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Thermal ecology of the Santa Cruz lava lizard (Microlophus indefatigabilis) from Galápagos, Ecuador: implications of the El Niño event

Abstract:

Temperature is the main environmental variable that lizards depend on to maintain their metabolic processes, this influence locomotor performance. Thereafter, if the environmental temperature increases, because of climate change, the lizards could be affected physiologically and ecologically. We evaluated the thermal efficiency and locomotor performance of 3 populations of Microlophus indefatigabilis. We recorded body, selected and critical temperatures of the organisms, their locomotor performance, and operative temperatures during the cold season of 2017. We obtained the environmental temperatures during the El Niño 1997 and 2015 events. We calculated their restriction hours during the sampling year and in possible increases in the cold season during El Niño. We found that body temperatures varied significantly among populations, but keep their selected temperatures, which are close to their optimum temperature for locomotor performance. Microlophus indefatigabilis is a thermoregulator in which its maximum values are close to its critical maximum temperature. Under normal years without El Niño event, the population with scarce vegetation cover presented hours of restriction, but with the increase in environmental temperatures, the species could increase its hours of restriction, limiting its feeding hours.