ANALYZING LINKS BETWEEN SPECIATION, BIOGEOGRAPHY, AND NICHE STABILITY: THE ROLE OF COMPLEX FEEDBACKS IN DRIVING MACROEVOLUTIONARY PATTERNS

Understanding the processes that drive speciation is critical to any modern macroevolutionary synthesis. A variety of theoretical constructs exist to explain various patterns of differential speciation observed in the fossil record, such as higher rates of speciation among stenotopic vs. eurytopic species. 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 size and location of species’ geographic distributions, continuity or isolation of populations, bounding parameters of species’ niches, and relative stability of species’ niches during environmental change (biotic and abiotic). The relationships between speciation, evolutionary history, biogeography, and ecological niches are explored through a series of case studies focusing on the Late Ordovician and Late Devonian shallow marine brachiopods and bivalves and Neogene horses of North America.