notatus and F. olivaceus display habitat preferences of downstream and upstream, respectively, with minimal coexistence at confluences. However, in some drainages, these preferences are flipped, like those in the Tombigbee River basin. Members of both species were collected from the Tombigbee River, tagged with species and sex specific colored elastomer marks, and placed in either a homogeneous control or heterogeneous mesocosm designed to mimic an upstream and downstream habitat. Both mesocosms then had a camera placed over each pool (three upstream and downstream pools in each treatment). Pictures were taken every 30 seconds through two hour trials. Images were processed through an artificial intelligence (AI) system (Tensorflow) trained to recognize fish and colored elastomer tags. After processing, images were manually reviewed to assess AI accuracy and make any necessary corrections. Results showed coexistence was higher within homogeneous than in heterogeneous treatments. Both sexes of F. notatus and female F. olivaceus displayed a strong preference for the downstream orientation in the heterogeneous treatment, whereas F. olivaceus males showed a weak preference for the upstream orientation. Both species showed weaker preference in the homogeneous treatment. All categories involving treatment as a factor were determined to be statistically significant. The original hypothesis that the species within the heterogeneous treatment would show a higher preference than those in the homogeneous treatment was supported.
Keywords: niche, habitat preference, Fundulus olivaceus, Fundulus notatus, coexistence, mesocosms
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Williams, Elizabeth Hart, "Habitat preference of F. notatus and F. olivaceus from a reversed hybrid zone" (2022). Honors Theses. 826.