To Be a Dominant Female: A Hard Way to Go

Abstract

Copyright: © 2012 da Silva Mota MT. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Reproduction is a very demanding task for any species. It is a combination of mating effort (time and energy spent searching and attracting sexual partners) and parental effort (time and energy invested in infant care) which are the main determinants of male and female reproductive success [1]. As an example, I am going to focus this editorial on a small primate endemic to Brazil, the common marmoset, Callithrix jacchus. They live in extended family groups with 5 to 17 individuals that may or may not be genetically related [2,3]. Reproduction is restricted to a single pair but polygynous and polyandrous groups have been also reported [4,5]. Concerning adult females, social hierarchy determines their reproductive status that competes for breeding positions and mating opportunities. The competition can be expressed by behavioral and physiological mechanisms such as intrasexual aggression, infanticide, inadequate alloparental care, puberty delay and ovulatory suppression [6]. Adult female usually gives birth to twins that are around 15% of the mother’s weight which need full time care. They are cooperative breeders and all members of the social group are potential helpers from the first day after the birth of infants [7]. It is important to note that the distribution of care varies between individuals, with adult males being the main caretakers [8]. Their participation in infant care and the number of infants being carried change prolactin levels which may be related to physical effort following carrying behavior [9]. Thus, the participation of helpers is essential to reproductive success and influence the hormonal profile of caretakers.