crayfish, aggressive behaviors, winner and loser effects




Agonistic and aggressive behaviors are a common occurrence within crayfish populations in the natural world. These behaviors appear to be very important to individual crayfish in establishment of their social status and in dominance hierarchies that inevitably form within the populations. An important factor in the founding of these hierarchies and an individual’s status within them is the occurrence of winner and loser effects. The winner effect can be defined as the increased probability of an individual winning the next fight after a pervious winning experience. The inverse of this defines the loser effect. The winner effect is a well‐established occurrence within crayfish species. However, the loser effect has not yet been as extensively demonstrated. This study was designed to observe the loser effect in a novel crayfish species. The experimental crayfish were first given a losing experience and then the result of their next fight was observed and recorded. The importance of loser effect is in its ability to aid in the formation and stability of dominance hierarchies and also as a contributing factor in the overall fitness of crayfish. The loser effect is beneficial to an individual’s fitness, because it leads to behavior that seeks to avoid situations in which the chance for injury is high and increased energy expenditure would occur. Our findings in this study indicate that the loser effect is a statistically reliable event in the novel crayfish species and, further, that it is as strong and stable as the winner effect.

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