Bacterial infection and female visual assessment of male courtship signals in wolf spiders

Abstract

By Olivia Bauer-nilsen, Biological Sciences

Advisor: George Uetz

Presentation ID: PM_ATRIUM29

Abstract: Animal immune systems have evolved to combat invasion by a variety of pathogens and parasites. However, fighting infections comes with an energy cost that results in resource trade-offs with other life history processes, such as reproduction. This experiment examined the trade-offs between immunity and mate choice in a well-studied spider. Female Schizocosa ocreata wolf spiders usually mate only once and therefore are choosey, opting for males displaying condition-dependent traits indicative of higher mate quality (larger and more symmetrical tufts of foreleg bristles, production of higher amplitude vibratory signals). Female S. ocreata were tested to determine whether infection by Pseudomonas aeruginosa, a common bacterium in their habitat, impacts choosiness when presented with the stimulus of courting males. Four treatment groups were utilized, including: two groups based on age of treatment and the other two regarding infection status. During trials females were presented with a choice: two iPods with video playback of visual signals from high and low quality courting males (large vs. small foreleg tufts). Female behavior was scored using the number of receptivity displays and time spent visiting either of the two screens within the 5-minute trials. Preliminary results show a significant impact of time of infection, as females infected in the penultimate stage expressed stronger mate preferences for males with smaller tufts, while females infected as adults showed no preference. Results will be discussed in the context of previous results and current mate choice theory.