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The Burden of Motherhood: The Effect of Reproductive Load on Female Lizard Locomotor, Foraging, and Social Behavior


Michele A. Johnson, Department of Biology, Trinity University, San Antonio, TX 781212, USA.


The costs of reproduction, involving demands associated with both current and future reproductive efforts, may place a substantial burden on females. However, animals may minimize these costs by modifying their behavior across the reproductive cycle. We examined the effects of reproductive load on three types of behavior (locomotion, foraging, and social displays) in green anole lizards (Anolis carolinensis) by comparing egg, follicle, and oviduct mass and volume with field observational data. We found that female locomotor and social display behaviors decreased as reproductive load increased, suggesting behavioral modification in these traits, but we detected no relationship between foraging and reproductive load. We also examined these relationships across eight Anolis species using a phylogenetically informed analysis and found no associations between the evolution of reproductive load and any of the three behaviors. These results suggest that the evolution of increased reproductive load is not associated with the interspecific variation in behavior across the anoles and may result from varying life history traits or selective ecological pressures across species.