Does predation environment affect repeated responses to predation cues in the fish Brachyrhaphis rhabdophora?

Abstract

More time spent by prey avoiding predators often results in less time allocated to energy acquisition and reproductive-related activities. Thereby, individuals that optimize this trade-off and respond appropriately to current risk levels in their environment should be at an advantage. But how does this tradeoff change when individuals repeatedly encounter predation threats? There may be advantages to prey by modulating behavior in response to repeated exposures to a threat. Moreover, it is unclear how evolutionary history of a population might affect such individual responses. Our study addressed two questions: (1) how does the fish Brachyrhaphis rhabdophora respond to repeated predation cues; and (2) do responses to repeated cues differ based on predation environment? To answer these questions, we repeatedly exposed B. rhabdophora individuals from high- and low-predation populations to a chemical predation cue. We measured the change in total distance traveled during 15-minutes before and after each cue exposure and compared the proportional change in response of each successive cue. We found that fish from both populations responded consistently to each of the four successive cue exposures. These results provide insights in understanding how both recent risk exposure and evolutionary history of risk influence individual response to threats over time.