CANCELLED - How does previous experience affect response to conspecific vs. heterospecific alarm cues in Brachyrhaphis rhabdophora?

Background/Question/Methods

A variety of animal species sample alarm cues from their environment to gain information about predation threats. Fish, specifically, release chemical alarm cues from damaged skin cells when injured and the majority of fish species demonstrate innate antipredator behavioral responses when exposed to such alarm cues. However, these responses are often phylogenetically-conserved and species-specific, elicited only when the cue is sourced from a conspecific fish. Fish exposed to alarm cues from other closely-related species sometimes demonstrate lessened or different types of responses. Factors that contribute to a broad or specific alarm cue recognition and response are still being understood, but higher levels of background risk might lead to broader recognition ability. Here we investigate whether different predation environments contribute to the specificity of a population’s alarm cue recognition. Specifically, we tested two populations that differ in co-occurrence with predators. We measured the behavioral responses of lab-bred B. rhabdophora when exposed to alarm cues from conspecifics of their own population, a heterospecific species (Poecilia reticulata), or water as a control. We recorded the activity, area use, and dashing behavior before and after administering each cue. We then re-tested each fish 30 days later to determine the repeatability of each individual’s response.

Results/Conclusions

B. rhabdophora reduced activity and increased bottom-dwelling behavior in response to both conspecific and heterospecific alarm cue treatments relative to the control. Preliminary data indicates that populations do not differ in their strength of response to heterospecific cues, with both populations displaying a similar reduction in mean swimming velocity. While there was no difference in activity reduction based on alarm cue donor, conspecific cues resulted in more bottom-dwelling and freezing behavior than heterospecific cues. Baseline swimming behavior of an individual was not repeatable, and was instead dependent on the treatment and whether it was their first or second trial. While control fish behaved similarly in both trials, individuals exposed to either alarm cue treatment had lower baseline activity levels after their first trial. However, they still displayed a similar proportional reduction in activity after exposure to alarm cues in both their first and second trials. Preliminary results for the low-predation population, Rio Grande, indicates that individuals may display repeatable proportional changes in activity when exposed to alarm cues. This study highlights how an individual’s experience changes their behavior over time and contributes to our broader understanding of how chemosensory information and selective environment shapes decision-making in predator-prey interactions.