The sooner the better: Reproductive phenology drives ontogenetic trajectories in a temperate squamate (Podarcis muralis)

Abstract

Understanding variations in individual trajectories is a crucial evolutionary issue. Terrestrial ectotherms from temperate regions typically face thermal constraints and limited activity periods. Developmental conditions (i.e. embryonic life) and reproductive timing (laying date) should induce phenotypic variations and influence subsequent ontogenetic trajectories (growth and survival). We studied these combined influences in an oviparous squamate, the wall lizard (Podarcis muralis), comprising a multiple clutch species with natural variations in laying date for the first clutch. We experimentally manipulated maternal basking opportunities during gravidity (3, 6 or 9h per day) and incubation temperature (23 or 29°C). Early laying date positively influenced winter survival in both incubation treatments. Survival was significantly lower in cool than warm-incubated individuals (14.8% and 73.6%, respectively) because of delayed hatching date and reduced activity period before winter. Individuals from cool incubation temperature were slightly smaller but had a higher body condition and grew faster during the first month of life. Offspring behaviour was driven by complex interactions between gravidity and incubation treatments. Under cool incubation temperature, defensive behaviour was high, independently of gravidity treatment. Warm incubated individuals showed low defensive response except when maternal basking opportunities were restricted to 3h. Defensive behaviour at birth had a positive influence on survival in cool-incubated individuals. The results of the present study highlight the long-term influence of hatching date that integrates female reproductive timing and incubation conditions. © 2012 The Linnean Society of London.