Androgen levels and female social dominance inLemur catta

Abstract

Morphological and behavioural traits which improve agonistic power are subject to intrasexual selection and, at the proximate level, are in£uenced by circulating androgens. Because intrasexual selection in mammals is more intense among males, they typically dominate females. Female social dominance is therefore unexpected and, indeed, rare. Ring-tailed lemurs (Lemur catta) are sexually monomorphic primates in which all adult females dominate all males. The goal of our study was to test the prediction that female dominance in this species is associated with high androgen levels. Using two captive groups, we collected data on agonistic behaviour and non-invasively assessed their androgen concentrations in faeces and saliva by enzyme immunoassay. We found that adult female L. catta do not have higher androgen levels than males. However, during the mating season there was a twofold increase in both the androgen levels and con£ict rates among females. This seasonal increase in their androgen levels was probably not due to a general increase in ovarian hormone production because those females showing the strongest signs of follicular development tended to have low androgen concentrations. At the individual level neither the individual aggression rates nor the proportion of same-sexed individuals dominated were correlated with their androgen levels. We conclude that female dominance in ring-tailed lemurs is neither based on physical superiority nor on high androgen levels and that it is equally important to study male subordination and prenatal brain priming e¡ects for a complete understanding of this phenomenon.

Androgens in a female primate: Relationships with reproductive status, age, dominance rank, fetal sex and secondary sexual color

“…Our results for the relationship between fecal androgens and rank in female mandrills are similar to those reported for female yellow baboons (fecal testosterone, Altmann et al, 1995), ring-tailed lemurs (fecal and salivary testosterone, von Engelhardt et al, 2000), and bonobos (fecal 5a-androstan-17a-ol-3-one, Sannen et al, 2004), in which rank is also not related to androgens. However, our findings differ from those for captive talapoins (serum testosterone, Batty et al, 1986), hybrid baboons (fecal testosterone, Beehner et al, 2005), and Barbary macaques (fecal 17b-OH-androgens, Grant et al, 2011), in which dominant females show higher androgen levels than subordinates.…”

“…However, there is no relationship between rank and fecal testosterone in female yellow baboons (Papio cynocephalus, Altmann et al, 1995), between rank and fecal and salivary testosterone in ring-tailed lemurs (Lemur catta, von Engelhardt et al, 2000), or between rank and fecal 5a-androstan-17a-ol-3-one in bonobos (Pan paniscus, Sannen et al, 2004).…”

“…For example, rank is inherited maternally in yellow baboons (Hausfater et al, 1982), where there is no relationship between rank and fecal testosterone, while the hybrid population may have more potential to contest their position, and show is a relationship between rank and fecal testosterone (Beehner et al, 2005). However, ring-tailed lemurs contest their rank position, yet there is no relationship between rank and testosterone, measured either in feces or in urine (von Engelhardt et al, 2000). Thus, there is as yet no comprehensive understanding of the link between dominance rank and androgens in female primates.…”

Non-invasive monitoring of endocrine status in laboratory primates: methods, guidelines and applications

“…Most of the studies have involved analysis of salivary cortisol to assess adrenal activity in relation to behaviour and acute stress (e.g. Ange-van Heugten et al, 2009;Cross et al, 2004;Hohmann et al, 2009;Kuhar et al, 2005), although the measurement of reproductive hormones has also been reported (DiGiano et al, 1992;von Engelhardt et al, 2000). 6 M. Heistermann: Non-invasive monitoring of endocrine status in laboratory primates 2.4 Hormone analysis from hair Steroid hormones from blood are able to diffuse into the cells of the hair follicle and subsequently become deposited in the hair shaft from which they can be measured (Koren et al, 2002).…”

“…Ange-van Heugten et al, 2009;Hohmann et al, 2009;Pearson et al, 2008;von Engelhardt et al, 2000). This procedure allows samples to be collected voluntarily from animals on a regular basis and under various housing conditions, including group-living.…”