Quantifying climate and habitat effects on biogeography and range shifts across local and global scales

Abstract

Species distributions globally are ultimately shaped by the environment, and have been shifting at accelerating rates in response to ongoing environmental changes, with profound social and economic impacts. In this thesis, I examined the quantitative effects of climate and habitat factors on determining species geographic ranges and driving redistribution across both local and global scales. At local scales, I synthesized published resurvey data and studied elevational range shifts of montane species in the context of warming and land-use change. I found strong synergistic effects between these two drivers on species’ upslope movement across elevational gradients. At the global scale, I projected geographic ranges of ant genera based on their physiological and behavioural thermal constraints, and compared such projections with actual occurrence records. The results suggest that surface temperature is a primary determinant of ant distributions, most likely by constraining daily schedules of foraging activities.

Overall, my research illustrates how key environmental features, including temperature and habitat, act interactively in determining species distribution and range shifts. Statistics and modelling tools can be applied to quantify the influence of different factors and reveal often overlooked interactions that can be crucial in predicting future species distributions. Therefore, by providing a quantitative background of biogeography and biodiversity redistribution under global change, this study contributes to global conservation planning and management in the age of the Anthropocene.