Date of Award

Summer 8-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Committee Chair

Dr. Jacob Schaefer

Committee Chair Department

Biological Sciences

Committee Member 2

Dr. Brian Kreiser

Committee Member 2 Department

Biological Sciences

Committee Member 3

Dr. Carl Qualls

Committee Member 3 Department

Biological Sciences

Committee Member 4

Dr. Frank Moore

Committee Member 4 Department

Biological Sciences

Committee Member 5

Dr. Brett Albanese

Abstract

Movement of individuals throughout a landscape is a complex behavior that has important consequences on numerous ecological and evolutionary processes. Perhaps most notably is the relationship between movement and reproduction, as this has implicit ramifications on individual fitness and consequently, population level processes. Although this relationship has been theoretically and empirically demonstrated across a number of animal taxa, its role in fishes remains understudied and largely unknown. Using a series of outdoor mesocosms, in combination with a field study, I employed passive integrated transponder (PIT) tags to experimentally assess the sex-specific movement dynamics of a small-bodied, sexually-dimorphic stream fish, the blackspotted topminnow (Fundulus olivaceus), in response to a suite of local biotic (population density sex ratio and predators) and abiotic (seasonality and habitat complexity) factors. Movement behaviors were strongly influenced by reproductive timing, with distinct sex-specific movement patterns operating at different temporal scales. More broadly, small-scale (less than 10 meters) movement dynamics of F. olivaceus were consistent across mesocosm and field settings, with males displaying increased activity and frequency of movement, patterns that were magnified at lower densities. Concomitantly, I also observed habitat and predator effects at smaller, local scales. Predators were found to restrict movement in the mesocosm study, and movement was reduced in reaches with increased abundance of local predators in the field study. Simultaneously however, activity levels were mediated as habitat complexity increased. Consequently, this appeared to promote establishment and defense of territories among males, limiting the longitudinal distance of male movement. In contrast, at larger spatial scales, females tended to engage in longer and more frequent long-distance moves (greater than 30 meters); a pattern that was presumably related to habitat quality and reproductive resource demands. Taken together, these results indicate that local environmental conditions, in combination with phenotypic factors, may function to shape the movement behaviors of stream fishes at various spatiotemporal scales. Moreover, as the magnitude of sex-specific movement responses to local factors appears to be scale dependent, questions that address sex-specific patterns should consider the scale at which movement is quantified in order to capture the nature of sex-biased tendencies.

Available for download on Monday, August 06, 2018

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