Correa Loreto A, Aspillaga-Cid Antonia, Riquelme Juan D, Ly-Prieto Álvaro, Hayes Loren D, Ebensperger Luis A
Escuela de Medicina Veterinaria, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Camino la Pirámide, 5750, Huechuraba, Santiago, Chile.
Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
Sci Rep. 2025 Jul 1;15(1):22411. doi: 10.1038/s41598-025-03708-y.
The timing of exposure to testosterone produces activational and organizational effects in vertebrates. Evidence in female birds and mammals suggests that high serum testosterone levels, and the exposure to high testosterone levels during early development, are negatively associated with female fertility and sexual attractiveness to males. We tested these hypotheses by examining associations between serum testosterone levels (an indirect index of activational effects), anogenital distance (AGD, a direct index of organizational effects), the number of male mating partners attained by females, and the number of offspring weaned. We examined 160 wild degu (Octodon degus) females during the mating season, and 308 females during the nursing season, across an 11-year study. During the mating season, we found no association between female serum testosterone levels or AGD on the number of male mating partners, and on the number of offspring weaned. However, we found that the number of male mating partners was positively associated with the number of offspring weaned, suggesting that females attain direct fitness benefits from polyandrous mating. During the nursing season, we recorded a positive association between female AGD and the number of offspring weaned. This indicates that testosterone organizational effects positively impact female fertility. This finding is unique and adds to the theoretical framework of female phenotypical masculinization via intrauterine position phenomenon.
在脊椎动物中，接触睾酮的时间会产生激活和组织效应。雌性鸟类和哺乳动物的证据表明，高血清睾酮水平以及在早期发育过程中暴露于高睾酮水平与雌性生育能力和对雄性的性吸引力呈负相关。我们通过检查血清睾酮水平（激活效应的间接指标）、肛门生殖器距离（AGD，组织效应的直接指标）、雌性获得的雄性交配伙伴数量和断奶后代数量之间的关联来检验这些假设。在一项为期11年的研究中，我们在交配季节检查了160只野生八齿鼠（Octodon degus）雌性，在哺乳季节检查了308只雌性。在交配季节，我们发现雌性血清睾酮水平或AGD与雄性交配伙伴数量以及断奶后代数量之间没有关联。然而，我们发现雄性交配伙伴数量与断奶后代数量呈正相关，这表明雌性通过一妻多夫制交配获得了直接的适应性益处。在哺乳季节，我们记录到雌性AGD与断奶后代数量之间呈正相关。这表明睾酮的组织效应积极影响雌性生育能力。这一发现是独特的，并为通过子宫内位置现象导致雌性表型男性化的理论框架增添了内容。
