Managing Wildlife Through ‘Evolutionary Traps’

Evolutionary traps cause animals to prefer and select resources or behaviors that result in poor outcomes in terms of the survival of their particular species. Examples include selecting habitats, food, or mates that minimize species’ fitness level or create a dangerous situation for individual animals. In other words, the animal adopts a set of maladaptive behaviors that result in the decline of the species’ population. 

The emergence of evolutionary traps is typically a result of a rapidly changing environment. For example, climate change could cause an environment to change more rapidly than a given species can keep up with. From a traditional standpoint, evolutionary traps have been viewed as a significant threat to a broad range of species and have therefore been viewed as a negative phenomenon. However, evolutionary traps can also be intentionally created as a form of wildlife or species management. 

There are three general mechanisms by which intentional traps can be used to manage wildlife. The first mechanism is to introduce a new resource or modify existing environmental cues to make a poor behavioral option appear at least as attractive as an optimal behavioral option. An example of this is creating artificial surfaces that reflect more sunlight than natural bodies of water, encouraging aquatic insects to lay their eggs on objects that result in a failure to hatch. A second mechanism is to minimize the benefits associated with a behavioral option without actually modifying the environmental cues, such as having beetles feed and lay their eggs on piles of wood that will be destroyed. The beetles are selecting an environment as they normally would, but the environment is planned to be destroyed post the deposit of eggs. The third and final mechanism is a hybrid approach of these first two approaches. 

Based on a synthesis of the existing literature, the authors of this paper then identified best practices for leveraging evolutionary traps as a form of management. 594 papers were reviewed, of which 44 had clear evidence of evolutionary traps used in practice. Of those articles, 27 had associated data that could be used for a quantitative meta-analysis. Based on the analysis of that data, the overall effects across the studies ranged from moderate to large in terms of the reduction of population, with the majority of studies yielding large effects. Furthermore, the first mechanism (a new resource or modification of existing environmental cues) was found to be most effective. Also, as expected, situations where the preference for the poor option was severe yielded larger effects. These results indicate that evolutionary traps are most effective when a new resource or modification of an existing environment cue causes the animal to strongly prefer the poorer option. With that being said, another factor to consider is the likelihood that the organism will encounter the trap. 

While evolutionary traps can be highly effective in wildlife management, their use can generate some unintended consequences. For example, one caveat to consider when implementing environmental traps as a species reduction strategy is to design the traps so that they do not impact nontarget species, which has unfortunately occurred in ecological restoration projects. There is also, of course, an ethical dimension to consider; in many situations, wildlife “management” means trying to reduce populations. Evolutionary traps may do so without the need for hunting, for example, but that doesn’t mean that the target population (be they invasive or not) isn’t suffering. 

In summary, this research shows that the use of evolutionary traps can be an effective strategy for managing wildlife populations. These traps could be used in situations where species are invasive or grossly overpopulated, causing a significant negative impact on other nearby species who share the same ecosystem. Although evolutionary traps can help manage wildlife, care should be taken to ensure that they are designed in a most effective and ethical manner, with the fewest unintended consequences possible.