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

Abstract

Aim Understanding the mechanisms that drive phenotypic divergence along climatic gradients is a long‐standing goal of biogeography. To fulfil this objective, we tested if neutral and/or adaptive effects drive phenotypic diversification. We quantified the effects of neutral evolution and natural selection on morphological variability 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‐ or long‐term neutral evolution. We inferred genetic population structure using mitochondrial and nuclear markers, we quantified morphological differences among populations by performing geometric morphometric analyses, and we inferred an ecological 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 shape variation is explained by population structure. Skull size showed a clear Bergmannian pattern with larger animals in higher latitudes (in absolute values). Skull size divergence is driven by the combined effects of environmental factors and population structure. Intriguingly, none of the models explains the variation observed in jaw shape. Main Conclusion Population phenotypic variation in the Andean fox L. culpaeus is driven by deterministic and neutral processes. The methodological framework presented here opens up new opportunities to study phenotypic evolution; it allowed us to demonstrate that the processes explaining trait variation can differ among traits and to show empirically for the first time that a trait can diverge among populations due to simultaneous adaptation and neutral evolution.

Sistemática De Los Grandes Cánidos (Mammalia, Carnivora, Canidae) Fósiles De América Del Sur

“…Otro trabajo más reciente encontró un patrón de variación clinal en el tamaño del cráneo de esta especie, diferenciada en dos regiones: al norte del Ecuador coincide con la regla de Bergmann, ya que los cráneos aumentan al aumentar la latitud; al sur del Ecuador el tamaño disminuye con la temperatura y aumenta con la precipitación (Martínez et al, 2013). Martínez et al (2018) también exploraron la relación entre la forma del cráneo de Lycalopex culpaeus, utilizando morfometría geométrica 2D, con factores ambientales y la estructura genética de la especie, encontrando que su evolución está relacionado a factores adaptativos, como a procesos de evolución neutral. Schiaffini et al (2019) (Información Suplementaria online 2).…”

Andean rain shadow effect drives phenotypic variation in a widely distributed Austral rodent

“…Previous contributions documented that the morphology of some rodent species varies predictably and in strong association with geographic gradients of temperature and precipitation (Cordero & Epps, 2012; Wolf et al, 2009). However, only few previous studies were conducted using a southern Andean mammal species as a model (Martinez et al, 2018; Naya et al, 2014). In turn, there are no studies that have evaluated the existence of morphological changes along a rain shadow gradient such as the one that occurs in the southern Andes.…”

Divergent selection along elevational gradients promotes genetic and phenotypic disparities among small mammal populations

“…Therefore, we use two variables to provide a more complete description of shape in the mixed analyses. The first univariate term consisted of the score of regression of Procrustes coordinates on the log of centroid size, which has been shown to be an effective descriptor of intraspecific shape variation (Drake & Klingenberg, 2008;Maestri et al, 2016;Martinez et al, 2018). The second variable was the first principal component of the Procrustes coordinates, which summarized most of the shape variation.…”