Macroevolution provides a lens to investigate how species originate, adapt, diversify, respond to environmental changes and go extinct. My doctoral thesis leverages tarantulas (Family Theraphosidae) as a model system to explore these questions, weaving together biogeography, trait evolution, morphology, and climate to understand the forces shaping biodiversity patterns.
The first chapter reconstructs the complex biogeographic history of tarantulas, addressing the paradox of decoupled centers of origin and diversity. Using fossil-calibrated phylogenies and ancestral range reconstructions, it reveals how plate tectonics and dispersal events sculpted their global distribution, refuting the classical “centrifugal” model of speciation.
The second chapter examines the drivers of asymmetric species richness in tarantula subfamilies. Disentangling the effects of evolutionary time and trait-driven diversification, it demonstrates how defensive innovations, such as urticating hair, increase diversification rates. By empirically testing the “escape and radiate” hypothesis alongside alternative models, this chapter offers insights into how traits drive long-term biodiversity patterns.
The third chapter explores the interplay between morphology and ecology, focusing on miniaturization. It links shifts to non-burrowing terrestrial microhabitats with reduced body size and altered limb proportions, illustrating how ecological opportunity can catalyze morphological evolution. Defying Cope’s rule, this study emphasizes the role of niche shifts in driving body size reduction.
The fourth chapter investigates the impact of recent climate change on tarantula genetic diversity and niche dynamics. By integrating genetic analyses with species distribution models projected across past climates, it reveals how environmental changes since the Last Glacial Maximum have shaped population structures. The findings underscore the vulnerability of biodiversity to rapid environmental shifts, bridging ecological and evolutionary perspectives on climate change.
Together, these chapters address core themes in macroevolution, including the roles of geography, traits, ecological transitions, and environmental change in shaping biodiversity. By contextualizing tarantulas within broader eco-evolutionary frameworks, this thesis offers insights into how life diversifies and adapts, with implications for addressing the global biodiversity crisis.