Thermal quality along an altitudinal gradient for a lizard community in Sierra del Ajusco and Pedregal de San Ángel, Mexico

Abstract

We evaluated and compared the thermal quality for a lizard community (9 species) in Sierra del Ajusco andPedregal de San Ángel (central Mexico) along an altitudinal gradient (2 320-3 530 m) to determine whether differentthermal environments may be influencing species distribution and thermoregulatory behavior. Six areas that differ inelevation and vegetation type are chosen to survey environmental operative temperatures. Habitat thermal quality isestimated from the mean deviation of operative temperatures from lizards’ selected thermal range. Results indicate 3key findings: 1) operative temperature and thermal quality are higher at lower elevations (2 320 and 2 540 m), wherexeric scrub vegetation was abundant; 2) thermal quality is lowest in closed-canopy pine forest (2 870 and 3 220 m);and 3) intermediate values of operative temperature and thermal quality are observed in open grassland habitat (3 000and 3 530 m). These results support our hypothesis that elevation and vegetation type affect thermal quality and weconclude that thermal ecology studies should be conducted at multiple spatial scales to gain a better understanding offactors influencing the thermal niche and thermoregulatory profiles.