Effects on the thermoregulatory efficiency of two native lizards as a consequence of the habitat modification by the introduction of the exotic tree Acacia longifolia

STELLATELLI O; VEGA L.E; BLOCK C; CRUZ FB

JOURNAL OF THERMAL BIOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2013 vol. 38 p. 135 - 142

0306-4565

Habitat modification alters several aspects of the original fauna, among them the opportunity forthermoregulation. Here, we studied the thermal biology of sympatric populations of two lizard species(Liolaemus multimaculatus and Liolaemus wiegmannii) in two different situations; a grassland withouttrees (natural habitat) and in a grassland plus the exotic tree Acacia longifolia (modified habitat), aimingto assess whether the structural alteration of native Pampean coastal grasslands of Argentina affects thethermal biology of these lizards. Field body temperatures, laboratory preferred temperatures, microenvironmentaltemperatures, operative temperatures, thermoregulatory efficiency and spatial distribution ofeach species were analyzed in both habitats. Environmental operative temperature was 0.64 1C lower inthe modified habitat (Te¼38.39 1C) than in the natural (Te¼39.03 1C). Thermoregulatory efficiency (E)of L. wiegmannii was lower in modified sites (E¼0.58) than in natural sites (E¼0.70). This differencemay be because this lizard occupied shaded microhabitats under acacias, with suboptimal thermalfeatures. In contrast, L. multimaculatus in the modified habitat restricted its activity to openmicroenvironments that retained a similar structure to that of the native habitat, while maintaininghigh thermoregulatory efficiency in both habitat types (Emodified¼0.92; Enatural¼0.96). Although thesetwo lizard species are phylogenetically close, they respond differently to human-induced changes intheir thermal environments. The introduction of A. longifolia into coastal grasslands for L. wiegmannii inparticular, this introduction converts its native habitat into a suboptimal thermal environment