Thermal divergence in a color polymorphic lizard inhabiting contrasting environments in central Mexico

Abstract

The niche partitioning hypothesis predicts differential use of resources among morphs depending on resource dynamics and morph frequencies. Additionally, morphs might select microhabitats favorable for the regulation of body temperature through behavioral mechanisms. Intra- and intersexual social interactions among morphs can also affect patterns of niche partitioning. Here, we evaluated whether body size, thermal traits (body and environmental temperatures, and behavioral thermoregulation), microhabitat use, and perch height differ among male and female throat color morphs of the lizard Sceloporus grammicus in four different habitat types. Color morphs of both sexes differed in body size, thermal traits, and perch height but not microhabitat use. Lizards of grassland and xeric scrubland were larger, and had greater values of thermal traits but exhibited lower perch height than lizards of mountain cloud forest and pine-oak forest. We found clear evidence of thermal niche partitioning and partial space niche partitioning among color morphs of both sexes of S. grammicus in central Mexico. These results improve our knowledge of the ecology of color polymorphic vertebrate species and show that color morphs of each sex have specific trait combinations to facilitate the use of thermal resources.