The effect of parental age on the quantity and quality of offspring in , a species with male pregnancy.

Parental age impacts offspring quantity and quality. Most prior research focused on maternal age. Since in most organisms the mother produces the costly eggs plus provides all or most parental care, it is difficult to distinguish maternal effects mediated via the egg from later maternal care.

Navigating sex and sex roles: deciphering sex-biased gene expression in a species with sex-role reversal ().

Sexual dimorphism, the divergence in morphological traits between males and females of the same species, is often accompanied by sex-biased gene expression. However, the majority of research has focused on species with conventional sex roles, where females have the highest energy burden with both egg production and parental care, neglecting the diversity of reproductive roles found in nature. We investigated sex-biased gene expression in , a sex-role reversed species with male pregnancy, allowing us to separate two female traits: egg production and parental care.