The Effect of Diet on Venom Gene Expression in Tetragnatha versicolor

Abstract

Tetragnatha versicolor is an orb weaving spider that can be found throughout North America from Alaska to Nicaragua. This along with the fact the T. versicolor is a habitat generalist means that the species encounters a diverse array of insect prey species throughout its range. The purpose of this study is to determine if two populations of T. versicolor that feed on different insect species also differentially express venom genes. First, I determined whether two populations of T. versicolor were eating different prey species by measuring the [delta]15N values of T. versicolor from each site. The results of this analysis were that the [delta]15N values for the two populations of T. versicolor were significantly different. This suggests that the two populations are at different trophic levels which indicates that the two populations of T. versicolor are eating different insect species. Next, I used the RNA isolated from the venom glands of three males and three females from each of the two populations to construct a venom gland transcriptome which I used to perform a differential expression analysis comparing the males of each population, the females of each population, and the males and females within each population. The results of this analysis showed that when comparing the females of each population, they were differentially expressing genes that are likely to be venom related. Also, when comparing the males to females, the males of each population were differentially expressing potential venom related genes despite the fact that their isotopic signatures were not significantly different from those of the females in the same population.