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Costs of reproduction in a tropical invariant-clutch producing lizard (Carlia rubrigularis)


Brett A. Goodman, School of Tropical Biology, James Cook University, Townsville, Qld 4811, Australia. Tel: 61-7-47815715; Fax: 61-7-47251570


Reproduction involves costs and benefits, whereby increased expenditure into current reproduction can reduce future reproductive success. Costs of reproduction, often assessed using the reduction in locomotor speed, have become well established in temperate-zone lizard species. However, substantial differences in biotic conditions and life-history traits between temperate- and tropical-zone lizards suggest that such costs may be different or of less importance for tropical species. This study examined the effects of reproduction on locomotor speed in the tropical invariant-clutch producing lizard Carlia rubrigularis. Counter to predictions and despite a low relative clutch mass (RCM), gravid and post-oviposition females experienced a reduction in locomotor speed with a physiological basis that was unrelated to the level of reproductive investment. In addition, gravid and postoviposition females exhibited locomotor speeds that were inversely related to the timing of oviposition and approached the speed of non-reproductive females after 3 weeks of oviposition. These results suggest that in addition to RCM, selection may act to reduce the period of recovery in species with extended reproductive seasons and which make numerous bouts of reproduction, such as C. rubrigularis.