Meeting Abstract
Phalangium opilio, a globally distributed species of daddy long-legs, is often referred to as the “common harvestman.” Although it is a familiar animal, very little is known about its mating behavior. This study aimed to clarify the effect of male size on female mating preference. We collected P. opilio around the campus of Macalester College in St Paul, Minnesota. During mating trials, one male and one female were put into an acrylic “arena” that provided visibility and control over the trial conditions. We recorded each encounter as either a copulation, a rejection by the female, or a lack of interaction between the individuals. Each block of trials contained 3 males and 18 females all of which were paired with with each male in varying orders to control for potential effects of mating order. Each block contained one male of each different size class (small, medium or large) based on measurements of body and appendage length. Rstudio and JMP software were used to test for relationships between measurements of male size and likelihood of copulation, rejection or lack of interaction with females. This experiment strongly suggested that females do not have a preference in mate related to size. However, we found significant negative relationships between a male’s likelihood of interaction and various measures of male size, suggesting that a smaller size leads to a greater likelihood of interaction with a female. Many aspects of the life history of P. opilio are currently unknown and understudied. Further research into the connections between size, ontogeny, and mating behavior will lead to a greater understanding of the reproductive biology of this common yet poorly understood animal.
