Speciation: Expanding the Role of Biogeography and Niche Breadth in Macroevolutionary Theory

Abstract

Understanding the processes that control speciation is critical to building a comprehensive macroevolutionary synthesis. A variety of theoretical constructs have been proposed to explain various differential speciation patterns observed in the fossil record, such as higher rates of speciation among specialist versus generalist taxa. Most of these explanations, however, rely on only one or two explanatory variables and may be overly simplistic. Developing a more complete understanding of speciation processes requires a broader synthesis of multiple explanatory factors including the role of external factors such as climatic and tectonics, impact of ecosystem-level processes, relative niche breadth, and relative stability of species’ niches during environmental change (biotic and abiotic). This chapter explores the relationship between biogeography, ecological niches, and speciation in a series of case studies focused on Paleozoic (Late Ordovician and Late Devonian) shallow marine brachiopods and bivalves and Cenozoic (Neogene) horses of North America.