Wednesday , December 8 2021

Birds in the “sand forests” of the Amazon meet different rules of evolution



White sand ecosystem patch in the Uatuma Sustainable Development Reserve (RDS), Central Amazon. Credit: João Capurucho

Imagine Amazon. You’re thinking of lush, lush forests full of animals, right? It seems that the Amazon Basin has other less-known ecosystems that biologists have recently studied for years, including habitat patches that grow in white sand. Scientists have begun to pay attention to these “sandy forests” and the animals that live there. In a new study, researchers studied birds in the region and found that unlike birds in dense forest, white-sand birds travel from one habitat patch to another and cross paths. One feature is that conservationists can change the way they protect birds in the residual forest.

“We’re always interested in knowing where species are and why they exist, what type of habitat they need,” says João Capurucho, a postdoctoral researcher at the Field Museum in Chicago and lead author of the study. Royal Society Procedure B. “White sand ecosystems are very different from the rest of the Amazon and we know very little about them.”

“We wanted to know that the behavior and evolutionary patterns of white sand birds were similar to those of birds living in dense forest and found to be surprisingly different,” says John Bates Field Museum curator and lead author of the study.

White sand ecosystems are found throughout the Amazon Basin, in patches the size of Manhattan. Scientists do not know how sand forests were created; ecosystems cover so much land scattered throughout the Amazon, it’s hard to imagine that they were created from a single ancient beach system. And for a long time, scientists didn’t pay much attention to them. “The thought was that you’re not going to the Amazon to see short, sandy forests, you’re going to see tall, dense trees, so you’re not going to stop in those areas,” Bates says.

As parts of the white sand are separated from each other, the plants and animals that live in it are also isolated. “The patches of white sand in the rainforest are like islands, and you usually start to see genetically different populations with the islands,” Bates says. That’s why Australia has such weird animals compared to the rest of the world – when a population is cut off from the rest, the organisms will cross each other and evolve along their lines. Previous research has shown that plants and insects genetically vary from one part of the sand to another, indicating that they are in different sets of genes and are often different species. Capurucho and his colleagues wanted to see if the same thing happened to birds.


Neopelma chrysocephalum, a saffron-crested Tirano-Manakin, in the white sand ecosystem of the RDS Uatumã. Credit: João Capurucho

“We’ve also been researching the genetic diversity of these birds and comparing them to birds from other Amazon ecosystems. These birds were mostly isolated in different patches, so scattering can be a very important thing to move through the landscape,” says Capurutxo.

The researchers compared the DNA of the birds in different patches of the white sand ecosystem and found that the DNA of the birds was very similar. That was amazing. In the dense dense forest of the Amazon, many birds are separated from each other and begin to branch into different species if they are separated from each other by a barrier like a river that is too wide to cross. But DNA data show that white sand birds support this evolutionary trend: they fly between pieces of white sand, sometimes hundreds of miles away, and cross paths with the birds there.

“It is undeniable that genetic data scatter and maintain connectivity across these landscapes,” Bates says. “And that sometimes involves crossing big rivers. That’s something we were really interested in.”

Other elements of the study adhered to biological rules: for example, birds with long and thin wings traveled a greater distance and reached larger areas than birds with short, round wings, coming from white sand or the surrounding forest. Also, white sand birds had smaller geographical areas on average than their forests. But the breeding of white sand birds between habitat areas shows that they behave according to different evolutionary rules. Now that scientists know more about the ranges and genetic patterns of white sand birds, conservationists would help them set aside the land and help protect it in ways that will benefit the animals that live there. This is a matter of urgency, given the threat of climate change changing Amazonian ecosystems.

“As the climate changes, these habitats will also change in distribution. So we need to understand how birds are distributed in these habitats,” says Capurucho. “We need to know what these differences are that are large-scale or limited to a small area and what characteristics affect them. If we understand that, we can manage the threats to these birds and their habitats.”

“People don’t prioritize protecting white sand ecosystems, but this research emphasizes how much we still need to learn,” says Bates. “They’re really special habitats, and we can’t protect them unless we know how they work.”

Hidden losses in the Amazon jungle

More information:
The dispersal capacity is related to the size of the range of birds in the limited Amazon habitat, Royal Society Procedure B (2020). rspb.royalsocietypublishing.or … .1098 / rspb.2020.1450

Mention: Birds in Amazon’s “sand forests” behave according to different evolutionary rules (2020, November 17) Retrieved November 18, 2020 html

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