Miguel’s research is broadly focused on macroecology and conservation biogeography and has encompassed studies of vertebrates and plants. Most of his work has been centred on two vertebrate groups that remain largely underrepresented in the macroecological literature: amphibians and reptiles. He is particularly interested in describing broad-scale spatial patterns in the variation of biological traits at the interspecific level to examine the validity of some well-known ‘ecogeographical rules’. This includes the investigation of Bergmann’s rule, a trend of increasing body size towards colder climates, which formed the core of his PhD thesis.