He's Compensating for Something: Can Male Schizocosa ocreata Wolf Spiders Use Increased Courtship Vigor to Compensate for a Physical Trait Indicating Poor Condition?

Abstract

By Autumn Otto , Biological Sciences and Environmental Studies

Advisor: George Uetz

Awards: Presenter Award: Excellence in Research Communication

Presentation ID: 195

Abstract: Males of the brush-legged wolf spider, Schizocosa ocreata, court potential mates with visual and vibratory signals. These signals reflect male health and condition, draw attention to the male presence and increase sexual receptivity of the female. Previous studies have shown increased female receptivity is linked to courting males with larger leg tufts, which are a secondary sexual characteristic of S. ocreata that is fixed at adulthood. Additionally, higher courtship vigor (rate of leg waving) has also been correlated with increased receptivity. The main objective of this study is to test the Courtship Compensation Hypothesis, which predicts that smaller males, or those with smaller tufts, will compensate for their deficiency by increasing courtship effort to match or exceed the overall average of the population, and potentially increase mating success. This hypothesis was tested with digital video playback trials wherein females were presented with video males with manipulated courtship vigor and size to see how receptivity is affected by the combination of tuft size and courtship vigor. Once analyzed, data on female responses to altered videos will allow us to see if males can overcome constraints of size with more vigorous courtship behavior. If female responses to males with small tufts but increased courtship vigor are equivalent to those seen with controls (average tuft size and mean vigor levels), that will mean male spiders can "level the playing field" and compensate behaviorally for limits of size and morphology, supporting the Courtship Compensation Hypothesis.