Testosterone inhibits growth in juvenile male eastern fence lizards (Sceloporus undulatus):: Implications for energy allocation and sexual size dimorphism
Testosterone inhibits growth in juvenile male eastern fence lizards (Sceloporus undulatus):: Implications for energy allocation and sexual size dimorphism
复制标题
DOI：
10.1086/430226
复制
发表时间：
2005-07-01
影响因子：
1.6
通讯作者：
John-Adler, HB
中科院分区：
文献类型：
--
作者：
Cox, RM;Skelly, SL;John-Adler, HB
在东部栅栏蜥蜴，Sceloporus undulatus，女性较大的性别大小二型性的发展，因为一岁的女性比男性在第一次繁殖前生长得更快。这种性生长差异与成熟期雄性攻击性、运动和腹侧着色的增加相一致，所有这些都受到性类固醇睾酮（T）的影响。这些观察结果表明，男性的增长可能会受到精力充沛的活动成本的限制，并牵连T作为这种潜在的权衡的生理调节。为了验证这一假设，我们使用手术阉割和随后的外源性T管理，以改变生理和行为表型的字段活跃的男性在性生长分化期间。正如预测的那样，T抑制雄性的生长，而阉割促进长期生长。用T处理的雄性动物也表现出日常活动时间、运动和家域面积增加。食物消耗量没有显着差异，男性治疗或性别，这表明T对生长的抑制作用是介导的能量分配模式，而不是收购。根据已发表的数据估计，我们得出结论，T操纵后增加日常活动期的能量成本足以解释大部分（79%）相关的增长减少。此外，生长可能受到T操纵后增加的外寄生虫负荷的额外能量成本的限制。类似的研究，近的行为，生态和生理机制参与生长调节，应大大提高我们的性别大小二型性的理解。
In the eastern fence lizard, Sceloporus undulatus, female-larger sexual size dimorphism develops because yearling females grow faster than males before first reproduction. This sexual growth divergence coincides with maturational increases in male aggression, movement, and ventral coloration, all of which are influenced by the sex steroid testosterone ( T). These observations suggest that male growth may be constrained by energetic costs of activity and implicate T as a physiological regulator of this potential trade-off. To test this hypothesis, we used surgical castration and subsequent administration of exogenous T to alter the physiological and behavioral phenotypes of field-active males during the period of sexual growth divergence. As predicted, T inhibited male growth, while castration promoted long-term growth. Males treated with T also exhibited increased daily activity period, movement, and home range area. Food consumption did not differ among male treatments or sexes, suggesting that the inhibitory effects of T on growth are mediated by patterns of energy allocation rather than acquisition. On the basis of estimates derived from published data, we conclude that the energetic cost of increased daily activity period following T manipulation is sufficient to explain most (79%) of the associated reduction in growth. Further, growth may have been constrained by additional energetic costs of increased ectoparasite load following T manipulation. Similar studies of the proximate behavioral, ecological, and physiological mechanisms involved in growth regulation should greatly improve our understanding of sexual size dimorphism.