Roff D A, Wolak M E, Correa L A, Soto-Gamboa M
Department of Biology, University of California, Riverside, CA, USA.
Institute of Biological and Environmental Sciences, School of Biological Sciences, Zoology Building, University of Aberdeen, Aberdeen, UK.
Heredity (Edinb). 2017 Sep;119(3):136-141. doi: 10.1038/hdy.2017.20. Epub 2017 Apr 12.
In some mammals, female characteristics have been shown to depend, in part, on the intrauterine position during development of female fetuses relative to male fetuses. Females developing in close proximity to males show behavioral, physiological and life history characteristics that are masculinized. With the exception of one inconclusive study, nothing is known of the genetic basis of this phenomenon. In this paper, we reported an analysis of the quantitative genetic basis of masculinization, as indicated by the anogenital distance (AGD) at birth and weaning, in the rodent Octodon degus. Because AGD is related to weight, we included a genetic analysis of pup weight at birth and weaning. Pairwise correlations showed that AGD at birth varied negatively with litter size and parturition number but positively with weaning AGD, birth weight, dam AGD and percentage of males in the litter. AGD at weaning varied similarly except that it tended to vary positively with litter size. Genetic (co)variances of AGD at birth and weight at birth differed in females and males. In females, the best genetic model included substantial effects of direct additive, additive maternal and a negative additive genetic covariance between these two. In males, variances were small and there was difficulty in discriminating between additive maternal and common environmental variances. By weaning, genetic (co)variances had somewhat declined in weight and were not statistically significant in AGD in either sex. This paper showed the occurrence of both phenotypic and genetic components in masculinization with effects being greater in females.
在一些哺乳动物中，已表明雌性特征部分取决于雌性胎儿在发育过程中相对于雄性胎儿的子宫内位置。在靠近雄性的环境中发育的雌性表现出行为、生理和生活史特征的雄性化。除了一项尚无定论的研究外，对于这一现象的遗传基础一无所知。在本文中，我们报告了对啮齿动物八齿鼠出生时和断奶时的肛门生殖距离（AGD）所表明的雄性化定量遗传基础的分析。由于AGD与体重有关，我们还纳入了对出生时和断奶时幼崽体重的遗传分析。成对相关性表明，出生时的AGD与窝仔数和产仔数呈负相关，但与断奶时的AGD、出生体重、母鼠AGD以及窝中雄性的比例呈正相关。断奶时的AGD变化情况类似，只是它往往与窝仔数呈正相关。出生时AGD和出生体重的遗传（协）方差在雌性和雄性中有所不同。在雌性中，最佳遗传模型包括直接加性效应、母体加性效应以及这两者之间的负加性遗传协方差。在雄性中，方差较小，难以区分母体加性方差和共同环境方差。到断奶时，体重的遗传（协）方差有所下降，且在任何性别中AGD的遗传（协）方差均无统计学意义。本文表明雄性化中存在表型和遗传成分，且在雌性中的影响更大。
