David Hembry (University of Arizona)
Abstract. The argument that interactions promote the generation and maintenance of species diversity, thereby engendering the generation of even more biodiversity in a sort of virtuous circle, is long-standing and highly influential in ecology and evolutionary biology. Not only is this one of the major problems in biology and the study of ecological complexity, but it is fundamental to understanding biodiversity’s response to global change, both past and future. However, evidence that interactions promote diversification is notoriously mixed. In this talk I will highlight two approaches to addressing this problem in biology. First, I will present empirical work on the dynamics of coevolution and diversification of a specialized insect-plant mutualism (leafflower trees in the genus Phyllanthus s. l. and leafflower moths in the genus Epicephala) on remote islands in the Pacific Ocean. In Asia and the South Pacific, leafflower trees depend on leafflower moths to pollinate their flowers; in turn, the moths’ larvae consume some of the seeds of the trees as food. There are hundreds of species of leafflower trees; because species-specificity between trees and moths is very high, there are presumably also hundreds of species of leafflower moths. Examination of the diversification of these two clades across Pacific islands has revealed the ease with which these interactions dynamically dissemble and reassemble over evolutionary timescales and provide insights into the evolution of ecological networks. Second, I will discuss outstanding problems in addressing the role of biotic interactions in the diversification of life. In particular, I will suggest conceptual and theoretical advances—particularly the integration of coevolutionary biology, macroevolution, and network ecology—which are necessary to address the role of biotic interactions in generating biological diversity.