LOVERN, M.B.*; MCNABB, F.M.A.; JENSSEN, T.A.: Developmental effects of testosterone on behavior in male and female green anole lizards.

This study addressed the role of testosterone (T) in the development of sexually dimorphic behavior in the green anole lizard, Anolis carolinensis. We described the developmental pattern of endogenous T concentrations, and determined the behavioral effects of experimentally elevated T, in both juvenile males and females. T concentrations in the plasma ofhatchlings from laboratory-incubated eggs and field-sampled juveniles of all sizes, as well as in the yolks of freshly laid eggs in the laboratory, were compared to plasma T concentrations in adult males and females. There were no sex-specific differences in plasma T in hatchlings and small juveniles (< 26 mm snout-vent length, SVL; < 14 d old). However, plasma T sharply increased in juvenile males, but not females, after approximately 14 d post-hatching, and it became significantly higher after approximately 38 d post-hatching (> 30 mm SVL). 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, breeding or post-breeding. Furthermore, eggs that gave rise to males contained nearly twice as much yolk T on the day of oviposition as those that gave rise to females (0.9 vs. 0.5 pg/mg, respectively). Behavior trials revealed that, in comparison to juveniles given empty implants, juvenile males and females given T-implants had increased rates of nearly every behavior monitored, approaching those found in breeding adult males. These results demonstrate that in spite of sex differences in endogenous T exposure during ontogeny, juveniles of both sexes exhibit an equivalent behavioral response to elevated T.