acroevolution provides a lens to investigate how species originate, adapt, diversify, respond to environmental change, and go extinct over deep time. However, many of the processes that generate large-scale biodiversity patterns ultimately operate through population-level demographic and genetic dynamics. This doctoral thesis leverages tarantulas (family Theraphosidae)—one of the most iconic and globally distributed groups of spiders, as a model system to integrate macroevolutionary, macroecological and population genetic perspectives, thereby linking evolutionary processes across temporal and biological scales.
The first chapter reconstructs the complex biogeographic history of tarantulas, addressing the paradox of decoupled centres of origin and centres of diversity. Using fossil-calibrated phylogenies and model-based ancestral range reconstructions, it reveals how plate tectonics, and asymmetric dispersal shaped their global distribution, challenging classical expectations of diversification centered around regions of origin.
The second chapter examines the drivers of asymmetric species richness among tarantula subfamilies. By disentangling the effects of evolutionary time and trait-mediated diversification, it demonstrates that clade age is the primary determinant of species richness, while defensive innovations such as urticating hairs elevate net diversification rate. This chapter presents an empirical support for “key innovations” correlating with higher diversification.
The third chapter explores the interplay between morphology and ecology, focusing on patterns of miniaturization. It links repeated transitions to non-burrowing terrestrial microhabitats with reduced body size and altered limb proportions, illustrating how ecological opportunity can disrupt long-term stabilizing selection and generate novel phenotypes.
The fourth chapter investigates how recent climatic change has shaped genetic diversity and demographic history across latitudes in tarantulas. By integrating mitochondrial genetic data with ecological niche models projected onto past climatic conditions, it reveals latitudinal variation in demographic responses since the Last Glacial Maximum, connecting macroecological patterns with population-level processes.
The final chapter extends this framework using whole genome sequencing of a Western Ghat endemic tarantula species to show that long-term climatic instability can generate fine-scale genetic structure even in the absence of physical barriers. By linking paleoclimate dynamics to genomic diversity and demographic history, this chapter demonstrates how past habitat dynamics leave enduring signatures at the genomic scale.
Together, these chapters integrate deep-time evolutionary history with contemporary genetic processes, highlighting how geography, traits, ecological transitions, and climate interact across scales to shape biodiversity.