Home Biologist Turtle vocalizations reframe the origins of auditory communication

Turtle vocalizations reframe the origins of auditory communication


JTurtles may never take the top spot among the most prolific vocalizers in the animal kingdom, but it turns out they do indeed have something to say. In a new study published on October 25 in Nature Communication, researchers have found that turtles, along with other understudied animals, actually communicate using a diverse repertoire of vocal sounds. The study authors suggest their discovery may push the origins of acoustic communication back in time to the common ancestor of all lung vertebrates.

Prior to the current study, many included species “were considered dumb,” says Gabriel Jorgewich-Cohen, a PhD student at the University of Zurich. American scientist. Listening carefully to recordings of 53 species, including turtles, lungfish, caecilians (a group of limbless amphibians) and the lizard-like endemic New Zealand tuatara, the team came to a different conclusion. : this vocalization is more widespread than previously thought, and that “the sounds emitted by turtles have the same evolutionary origin as our own vocal communication”, says Jorgewich-Cohen.

The findings of the article fuel the debate around the ability of certain animals to communicate with each other. In 2020, two scientists published an article in Nature Communication in which they mapped the evolutionary phylogenies of approximately 1,800 voiced and unvoiced species and postulated that acoustic communication evolved independently in major Earth lineages (including frogs, birds, and mammals) in association with nocturnal lifestyles, new scientist reports. In this analysis, turtles were grouped into the non-vocal group.

But evidence that seemingly unvoiced species actually use sound has been circulating outside scientific circles for decades, if not generations. Irene Ballagh, a UBC zoologist who was not involved in the work, says American scientist that his mother remembered hearing tuatara communicating with each other despite “quite definitive statements” to the contrary from the scientific community.

Jorgewich-Cohen began probing hitherto understudied species by studying his own pet turtles. “I decided to record them, just to check”, he says new scientist. “I found several sounds there, then we continued [with more species]. And suddenly I had a good sampling and I could understand a bigger picture.

From there, the team collected sounds from 50 additional turtle species, as well as lungfish, tuatara and caecilians. To better identify scenarios that could trigger sounds, Jorgewich-Cohen traveled to five countries to record each species for at least 24 hours, and did so in a variety of settings, including when the animals were alone or in same-sex or mixed groups, and even when underwater. Every species studied by the group produced at least one sound, and in many cases these recordings were the first time such sounds had been heard.

While the study adds to scientists’ understanding of vocalizations in these groups, it also has implications for the evolution of auditory communications more broadly. When the researchers reanalyzed past phylogenies with their added data, they concluded that, rather than evolving multiple times, vocalization evolved once in a common ancestor. Specifically, Jorgewich-Cohen and colleagues traced vocalization back to lobe-finned fish. Eoactinistia foreyi, which is considered a possible last common ancestor of all vertebrate choanae (lungs). This would mean that voice communication evolved around 407 million years ago, at least 100 million years earlier than previously thought.

University of Western Australia biologist Gerald Kuchling, who was not involved in the study, says new scientist that he was “not surprised that all seem to vocalize”, echoing the point of other experts that many choanates were omitted from previous studies. Talk to American ScientistTecumseh Fitch, an evolutionary biologist at the University of Vienna who reviewed the new study but was not involved in the work, calls it “an important contribution, both because the vocalizations of many species important are analyzed for the first time and because they lead to a convincing argument” that the behavior is well conserved over time.

Jorgewich-Cohen recounts new scientist this vocalization may be even older, as lungless fish also produce sounds. “It could be that a lineage of these fish was the precursor to the type of sound we produce as [choanates],” he says. “So it could be that this sound production line is older than what I found.”

Talk to American scientist, John Wiens, an evolutionary biologist at the University of Arizona and co-author of the 2020 study, says he doesn’t necessarily agree with the team’s findings. “One of the main purposes of their paper seemed to be to re-analyze our data and come to a different conclusion,” rather than to collect evidence to demonstrate that animals “actually use these sounds to communicate with each other.” That, he adds, “seems like a big omission.”

Jorgewich-Cohen agrees that future studies will need to better establish the function of these sounds, American scientist reports, and speaking to the outlet, Ballagh says she hopes scientists will start to listen to and accept the knowledge of people living near these creatures. “I would really like to see more people follow up with more work linking sources of local and indigenous knowledge on potential vocalizations for species groups that are still listed as ‘no data’ in this article,” says Ballagh. . “I think the data might already be available in some form if we just start thinking more carefully about who we should be listening to.”