Comportamento agonístico em lagostins: mudanças ao longo dos estágos de vida e sistemas de avaliação

Abstract

The present study was developed by two steps which include respectively: the aggression development along the life stages of the burrowing species Parastacus brasiliensis; and the determination of the type of information used and the comparison of the assessment strategies in agonistic interactions in P. brasiliensis and in the open water species Pacifastacus leniusculus. We aimed to demonstrate how life habit can lead to different life and assessment strategies, using crayfish species as models. In the first step, we paired individuals according to their body size among different life stages of P. brasiliensis and analyzed the contest dynamics to determine how aggression escalates. We tested the relation between body size and contest duration, number of bouts, and frequency of low and highly aggressive behaviors. Contest duration and low aggressive behaviors increased with body size, whereas the number of bouts and frequency of highly aggressive behaviors were not related to body size. Individuals may have distinct motivations to fight throughout the life stages. As the individual threshold follows the body development, it could influence the willingness to persist in a contest. While larger individuals persist more, smaller individuals could perceive themselves as potential losers and attempt to withdraw from the contest earlier. In the second step, we assembled the individuals of P. brasiliensis and P. leniusculus in intraspecific pairs according to three experimental setups based on the Resource Holding Potential (RHP) and communication: random pairs; RHP-matched pairs that could not communicate; and RHPmatched pairs that could communicate. To differ between self-assessment (SA) and Sequential Mutual Assessment (SAM)/Cumulative Assessment (CAM) models, we regressed RHP proxies with contest duration of the random pairs, and the RHP-matched pairs that could not communicate. When SAM/CAM strategies were the best fit, we tested the difference in contest duration between RHP-matched pairs that could not communicate with those that could communicate, thus testing role of communication in decision-making. Species differed in their type of assessment: the open water species relied on a mixed strategy of SAM and CAM, and the burrowing species relies on a SA strategy. Therefore, the habitat could be influencing information reliability and exchange, selecting the most suitable strategy for each species.