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The gut microbiome is gaining recognition for its role in primate nutrition, but we stand to benefit from microbiome comparisons across diverse hosts and environmental conditions. We compared gut microbiome structure in four lemur species from four phylogenetic lineages, including 9 individual mouse lemurs (Microcebus danfossi), 6 brown lemurs (Eulemur fulvus), 20 sifakas (Propithecus coquereli), and a single sportive lemur (Lepilemur grewcockorum). In northwestern Madagascar, these species are sympatric, but use different feeding strategies to cope with environmental challenges, including relying on tree gums and insects (mouse lemurs), and some vs. significant leaf matter (brown lemurs vs. sifakas and sportive lemurs). From one fecal sample collected per lemur in the dry season in the Anjajavy Forest, we determined gut microbiome diversity, variability, and membership via 16S rRNA sequencing. The lemurs harbored strongly species-specific gut microbiomes. Brown lemurs showed more diverse and generalized consortia; mouse lemurs, sifakas, and the sportive lemur had less diverse consortia with more distinct memberships. Consistent with their fallback foods, mouse lemur microbiomes included taxa putatively associated with gum and insect digestion, whereas those of sifakas and the sportive lemur showed stronger and distinct signatures of leaf fiber and secondary compound metabolism. These results point to feeding strategy, intertwined with host phylogeny, as a driver of gut microbiome composition, but highlight real-time dietary specificity as a contributing driver of microbiome diversity. While illuminating how gut microbiomes facilitate host nutrition on challenging foods, these results help explain how ecologically diverse primates living in sympatry may differentially cope with seasonal or stochastic lean times.

Population decline and fragmentation often lead to reduced genetic diversity and population differentiation. Habitat destruction throughout Madagascar has caused population decline and extinction of many endemic species. Lemur populations, including those of the largest extant lemur, Indri indri, have been fragmented into remaining forest patches. We assessed the level of genetic diversity in indri populations in three protected reserves by genotyping a total of 43 individuals at 17 microsatellite loci. Genetic diversity in terms of heterozygosity was high in all three reserves, with no differences between reserves. Population structure and F ST analyses revealed Analamazaotra Forest Station and the Torotorofotsy Conservation Area, which are separated by ca. 18 km to be genetically differentiated from each other with some admixture. Betampona Strict Nature Reserve, which is separated from the other reserves by ca. 130 km, exhibited clear population genetic differentiation, with no signs of admixture with the other reserves. Our genetic diversity estimates are similar to those for other Indridae in similar habitats and may reflect past rather than current population processes, given that populations have declined recently. Our results suggest that Betampona may be genetically isolated and that it is important to maintain gene flow between remaining populations to prevent loss of genetic diversity for the future conservation of Indri indri.

The number of newly discovered Malagasy vertebrate taxa has multiplied in recent years, emphasizing the importance of complete taxon sampling for phylogenetics, biogeography, functional ecology, and conservation biology, especially in such a biodiversity hotspot. In particular, the diversity of extant lemurs is much higher than previously thought, and we have yet to comprehend fully the full extent of lemuriform biodiversity. A recent genetic analysis of mtDNA and nDNA sequence data in Malagasy mouse lemurs revealed the existence of several novel mtDNA clades based on new field sampling. These geographically defined and previously unrecognized mtDNA clades corresponded precisely to patterns of population structure revealed in the analysis of the nDNA data, thus confirming their evolutionary divergence from other mouse lemur clades. Two of these independently evolving lineages correspond to specimens that were collected by us in the Marolambo and Manantantely/Ivorona regions. Here we summarize the genetic evidence and report on the morphometric and external characteristics of these animals, formally describing them as new species. This report thus brings the number of currently recognized and described mouse lemur species to 20. The forests in which these mouse lemurs were discovered have been heavily degraded in the past decade, prompting the classification of one of the new species as Endangered by the IUCN, even before its formal description. As with several other newly described lemur species, immediate field studies and appropriate conservation actions are therefore urgent.

Recent morphological and molecular phylogenetic studies of mouse lemurs (Microcebus) living in the western and southern regions of Madagascar have shown that specific diversity had been considerably underestimated. In large part, this underestimate was due to the lack of sufficient specimens from given localities to assess properly the level of phenotypic variation within and between populations. The accurate delineation of specific boundaries has no doubt been confounded by the diminutive size, nocturnal habits, and subtle morphological variation characteristic of mouse lemurs, which can make field identification of individuals problematic. We illustrate the use of molecular phylogenetic analysis to reveal reproductive isolation in two sympatric mouse lemur species, Microcebus murinus and M. griseorufus. Their documentation in the Berenty Private Reserve in the extreme south of Madagascar verifies the historically-broad distribution of Microcebus griseorufus, a species recently resurrected from synonomy.