CONICET | Buscador de Institutos y Recursos Humanos

The extent of stress caused by acute and chronic environmental disturbances depends on the adaptive ability of organisms to behaviorally and physiologically buffer against change and on the timing and magnitude of the disturbances. The resilience of populations is linked not only to the current environmental conditions but also to whether populations have been exposed to selection pressures from similar perturbations in the past. Volcanic eruptions cause great and variable perturbation in populations and communities. An eruption of the Puyehue-Cordón Caulle volcano on June 4, 2011 dispersed about 100 M tons of pyroclastic material across the Patagonian steppe to a mean depth of more than 30 cm, affecting many reptile populations including several lizard species. At the other end of the disturbance spectrum, a gradual but chronic increase in temperature exacerbated by ozone depletion in the southern hemisphere could affect reptile populations differently because of the vital role that temperature plays during ontogeny. Recent studies show that populations of tropical viviparous reptiles are more vulnerable to an increase in environmental temperature due to the decrease in the number of hours of activity per day to perform their vital activities. In contrast, reptiles that inhabit cold-temperate environments of Patagonia as well as those at high elevation in the Andes could benefit from the increase in global temperature due to the fact that in general their body temperatures are below preferred and optimum temperatures for physiological performance. Furthermore, cold temperate environments may provide refuge for northern species, which might shift their geographic ranges southward, potentially impacting extant local populations by competing for resources and bringing new pathogens. In this chapter we summarize the baseline studies on whole-animal physiological adaptations of lizards from Patagonia and discuss the biotic and abiotic selective factors. We integrate thermal biology (field and preferred temperatures, heat sources, and efficiency of thermoregulation), influence of the immune system on body temperature, sensitivity of locomotion to temperature and plasticity (optimal performance temperature, thermal performance breadth and acclimation capacity), and thermal sensitivity of development at geographic and temporal scales (age at sexual maturity and longevity). The complex interplay of ecophysiological traits of lizards from Patagonia is discussed in relation to their legacy of survival, having withstood and recovered from fluctuations in temperature and the catastrophic events that have occurred over the past ~140Mya as are predictions of the possible effects of acute and chronic disturbances, such as volcanism and climate change, on extant populations.

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