Recent studies suggest that climatic changes may tip the balance between interacting species, leading to the extinction of one or more species. Interspecific interactions, however, are complicated by coevolution between the two species, potentially altering the likelihood of extinction. Here, we use simple models to organize and synthesize the ways coevolution modifies species coexistence when climatic changes favor one species over another.
Results/Conclusions
In cases where species have conflicting interests (i.e., selection for interspecific interaction strengths on one species is detrimental to the other), we show that coevolution reduces the effects of climate change, leading to reduced chances of extinction. Conversely, when species have non-conflicting interests (i.e., selection for interspecific interactions on one species benefits the other), coevolution increases the effects of climate change, increasing extinction risk. These phenomena occur because in each case coevolutionary selection pressure increases with the density of the other species. Thus, as the climate changes, the species without direct benefits from climate change experiences stronger selection pressure, which speeds up evolution and decreases (increases) the negative (positive) effects of the interaction on the less-benefited species. Thus, coevolution may increase or decrease the effect of climate change on species extinctions, depending on the form that coevolution takes between species.