Doctoral Dissertation Research: The Impacts of Environment and Host Evolutionary Relationships on Lemur Microbiota
Recent studies have shown that the mammal microbiome (the community of microscopic organisms that live in a host animal’s body) is modified by environmental conditions, and that reduced microbiome diversity is associated with host health issues. Microbiome data in wild and captive primate populations can therefore be used to assess their health as they encounter a variety of environments. Additionally, species-specific host factors influence the relationship between host microbial diversity and the environment (Perofsky, Lewis, & Meyers, 2019; Barelli et al., 2020), making comparative research a way to understand the evolution of microbiome diversity across primates. Comparative studies of the microbiome can also inform disease ecology, conservation, and captive management strategies tailored to different primate species. Therefore, the purpose of this study is to examine how the hair, oral, and gut microbiota of wild and captive lemur species are determined by host phylogenetic relationships and host environment. The research is partially conducted at Beza Mahafaly Special Reserve (BMSR) in southwest Madagascar and focuses on three species found there: Verreaux’s sifaka (Propithecus verreauxi), ring-tailed lemurs (Lemur catta), and reddish-gray mouse lemurs (Microcebus griseorufus). These three lemur species’ overlapping ranges throughout BMSR allows me to explore how the same environmental stressors distinctively affect their microbiota, given these species’ notable differences in behavior and ecology. I am also collecting samples from captive lemurs at the Duke Lemur Center, Zoo Atlanta, and the Lemur Conservation Foundation from a wide diversity of lemur species. I will address the following research questions:
Question 1: Does host environment alter microbiome diversity?
Question 2: Does host environment differentially impact the microbiome diversity of different lemur species?
Question 3: Does host environment affect the microbiome diversity of different body regions in distinct ways?
The Evolutionary Ecology of Primate Hair Coloration: A Phylogenetic Approach
Understanding trait evolution is essential for explaining modern biological diversity, and this is particularly exemplified by studies of coloration. Recent studies have applied evolutionary models to understand animal coloration, yet we have limited knowledge of how this trait evolves in mammals in a comparative context. Here we use phylogenetic methods to examine how different traits are associated with the evolutionary diversity of primate hair color. We hypothesize that hair color evolves independently across body regions, and that variation in biological and ecological traits influence patterns of hair color evolution. To test this, we quantify the phylogenetic signal of coloration for each body region, then compare the fit of three evolutionary models and a null, non-phylogenetic model to explain color variation across 94 primate species. We then test how trait optima and rate of color evolution covary with biological traits, clade membership, and habitat. Phylogenetic signal varies across regions, with head and forelimb coloration exhibiting the highest values. Head and forelimb coloration is best explained by an Ornstein-Uhlenbeck model, which could suggest stabilizing selection, whereas a null model best fits other body regions. Rates of hair color evolution and optimal color values vary across species with different visual systems, activity patterns, habitat types, and clade memberships. These results suggest that selective pressures are acting independently across body regions and across different primate taxa. Our results emphasize the importance of investigating patterns of trait evolution across regions of the body, as well as incorporating relevant biological and ecological traits into evolutionary models.
This research was published in Journal of Mammalian Evolution (full text link here).