Microgeographic diversity does not drive macroevolutionary divergence in bite force of the Ibiza wall lizard, Podarcis pityusensis.

Despite extensive research, it is still poorly understood how microgeographic phenotypic variation translates to the macroevolutionary level. Here, we use the Ibiza wall lizard, Podarcis pityusensis, an endemic species of the Balearic Islands, to study microgeographic variation across different scales of evolutionary isolation. We quantify bite force and morphology alongside biotic and abiotic environment in 11 populations, which have been variably isolated from one another over the Quaternary period. While we generally find increasing divergence in form and function as populations become more isolated from each other, this is not true when isolation is the highest; phenotypic differences between the 2 major clades of P. pityusensis are negligible, despite populations being isolated for over 100,000 years. Our results show that how environmental selective pressures drive form-function evolution differ by sex. Natural selection appears the most important driver of female evolution, while male phenotypes are apparently driven by both natural and sexual selection, but precise drivers of form-function evolution vary according to the scale of isolation investigated. Our study demonstrates incongruence in form-function-environment relationships within a constrained geographical area, highlighting how convergence at greater evolutionary scales can obscure microevolutionary diversity.