Personality and the pace-of-life syndrome: variation and selection on exploration, metabolism and locomotor performances

Consistent individual differences in behaviour are seen in numerous animals and could be maintained by life-history trade-offs and integrated within a pace-of-life syndrome involving physiological and locomotor traits. Lizard species are characterized by inter-specific variation in activity and foraging behaviours associated with differences in locomotor performances and metabolic rates. Similar syndromes could exist within species, but have not been investigated so far. We scored the exploratory behaviour of newborn common lizards (Zootoca vivipara) using a neutral arena test and measured concomitantly resting metabolic rate (RMR), maximal sprint speed (MSS) and endurance capacity. Animals were released in outdoor enclosures exposed to avian predation and measured again for the same traits 1 year later. Common lizards displayed consistent individual differences over a week for an exploration score associated with high activity in the neutral arena. Individual differences in three activity scores were also consistent over the first year of life. Correlations among behavioural, metabolic and locomotor traits were weak, except for a marginally significant, positive correlation between exploration score and MSS and endurance at the age of 1 year. Correlational survival selection was found for RMR and exploration score such that newborns with low exploration score and high RMR and newborns with high exploration score and low RMR survived better. Correlational growth selection was also found with faster growth in newborns with low exploration score and high RMR. The results are discussed against recent hypotheses to explain the maintenance of animal temperaments.