Date of Award

8-2013

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Scott Kight

Committee Member

Lisa Hazard

Committee Member

John Smallwood

Abstract

Sexual selection theory predicts that the sex that shows a greater parental investment in the offspring should be limiting to the reproductive success of the opposite sex. Males of the giant waterbug Belostoma flumineum exhibit greater parental investment than females by providing all of the parental care for the eggs, which are firmly attached to their dorsal surface. While male backspace availability can be limiting to female reproductive success, it has previously been found to be more limiting during the spring than during the fall, due to newly emerged males being able to breed more quickly than newly emerged females. In light of different thermal regimes in the two breeding seasons, this study examined the relationship between ambient temperature and male backspace availability. Males were exposed to one of four temperature treatments within the laboratory: mating and brooding at 20°C, mating at 20°C and brooding at 26°C, mating at 26°C and brooding at 20°C, or mating and brooding at 26°C. Overall, the size of the egg pad was larger and the time until mating was shorter for males that mated at 26°C, while the time spent brooding was longer for males that brooded at 20°C. The proportion of males that received an additional egg pad, when they had the opportunity, was found to be greater than that of males that received any egg pads at all. While the temperature treatment and the number of brooding attempts were not associated with the result of brooding, the rate of brooder mortality was found to be higher than that of nonbrooders when males were exposed to different mating and brooding temperatures. The high rate of brooder mortality, in addition to the delayed date of mating events and relatively long brooding periods observed in this study, are not consistent with previous studies and may be due to a recent change in the natural population of B. flumineum.

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