Honors Program

University Honors

Date of Award

5-2020

Thesis Professor(s)

Thomas C. Jones

Thesis Professor Department

Biological Sciences

Thesis Reader(s)

Darrell Moore

Abstract

Several studies have investigated the ecological factors that affect behavior in Micrathena gracilis, a diurnal orb-weaving spider that forages on flying insects during the day. However, none yet have considered how the temporal distributions of prey and predator occurrences shape their daily behavioral rhythms, especially web construction, which involves a heavy energetic investment well in advance of potential nutritional benefit. Recently, several orb-weaving spider species have been shown to exhibit a variety of abnormal rhythms, suggesting that circadian clock-controlled rhythms may play an unexpected role in behavioral evolution. Despite the appearance of significant insect abundance in the evenings, M. gracilis individuals stop foraging, take down their webs, and retreat before they can capitalize on this opportunity. Is the nutritional benefit of this forfeited prey significant compared to what they collect during the day, and if so, what potential cost might justify opting out of this potential gain? To investigate, sticky traps for prey collection and a camera array for recording predator activity were used at a local field site to survey what risks and rewards these spiders face throughout the 24-hour day. Spider activity and web captures in the field were also used to confirm behavioral patterns and capture success throughout the day. It was found that spiders begin foraging when prey becomes available but cease while prey is still abundant. These observations appear to support a theoretical model of behavioral decisions under predation risk. However, recorded predation events were rare, and predation was not confirmed outside of the foraging timeframe. These results support the notion that the circadian rhythm of Micrathena gracilis is shaped by factors other than prey availability, but the theoretical pressure from predation risk requires further investigation.

Publisher

East Tennessee State University

Document Type

Honors Thesis - Withheld

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

Copyright

Copyright by the authors.

Available for download on Monday, April 26, 2021

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