Lewis Honors College Capstone Collection

Year of Publication

2019

College

Arts and Sciences

Department/School/Program

Biology

Degree Name

Bachelor of Science, Biology

First Capstone/Thesis Advisor

Dr. Catherine R. Linnen

Abstract

Carotenoids serve various ecological roles in animals including coloration, immune responses, and vision. Carotenoid-derived coloration is greatly emphasized in the literature, particularly relating to mate choice and aposematic warning. However, the trade-offs between the color and non-color functions of carotenoids are not thoroughly explored. In the redheaded pine sawfly (Neodiprion lecontei), some larval populations have yellow pigmentation, using carotenoids derived from their diets for aposematic warning coloration. Other larval populations are white in color, having genetically lost the ability to produce the yellow pigment. Because carotenoids are essential to life functions in both the yellow and white populations, we aim to explore the selective pressures favoring a loss of yellow coloration in white populations. We hypothesize that trade-offs between color and non-color functions have driven the white populations to stop producing yellow pigment, thereby retaining carotenoids for other life functions. Through analyses of field trip notes, we find that white larvae are more common on pitch pine (Pinus rigida) than on other pine hosts. After extracting and quantifying the carotenoids in multiple N. lecontei hosts, we find P. rigida has lower carotenoid content than other hosts. Our findings support the hypothesis that selection favors white populations who use limited carotenoid sources for non-color functions despite an increased predation risk

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