Hair cortisol concentrations correlate negatively with survival in a wild primate population

Abstract Background Glucocorticoid hormones are known to play a key role in mediating a cascade of physiological responses to social and ecological stressors and can therefore influence animals’ behaviour and ultimately fitness. Yet, how glucocorticoid levels are associated with reproductive success or survival in a natural setting has received little empirical attention so far. Here, we examined links between survival and levels of glucocorticoid in a small, short-lived primate, the grey mouse lemur (Microcebus murinus), using for the first time an indicator of long-term stress load (hair cortisol concentration). Using a capture-mark-recapture modelling approach, we assessed the effect of stress on survival in a broad context (semi-annual rates), but also under a specific period of high energetic demands during the reproductive season. We further assessed the power of other commonly used health indicators (body condition and parasitism) in predicting survival outcomes relative to the effect of long-term stress. Results We found that high levels of hair cortisol were associated with reduced survival probabilities both at the semi-annual scale and over the reproductive season. Additionally, very good body condition (measured as scaled mass index) was related to increased survival at the semi-annual scale, but not during the breeding season. In contrast, variation in parasitism failed to predict survival. Conclusion Altogether, our results indicate that long-term increased glucocorticoid levels can be related to survival and hence population dynamics, and suggest differential strength of selection acting on glucocorticoids, body condition, and parasite infection

Data from: Shared evolutionary origin of MHC polymorphism in sympatric lemurs

Genes of the Major Histocompatibility Complex (MHC) play a central role in adaptive immune responses of vertebrates. They exhibit remarkable polymorphism, often crossing species boundaries with similar alleles or allelic motifs shared across species. This pattern may reflect parallel parasite-mediated selective pressures, either favouring the long maintenance of ancestral MHC allelic lineages across successive speciation events by balancing selection (‘trans-species polymorphism’), or alternatively favouring the independent emergence of functionally similar alleles post-speciation via convergent evolution. Here we investigate the origins of MHC similarity across several species of dwarf and mouse lemurs (Cheirogaleidae). We examined MHC class II variation in two highly polymorphic loci (DRB, DQB) and evaluated the overlap of gut-parasite communities in four sympatric lemurs. We tested for parasite-MHC associations across species to determine whether similar parasite pressures may select for similar MHC alleles in different species. Next, we integrated our MHC data with those previously obtained from other Cheirogaleidae to investigate the relative contribution of convergent evolution and co-ancestry to shared MHC polymorphism by contrasting patterns of codon usage at functional versus neutral sites. Our results indicate that parasites shared across species may select for functionally similar MHC alleles, implying that the dynamics of MHC-parasite co-evolution should be envisaged at the community level. We further show that balancing selection maintaining trans-species polymorphism, rather than convergent evolution, is the primary mechanism explaining shared MHC sequence motifs between species that diverged up to 30 million years ago

Capture-mark-recapture data modelling survival rates of Microcebus murinus in relation to glucocorticoid level, parasite infection and body condition

<p>This dataset consists of an Excel spreadsheet containing capture-mark-recapture data, which were used to model survival of <i>Microcebus murinus</i> in different contexts.</p> <p>These were:</p> <p>- a Multistate modelling approach to model semi-annual survival relative to hair cortisol concentration (HCC) and scaled mass index (SMI). Median or third quartile were used as categorization cut-off.</p> <p>- a Cormack-Jolly-Seber (CJS) modelling approach to model survival over the reproductive season relative to hair cortisol concentration, scaled mass index, and pattern of parasitism which was measured as the parasite species richness (number of distinct parasite morphotypes found per individual), the multiple infection (presence of more than one parasite morphotype), and the overall parasite prevalence (presence of at least one parasite morphotype).</p> <p>The data used to assess the link between semi-annual survival rates and HCC includes the results of capture sessions held in October 2012, 2013, 2014, April 2013, and March 2014, during which a total of 171 individuals (74 females, 97 males) were captured. The same dataset, excluding the October 2014 session, was used to assess the effect of SMI on semi-annual survival probabilities, for a total of 149 individuals (63 females, 86 males). The dataset used for the CJS models includes data collected during monthly trapping sessions between September 2012 and April 2013, for a total of 48 individuals (16 females, 32 males).</p> <p> All research activities conducted in Madagascar received official approval from the Ministère de l´Environnement, de l´Ecologie, and de la Mer et des Forêts, and comply with national animal care legislation of Madagascar.</p