Bluer in the city: urban male lizards exhibit more intense sexual coloration and lower parasite loads than non-urban males.

Urbanization is a global phenomenon that involves the transformation of natural areas into urban spaces, thereby subjecting organisms to new selective pressures including a wide variety of pollutants and changes in intra- and interspecific interactions. Considering that projections indicate that by the year 2050, 65% of the human population will live in urban areas and that urbanization is a phenomenon with an upward pattern, identifying these phenotypic traits is vital to implementing conservation and management plans for urban fauna. The urban environment may exert different selective pressures on sexually selected traits than more pristine environments, a phenomenon which has been well studied in birds but is less understood in other vertebrates such as lizards, although they are common inhabitants of urban environments.

Thermoregulatory behavior varies with altitude and season in the sceloporine mesquite lizard.

In ectothermic animals, body temperature is the most important factor affecting physiology and behavior. Reptiles depend on environmental temperature to regulate their body temperature, so geographic variation in environmental temperature can affect the biology of these organisms in the short and long term. We may expect physiological and behavioral responses to temperature change to be especially important in ectotherms inhabiting temperate zones, where different seasons present different thermal challenges.

Genetic determination and JARID2 over-expression in a thermal incubation experiment in Casque-Headed Lizard.

Non-avian reptiles, unlike mammals and birds, have undergone numerous sex determination changes. Casque-Headed Lizards have replaced the ancestral XY system shared across pleurodonts with a new pair of XY chromosomes. However, the evolutionary forces that triggered this transition have remained unclear.

Corytophanids Replaced the Pleurodont XY System with a New Pair of XY Chromosomes.

Almost all lizard families in the pleurodont clade share the same XY system. This system was meticulously studied in Anolis carolinensis, where it shows a highly degenerated Y chromosome and a male-specific X chromosome dosage compensation mechanism. Corytophanids (casque-headed lizards) have been proposed as the only family in the pleurodont clade to lack the XY system.