Department of Zoology, Box 351800, University of Washington, Seattle, Washington 98195.
Integr Comp Biol. 2002 Feb;42(1):11-20. doi: 10.1093/icb/42.1.11.
Vertebrates show a diverse array of social behaviors associated with territoriality. Field and laboratory experiments indicate that underlying themes-including mechanisms-may exist. For example in birds, extensive evidence over many decades has implicated a role for testosterone in the activation of territorial aggression in reproductive contexts. Territoriality at other times of the year appeared to be independent of gonadal hormone control. One obvious question is-why this diversity of control mechanisms for an apparently similar behavior? Control of testosterone secretion during the breeding season must balance the need to compete with other males (that tends to increase testosterone secretion), and the need to provide parental care (that requires lower testosterone concentrations). Regulation of aggressive behaviors by testosterone in the non-breeding season may incur substantial costs. A series of experiments on the male song sparrow, Melospiza melodia morphna, of western Washington State have revealed possible mechanisms to avoid these costs. Song sparrows are sedentary and defend territories in both breeding and non-breeding seasons. Dominance interactions, territorial aggression and song during the non-breeding season are essentially identical to those during the breeding season. Although in the non-breeding season plasma testosterone and estradiol levels are very low, treatment with an aromatase inhibitor decreases aggression and simultaneous implantation of estradiol restores territorial behavior. These data suggest that the mechanism by which testosterone regulates territorial behavior at the neural level remains intact throughout the year. How the hormonal message to activate such behavior gets to the brain in different season does, however, appear to be different.
脊椎动物表现出多种多样与领地性相关的社会行为。野外和实验室实验表明，可能存在潜在的主题机制。例如，在鸟类中，几十年来的大量证据表明，睾丸激素在生殖环境中激活领地攻击性方面发挥了作用。而在一年中的其他时间，领地性似乎与性腺激素控制无关。一个显而易见的问题是——为什么对于一种明显相似的行为会存在如此多样化的控制机制？繁殖季节睾丸激素分泌的控制必须平衡与其他雄性竞争的需要（这往往会增加睾丸激素分泌），以及提供亲代照顾的需要（这需要较低的睾丸激素浓度）。非繁殖季节睾丸激素对攻击行为的调节可能会产生巨大的代价。对来自华盛顿州西部的雄性歌雀，Melospiza melodia morphna 的一系列实验揭示了可能的机制来避免这些代价。歌雀是定居性的，在繁殖和非繁殖季节都捍卫领地。非繁殖季节的支配性相互作用、领地攻击性和鸣叫与繁殖季节基本相同。尽管在非繁殖季节血浆睾丸激素和雌二醇水平非常低，但用芳香化酶抑制剂处理会降低攻击性，同时植入雌二醇会恢复领地行为。这些数据表明，睾丸激素调节神经水平领地行为的机制在全年都保持不变。然而，在不同季节，向大脑传递激活这种行为的激素信息的方式似乎不同。
