A new study led by a Museum researcher has uncovered a close connection between the diversity of Madagascar’s lemurs and the abundance of their food resources. The work, published in the Journal of Animal Ecology, provides valuable information for conservation plans involving these small primates, 95 percent of which are considered at risk of extinction.
Lemurs have called Madagascar home for more than 50 million years and are found nowhere else on Earth. These one-of-a-kind primates have co-evolved with the island’s plants, playing a vital role in the dispersal of seeds from fruit trees. While some eat insects, many lemurs are vegetarians, and picky eaters at that—most depend on the fruits or leaves of just a few key tree species for most of their diet.
“Fruit-eating lemurs are important seed dispersers; when lemurs eat the fruit, they pass the seeds whole, which germinate much better than seeds not passed by lemurs,” said James Herrera, a postdoctoral fellow in the Museum’s Department of Mammalogy and the author of the study. “Different lemurs specialize on different trees and disperse the seeds far from the parent trees, like gardeners sowing the future forests.”
But practices such as mining, logging, and cattle grazing have depleted Madagascar’s forests, threatening the trees that are both food and habitat for lemurs. Herrera spent two years in southeastern Madagascar recording lemur species abundance and diversity in relation to factors like human activity, tree populations, and altitude. In the end, 13 species of lemurs were surveyed by the study.
This research revealed the significant influence of food tree abundance on lemur diversity. The areas with the most food trees were dominated by several different species of large-bodied lemurs, but as altitudes increased and food trees grew more scarce, species of smaller-bodied lemurs dominated the landscape.
“It makes sense that larger-bodied lemur species exist in areas with higher occurrence of food trees,” Herrera said. “Large species need more resources, and more fruit-eating lemurs exist in lower altitudes, helping to spread the seeds of food trees. In addition, there is less competition for food resources in higher altitudes, making it easier for smaller-bodied lemurs to thrive there.”
Surprisingly, Herrera’s study also found that human disturbance did not have a significant effect on lemur diversity. Heavily degraded sites mimicked the conditions found at high altitudes, acting as home to small groups of smaller lemur species. This suggests that some lemur species may be resilient to habitat disturbance, which helps to predict how entire lemur communities will respond to future habitat loss.