August 31, 2012

Hyenas Found To Use Scent Glands To Communicate

Brett Smith for — Your Universe Online

Researchers from Michigan State University working in Kenya have shown for first time that groups of hyenas possess different odor-producing bacterial communities within their scent glands that they use to communicate everything from age to social status.

“A critical component of every animal´s behavioral repertoire is an effective communication system,” said Kevin Theis, an MSU molecular biologist. “It is possible that without their bacteria, many animals couldn´t ℠say´ much at all.”

According to the group´s report in this week´s edition of Scientific Reports, the team theorized that fermentation bacteria contained within the scent glands generate odors that the mammals then co-opt for communication purposes and any variation in scent gland odors is the result of the different make-ups of each bacterial community.

To collect samples from the hyenas, the team searched the grassy plains of Keyna for samples of paste, a sour-smelling emission that hyenas leave on tall stalks of grass. They also tranquilized hyenas and collected samples from their scent pouches, which were sent back to MSU labs for analyzing and genetic sequencing.

Genetic surveys of RNA show that spotted hyena secretions are densely populated by fermentation bacteria that are closely linked to well-known odor producers. The next-generation sequencing techniques used by the molecular biologists also showed a high degree of similarities among microbial populations left by members of the same clans. However, the microbial populations´ genetic make-up varied distinctly from clan-to-clan.

“One benefit of sharing a common microbial community in their scent pouches would be in terms of job sharing when hyenas scent mark their territory,” Theis said. “Multiple members of the clan could more efficiently carry out the job and mark more territory.”

The analysis of these bacterial colonies could also point to social interactions among hyena clans, the report suggested. To explain why the scent pouch communities of one hyena clan closely resembled two others, the report said it might have only recently formed, that it may have experienced a recent arrival of immigrants, or that it may be less cohesive than the others. This finding indicated that there are still some underlying factors of the phenomenon that need to be identified.

The report speculated that the microbial community shared by members of a hyena clan could be a product of shared environments, genetic similarity, or a combination of these two factors. Many members of the same clan will mark the same grass stalks several times as they share the same habitat. This “overmarking” could be a viable pathway for the microbial communities to transmit form animal to animal, the study´s authors wrote. Also, many members of hyena clans are genetically related, which could lead to the emergence of similar microbial communities emerging within each individual animal.

In futures studies, the scientists plan to investigate other aspects of the use of fermentation bacteria for chemical communication among hyenas. Specifically, they hope to find the link between microbial genetic profiles and the various scent profiles they produce.

“The complex social lives of these animals may ultimately be reliant upon their unheralded symbiotic microbial communities,” Theis said.