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Food choice leaves some lemurs more vulnerable to loss of forest habitat

  • The gut microbes of some lemur species are specialized to help in digesting food found in their habitats, a new study has found.
  • Lemurs are only found in Madagascar and the Comoros Islands in the Indian Ocean, and are one of the most threatened primate groups in the world.
  • The study suggests the mostly leaf-eating group of lemurs known as sifakas, in the genus Propithecus, host gut microbes that are specialized for their diets and therefore less adaptable to food sources found in other habitats.
  • Madagascar reports alarming rates of deforestation, losing 2 percent of its primary rainforest just last year, the highest rate of any country.

Imagine the plight of a lactose-intolerant person whose neighborhood grocery store started selling only dairy products. This is how Lydia Greene, an ecologist at Duke University in the U.S., describes the predicament of the sifakas, a genus of lemur (Propithecus) that she studies.

In a paper published recently in the journal Biology Letters, Greene and colleagues shine a light on what determines their odds of survival.

Part of the answer lies in their guts. Lemurs like sifakas whose diets and gut microbes are customized to their habitats are at greater risk as forest cover shrinks, the study found. “Animals that are constrained to particular dietary items, to particular geographic regions, or particular habitats are likely more susceptible to extinction, compared to animals with more flexible strategies and wide geographic distributions,” Greene said.

Lemurs, found only in Madagascar and the neighboring Comoros Islands in the Indian Ocean, are one of the most threatened primate groups in the world: of 111 known species, 105 are endangered. Habitat loss threatens all lemur species because their range is limited to this corner of the world, and Madagascar’s forests are disappearing at an alarming pace. Last year, 2 percent of the country’s primary rainforests were wiped out — the highest rate of any country.  Every species of lemur occupies its own niche forest habitat, which only amplifies their risk of dying out.

How habitat loss impacts species is a growing field of research. Scientists are increasingly interested in the link between microbial environments and broader ecologies.

Sifakas, a common name given to lemurs from nine different species belonging to the Propithecus genus, have a predominantly leafy diet. Their gut microbes, the microorganisms that line their digenstive tracts and aid digestion, are specialized for breaking down tough fibers and extracting nutrients.

A territorial chase between a pair of Verreaux’s Sifaka (Propithecus verreauxi). Image by Rhett A. Butler.

To understand how this diet and microbiome make-up impacts the primates’ adaptability, Greene and her team collected fecal samples from 128 lemurs belonging to 12 species, both leaf eaters and fruit eaters, to investigate the gut microbial mix. They found that fruit-eating brown lemurs (genus Eulemur) hosted a similar mix of microbes no matter which part of the island they lived on. For sifaka species the assemblage of gut microbes varied with their habitats: those living in dry forests and those inhabiting rainforests host a different mix of microbes.

The study suggests that when forests that provide the right concoction of plants for their diets are razed, the lemurs can’t just hop on over to the next forest.

“Forest loss is a serious threat that shapes the future of all lemurs in Madagascar, and ecological specialization plays a role in how lemurs respond to past, ongoing, and future forest loss,” Greene said.

Citations

Greene, L. K., Clayton, J. B., Rothman, R. S., Semel, B. P., Semel, M. A., Gillespie, T. R., … Drea, C. M. (2019). Local habitat, not phylogenetic relatedness, predicts gut microbiota better within folivorous than frugivorous lemur lineages. Biology Letters15(6), 20190028. doi:10.1098/rsbl.2019.0028

Banner Image: A Coquerel’s Sifaka (Propithecus coquereli) with its baby in Madagascar. Image by Rhett A. Butler.

Malavika Vyawahare is the Madagascar staff writer for Mongabay. Find her on Twitter: @MalavikaVy

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