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Stumpy illustrates the costs of combat
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Many animals resolve disputes prior to escalated combat by displaying signals of potential strength. Weapons and their size are often used as signals in theses displays. Unreliable signals of weapon strength are considered to be problematic for signalling theory and reliable signals are predicted to be the dominant form of communication. Crayfish routinely use their enlarged front claws for both intimidation and fighting, making these species ideal for studying the reliability of weapon size as signals of strength or ability. The lab has been involved with several research projects looking into unreliable signalling in freshwater crayfish. Our research to date has focused on two species, the Australian Slender Crayfish, Cherax dispar, and the Common Freshwater Crayfish Cherax destructor with projects investigating the relationship between morphology, performance, perceived resources and social dominance.
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| Mattress Creek, North Stradbroke Island |
The Slender Crayfish, Cherax dispar
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For female C. dispar claw size and claw strength determine dominance; that is, individuals with larger, stronger claws are dominant. In male C. dispar dominance is also determined by claw size however, claw strength has little influence, suggesting unreliability in the signal. The level of unreliability in this system may change with resource availability and potential performance trade-offs.
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The Common Freshwater Crayfish, Cherax destructor
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On the other hand………
Studies on C. destructor found social dominance for males was strongly correlated with both claw size and claw strength while in females it could be explained by claw size alone. Interesting questions arose as to why this would be…
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Researchers: Robbie Wilson, Candice Bywater, Greg Walter, Billy van Uitregt, Jess Oliver
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Publications
Wilson, RS, James, RS, Bywater, C, Seebacher, F. 2009. Costs and benefits of increased weapon size differ between sexes of the slender crayfish, Cherax dispar. Journal of Experimental Biology. 212: 853-858
Bywater, C, Angilletta, MJ and Wilson RS. 2008. Weapon size is a reliable predictor of weapon strength and social dominance in females of the slender crayfish. Functional Ecology. 22:311-316.
Wilson, RS, Angilletta, MJ., James, RS, Navas, C & F. Seebacher.2007. Dishonest signals of strength in male slender crayfish (Cherax dispar) during agonistic interactions. The American Naturalist. 170:284-291
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