The contribution of neutral evolution and adaptive processes in driving phenotypic divergence in a model mammalian species, the Andean fox Lycalopex culpaeus

MONTOYA-BURGOS, JUAN I.; BAHECHAR, ILHAM A.; MOLINA, WAGNER F.; MARTINEZ, PABLO A.; BIDAU, CLAUDIO J.; PIA, MONICA V.

JOURNAL OF BIOGEOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2018 vol. 45 p. 1114 - 1125

0305-0270

Aim: Understanding the mechanisms that drive phenotypic divergence along climaticgradients is a long-standing goal of biogeography. To fulfil this objective, wetested if neutral and/or adaptive effects drive phenotypic diversification. Wequantified the effects of neutral evolution and natural selection on morphologicalvariability of a well-suited mammalian species, the fox, Lycalopex culpaeus.Location: South America.Methods: We analysed variations in skull shape, jaw shape and skull size in L. culpaeus.The processes underlying our models were: local adaptation, and short- orlong-term neutral evolution. We inferred genetic population structure using mitochondrialand nuclear markers, we quantified morphological differences among populationsby performing geometric morphometric analyses, and we inferred anecological niche model for calculating environmental resistance between populations.Results: We identified six genetically differentiated populations of the Andean fox,which correspond well to the described subspecies. We showed that skull shapevariation is explained by population structure. Skull size showed a clear Bergmannianpattern with larger animals in higher latitudes (in absolute values). Skull sizedivergence is driven by the combined effects of environmental factors and populationstructure. Intriguingly, none of the models explains the variation observed injaw shape.Main Conclusion: Population phenotypic variation in the Andean fox L. culpaeus isdriven by deterministic and neutral processes. The methodological framework presentedhere opens up new opportunities to study phenotypic evolution; it allowedus to demonstrate that the processes explaining trait variation can differ amongtraits and to show empirically for the first time that a trait can diverge among populationsdue to simultaneous adaptation and neutral evolution.