Natures wonders:bat gut microbiome differ from other mammals (Introduction)

by David Turell , Tuesday, November 12, 2019, 22:50 (1836 days ago) @ David Turell

They have their own specialized biome fitted to individual environment. Other mammals' biomes appear to be more related through evolution:

https://phys.org/news/2019-11-dont-gut-bacteria-humans.html

"Right now, there are trillions of bacteria living in your gut, making up about one percent of your body weight. They're supposed to be there—we need them to help us digest food and fight off diseases. The same is true for most mammals; in general, just about every mammal from dogs to dolphins relies on a community of helpful bacteria, called a microbiome, living inside them for health and survival. Many animals have even evolved along with their gut bacteria to better work together, to the point that closely related host species typically share more similar microbiomes. But a new study has identified one group of mammals that seems to buck that trend: bats. A new paper in mSystems reveals that the microbiomes of closely-related bats can be totally different from each other, which suggests that having a community of helpful gut bacteria may not be so important for this already eccentric group of mammals.

"'It shifts the paradigm we've been operating under, that animals require microbes for digestion and nutrient acquisition. That's true for us, but it may not be true for all species," says lead author Holly Lutz, a research associate at Chicago's Field Museum and post-doctoral researcher at the University of California, San Diego. "The trends we're seeing suggest that bats may not depend on bacteria the same way many other mammals do, and that they can survive just fine without a strict suite of bacteria in their guts to help them digest.

***

"'There's essentially no relationship between the bat microbiome and bat evolutionary history," says Lutz. "You'd expect to see similar microbiomes in closely-related bat species if these animals depended strongly on their bacteria for survival. This is largely what we've seen in other mammals that have been studied, but it's just not there in bats."

***

"Lutz suspects that bats' unique relationships with gut bacteria are related to another trait that sets them apart from their fellow mammals: their ability to fly.

"'Bats have extremely shortened guts," she explains. Food takes just fifteen to thirty minutes to pass through a bat's digestive system, a third as long as it would take for a similarly-sized rodent. That's likely because a long, winding digestive tract would weigh the bats down. "For bats, you can't be carrying around non-essentials. You need to reduce weight for flying—you don't want a heavy gut." Since bats evolved short digestive tracts, presumably to make them lighter for flight, they may not have evolved the same intimate relationships with their gut bacteria that us land-dwelling mammals have.

"The discovery that bats' microbiomes are closely linked to the world around them means that changes to that world could put the bats in danger. In addition to helping digest food, stable gut bacteria help maintain healthy immune systems to fight off disease, and scientists are still learning about the relationship between microbes and skin, gut, and oral health in wildlife. "Bats may be very susceptible to environmental change—if they have a transient microbiome, they might not have the most stable defense mechanisms," says Lutz. "Human-caused disturbances to the environment are a very important issue. Bats may be extra-fragile and more at risk.'"

Comment: Bats certainly look designed. They came from non-flying rodents and had to initially take off with shortened guts. They may have a different gut biome for reasons we do not yet understand. Echolocation evolved later. Note this website:

https://www.theguardian.com/science/2008/feb/13/bat.evolution

"The oldest fossilised bats ever discovered have given palaeontologists an unprecedented insight into the flying mammals' evolution. The find puts to rest a long-standing argument over which came first, flight or echolocation - the bats' exotic navigation system. The new species of bat could fly, but didn't use echolocation.

***

"'There has been much debate about how bats evolved, because there were no specimens to address this issue," said Dr Kevin Seymour at the Royal Ontario Museum in Toronto. "Now the combination of features seen in this species finally gives us an answer: that flying evolved first and echolocation must have evolved later."

***

"One unanswered question is how O. finneryi could have flown without being able to echolocate. Also writing in Nature, physiologist Prof John Speakman of the University of Aberdeen speculates that the earliest bats were day-fliers who used their eyes to navigate."