Honors Theses

Date of Award

2004

Document Type

Undergraduate Thesis

Department

Biology

First Advisor

David Reed

Relational Format

Dissertation/Thesis

Abstract

The diets of two species of spiders in the genus Rabidosa, Rabidosa punctulata and R. rabida, were intensively studied. These two species generally inhabit the same fields, but display very different life histories. This study has three major objectives. (1) Quantitatively address the commonly held belief that these spiders are opportunistic predators (Le., predators that take prey in the abundances in which they occur in the environment). (2) Measure the degree of niche overlap in diet for the two species (as a measure of the potential for competition). (3) Speculate on whether the overlap in diet or other factors may have caused these two species to evolve different life histories. We found that the two species have extremely broad diets. We found spiders feeding on 21 different identifiable species. However, the spiders did not take prey items in the frequency in which they occur in the habitat. Rather, the spiders take slow moving prey, such as Lepidoptera larvae (caterpillars) and Coleoptera (beetles) in higher than expected frequencies Vand potentially dangerous prey such as other spiders and Hymenoptera (ants, bees, and wasps) in lower frequencies. The diets of R. punctulata and R. rabida are nearly identical. Such niche overlap between the two species would normally lead to intolerable levels of competition, driving one species or the other extinct (Dodson et al. 1998). We conjecture that the potential for competition for food and the risk of predation for R. punctulata from the larger R. rabida has led to the evolution of non-overlapping adult life histories for both species.

Accessibility Status

Searchable text

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.