PARALLEL GEOGRAPHIC-VARIATION IN BODY SHAPE AND REPRODUCTIVE LIFE-HISTORY WITHIN THE AUSTRALIAN SCINCID LIZARD LAMPROPHOLIS-DELICATA

1. Interspecific comparisons suggest that lizard life history and morp hology coevolve and that reproductive output may be constrained by mor phology. However, the interplay between morphology and life-history ch aracteristics remains poorly investigated in intraspecific comparisons . We studied variation in body shape (relative interlimb length) and r eproductive life-history characteristics along a latitudinal gradient of populations of Lampropholis delicata, a small oviparous Australian scincid lizard, to examine whether reproductive expenditure is correla ted with body shape. 2. Our analyses revealed considerable geographic variation in mean body size, body shape and reproductive life history. The variation in reproductive traits (i.e. clutch size, egg size, clu tch volume and relative clutch volume) was not a simple consequence of variation in body size among populations. Mean clutch size and mean e gg size were equally variable among populations. 3. Latitude accounted for approximately 30% of the variance in life-history phenotypes amon g populations, presumably mediated by differences in climate. Overall, lizards in southern populations tended to mature at a smaller size, h ave larger interlimb lengths as adults and produce clutches with more and larger eggs, as compared to lizards in northern populations. 4. Ou r results suggest a trade-off between the number and the size of offsp ring within but not among populations. Lizards in southern populations were able to produce larger eggs, without a concomitant reduction in clutch size, because adults were larger in absolute terms, and they ha d larger abdominal volumes relative to body size. 5. Relative interlim b length accounted for 71% of the variance in relative clutch volume a mong populations. This positive correlation between body shape and rel ative clutch volume may have arisen because: (1) body shape constrains reproductive expenditure below optimal levels or (2) body shape has i tself evolved to allow optimal levels of reproductive expenditure, as determined by life-history trade-offs.