Asteroid that wiped out the dinosaurs led to the invention of ‘ant agriculture’
When the dust that covered the skies 66 million years ago prevented plants from photosynthesizing and benefited creatures that fed on decomposing organic matter, these insects selected species that could fill their nutrient void, confirms a study.
Fundação de Amparo à Pesquisa do Estado de São Paulo
image:
Colony of the species Atta colombica, unearthed in Gamboa, Panama. In the center of the photo, much larger than the workers, is the queen
view moreCredit: Pepijn W. Kooij/IB-UNESP
The event that wiped out the dinosaurs wasn’t all bad. The low-light environment caused by the meteor impact some 66 million years ago favored the spread of fungi that feed on organic matter, which was abundant at the time as plants and animals were dying in droves.
It was the perfect opportunity for the ancestor of a group of ants to start cultivating these microorganisms, according to a study published on October 3 in the journal Science.
“The origin of fungus-farming ants was relatively well understood, but a more precise timeline for these microorganisms was lacking. The work provides the smallest margin of error to date for the emergence of these fungal strains, which were previously thought to be more recent,” explains André Rodrigues, professor at the Institute of Biosciences of São Paulo State University (IB-UNESP) in Rio Claro, Brazil, and one of the authors of the paper.
The researcher coordinates the project “Collaborative research: Dimensions US-São Paulo: integrating phylogeny, genetics, and chemical ecology to unravel the tangled bank of the multipartite fungus-farming ant symbiosis,” supported by FAPESP through its Research Program on Biodiversity Characterization, Conservation, Restoration and Sustainable Use (BIOTA), in collaboration with the National Science Foundation (NSF), of the United States.
The dating was made possible by analyzing the so-called ultraconserved elements (UCEs) of the genomes of 475 fungal species cultivated by ants and collected from different parts of the Americas. UCEs are regions that remain in the genome throughout the evolution of a group, derived from its most ancient ancestors.
“In this case, we were interested in the regions close to these elements. They show the most recent differences between species and allow us to trace a fairly accurate evolutionary line,” adds Pepijn Wilhelmus Kooij, a researcher at IB-UNESP supported by FAPESP and also co-author of the work.
Using this method, it was possible to establish the near-simultaneous emergence of two distinct fungal lineages from the same ancestor of today’s leafcutter ants (a group known as Attini) 66 million years ago.
Specialists in the mutualism between fungi and ants have long argued that the beginning of this relationship defines the emergence of agriculture, tens of millions of years before humans began domesticating plants, just 12,000 years ago.
The study also revealed the emergence of an ancestor of coral fungi, a second group that began to be cultivated by ants 21 million years ago. The fungus gets its name from the fact that it forms structures that resemble miniature colonies of sea coral.
Mutualism
The results support the hypothesis that fungi had already undergone pre-adaptation before being cultivated by ants. It is likely, the authors point out, that the ancestor of the leafcutter ant group lived in close proximity to fungi, either inside the colonies or even collecting them from time to time to feed on them or their products.
“But the fungi were not an essential part of the ants’ diet. The pressure exerted by the meteor impact may have turned this relationship into an obligatory mutualism, in which these fungi come to depend on the ants for food and reproduction, while at the same time the ants depend exclusively on the fungi as a food source,” Rodrigues contextualizes.
Today, four different groups of ants cultivate four types of fungus. In some cases, the insects even alter the growth of the cultivated product so that it provides certain nutrients.
“When we cultivate them in the lab, the fungi take the expected form of hyphae. However, inside the colony, one of these hyphae types becomes swollen and forms structures similar to grape clusters, rich in sugars. We still don’t know how the ants do this,” says Kooij.
For Mauricio Bacci Junior, professor at IB-UNESP and co-author of the paper, the origin of the cultivation of fungi probably points to an adaptation in the face of a nutritional shortage faced by the ants at that time.
With the abundance of fungi spreading across what are now the Americas, and fewer options for food sources, those that already had some possible relationship with ants ended up proving more useful when cultivated.
“To feed itself, the fungus decomposes the organic matter carried by the ants. In turn, the ant consumes substances produced by the fungus that it couldn’t obtain from any other source. It’s as if the fungus were the insect’s external stomach,” compares the researcher, who is deputy director of the Center for Research on Biodiversity Dynamics and Climate Change (CBioClima), one of the Research, Innovation and Dissemination Centers (RIDCs) supported by FAPESP.
After this founding event, fungus-farming ants, which had previously lived in humid forests, experienced a second selective pressure with the expansion of the Cerrado savanna-like biome 27 million years ago. With more open and arid areas, there was a diversification of these agricultural insects, leading to the origin of today’s leafcutter ants (read more at: agencia.fapesp.br/38315/).
This event also certainly favored the diversification of fungi, which became more efficient at producing food for the ants and decomposing organic matter.
So much so that the enzymes produced by fungi cultivated by ants are now being studied for their biotechnological potential to degrade not only organic matter but also other materials, including plastics.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.
Lemon leafcutter Atta colombica workers carry leaves to the colony in Gamboa, Panama
Credit
Pepijn W. Kooij/IB-UNESP
Image magnified a thousand times shows nutritive vesicles (gongylids) produced by the fungus Leucoagaricus gongylophorus, cultivated by the lemon leafcutter (Atta sexdens)
Credit
André Rodrigues/IB-UNESP
Journal
Science
Article Title
Asteroid impact may have turned ants into fungus farmers 66 million years ago
Article Publication Date
3-Oct-2024
Ant agriculture began 66 million years ago in the aftermath of the asteroid that doomed the dinosaurs
Smithsonian scientists assembled and analyzed sprawling genetic database, finding some fungal crops later became completely reliant on ants 27 million years ago
Smithsonian
image:
A lower-fungus-farming worker of the rare fungus-farming ant species Mycetophylax asper, collected in Santa Catarina, Brazil, in 2014, on its fungus garden.
Nearly 250 different species of ants in the Americas and Caribbean farm fungi. Researchers organize these ants into four agricultural systems based on their cultivation strategies.
In a paper published today, Oct. 3, in the journal Science, scientists at the Smithsonian’s National Museum of Natural History analyzed genetic data from hundreds of species of fungi and ants to craft detailed evolutionary trees. According to the new study, colonies of ants began farming fungi when an asteroid struck Earth 66 million years ago. This impact caused a global mass extinction but also created ideal conditions for fungi to thrive. Innovative ants began cultivating the fungi, creating an evolutionary partnership that became even more tightly intertwined 27 million years ago and continues to this day.
view moreCredit: Don Parsons.
When humans began farming crops thousands of years ago, agriculture had already been around for millions of years. In fact, several animal lineages have been growing their own food since long before humans evolved as a species.
According to a new study, colonies of ants began farming fungi when an asteroid struck Earth 66 million years ago. This impact caused a global mass extinction but also created ideal conditions for fungi to thrive. Innovative ants began cultivating the fungi, creating an evolutionary partnership that became even more tightly intertwined 27 million years ago and continues to this day.
In a paper published today, Oct. 3, in the journal Science, scientists at the Smithsonian’s National Museum of Natural History analyzed genetic data from hundreds of species of fungi and ants to craft detailed evolutionary trees. Comparing these trees allowed the researchers to create an evolutionary timeline of ant agriculture and pinpoint when ants first began cultivating fungi.
“Ants have been practicing agriculture and fungus farming for much longer than humans have existed,” said entomologist Ted Schultz, the museum’s curator of ants and the lead author of the new paper. “We could probably learn something from the agricultural success of these ants over the past 66 million years.”
Nearly 250 different species of ants in the Americas and Caribbean farm fungi. Researchers organize these ants into four agricultural systems based on their cultivation strategies. Leafcutter ants are among those that practice the most advanced strategy, known as higher agriculture. These ants harvest bits of fresh vegetation to provide sustenance for their fungi, which in turn grow food for the ants called gongylidia. This food helps fuel complex colonies of leaf cutter ants that can number in the millions.
Schultz has spent 35 years studying the evolutionary relationship between ants and fungi. He has conducted more than 30 expeditions to locales in Central and South America to observe this interaction in the wild and has reared colonies of leafcutter and other fungus-farming ants in his lab at the museum. Over the years, Schultz and colleagues have collected thousands of genetic samples of ants and fungi from throughout the tropics.
This stockpile of samples was crucial to the new paper.
“To really detect patterns and reconstruct how this association has evolved through time, you need lots of samples of ants and their fungal cultivars,” Schultz said.
The team used the samples to sequence genetic data for 475 different species of fungi (288 of which are cultivated by ants) and 276 different species of ants (208 of which cultivate fungi)—the largest genetic dataset of fungus-farming ants ever assembled. This allowed the researchers to create evolutionary trees of the two groups. Comparing wild fungal species with their cultivated relatives helped the researchers determine when ants began utilizing certain fungi.
The data revealed that ants and fungi have been intertwined for 66 million years. This is around the time when an asteroid struck Earth at the end of the Cretaceous period. This cataclysmic collision filled the atmosphere with dust and debris, which blocked out the sun and prevented photosynthesis for years. The resulting mass extinction wiped out roughly half of all plant species on Earth at the time.
However, this catastrophe was a boon for fungi. These organisms proliferated as they consumed the plentiful dead plant material littering the ground.
“Extinction events can be huge disasters for most organisms, but it can actually be positive for others,” Schultz said. “At the end of Cretaceous, dinosaurs did not do very well, but fungi experienced a heyday.”
Many of the fungi that proliferated during this period likely feasted on decaying leaf litter, which brought them in close contact with ants. These insects harnessed the plentiful fungi for food and continued to rely on the hardy fungi as life rebounded from the extinction event.
The new work also revealed that it took nearly another 40 million years for ants to then develop higher agriculture. The researchers were able to trace the origin of this advanced practice back to around 27 million years ago. At this time, a rapidly cooling climate transformed environments around the globe. In South America, drier habitats like woody savannas and grasslands fractured large swaths of wet, tropical forests. When ants took fungi out of the wet forests and into drier areas, they isolated the fungi from their wild ancestral populations. The isolated fungi became completely reliant on ants to survive in the arid conditions, setting the course for the higher agriculture system practiced by leafcutter ants today.
“The ants domesticated these fungi in the same way that humans domesticated crops,” Schultz said. “What’s extraordinary is now we can date when the higher ants originally cultivated the higher fungi.”
In addition to Schultz, the new paper included contributions from several coauthors affiliated with the National Museum of Natural History, including Jeffrey Sosa-Calvo, Matthew Kweskin, Michael Lloyd, Ana Ješovnik and Scott E. Solomon. The study also includes authors affiliated with the University of Utah; the Royal Botanic Gardens, Kew; the University of California at Berkeley; the U.S. Department of Agriculture; São Paulo State University; the Instituto de Investigaciones Científicas y Servicios de Alta Tecnología; the Smithsonian Tropical Research Institute; the University of Copenhagen; Emory University; McMaster University; Universidade Federal de Uberlândia; Arizona State University; the University of Hohenheim; and Louisiana State University.
The research was supported by the U.S. National Science Foundation; the Smithsonian; the University of Maryland; Louisiana State Board of Regents; Sistema Nacional de Investigación; Cosmos Club Foundation; Explorer’s Club in Washington, D.C.; São Paulo Research Foundation; Brazilian Council of Research and Scientific Development; Brazilian Federal Agency for Support and Evaluation of Graduate Education; the Royal Botanic Gardens, Kew; and the Carl Zeiss Foundation.
About the National Museum of Natural History
The National Museum of Natural History is connecting people everywhere with Earth’s unfolding story. It is one of the most visited natural history museums in the world. Opened in 1910, the museum is dedicated to maintaining and preserving the world’s most extensive collection of natural history specimens and human artifacts. The museum is open daily, except Dec. 25, from 10 a.m. to 5:30 p.m. Admission is free. For more information, visit the museum on its website, blog, Facebook, Twitter and Instagram.
The queen and workers of the leaf-cutting fungus-farming ant species Atta cephalotes, collected in Panama, on their higher-agriculture fungus garden.
Nearly 250 different species of ants in the Americas and Caribbean farm fungi. Researchers organize these ants into four agricultural systems based on their cultivation strategies.
In a paper published today, Oct. 3, in the journal Science, scientists at the Smithsonian’s National Museum of Natural History analyzed genetic data from hundreds of species of fungi and ants to craft detailed evolutionary trees. According to the new study, colonies of ants began farming fungi when an asteroid struck Earth 66 million years ago. This impact caused a global mass extinction but also created ideal conditions for fungi to thrive. Innovative ants began cultivating the fungi, creating an evolutionary partnership that became even more tightly intertwined 27 million years ago and continues to this day.
Credit
Karolyn Darrow.
Entomologist Ted Schultz, the curator of ants at the Smithsonian’s National Museum of Natural History and the lead author of the new paper, on an ant-collecting expedition to the Acarai Mountains of southern Guyana in October 2006.
Schultz has spent 35 years studying the evolutionary relationship between ants and fungi. He has conducted more than 30 expeditions to locales in Central and South America to observe this interaction in the wild and has reared colonies of leafcutter and other fungus-farming ants in his lab at the museum. Over the years, Schultz and colleagues have collected thousands of genetic samples of ants and fungi from throughout the tropics.
In a paper published today, Oct. 3, in the journal Science, scientists at the museum analyzed genetic data from hundreds of species of fungi and ants to craft detailed evolutionary trees. According to the new study, colonies of ants began farming fungi when an asteroid struck Earth 66 million years ago. This impact caused a global mass extinction but also created ideal conditions for fungi to thrive. Innovative ants began cultivating the fungi, creating an evolutionary partnership that became even more tightly intertwined 27 million years ago and continues to this day.
Credit
Jeffrey Sosa-Calvo
Journal
Science
Method of Research
Observational study
Subject of Research
Animals
Article Title
The coevolution of fungus-ant agriculture
Article Publication Date
4-Oct-2024
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