Phenotypic plasticity in reproductive traits induced by food availability in a lacertid lizard, Takydromus septentrionalis

Abstract

Understanding the proximate determinants of phenotypic variations in life‐history traits can provide powerful insights into a species’ life‐history strategies. I experimentally manipulated availability of food (high vs low) to examine plasticity in the reproductive traits of northern grass lizards, Takydromus septentrionalis (Lacertidae), from eastern China. Food availability significantly affected reproductive frequency and thereby seasonal reproductive output, but had little effect on reproductive output per clutch. Low‐food females postponed reproduction and produced less clutches in the reproductive season than did high‐food females. After producing their second clutches, low‐food females were in lower body condition than the high‐food counterparts. By the end of the experiment, however, all females exhibited similar body condition. Clutch size and clutch mass differed between the first and second clutches but not between the treatments. Egg size and phenotypic traits of hatchlings (body size, morphology and locomotor performance) in T. septentrionalis did not vary significantly from first to second clutches nor between the two treatments. These results support optimal egg size (offspring) theory. Female T. septentrionalis “decide” whether or not to reproduce largely based on current energy intake; lowered feeding rates thus delay oviposition and reduce reproductive frequency. In contrast, clutch size, egg size and relative clutch mass remain unchanged.