Reproductive Tactics of Sympatric Gekkonid Lizards with a Comment on the Evolutionary and Ecological Consequences of Invariant Clutch Size

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Abstract
Four sympatric species of gekkonid lizards were studied simultaneously in northeastern Brazil for 12 months. Lygodactylus klugei was the smallest species and Phyllopezus pollicaris was the largest with Gymnodactylus geckoides and Hemidactylus mabouia intermediate in size. Lygodactylus is diurnal whereas Hemidactylus and Phyllopezus are primarily nocturnal. Gymnodactylus may be partially noctural and partially diurnal but is usually active in dark microhabitats. Females are larger than males in two species and sexes were similar in the other two. In L. klugei, the only diurnal species, male head size increased with SVL more rapidly than in females. This sexual dimorphism is most likely a consequence of sexual selection. Sexually dimorphic characters may differ in visually-oriented lizards compared to auditory-oriented species. Reproduction is continuous in all four species and egg size among species is correlated with female size. Egg size is not correlated with female size within a species. A summary of data on offspring size of additional gekkonids reveals a tight correlation between female size and offspring size. It is suggested that selection for optimal offspring size may be a partial determinant of female body size in species with invariable clutch size. A comparison with sympatric species studied during the same time period adds to the diversity of reproductive strategies exhibited by lizards occurring at the same place. Nearly every known lizard reproductive strategy is represented by at least one species occurring in the semi-arid caatinga of northeast Brazil.