SALEH, N.; MOZEL, L.; GUIASU, R.C.; DUNHAM, D.; University of Toronto; University of Toronto; University of Toronto; University of Toronto: Agonistic interactions in the semi-terrestrial crayfish Fallicambarus fodiens : the dynamics between winners and losers

Agonistic displays evolved due to competition for resources. Combat between two animals usually results in one animal, the winner, gaining access to these resources. Previous crayfish studies have found that winners and losers differ in their use of approach and submissive behaviours. Thus winners and losers use different strategies in agonistic interactions. Fallicambarus fodiens is a semi-terrestrial freshwater crayfish that, unlike most other studied crayfish species, lives in groups of conspecifics. Studying this species is important, because it will allow comparisons to be made between solitary and more social species. Very few studies have compared male and female agonistic behaviour in crayfish. This study investigated some of the agonistic dynamics between winners and losers as well as males and females. Winners and losers use different types of approach and submissive behaviours. Losers tend to be less aggressive and use less energetically costly behaviour than the more aggressive and energetically costly approaches used by winners. The different strategies may serve to minimize costs associated with the assessment of fighting abilities by providing information about the individual�s motivational state. Male fight dynamics are less stable than female fight dynamics. Males also use more aggressive approach behaviours. They may be competing for more resources or less abundant resources. This may have been a factor in the evolution of increased use of highly aggressive approaches and the delayed establishment of dominance.