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African bush babies gain a new genus

  • Genetic data has pointed toward a unique group of dwarf galagos living in Africa for a long time, but the physical similarity between the primates in the Galago family has confounded scientists.
  • Using these genetic clues as a guide, a team of researchers examined the skulls and teeth of galagos and analyzed their calls.
  • They concluded that five species previously placed in other genera should be placed in a sixth genus of the family Galagidae. They chose the name ‘Paragalago’ for the new genus.

Galagos have a reputation among scientists for being one of the more mysterious primates, in large part because they’re so tough to study. Endearingly known as bush babies, they stick mostly to forest treetops, and some weigh in at less than 100 grams (3.5 ounces). They’re also creatures of the night, when their bugged-out eyes and swiveling ears lend them an advantage in tracking down their insect prey.

But a recent deep dive examining the genetic relationships of galagos, as well as their physical traits and the calls they make, has uncovered the need for a new, distinct genus of the tiny primates, and with it more evidence of how little we know about animals that live in forests under threat in eastern and southern Africa.

Different galago species haven’t evolved vastly distinctive physical features, probably because they rely more on other cues like sounds to pick out members of their own species rather than looks, said Luca Pozzi, an evolutionary primatologist and coauthor of a study published online on Feb. 8 by the Zoological Journal of the Linnean Society.

That’s made it difficult to pick out which groups share a common ancestor solely based on appearances, and it has led scientists to lump the smallest galagos into a group known as the dwarf galagos under the genus Galagoides.

Map showing approximate geographic ranges of the two independent dwarf galago groups, Galagoides (red) and the eastern dwarf galagos (blue), now called Paragalago. Map courtesy of Masters et al. 2017

“We couldn’t really tell them apart that much,” Pozzi said in an interview. But when they looked at the animals’ DNA on a molecular level, “we finally saw there was something weird going on.”

Those genetic differences, which appeared as differences in the DNA of the mitochondria – or the bit of a cell that provides it with energy – meant that a handful of the galagos didn’t share a common ancestor with other species in the Galagoides genus.

“The genetics were actually the first evidence that these guys might actually be something different,” he added.

Pozzi’s colleague and coauthor of the current study, Judith Masters of the University of South Africa, led an effort to sift through hundreds of specimens at museums in the U.S. and Europe using these genetic clues as a guide. The team made a series of measurements, keeping an eye out for any physical differences to tip them off that some of the dwarf galagos belonged on a different twig on the tree of life.

Like forensic scientists, they identified subtle differences, such as the shape of the skull and the arrangement of teeth, that backed up what the molecular genetic data was telling them.

Further proof came from analysis of the sounds that galagos make to identify mates and alert each other of danger. These “buzzy alarms,” “mobbing yaps,” and “advertisement calls” tended to be similar among the species in the newly proposed genus and distinct from those in the original genus.

That data in hand, Masters, Pozzi, and their team argue in their paper that five species of dwarf galagos belong in a new genus, which they called Paragalago. The official process to create a new genus, and thus change the scientific names of these five galagos, requires a submission to the International Commission on Zoological Nomenclature, which is underway. But Pozzi said that primatologists will likely start using the new classification now that they’ve published their research.

“We now know that the western part and the eastern part are different beasts,” he said. “Literally, they’re two different animals.”

A Kenya coast galago (Paragalago cocos). Photo courtesy of Luca Pozzi

The East African Rift separates the western or “true” dwarf galagos from an eastern population comprising these five species, which inhabit a patchwork of mountain and coastal forest along the southeastern coast of Africa in Tanzania, Kenya, Mozambique and Malawi.

“Those forests are in extremely bad shape” as a result of deforestation and fragmentation, Pozzi said. Based on counts from previous surveys, “we have at least two species that are not doing that well.”

Galagos are not alone in the threats they face. A recent study found that 60 percent of primates face the specter of extinction.

The rondo dwarf galago (Paragalago rondoensis) is currently listed as Critically Endangered by the IUCN. In 2016, the International Primatological Society unveiled its list of the 25 most endangered primates, replacing the rondo with the mountain dwarf galago (Paragalago orinus). That’s because we still have a lot to learn about it, Pozzi said.

“We know that they’re staying at the top of the mountain and that’s pretty much it,” he added.

In fact, scientists have found the Eastern Arc Mountains in Kenya and Tanzania, where the mountain dwarf galago lives, to be a sanctuary for all kinds of unusual and unknown life.

“Every time that they go [into] these forests,” he said, “they find things that are unique,” including birds, amphibians and other mammals.

For Pozzi, that points to a critical – and urgent – need to figure out what’s living in these forests and how to protect them before the habitat disappears.

“Understanding the biodiversity we have out there is kind of the first step to doing good conservation,” he said.

https://imgs.mongabay.com/wp-content/uploads/sites/20/2017/02/19122028/Udzungwas_00153_07_zanzibaricus.mp3?_=1

Audio recording of a Zanzibar galago (Paragalago zanzibaricus) courtesy of Luca Pozzi.

Correction: February 20, 2017
An earlier version of this article misstated Luca Pozzi’s profession. He is an evolutionary primatologist, not an ecologist.

CITATIONS:

Masters, J. C., Génin, F., Couette, S., Groves, C. P., Nash, S. D., Delpero, M., & Pozzi, L. (2017). A new genus for the eastern dwarf galagos (Primates: Galagidae). Zoological Journal of the Linnean Society, 1–13. https://doi.org/10.1093/zoolinnean/zlw028

Perkin, A., Bearder, S., Honess, P. & Butynski, T.M. (2008).  Galagoides rondoensis. The IUCN Red List of Threatened Species 2008: e.T40652A10350268. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T40652A10350268.en. Accessed on 19 February 2017.

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