What constitutes the composition of microbes in the warbler’s gut? New Research Suggests Microbiomes in Warblers Are Affected by Evolution More Than Diet – ScienceDaily


Differences between the group of bacteria and other microorganisms that live within the birds’ digestive tract—the gut microbiomes—are not primarily driven by diet diversity, contrary to a recently proposed hypothesis. Instead, a team of researchers from Penn State found that evolution may play a larger role in explaining these differences, which could have implications for how these species adapt to new habitats.

Depending on the species, an animal’s microbiome can influence its host’s digestion, immune function, response to disease, development, metabolism, and behavior. In terrestrial mammals, there is a clear indication that evolutionary history plays an important role in determining their microbiomes, with species that are more closely related tend to have the most similar microbiomes and those that are more distantly related tend to have more different microbiomes.

“By contrast, differences between species gut microbes in birds and bats are much less clear, and the drivers of these different patterns have remained unclear,” said Marcella Baez, a Penn State postdoctoral researcher who led the research. “It has recently been suggested that less pronounced differences between the gut microbiota of birds and bats may be the result of changes in the digestive tract as adaptations for powered flight. In this study, we investigated this hypothesis by examining the relative influence of birds’ evolutionary history and their environment, including diet, on Gut microbiomes of 15 species of wood warblers.”

Birds and bats have a shorter, more streamlined digestive tract compared to land mammals, which means food passes through more quickly, ultimately reducing weight when they fly. A recent study suggested that because of this higher turnover in food, there may also be a higher turnover of the microbial community within the gut, and thus diet would have a stronger effect on the gut microbiome. However, recent studies that have investigated the gut microbiome of birds either consider captive animals, have artificial food, or feature diets that use broad categories of diet types, providing an incomplete picture.

In the current study, which was published in a research paper published online November 21 in the journal Molecular EcologyThe research team collected fecal samples from more than 400 birds of 15 wood warbler species from central Pennsylvania and the Adirondack region of New York.

“One of the strengths of our study is that we were able to collect samples from many individuals of each species in two different regions,” Bayes said. “While some previous studies may have included more species, they may have only sampled a few individuals of each species, so it is unclear if the sampling is representative of the species as a whole.”

The researchers extracted and sequenced DNA from the stool samples to determine the types of bacteria present in the birds’ guts as well as the types of insects each bird ate. The most common types of bacteria identified are also found in other types of birds.

When the researchers examined the diversity of bacteria within the birds’ microbiomes, the bird’s species identity was the largest explanatory factor. The diversity of insects in their diet was not closely related to the diversity of bacteria in their gut. In addition, when the researchers classified warblers by their similarity to their gut microbiome, those relationships were closer to the Tree of Life vulgaris—a tree that grouped warblers by evolutionary linkage between species—than to a tree that grouped warblers by their diet. similarity.

“Our results suggest that diet diversity may not be the most important factor shaping the gut microbiome of these birds, so the hypothesis that faster gut turnover and short gut development favor environmental influences may be driving the formation of the gut microbiome,” Baez said. Follow how host evolution has shaped the intestinal microbiomes of songbirds, a highly diverse group of more than 100 species of songbirds that have diverged rapidly in the last 7 million years. If there is an imprint of evolution, it might be expected that the microbiome may play a role in how birds adapt to new habitats as they colonize, or — if two different types of mating and producing a hybrid bird, which is common among warblers — could influence microbiome compatibility and eventual success. for hybrid offspring.

The researchers acknowledge that much of the differences between avian microbiota remain unexplained, and that future studies should continue to explore evolution and other environmental factors. Next, the team plans to investigate whether certain food items are associated with specific bacteria in the gut.

“We’d like to know if the birds’ microbiota is affected by bacteria associated with the organisms they eat, or whether they pick up bacteria associated with the environment in which they forage,” Bayes said. “We also like to look across the entire migration cycle of a bird, since migration comes with a whole host of physiological changes that can affect gut chemistry. What birds eat when they migrate south will also be very different from what they eat as we sampled in eastern North America.” “.

In addition to Bayes, the Penn State research team includes Andrea Benavides Castaño, who was an undergraduate student at the time of the research. Andrew Wood, technical researcher; and David Toews, assistant professor of biology. The team also includes Elliott Miller, director of collection development at the Cornell Lab of Ornithology. This research was supported by the National Science Foundation, Penn State Department of Biology, Penn State Huck Institutes for Life Sciences, and Cornell Laboratory of Ornithology.

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Materials Introduction of Pennsylvania state. Original by Jill McCormick. Note: Content can be modified by style and length.



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