Supplementary data to: Trapped in the morphospace: the trade-off between morphological integration and functional performance can limit adaptation

<p>The evolution of complex morphological structures can be seen as the result of interplay between different anatomical units evolving in a coordinated fashion. These can be influenced by genetic, developmental and/or functional integration in response to selective pressures. Using the highly derived humeral morphology of talpid moles as model, here we test whether functional specialization (measured as performance) can be linked to increased levels of morphological integration and, if so, what is the extent of the relationship. Combining 2D geometric morphometrics, phylogenetic comparative methods and functional landscape modelling, we demonstrate that the high biomechanical performance of subterranean moles was coupled with a high degree of integration, whereas less specialized taxa displayed intermediate or low magnitudes of integration. Theoretical morphs occurring in high-performance areas of the functional landscape not covered by any species showed a marked drop in covariation levels, suggesting the existence of a genuine tradeoff between integration and performance in the evolution of talpid moles. We argue that the remarkable stability of the subterranean environment may have helped constraining humeral morphology over a restricted area of the functional landscape, trapping subterranean moles in a narrow region of the landscape, impeding any attempt to reposition on a new ascending slope.</p>