Giant Extinct Lemurs Cause Plant Orphans!

Had Jean-Paul Sartre studied nature and ecosystems, perhaps he wouldn’t have been an existentialist. The burden of others wouldn’t have looked so daunting had he understood that we are all connected. Every creature plays an important and different role in the ecosystem.

Take our isolated, adorable cousins, lemurs. These primates play an incredibly important role on Madagascar: seed dispersal. Many lemur species eat fruits and then poop the seeds, thus planting new trees in new places. But many lemurs are endangered and even extinct, so what does that mean for the plant species on Madagascar?

A team of scientists, led by Sarah Federman of Yale University, decided to take a closer look and examined food preferences of both extinct and living lemurs. The researchers investigated the genetic family tree of all the major lineages of lemurs, living and dead, and then studied evidence from tooth morphology, dental wear, and isotope analysis to determine which species ate leaves—and which prefered fruits and likely enabled seed dispersal.

Over a few thousand years, at least 17 lemur species went extinct, all of them giant lemurs, ranging in weight from 10–160 kilograms (22–350 pounds). Most of these extinctions occurred due to increased human activity around 1,700 years ago, although some took place as recently as 500 years ago. According to Feldman and her colleagues’ research, published today in the Proceedings of the National Academy of Sciences (PNAS), these extinctions meant that fewer seed dispersing lemurs remained.

The scientists then identified several “orphaned” large-seeded plants that do not appear to have any existing animal seed dispersers. Perhaps these plants’ seeds were consumed and spread by now-extinct lemur species. While the team suggests that these plant species exist today due to long generation times and less-efficient seed dispersal by rodents or cyclonic winds, “their long-term survival may be tenuous,” according to the PNAS article.

Furthermore, the scientists find that living species of lemurs continue to play this vital role in the Malagasy forests, “performing unique and irreplaceable ecosystem functions.” The researchers recommend that conservation efforts should take into account the effects of these seed dispersers, informing decisions and policy to save these amazing animals.

Lemurs beat existentialism every time!

Sifaka lemur image: Sarah Federman