Laboratorio de Ecología Conductual, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, campus Isla Teja s/n, Valdivia, Chile.
Physiol Behav. 2013 Jul 2;119:161-7. doi: 10.1016/j.physbeh.2013.06.002. Epub 2013 Jun 13.
Female phenotypic masculinization is a phenomenon widely described among mammals. In species that produce litters, female masculinization occurs in utero during late trimester of pregnancy as consequence of the intrauterine position phenomenon (IUP), affecting morphological, physiological and behavioral traits during adulthood. One morphological trait that is affected by IUP is anogenital distance (AGD) that is utilized as proxy of the female phenotypic masculinization. In rodents, IUP have ecological and behavioral effects including aggressiveness, territory marking, activity level, parental care and sociality. In this work, we evaluated how female masculinization (or feminization) affects aggressive behavior and determines social dominance, which in turn could lead to the structuring of social groups through dominance hierarchy formation in degus. We carried out a laboratory study where we established artificial social groups composed of females with the similar and different AGDs, and recorded all social interactions identifying initiator/recipient in dyad relationships and the nature of each interaction. Female aggression varied depending on the degree of females' masculinization, but only in mixed groups (those composed of females with different AGDs) was a hierarchical relationship observed. Furthermore, dominance hierarchies were constructed mostly on the basis of submissive, rather than aggressive interactions. Finally, female behavioral and morphological masculinization was not due to higher plasma testosterone levels, which would indicate that the masculinization of the female phenotype is the consequence of the organizational effects of steroid hormones during ontogeny.
女性表型雄性化是一种广泛存在于哺乳动物中的现象。在产仔物种中，女性雄性化发生在妊娠晚期的子宫内，这是由于子宫内位置现象（IUP）的影响，这种现象会影响成年后的形态、生理和行为特征。IUP 会影响到一种形态特征，即肛门生殖器距离（AGD），AGD 被用作女性表型雄性化的替代指标。在啮齿动物中，IUP 具有生态和行为影响，包括攻击性、领地标记、活动水平、亲代照顾和社会性。在这项工作中，我们评估了女性雄性化（或雌性化）如何影响攻击性行为，并确定了社会支配地位，这反过来又可以通过在毛丝鼠中形成支配等级结构来构建社会群体。我们进行了一项实验室研究，在研究中，我们建立了由具有相似和不同 AGD 的雌性组成的人工社会群体，并记录了所有社会互动，以确定对偶关系中的发起者/接受者以及每次互动的性质。女性的攻击性取决于女性雄性化的程度，但只有在混合群体（由具有不同 AGD 的雌性组成的群体）中才观察到等级关系。此外，支配等级主要是基于顺从而不是攻击的相互作用来构建的。最后，雌性的行为和形态雄性化不是由于血浆睾丸酮水平升高，这表明雌性表型的雄性化是类固醇激素在个体发育过程中组织效应的结果。
