PS 46-111 - Do anthropogenic stressors interact with predation risk to impact learning in Trinidadian guppies?

Background/Question/Methods

Freshwater ecosystems are undergoing dramatic changes due to anthropogenic disturbances. These disturbances may interact with preexisting biotic stressors like predation risk to impact prey in unpredictable and possibly synergistic ways. Prey rely on many sources of information concerning risk in their microhabitat such as chemical information like damaged-released cues, learned information, and phenotypically plastic neophobia. However, the information available to prey can be disrupted by anthropogenic perturbations. This can result in an ecological trap whereby individuals make choices which are maladaptive to their survival and can include responding to an illegitimate threat which is energetically costly, or failing to respond to a credible threat which can be deadly. The goal here was to understand how individual abiotic stressors, namely increased temperature, or turbidity, interact with predation risk to impact learning in Trinidadian guppies (Poecilia reticulata). In the laboratory, individual guppies were exposed to high vs normal levels of abiotic disturbance (temperature or turbidity) and high vs low levels of predation risk, before being conditioned to learn if a novel chemical stimuli was risky or not. The following day, they were tested for their learned response to this novel stimuli using observations of focal behaviours pre- and post-injection of the stimuli.

Results/Conclusions

Preliminary results suggest that indeed abiotic and biotic factors interact to influence learning in guppies. Notably, guppies exposed to both increased temperature and increased predation risk exhibited enhanced learning of a novel stimuli compared to those exposed to single stressors alone. This suggests that learning may convey a selective advantage in highly disturbed ecosystems. Exhibiting a learned response to a novel stimuli allows for prey to show context dependent neophobia and thus balance the energetic costs associated with antipredator behaviours. Given that approximately one in three freshwater species are at risk of extinction, it is critical to understand how freshwater prey species will respond to environmental change and ecological traps. Prey must cope with ecological unpredictability and variations in predation risk in tandem, and importantly, environmental stressors rarely exist in isolation. As such, the ability to make learned associations may be an important mechanism prey can use to manage variable risk in their environment. This has important implications for how prey will cope with anthropogenic disturbances such as climate change as well as animal behaviour and biodiversity more broadly.