Patrones latitudinales en la sensibilidad térmica de los anfibios

KREIMAN LUCAS

Montevideo

Seminario; Patrones latitudinales en la sensibilidad térmica de los anfibios; 2017

A number of hypotheses based on the relationship between ambient temperature (TA) and physiological variables (e.g., metabolic rates) have been proposed to explain geographic patterns of variation in distribution ranges. Accordingly, analyzing spatial variation in thermal sensitivity of standard metabolic rates (Q10-SMR) could be relevant to understand the mechanistic basis of species distribution patterns. However, at present there is minimal information published regarding latitudinal variation in Q10-SMR. Here, we propose a conceptual model based on the idea that species should show increased thermal sensitivity to the range of ambient temperatures usually experienced in nature. The basis for this idea is that species minimize maintenance costs during the colder hours of the day, but quickly take advantage of increases in TA during the warmer parts of the day. Thus, we predicted that Q10-SMR values estimated at lower temperatures should be higher for temperate species than for tropical species, while the contrary should hold true for Q10-SMR values estimated at higher temperatures. To test our prediction, we created a dataset that includes all records of Q10-SMR that have been published for amphibians worldwide (51 species). Using conventional and phylogenetic analyses, we demonstrate that, in line with our prediction, Q10-SMR values measured at 5-15 ºC and at 10-20 ºC were higher in temperate species, while Q10-SMR values measured at 15-25 ºC and at 20-30 ºC tended to be higher in tropical species. To our knowledge, this is the first study analyzing Q10-SMR in amphibians at a global scale, and reporting a pattern of latitudinal variation that is congruent with an adaptive hypothesis