Linking behavior and diet between and within populations of an invasive crayfish faxonius rusticus

Adey, Amaryllis K.

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Description

Title

Linking behavior and diet between and within populations of an invasive crayfish faxonius rusticus

Author(s)

Adey, Amaryllis K.

Issue Date

2019-07-01

Director of Research (if dissertation) or Advisor (if thesis)

Larson, Eric R

Committee Member(s)

• Taylor, Christopher A
• Fuller, Rebecca C

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Crayfish
• Diet
• Behavior

Abstract

Laboratory and mesocosm studies are often employed to study basic and applied ecology due to the complexities and lack of external controls in field environments. However, studies conducted on the same questions at different scales do not always have the same results. In my thesis, I used stable isotopes to relate laboratory behavior to field function within and between populations. In my first study, I explored whether stable isotopes of carbon and nitrogen could be used to relate laboratory dominance of Rusty Crayfish Faxonius rusticus to their field diet. I assessed whether methodological decisions around tissue analyzed for stable isotopes, laboratory acclimation time, and timing of primary consumer collection affects this relationship. I hypothesized that more dominant crayfish would have higher trophic positions, and tissues with faster turnover rates may exhibit a stronger association between laboratory behavior and recent field function. I failed to find a relationship regardless of these different methodological choices However, I still find this method promising, as other laboratory behaviors may be more related to diet or competition for food, such as exploration or feeding flexibility. In my second study, I expanded this method of relating behavior to diet through stable isotope analysis for questions between, rather than within, populations of F. rusticus. Here, I aimed to determine the relationship between individual specialization and relative population abundances or intraspecific competition. Theoretical studies propose a direct, positive relationship between abundance and individual specialization; however, empirical studies have not always supported these predictions. I assessed behavioral and dietary specialization across a gradient of relative population abundances of F. rusticus. I found a unimodal relationship between relative abundance and dietary specialization, likely due to limited food resources in high abundance lakes. Alternatively, I found a positive linear relationship between relative abundance and behavioral specialization, because this metric of individual specialization is not resource limited (i.e. density dependent). These results indicate that discrepancies between theoretical and empirical studies of the relationship between individual specialization and intraspecific competition might be a consequence of the metric of specialization used. My thesis shows that linking organismal diet and behavior with stable isotopes may be a useful approach in ecology and evolution, but may be best applied to questions between rather than within populations.

Graduation Semester

2019-08

Type of Resource

text

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Copyright and License Information

Copyright 2019 Amaryllis Adey

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