Thompson C W, Moore M C
Department of Zoology, Arizona State University, Tempe 85287-1501.
Horm Behav. 1992 Dec;26(4):568-85. doi: 10.1016/0018-506x(92)90023-o.
Species with alternative reproductive tacts are good models to investigate the poorly understood question of whether individual variation within sexes results from the same physiological mechanisms that control variation between sexes. We have shown previously that adult male tree lizards, Urosaurus ornatus, of different throat color morphs express different levels of aggression in the laboratory. Further field results support the suggestion that the two morphs practice alternative reproductive tactics because the two morphs express different levels of aggressive behavior under field conditions and exhibit dramatic and opposite responses to aggressive challenges. However, despite these behavioral differences, the two morphs do not differ in levels of testosterone or corticosterone either in undisturbed situations or following aggressive challenge. These results are consistent with the relative plasticity hypothesis which proposes that organizational, rather than activational, actions of steroid hormones will be more important in morph differentiation when morphs are fixed in adult life, as they are in tree lizards. These results also support the hypothesis that steroid hormonal levels are insensitive to social modulation in males of species such as U. ornatus without paternal care.
具有替代繁殖策略的物种是很好的模型，可用于研究一个尚未得到充分理解的问题，即两性内部的个体差异是否源于控制两性之间差异的相同生理机制。我们之前已经表明，不同喉部颜色形态的成年雄性树蜥（华丽角蜥）在实验室中表现出不同程度的攻击性。进一步的野外研究结果支持了这样一种观点，即这两种形态采用了替代繁殖策略，因为这两种形态在野外条件下表现出不同程度的攻击行为，并且对攻击性挑战表现出显著且相反的反应。然而，尽管存在这些行为差异，但在未受干扰的情况下或遭受攻击性挑战后，这两种形态的睾酮或皮质酮水平并无差异。这些结果与相对可塑性假说一致，该假说认为，当形态在成年期固定时，如在树蜥中那样，类固醇激素的组织作用而非激活作用在形态分化中更为重要。这些结果还支持了这样一种假说，即对于像华丽角蜥这样没有亲代抚育的物种的雄性，类固醇激素水平对社会调节不敏感。
