Maternal basking opportunity affects juvenile phenotype in a viviparous lizard

1. The effects of external conditions on embryonic development have been repeatedly examined in oviparous reptile species, but the effect of gestation conditions on offspring traits in viviparous species has rarely been examined. 2. The influence of maternal basking opportunities on gestation length and juvenile phenotype was investigated in a viviparous scincid lizard, Niveoscincus ocellatus. Females were housed under one of two experimental regimes (10 or 4 h access to basking) which reflected the natural variation in temperature, potentially one of the most important proximate sources of life-history variation. 3. Females with longer access to basking gave birth significantly earlier than those with reduced basking opportunities. Maternal access to basking significantly affected the phenotype and growth rate of her offspring. 4. Offspring born after relatively rapid development were longer, heavier and in better condition than offspring born after slower development. 5. In standard laboratory conditions, offspring born after rapid development grew more rapidly than those born after slower development, thus amplifying the difference in body size between these two groups postpartum. 6. These results suggest the existence of a strong selective pressure on female basking behaviour through the effect of the maternal environment on embryo development and offspring phenotype and highlight the role of temperature as a proximate source of variation in both the timing of reproductive events and in key life-history traits of neonates.