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 behavioural, 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.
Degus data Dryad submission: Data for analysis of AGD and wt in Degus
This work is licensed under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication license.
- Octodon degus