Bacteria Aid Social Communication

Twitter may limit humans to 140 characters, but a just-as-brief scent post can convey an encyclopedia of information about the animals that left them.

MSU BEACONites Kevin Theis and Kay Holecamp studied multiple groups of male and female spotted and striped hyenas in Kenya and found that “when hyenas leave paste deposits on grass, the sour-smelling signals relay reams of information for other animals to read.” However, it’s actually the bacteria in pastes that appear to be sending the messages. Variation in scent gland bacterial communities was strongly correlated with variation in the glands’ odor profiles, suggesting that bacteria were responsible for the variation in scent.

“Hyenas can leave a quick, detailed message and go. It’s like a bulletin board of who’s around and how they’re doing …Scent posts are bulletin boards, pastes are business cards, and bacteria are the ink.”

Using next-generation sequencing methods, the Theis team ‘read’ these messages through the eyes, or noses, of hyenas. They found that the diversity of odor-producing bacteria in spotted hyena scent glands is much greater than historical studies of mammals had suggested. This diversity, however, still consistently varies between hyena species, and with sex and reproductive state among spotted hyenas.

“There have been around 15 prior studies pursuing this line of research … but they typically  relied on culture-based methods, an approach in which many of the similarities and differences in bacterial communities can be lost. If we used those traditional methods, many of the key findings that are driving our research wouldn’t be detected at all.”

Theis’ team was the first to combine microbial surveys and complementary odor data from the wild animals. “The next phase of this research will be to manipulate the bacterial communities in hyenas’ scent glands to test if their odors change in predictable ways.”

Read more in the November preprint here: Theis et al 2013. “Symbiotic bacteria appear to mediate hyena social odors,” PNAS. Article DOI: 10.1073/pnas.1306477110

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