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Color polymorphisms are common across reptile species and are frequently correlated with variation in behavior and other functional traits. Here, we tested whether the ventral color morphs (yellow, orange and white pure, as well as yellow-orange and white-orange mosaic morphs) of European wall lizards (Podarcis muralis) exhibit differential temporal changes in their reaction to exposure to a novel environment. We conducted 15 min long trials of a novel environment test (open field test) in a set of populations from the eastern Pyrenees. Locomotion, boldness and freezing behavior changed over time, in agreement with a previous study carried out in central Pyrenees, but without highlighting a clear behavioral difference among color morphs. Only yellow-orange lizards showed a distinct correlation pattern between locomotion and body size compared to the other morphs. Carefully standardized studies involving more populations are needed to unravel the complex interactions between morphological and behavioral traits among lizard color morphs.

Abstract Explaining the evolutionary origin and maintenance of color polymorphisms is a major challenge in evolutionary biology. Such polymorphisms are commonly thought to reflect the existence of alternative behavioral or life‐history strategies under negative frequency‐dependent selection. The European common wall lizard Podarcis muralis exhibits a striking ventral color polymorphism that has been intensely studied and is often assumed to reflect alternative reproductive strategies, similar to the iconic “rock–paper–scissors” system described in the North American lizard Uta stansburiana. However, available studies so far have ignored central aspects in the behavioral ecology of this species that are crucial to assess the existence of alternative reproductive strategies. Here, we try to fill this gap by studying the social behavior, space use, and reproductive performance of lizards showing different color morphs, both in a free‐ranging population from the eastern Pyrenees and in ten experimental mesocosm enclosures. In the natural population, we found no differences between morphs in site fidelity, space use, or male–female spatial overlap. Likewise, color morph was irrelevant to sociosexual behavior, space use, and reproductive success within experimental enclosures. Our results contradict the commonly held hypothesis that P. muralis morphs reflect alternative behavioral strategies, and suggest that we should instead turn our attention to alternative functional explanations.

Colour polymorphism may be accompanied by alternative expressions of phenotypic traits that are directly or indirectly related to fitness, and selection forces may act on the traits separately or concurrently. In polymorphic species, natural selection may act through frequency- or density-dependent mechanisms and maintain polymorphism through interactions among morphs. We used an integrative approach to examine functionally relevant and interrelated life history traits in the context of colour polymorphism in the European wall lizard (Podarcis muralis). Body, head and limb morphology, bite and locomotor performance, and physiology, particularly metabolic and antioxidant capacity, were analysed in the three pure colour morphs (yellow, orange, white) and the two mosaic morphs (yellow-orange and white-orange). Morphological differences between morphs were present but subtle and consisted mainly of variations in head length. Head size and bite force were strongly associated between and within morphs. Limb and boot morphology and locomotor performance (sprinting and climbing) were variably associated among morphs. Finally, variation in biochemical indicators of cellular metabolism and antioxidant capacity appeared to be largely independent of morphology and performance. The results provide evidence for existing and non-existing relationships between colour and morphology, performance, and physiology that could have short- and long-term effects on selection.

Con más de 4400 especies reconocidas, los lagartos (un grupo parafilético, ya que no incluye a las serpientes) son los reptiles más abundantes y uno de los grupos más numerosos de vertebrados terrestres. Los lagartos conjugan un elevado número de especies con una tremenda diversidad morfológica, ecológica y de comportamiento. Algunos lagartos son diminutos, de tan sólo 2-3 cm de longitud total como adultos (Hedges y Thomas, 2001), mientras que otros pueden llegar a medir más de 3 m. Hay lagartos capaces de volar o correr sobre el agua y otros que carecen de patas y parecen serpientes. Hay especies muy longevas, que viven más de 40 años, y otras que apenas viven unos meses como adultos (Karsten et al., 2008). Excepto en las zonas de mayor latitud o altitud, donde están limitados por su ectotermia, encontramos lagartos en casi todos los hábitats conocidos. Algunos desiertos y selvas tropicales albergan comunidades compuestas por más de una docena de especies distintas (Pianka, 1986). Su comportamiento social, de forrajeo y antidepredador es muy variable. En algunas especies, machos y hembras se asocian apenas unos minutos cada año para reproducirse, mientras que en otras establecen vínculos duraderos de pareja. La diversidad es sin duda una de las características más destacadas de los lagartos. Es responsable de su éxito evolutivo y contribuye a la fascinación que ejercen los lagartos y a su utilización, desgraciadamente cada vez más frecuente, como mascotas. Pero los lagartos poseen además otras características que, junto a la diversidad, los convierte en sujetos ideales para estudios de ecología y de comportamiento. Las dos más frecuentemente citadas suelen ser su crucial posición filogenética y su accesibilidad al trabajo experimental. De hecho, durante las últimas décadas varios autores han sugerido que los lagartos podrían reemplazar a las aves como organismos ‘modelo’ en estudios de la biología de los vertebrados (Greenberg et al., 1989; Vitt y Pianka, 1994; Pianka y Vitt, 2003; Lovern et al., 2004).