Award Lecture

Abstract

How does speciation, the birth of new species, occur? The vast array of species on Earth today has emerged through multiple cycles of speciation from common ancestors, making speciation a universal phenomenon in life's history. The mechanisms driving the origination of diverse species are also diverse, and theoretical approaches employing mathematical models have long played a crucial role in our understanding of speciation. In this talk, I will provide a concise overview of a series of theoretical studies I have conducted to understand patterns of species diversity. Rather than viewing speciation as a one-time event when new species arise, I propose a perspective of the "speciation cycle." In this view, speciation is seen as a recurring cycle where populations that have already undergone speciation continue to engage in further speciation events. This perspective considers not only the evolution of reproductive isolation but also ecological factors such as interspecific competition, coexistence of multiple species, and the formation of subpopulations through the dispersal of individuals. These ecological elements interact with the microevolutionary processes, enabling the speciation cycle to continue. I will discuss how microevolutionary processes scale up to shape the current species diversity over much longer evolutionary timescales and explore the prospects for future theoretical research based on our current understanding.