We examined the relationships between maternal size, breeding season stage, and offspring sex at hatching for the oviparous lizard Anolis carolinensis. Specifically, we tested two hypotheses: (1) large females produce offspring with male-biased sex ratios and small females produce offspring with female-biased sex ratios; and (2) females, regardless of size, produce offspring with male-biased sex ratios early in the breeding season and female-biased sex ratios late in the breeding season. We found no support for either hypothesis. Rather, we found that individual females of all sizes and throughout the breeding season alternated offspring sex of sequentially laid eggs. Because female anoles also alternate the ovary that produces successive eggs, we tested a third hypothesis: females produce eggs of only one sex with each ovary. Both palpation to track which ovary produced which eggs, and unilateral ovariectomies, leaving females with only one functioning ovary, failed to support this hypothesis. Regardless of whether an ovary was removed, females were capable of producing both male and female offspring from either ovary. To account for this and potentially other unusual patterns of offspring production, we provide evidence that maternal hormone levels around the time of fertilization may affect offspring sex.
We examined the relationship between body size and pursuit success in the lizard Cnemidophorus uniparens. Using grasshoppers as prey in experimental feeding trials, we found a significant positive relationship between lizard body size and pursuit time. In addition, larger individuals were significantly more likely to be unsuccessful at capturing the grasshoppers. We also examined the relationship between the mean body size of Cnemidophorus populations and diet composition. We found a significant negative relationship between mean body size and the proportion of grasshoppers in the diet and a significant positive relationship between mean body size and the proportion of termites in the diet.
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