Date Thesis Awarded

4-2016

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

Matthias Leu

Committee Member

Brad Lamphere

Committee Member

Joshua Puzey

Committee Member

Leah Shaw

Abstract

Local climate affects the occurrence and turnover of butterfly populations in a variety of ways, demonstrating a need to explore these interactions in the face of climate change. This study aimed to investigate the influence of climate variation on the population dynamics of five butterfly species with differing life history traits (number of broods and overwintering strategy) and diet preference (sap vs. nectar). Detection/non-detection data were gathered for four consecutive years (2012-2015) across six annual surveys on 67 different sites. I used multi-season occupancy models to analyze the detection/non-detection data. Occupancy models estimate the probability that a species occupies a given area, but also the probability of expansion (previously unoccupied locations become occupied in current year) and contraction (previously occupied locations become unoccupied in current year). To construct multi-season occupancy models for each species, detection probabilities (the probability that a species is detected given that it is present at a given location) were first modeled to account for heterogeneity in the detection conditions across surveys. I then related 30 different climate variables to probability of expansion and contraction while keeping the top detection model constant. Variables that produced the best univariate models were added to a candidate set. From the candidate set of climate variables for each species, multivariate models were generated and model averaged. Model averages informed which climate variables most strongly influenced inter-annual population dynamics. I found that the population dynamics of sap feeders were not driven by climate variability, while nectar feeders were driven by climate variability. The population dynamics for two of the three nectar-feeding butterflies correlated strongly with spring total rainfall. I found no difference in the effect of climate variability on overwintering strategy (pupae vs. larvae) and number of broods. The results from my research can be used to forecast distributions of these species under various future climate scenarios and provides hypotheses for future research to investigate the specific mechanisms driving population dynamics of these species.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

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