Meeting Abstract

P3.16  Monday, Jan. 6 15:30  Big wigs and small wigs: the roles of size, sex and shelter in spatial distribution patterns in the maritime earwig Anisolabis maritima HACK, N/L*; IYENGAR, V/K; University of California Santa Cruz; Villanova University nhack@ucsc.edu

Animal aggregations can occur for a variety of abiotic factors, such as resource limitation, or biotic factors including sexual selection and predator-prey interactions. Although it is challenging to determine the underlying mechanism of such grouping behavior, we conducted experiments in which we examined the interactions and distribution patterns among pairs of the maritime earwig Anisolabis maritima (Order Dermaptera). This insect, found in aggregations under beach debris around the world, is sexually dimorphic regarding its most distinctive feature in that females have straight posterior forceps/pinchers whereas males have asymmetrical, curved forceps. We placed pairs of individuals varying in sex and size and monitored their distribution with and without shelter at 15 min, 12 h and 24 h to determine the roles that these factors may play in spatial patterns and gain insight into the mating system. Overall, we found that females were less likely to cohabitate than males, and they were more tolerant of males than other females. Males, on the other hand, were less aggressive and distributed themselves randomly, except when males were different-sized, in which case they preferred cohabitation. Shelters appeared to play a key role in reducing aggressive interactions, and our results have interesting implications regarding how inter- and intrasexual interactions influence distributional patterns in nature.