Aggression in Crayfish: the Influence of Sex on Agonistic Behavior
All animals employ a vast array of behaviors that contribute to their ability to find resources, increase their chances of utilizing them efficiently, and therefore increase their overall fitness. One of the behaviors observed extensively throughout the animal kingdom to accomplish these tasks is aggression. Agonist conflict and aggressive behavior occurs both between species and within species. Curiously, within-species agonism is common in many animals because it can manipulate social hierarchies which can affect the distribution of resources within a population (Moore 2007 and Wofford 2013). Evaluating agonistic behavior is therefore a valuable means by which to examine expenditure of energy for resources (Moore 2007 and Wofford 2013).
In this study, we analyze aggression in crayfish, because they are known to fight with each other, and they have a distinct ethogram from which to compare and contrast all of their behaviors (Moore 2007 and Wofford 2013). We seek to find out the affect of sex on agonistic interactions, and whether different ratios of between-gender interactions affect levels of aggression. It has been previously observed that male crayfish are usually dominant over females (Moore 2007). Additionally, male-male agonism is generally the most intense, while male-female and female-male interactions are less intense (Moore 2007). Since males are more aggressive than females, and male-male interactions are the most intense, we hypothesize that aggression levels vary by sex when fighting in groups of differing sexual ratios. Will males be less aggressive when outnumbered by females? Similarly, will males be more ag...
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...sity profiles, taken from Moore 2007.
Figure 1. Predicted average intensity scores for each treatment group across total experiment duration. Males are predicted to exhibit the highest intensity scores in the 3:1 Male : Female group. The 1:1 Male : Female control group is expected to display the lowest average intensity score.
1) Moore, Paul. “Agonistic Behavior in Freshwater Crayfish: The Influence of Intrinsic and Extrinsic Factors on Aggressive Encounters and Dominance.” 2007. PDF file.
2) Rubenstein, D.I., and Hazlett, B.A. (1974) Examination of the Agonistic Behaviour of the Crayfish Orconectes virilis by Character Analysis. Behaviour. 50:193-216.
3) Wofford, Sarah Jane. "Sex and Fighting: Male and Female Crayfish Utilize Different Assessment Strategies During Agonistic Behavior." MS thesis Graduate College of Bowling Green, 2013. Web.