Conclusions
Taken together, HIRECs have profound and potentially cascading effects on wild animals’ behavior and physiology that are likely to change the proportion of proactive and reactive individuals in a population, and these changes may lead to changes in species’ distribution and abundance. These are the results of three distinct time-related steps: 1) migration of proactive individuals, 2) survival of reactive individuals, and 3) genetic evolution. Based on our current knowledge, we propose that HIRECs which may not systematically relax predation pressure, such as climate change, pollution or harvesting, mostly lead to a genetic evolution towards reactive individuals with reduced boldness and aggressive behavior, and increased plasticity and that these changes are associated with changes in underlying physiology. In parallel, we suggest that other HIRECs which relax predation pressure, such as tourism, urbanization, captivity and domestication, will favor the emergence of a new coping style between reactive and proactive individuals that we refer to as preactive.
While there is now a large literature on individuality and personality traits in nature, we suggest that by systematically investigating the underlying physiological mechanisms, we will be better able to develop predictive models of response to HIREC. Additionally, we emphasize that multigenerational and multivariate studies investigating the effects of HIREC on coping styles are warranted and we hope that future studies will allow us to better understand the conditions and the dynamics of the process that favor the emergence of preactive individuals. Finally, given the vital importance of coping style by environment interactions, we must learn more about the cascading effects of HIREC on ecological systems.