Developmental effects of testosterone on behavior in male and female greenanoles (Anolis carolinensis)

This study addressed the role of testosterone (T) in the development of sex ually dimorphic behavior in the green anole lizard, Anolis carolinensis, We documented the pattern of endogenous T concentrations during ontogeny and we determined the behavioral effects of experimentally elevated T in juveni le males and females. T concentrations were measured in the plasma of hatch lings from eggs incubated in the laboratory, in juveniles of all sizes samp led in the field, acid in the yolks of freshly laid eggs in the laboratory and were compared to plasma T in adult females (measured in this study) and adult males. There were no sex differences in plasma T in hatchling acid s mall juvenile (<26-mm snout-vent length, SVL; <14 days old) males and femal es, concentrations of which in both sexes tended to decline over the 14-day posthatching period. Plasma T sharply increased in juvenile males, but not females, after approximately 14 days posthatching (>25-mm SVL), and it bec ame significantly higher after approximately 38 days posthatching (>30-mm S VL). Plasma T for juvenile males was within the range detected in breeding adult females, but it was 20- to 45-fold lower than that of adult males, br eeding or postbreeding. All eggs contained detectable yolk T, but eggs that gave rise to males contained nearly twice as much yolk T as those that gav e rise to females, We do not know whether this yolk T comes from the mother , embryo, or both, In behavior trials conducted in the laboratory, juvenile s 136- to 42-mm SVL) with T implants, regardless of whether they were male or female, had increased activity levels compared to juveniles with blank i mplants, due to increased rates of nearly every behavior monitored. These r esults are discussed in the context of the organization-activation theory o f sexual differentiation and the particular life history of A, carolinensis , (C) 2001 Academic Press.