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University of Michigan Biological Station

The University of Michigan Biological Station (UMBS) was founded in 1909.

Social

The effects of altered RHP perception of self and opponent on fight dynamics and assessment in crayfish (Orconectes virilis)

Aquatic
Project Abstract: 
Agonism is an important social aspect of animal behavior and the outcome of agonistic interactions is critical to the acquisition of vital resources. During agonistic interactions, individual participants make behavioral decisions based on energy and time investment. In order to make optimal decisions, individuals must assess costs as well as benefits. These decisions can be informed through assessment strategies that are based only on internal energy reserves or involve complex comparisons between self and opponent. Unfortunately, most studies involving agonistic interactions and, consequently, assessment strategies have focused solely on males although females also fight for mating opportunities and both sexes vie for shelter and food. Previous studies have shown that male and female crayfish utilize self assessment in same sex interactions, but no discernible strategy could be found in mixed sex interactions. These findings suggest that something is fundamentally different in the way males and females fight and assess themselves and/or opponents and warrants further investigation. This study aims to elucidate those fundamental differences between males and females via the alteration of self and opponent by altering the energy thresholds of individuals and examining the affect of this alteration on fight dynamics and assessment in same sex and mixed sex interactions.
Investigator(s): 
Sarah Jane Wofford
Paul Moore
Status of Research Project: 
Complete (archive)
Years Active: 
2013
Methods: 
The first step of my project is to further illicit exactly what role energy reserves play in crayfish contests and assessment. Through the use of a specialized underwater treadmill (Thibodeaux et al. 2009), I will lower energy reserves by fatiguing crayfish for varying amounts of time and then measure the effects of that reduced energy threshold on fight duration and dynamics. I will examine correlations between contest duration and various RHP values of individuals to further examine the type of assessment strategies in place for males and females in same and mixed sex interactions. Using this technique, I will evaluate the effects of perceived energy deficits on fight duration and dynamics for various size classes of individuals as well the role those deficits play in same sex and mixed sex interactions. These data will provide a more comprehensive picture of factors that affect decision making in agonistic contests which dictate resource allocation and dominance within populations.