Androgens predict parasitism in female meerkats: a new perspective on a classic trade-off

Abstract

The immunocompetence handicap hypothesis posits that androgens in males can be a 'double-edged sword', actively promoting reproductive success, while also negatively impacting health. Because there can be both substantial androgen concentrations in females and significant androgenic variation among them, particularly in species portraying female social dominance over males or intense female -female competition, androgens might also play a role in mediating female health and fitness. We examined this hypothesis in the meerkat (Suricata suricatta), a cooperatively breeding, social carnivoran characterized by aggressively mediated female social dominance and extreme rank-related reproductive skew. Dominant females also have greater androgen concentrations and harbour greater parasite loads than their subordinate counterparts, but the relationship between concurrent androgen concentrations and parasite burdens is unknown. We found that a female's faecal androgen concentrations reliably predicted her concurrent state of endoparasitism irrespective of her social status: parasite species richness and infection by Spirurida nematodes, Oxynema suricattae, Pseudandrya suricattae and coccidia were greater with greater androgen concentrations. Based on gastrointestinal parasite burdens, females appear to experience the same trade-off in the costs and benefits of raised androgens as do the males of many species. This trade-off presumably represents a health cost of sexual selection operating in females.

Social and environmental factors affect tuberculosis related mortality in wild meerkats

“…Female meerkats have previously been shown to have increased androgen levels, linked to an immunocompromised state (Smyth et al . ). Alternatively, infected males may be more likely to be lost to follow‐up before they develop signs.…”

“…The outcome of interest in the present study was disease rather than infection, and the possibility exists that males could have higher infection rates than females, but with infected females progressing to clinical disease due to sex-linked immunosuppression. Female meerkats have previously been shown to have increased androgen levels, linked to an immunocompromised state (Smyth et al 2016). Alternatively, infected males may be more likely to be lost to follow-up before they develop signs.…”

Incidence and biomarkers of pregnancy, spontaneous abortion, and neonatal loss during an environmental stressor: Implications for female reproductive suppression in the cooperatively breeding meerkat

“…These findings suggest that there is flexibility in a system that balances reproductive tradeoffs between classes (e.g. [113]) under varying environmental conditions. As revealed by the reduced differential in female reproductive success, it may be that certain environmental stressors, such as food shortage, are experienced comparably between the classes.…”

Trade-offs between immunity and testosterone in male African ground squirrels

“…There are other recent studies that have found support for testosterone playing an important role in parasite infections and fitness: in white-footed mice (Peromyscus leucopus), increased testosterone maintained social behaviours that increased the transmission potential of ectoparasites (Grear et al, 2009), and increasing testosterone in house mice (Mus musculus) increased their endoparasite intensity (Zhang and He, 2014). In red grouse (Lagopus lagopus), increased testosterone had a negative effect on body condition (Martínez-Padilla et al, 2014) and higher levels of testosterone were positively correlated to increasing ectoparasite intensity in female meerkats (Suricata suricatta) (Smyth et al, 2016). However, other studies have also failed to find a relationship between increased testosterone and immunocompetence measurements in mammals and birds (Nunn et al, 2009;van Oers et al, 2011;Roberts et al, 2007;Ros et al, 2006), and some studies have even found that elevated testosterone had immune-enhancing effects, completely opposite to predictions from the ICHH (Bilbo and Nelson, 2001;Evans et al, 2000).…”