Meeting Abstract
P1.146 Friday, Jan. 4 TESTING CAUSAL RELATIONSHIPS BETWEEN METABOLIC RATES AND FITNESS IN BLACK CAPPED CHICKADEE (Poecile atricapillus): IMPLICATIONS FOR THE EVOLUTION OF ENDOTHERMY CLAVIJO-BAQUET, S*; PETIT, M; VéZINA, F; Pontificia Universidad Católica de Chile; Université du Québec à Rimouski; Université du Québec à Rimouski sclavijo@bio.puc.cl
The evolution of endothermy and the associated heat production mechanisms are still one of the most intriguing questions in comparative biology. In this sense, several models have been proposed to explain it, named the parental care model, thermoregulatory model and aerobic capacity model. The main difference between these models is that they point out a different trait as target of natural selection during the evolution of endothermy. However, few studies have evaluated the relationship between these physiological traits and fitness and most studies used a correlational approach and mammalian models to test hypotheses. Here, we evaluated two of the most important models (parental care and thermoregulatory models) testing causal relationships between physiological traits as body temperature (Tb), basal metabolic rate (BMR) or thermogenic capacity (Msum) with fitness in black-capped chickadees (Poecile atricapillus). We first estimated the probability of survival based on two years of capture-recapture data and then performed structural equation modeling (SEM) including Msum, BMR, Tb and body mass. This provided a set of causal-effect relationships representing each model proposed for the evolution of endothermy which we could then evaluate using a model selection approach.
