The Evolution Of Asia’s Mammals Was Dictated By Ancient Climate Change And Rising Mountains

Newswise — The idea that climate change and geological events can shape evolution isn’t a new one: anyone who’s heard of dinosaurs knows that a big change in the environment (like, say, a meteor hitting the Earth 66 million years ago and causing a chain reaction of storms, earthquakes, cold, and darkness) can dictate how animals live, die, and evolve. But while it’s a generally agreed-upon concept, scientists rely on painstakingly precise data to map how these sorts of changes affect the course of evolution for even one species. A new study in PNAS compiles data on more than 3,000 species to show how climate and geologic changes across Asia over the last 66 million years have shaped the evolution of the continent’s mammals.

Asia is the world’s largest continent, and it’s home to just about every type of biome. “Asia has desert up north, tropical forests in the south, temperate forests in the east,” says Anderson Feijó, the study’s lead author, a researcher at the Institute of Zoology, Chinese Academy of Sciences and a former research fellow at Chicago’s Field Museum. “My idea was to understand how all these regions were connected and how we ended up with different species of mammals in different areas.”

“To understand historical events, scientists look for associations with their timing and location– when and where did species appear, and what else was happening then and there? This paper does that for the entire Asian mammal fauna,” says Bruce Patterson, a curator emeritus at the Field Museum and co-author of the paper.

Asia doesn’t have the most mammal species in the world, or the most different kinds of habitats, but “what makes it special is its connections,” says Patterson. “It’s a crossroads for connections to North America, Africa, Europe, and Australasia.” The researchers wanted to see how different mammals came to Asia and left from there over time, as well as how new species evolved, and determine whether they could link these changes in Asia’s mammal diversity with changes in the region’s geology (like shifting tectonic plates forming mountains) and climate.

“One big step of this project was building a very good understanding of the distribution of mammal species. And this took quite a while because I needed to go through the literature, public databases, and museum collections,” says Feijó. Museums like the Field and the National Zoological Museum of China house collections that include preserved animal specimens and fossils coupled with info about where the animal was found and when. They also used family trees showing how different species are related to shed light on the bigger picture of mammalian evolution. Combining both info, Feijó and his colleagues were able to map where different species have been found over time. 

Overall, the researchers found clear links between changes in the Earth’s climate over the past 66 million years and the mammals found in different regions of Asia. As the climate slowly warmed and cooled, some species were driven extinct or moved to new habitats, while others thrived. Similarly, tectonic plate activity, like when the Indian subcontinent inched towards the rest of Asia and eventually crashed into it, buckling the land and forming the Himalayas, played a big role in the movement, extinction, and evolution of mammals.

The researchers were even able to explore the effects of climate and geology on the evolution of individual species; Feijó gives the example of the pikas. Pikas look like their close relatives, rabbits, but have small rounded ears, and they’re adapted to live in high altitudes with low oxygen levels. “Pikas originated around 15 million years ago on the Tibetan Plateau, and we believe that the formation of this plateau was a big driver of the evolution of this group,” says Feijó. “Then from there, they colonized the lowlands of northern Asia and then invaded North America, where they’re still found today.”

Overall, “this paper made very clear that everything is connected.”says Feijó. “We are seeing a lot of climate change happen today, and this paper shows that every geological climate change event has led to either diversification or extinction or migration, and we can expect the same thing to happen in the future.” 

“Mystery Plant” From The Amazon Declared A New Species

Newswise — In 1973, a scientist stumbled upon a strange tree in the Amazon rainforest, unlike anything he’d ever seen. It was about 20 feet tall, with tiny orange fruits shaped like paper lanterns. He collected samples of the plant’s leaves and fruits, but all the scientists he showed them to wound up scratching their heads– not only were they unable to identify the plant as a species that had previously been described by scientists, but they couldn’t even declare it a new species, because they couldn’t tell what family it belonged to. But in a new study in the journal Taxon, scientists analyzed the plant’s DNA and determined where it belongs in the family tree of trees, finally giving it a name meaning “Mystery of Manu,” after the park in Peru it came from.

“When I first saw this little tree, while out on a forest trail leading from the field station, it was the fruit — looking like an orange-colored Chinese lantern and juicy when ripe with several seeds — that caught my attention,” says Robin Foster, the scientist who originally collected the mystery plant in Peru’s Manu National Park, a retired curator at Chicago’s Field Museum and now a researcher with the Smithsonian Tropical Research Institute. “I didn’t really think it was special, except for the fact that it had characteristics of plants in several different plant families, and didn’t fall neatly into any family.  Usually I can tell the family by a quick glance, but damned if I could place this one.”

Foster wasn’t the only one who couldn’t figure it out. Nancy Hensold, a botanist at the Field Museum, remembers him showing her a dried specimen of the plant more than 30 years ago. “I came to work at the Field Museum in 1990, and Robin showed me this plant. And I tried to get it identified using little fine technical characters like boiling up the ovaries of the flowers and taking pictures of the pollen, and after all that, we still didn’t know,” she recalls. “It really bugged me.”

The mystery plant sat in the Field Museum’s herbarium, a library of dried plant specimens, for years, but Hensold and her colleagues didn’t forget about it. “When you have a plant no one can put in a family, it can fall through the scientific cracks. I felt for it,” she says. The team eventually got a grant to study the plant, funded by the Field Museum’s Women’s Board, and the search was on.

The team attempted to analyze the plant’s DNA using the dried specimens, but when that didn’t work, they enlisted the help of Patricia Álvarez-Loayza, a scientist who works in the Manu National Park and has spent years monitoring the forest there, to find a fresh specimen of the plant. She did, and when the researchers back at the Field analyzed it in the museum’s Pritzker DNA Laboratory, they were shocked by what they found. “When my colleague Rick Ree sequenced it and told me what family it belonged to, I told him the sample must have been contaminated. I was like, no way, I just couldn’t believe it,” recalls Hensold.

The DNA analysis revealed that the mystery plant’s closest relatives were in the Picramniaceae family, which was a big deal to the botanists because it didn’t look anything like its closest relatives, at least at first glance. “L​​ooking closer at the structure of the tiny little flowers I realized, oh, it really has some similarities but given its overall characters, nobody would have put it in that family,” says Hensold. The researchers sent specimens to Wayt Thomas, a curator emeritus at The New York Botanical Garden and an expert in Picramniaceae. “When I opened the package and looked at the specimens, my first reaction was, ‘What the heck?’ These plants didn’t look like anything else in the family,” says Thomas, the lead author of the paper in Taxon. “So I decided to look more carefully–once I looked really carefully at the tiny, 2-3 milimeter long flowers, things fell into place.” With the DNA finally revealing what family the plant belonged to, the researchers were able to give it a formal scientific name, Aenigmanu alvareziae. The genus name, Aenigmanu, means “mystery of Manu,” while the species name is in honor of Patricia Álvarez-Loayza, who collected the first specimens used for the genetic analysis. (It’s worth noting that while Aenigmanu alvareziae is new to scientists, it has long been used by the Indigenous Machiguenga people.)

The researchers say that finally getting a scientific classification for Aenigmanu alvareziae could ultimately help protect the Amazon rainforest in the face of deforestation and climate change. “Plants are understudied in general. Especially tropical forest plants. Especially Amazon plants.  And especially plants in the upper Amazon. To understand the changes taking place in the tropics, to protect what remains, and to restore areas that have been wiped out, plants are the foundation for everything that lives there and the most important to study,” says Foster.  “Giving them unique names is the best way to organize information about them and call attention to them. A single rare species may not by itself be important to an ecosystem, but collectively they tell us what is going on out there.”