Individual strategies to cope with environmental change : a test of the pace-of-life syndrome hypothesis

Abstract

Understanding the evolutionary causes and effects of diverse life-history strategies (i.e. how organisms allocate limited energy resources throughout their lifetime) is a principal aim of life-history theory. The pace-of-life syndrome (POLS) hypothesis expands the slow-fast continuum of life-histories to incorporate associations with physiological and behavioural traits to explain life-history variation at the individual or population level. An important prediction of the POLS hypothesis is that variation in single traits (e.g. metabolic rate) cannot be understood by measuring them in isolation, because specific combinations of traits have co-evolved as integrated syndromes with environment- and state-dependent consequences to fitness. The POLS hypothesis suggests individuals at the "slow-end of the continuum will exhibit particular trait values, such as low metabolic rates, low activity levels, shy behavioural types, increased survival rates, and low rates of growth and reproductive output. In the same environment, other "fast POLS individuals might exhibit the opposite set of trait values, with equal long-term fitness consequences. Correlational selection of traits to form optimal syndromes could provide an explanation for the perplexingly high amount of variation in single behavioural and physiological traits that seem likely to be under strong directional selection. Metabolic rate, for example, is a trait that is likely to have important effects on fitness, yet this trait often varies several-fold even among individuals of the same population. The persistence of variation in metabolic rate could be explained if it represents one component of a correlated suite of traits that, acting as an integrated syndrome, provides an individual with increased fitness under specific environmental or intrinsic conditions. Hence, the POLS hypothesis, although not entirely a new idea, provides a unifying theory for predicting the importance of variation in key traits at the individual level. Despite the attraction of the POLS hypothesis, empirical studies are needed to test assumptions regarding links between behaviour and metabolism, and their ecological consequences in different environments. The current research project addresses that need using wild caught house mice (Mus musculus) as a model species. The research conducted here provides a robust test of the POLS hypothesis in a wild animal population by determining whether individuals exhibit consistent and correlated differences in key behavioural and physiological traits. Additionally, the research addresses a clear gap in our knowledge about the physiological ecology of wild-living house mice in Australia.

Date of Award	2018
Original language	English