Insect Species Coexistence and Conservation Amidst Global Change

Insects are well known for their extraordinarily high levels of species diversity and for the ecological and cultural services they provide. Yet global environmental change driven by humans is imposing numerous challenges on the ability of insect species to coexist and maintain diverse assemblages. Here, we provide an overview of insect coexistence in response to global change. First, we review recent developments in coexistence theory, which establishes the criteria to be met for identifying coexisting species, and the spatial scales at which this occurs. Second, because not all species may be coexisting, we identify how ecological differences or lack thereof may contribute to other patterns of species co-occurrence and community structure. Third, we present several examples of how global change, ranging from species introductions to species range shifts, is altering species coexistence at both local and regional scales. Finally, we examine how adaptive evolution and phenotypic plasticity may influence species responses to global change and affect their abilities to coexist. We may never know if the vast diversity of insects on this planet is being maintained via coexistence mechanisms. Nevertheless, we contend that developing this understanding should take priority for conservationists concerned with addressing the effects of global change on biodiversity.