Meeting Abstract

P2.2  Thursday, Jan. 5  Morphological determinants of aggression and fighting success in two species of Callinetes BYWATER, CL*; JAMES, C; MCELROY, E; The University of Queensland; The College of Charleston; The College of Charleston c.bywater@uq.edu.au

Intra-specific competition between males is driven by the need to procure territories, food and mates and thereby maximize survival and reproductive success. Due to the potential costs of combat, specialised weapons are often displayed to resolve disputes without direct physical contact. It is predicted that the evolution of increased weapon size should be associated with increased competition for resources and weapon strength should increase simultaneously with size. We investigated the morphological predictors of aggression and fighting performance in two species of blue crab (Callinectes similes and Callinectes sapidus). Blue crabs have large claws used during displays and physical combat. We measured morphological features including body size, claw size, claw muscle mass, apodeme area and maximum claw closing strength for each individual. We also recorded contests between individuals to establish a dominance ranking. We found each species responded differently to stimulation in aggression tests as well is during individual contests. We will discuss the variation observed in size of male weaponry among species and whether this explains variation in fighting performance and aggression.