A trio of Coquerel’s sifakas in Madagascar. Image (C) T. Steffens.
Research philosophy
By studying wild lemurs in Madagascar and their peers at the DLC, we have the potential to answer age-old and emerging questions across scientific disciplines. Lemur research can simultaneously inform conservation and husbandry strategies, train the next generation of American and Malagasy scientists, inspire curiosity and engage the general public, and promote international collaborations rooted in teamwork.
While the DLC supports a broad range of research from visiting researchers, the DLC has two research themes that are the focus of our staff scientists: hibernation and the gut microbiome.
Hibernation
From the Arctic landscapes to tropical environments, many animals use hibernation to cope with energetic crises, such as food shortages. Hibernators are at one end of the heterothermic response, which also includes more opportunistic strategies like daily torpor. Despite being a strategy that has evolved repeatedly in all major mammalian lineages, and although other primates, including the mouse lemurs, can use hibernation and torpor (facultative hibernators), dwarf lemurs are the only primates to always hibernate in the wild. This means that all dwarf lemurs must anticipate and prepare for hibernation, by switching their metabolism during the active season to store significant amounts of fat. That fat is metabolized during the hibernation season, which can last up to seven months a year.
At the DLC, we are undertaking a multidisciplinary approach, to understand the interplay between endogenous (e.g., molecular mechanisms) and environmental factors (e.g., ambient temperature) in the expression of primate hibernation, by studying dwarf lemurs under different natural environments in Madagascar, as well as under more controlled conditions at the DLC. Whereas we expect research from Madagascar to shed light into the long-term effect of habitat disturbance, e.g., forest fragmentation, on dwarf lemurs’ ability to hibernate and rely on alternative food sources, research at the DLC can elucidate the underlying mechanisms of hibernation, and how different conditions can modulate its expression. We are taking the challenge to investigate the genomics, metabolism and microbiome of hibernation while being true to the DLC research philosophy of using minimally invasive techniques and causing no harm to the lemurs.
The gut microbiome
The gut microbiome is the complex community of bacteria and other microorganisms that inhabit animal gastrointestinal tracts. Gut microbes perform key functions for their hosts and are critically important for digestion. The 108 recognized lemur species display a diversity of feeding strategies, from extreme frugivory (fruit eating) to extreme folivory (leaf eating). Other species rely on insects, and some even rely on cyanide-laced bamboo. Within groups of lemurs, diets can vary across habitats and geographic regions, across seasons and years. Thus lemurs offer significant opportunity for understanding how gut microbes facilitate digestion across species and dietary strategies; how they enable dietary specialization even on challenging resources; how they help diverse hosts meet their nutritional and energetic demands; and how they potentially help their hosts adapt to changing environments.
To study lemur gut microbes, we use a variety of approaches, but we almost always begin by non-invasively collecting fecal samples. From samples, we sequence a marker gene (the 16S rRNA gene) that tells us which microbes inhabit which guts. We might also profile the microbial metagenome, the metabolome, or even use feces to reconstruct dietary intakes. In some projects, we compare these measurements across wild lemurs living under various conditions. At the DLC, we can also use non-harmful experiments in which we modify diets or conditions to study the ensuing changes to the gut microbiome. In many cases, these experiments can help us determine the optimal diets to feed our lemurs and help us keep them healthy and well under our care.
