Effects of Different Social and Environmental Conditions on Established Dominance Relationships in Crayfish

Abstract

Like most social animals, crayfish readily form dominance relationships and linear social hierarchies when competing for limited resources. Competition often entails dyadic aggressive interactions, from which one animal emerges as the dominant and one as the subordinate. Once dominance relationships are formed, they typically remain stable for extended periods of time; thus, access to future resources is divided unequally among conspecifics. We previously showed that firmly established dominance relationships in juvenile crayfish can be disrupted by briefly adding a larger conspecific to the original pair. This finding suggested that the stability of social relationships in crayfish was highly context-dependent and more transient than previously assumed. We now report results that further identify the mechanisms underlying the destabilization of crayfish dominance relationships. We found that rank orders remained stable when conspecifics of smaller or equal size were added to the original pair, suggesting that both dominant and subordinate must be defeated by a larger crayfish in order to destabilize dominance relationships. We also found that dominance relationships remained stable when both members of the original pair were defeated by larger conspecifics in the absence of their original opponent. This showed that dominance relationships are not destabilized unless both animals experience defeat together. Lastly, we found that dominance relationships of pairs were successfully disrupted by larger intruders, although with reduced magnitude, after all chemical cues associated with earlier agonistic experiences were eliminated. These findings provide important new insights into the contextual features that regulate the stability of social dominance relationships in crayfish and probably in other species as well.

Prior social experience affects the behavioral and neural responses to acute alcohol in juvenile crayfish

“…Issa et al, 1999;Herberholz et al, 2007Herberholz et al, , 2016Graham and Herberholz, 2009), we cannot exclude the possibility that other factors, such as the difference in personal space between communally housed and isolated animals, may have contributed to our observed effects. For example, more crowded conditions could have led to higher gill ventilation rates and thus higher alcohol intake in Com animals.…”

Involvement of Melatonin in the Regulation of the Circadian System in Crayfish

“…Moreover, crayfish respond to external stimuli performing specific behaviors that have been extensively studied. For example, social crayfish species such as P. clarkii display an agonistic behavior by which they establish a hierarchical organization based on dominance [ 80 ]. Apparently, this behavior determines the access of the animals to limited ecological resources, such as food, shelters, mates, etc.…”