Biology subjects

Rakotondranary, S. J.

Publications and source records attributed to Rakotondranary, S. J..

3 recordsLinked to original sources

bioRxiv2022

Anthropogenic disturbance impacts gut microbiome homeostasis in a Malagasy primate

Increasing anthropogenic disturbances in Madagascar are exerting constrains on endemic Malagasy lemurs and their habitats, with possible effects on their health and survival. An important component of health is the gut microbiome, which might be disrupted by various stressors associated with environmental change. We have studied the gut microbiome of grey-brown mouse lemurs (Microcebus griseorufus), one of the smallest Malagasy primates and an important model of the convergent evolution of diseases. We sampled two sites: one situated in a national park and the other consisting of a more disturbed site around human settlement. We found that more intense anthropogenic disturbances indeed disrupted the gut microbiome of this lemur species with a marked reduction in its diversity and led to a shift in microbial community composition. Interestingly, we noted a decrease in beneficial bacteria together with a slight increase in disease-associated bacteria and alterations in microbial metabolic functions. Because of the crucial services provided by the microbiome to host health and in disease, such negative alterations in the gut microbiome of the lemur from anthropogenically disturbed habitat might impact the health of mouse lemurs, rendering them susceptible to diseases and ultimately affecting their survival in the shrinking biodiversity seen in Madagascar. Gut microbiome analyses might thus serve as an early warning signal for pending threats to lemur populations.

microbiology↗

bioRxiv2021

RADseq data reveal a lack of admixture in a mouse lemur contact zone contrary to previous microsatellite results

Despite being one of the most fundamental biological processes, the process of speciation remains poorly understood in many groups of organisms. Mouse lemurs are a species-rich genus of small primates endemic to Madagascar, whose diversity has only recently been uncovered using genetic data and is primarily found among morphologically cryptic, allopatric populations. To assess to what extent described species represent reproductively isolated entities, studies are needed in areas where mouse lemur taxa come into contact. Hybridization has previously been reported in a contact zone between two closely related mouse lemur species (Microcebus murinus and M. griseorufus) based on microsatellite data. Here, we revisit this system using RADseq data for populations in, near, and far from the contact zone, including many of the individuals that had previously been identified as hybrids. Surprisingly, we find no evidence for admixed nuclear ancestry in any of the individuals. Re-analyses of microsatellite data and simulations suggest that previously inferred hybrids were false positives and that the program NewHybrids can be particularly sensitive to erroneously inferring hybrid ancestry. Using coalescent-bases analyses, we also show an overall lack of recent gene flow between the two species, and low levels of ancestral gene flow. Combined with evidence for local syntopic occurrence, these data indicate that M. murinus and M. griseorufus are reproductively isolated. Finally, we estimate that they diverged less than a million years ago, suggesting that completion of speciation is relatively rapid in mouse lemurs. Future work should focus on the underpinnings of reproductive isolation in this cryptic primate radiation, which are mostly unknown. Our study also provides a cautionary tale for the inference of hybridization with microsatellite data.

evolutionary biology↗

bioRxiv2021

Evidence of MHC class I and II influencing viral and helminth infection via the microbiome in a non-human primate

Until recently, the study of major histocompability complex (MHC) mediated immunity has focused on the direct link between MHC variability and susceptibility to parasite infection. However, MHC genes can also influence host health indirectly through the sculpting of the bacterial community that in turn shape immune responses. We investigated the links between MHC class I and II gene variability gut microbiome diversity and micro- (adenovirus, AdV) and macro- (helminth) parasite infection probabilities in a wild population of non-human primates, mouse lemurs of Madagascar. This setup encompasses a plethora of underlying interactions between parasites, microbes and adaptive immunity in natural populations. Both MHC classes explained shifts in microbiome composition and the effect was driven by a few select microbial taxa. Among them were three taxa (Odoribacter, Campylobacter and Prevotellaceae-UCG-001) which were in turn linked to AdV and helminth infection status, evidence of the indirect effect of the MHC via the microbiome. Our study provides support for the coupled role of MHC variability and microbial flora as contributing factors of parasite infection. Author summaryThe selective pressure of the major histocompatibility complex (MHC) on microbial communities, and the potential role of this interaction in driving parasite resistance has been largely neglected. Using a natural population of the primate Microcebus griseorufus, we provide evidence of two outstanding findings: that MHCI and MHCII diversity shapes the composition of the gut microbiota; and that select taxa associated with MHC variability predicted adenovirus and helminth infection status. Our study highlights the importance of incorporating the microbiome when investigating parasite-mediated MHC selection.

evolutionary biology↗