Agriculture has been around for millions of years before humans started growing crops thousands of years ago. Long before humans evolved into species, some animal populations began to grow food. According to researchers at the Smithsonian Institution, ants began cultivating fungi 66 million years after the meteorite impact, and leaf-cutting ants have even evolved advanced agricultural techniques.
Worker ants of Mycetophylax asper, a rare fungus ant collected in Santa Catarina, Brazil, in 2014, are working in its fungus garden. There are nearly 250 different species of ants farming fungi in the Americas and the Caribbean. Based on the cultivation strategies of these ants, the researchers divided them into four agricultural systems. Source: Don Parsons
When an asteroid hit Earth 66 million years ago, ant colonies began growing fungi, according to a new study. Although the impact caused a global extinction, it also created ideal conditions for the fungus to thrive. Innovative ants began to cultivate fungi, creating an evolutionary partnership that became more intertwined 27 million years ago and continues to this day.
Cyphomyrmex cf.Ecuador The yeast-breeding worker ants of rimosus are in their fungal garden. There are nearly 250 different species of ants farming fungi in the Americas and the Caribbean. Based on the cultivation strategies of these ants, the researchers divided them into four agricultural systems. Source: Alex Wild
In the study, recently published in the journal Science, scientists at the Smithsonian's National Museum of Natural History analyzed genetic data from hundreds of fungi and ants and produced detailed evolutionary trees.
By comparing these evolutionary trees, the researchers mapped out the evolutionary timeline of ant agriculture and determined when ants first began cultivating fungi.
Queens and worker ants of the leaf-cutting fungal ant species Atta cephalotes collected in Panama in their high-yielding fungal orchards. Photo credit: Karolyn Darrow
"Ants have been engaged in agriculture and mushroom cultivation much longer than humans have been around, and we may be able to learn something from the past 66 million years of successful agricultural experience of these ants," said entomologist Ted Schultz. He is the museum's director of the Ant Pavilion and the first author of the new paper.
There are nearly 250 different species of ants farming fungi in the Americas and the Caribbean. The researchers divided these ants into four farming systems based on their planting strategies. Among them, the strategy of leafcutter ants is the most advanced, and it is called "high agriculture".
These ants pick the detritus of fresh vegetation to provide nourishment for the fungus, which in turn grows food known as ant gum. These foods fuel complex ant colonies that can number millions.
Entomologist Ted Schultz, director of the Ant Pavilion at the Smithsonian's National Museum of Natural History and lead author of the new paper, conducted an ant-collecting expedition in Mount Akale in southern Guyana in October 2006. Schultz spent 35 years studying the evolutionary relationship between ants and fungi. He made more than 30 expeditions in Central and South America, observing this interaction in the wild and raising leaf-shearing ants and other fungi-growing ants in the museum's laboratory. Over the years, Schultz and colleagues collected thousands of genetic samples of ants and fungi from across the tropics. Source: Jeffrey Sousa Calvo
Schultz spent 35 years studying the evolutionary relationship between ants and fungi. He made more than 30 expeditions in Central and South America, observing this interaction in the wild and raising leaf-shearing ants and other fungi-growing ants in the museum's laboratory. Over the years, Schultz and colleagues collected thousands of genetic samples of ants and fungi from across the tropics. This batch of samples is crucial for the publication of new papers.
Entomologist Ted Schultz (center), director of the Ant Hall at the Smithsonian National Museum of Natural History and first author of the new paper, excavates the nest of Mycetophylax asper, a rare lower fungal ant species, with Jeffrey Sousa Calvo (left) and Anna Jesovnik (right) in the Chapeco National Forest in Santa Catarina, Brazil, in 2014. Image Credit: Jeffrey Souza Calvo
"To really detect patterns and reconstruct how this association has evolved over time requires a large number of ant samples and their fungal cultivars," Schultz said. "
The team used these samples to sequence genetic data from 475 different fungi (288 of which were cultivated by ants) and 276 different ants (of which 208 were cultivated fungi) – the largest genetic dataset of fungal cultivated ants collected to date. The researchers thus created the evolutionary tree of the two populations. Comparing wild fungal species to their cultivated relatives helps researchers determine when ants began to exploit certain fungi.
Data shows that ants and fungi have been intertwined for 66 million years. This is about the time when an asteroid hit Earth at the end of the Cretaceous period. This catastrophic impact filled the atmosphere with dust and debris, obscuring the sun and hindering photosynthesis for years. The resulting mass extinction wiped out about half of the plant species on Earth at the time.
However, this catastrophe brought good news to the fungus. These creatures consume a large number of plant carcasses on the ground, thus multiplying in large numbers.
Coral fungal worker ants of the ant-species Apterostigma collare, farmed at the La Selva Biostation in Costa Rica, collected in 2015 in its fungal garden. Image courtesy of Alex Wild
"An extinction event can be a huge catastrophe for most organisms, but it can actually be positive for others as well," Schultz said. At the end of the Cretaceous period, dinosaurs did not do well, but fungi experienced their heyday. "
Many of the fungi that multiply in abundance during this period may have fed on decaying leaves, which brought them into close contact with ants. These insects use abundant fungi for food and continue to rely on these tough fungi after life is recovering from extinction events.
The new study also found that it took nearly another 40 million years for ants to develop advanced agriculture. Researchers were able to trace the origins of this advanced practice back about 27 million years. At that time, a rapidly cooling climate changed the global environment. In South America, drier habitats such as savannas and grasslands have fragmented large areas of moist tropical forest. When ants carry fungi from moist forests to drier areas, they isolate the fungus from wild ancestral populations. These isolated fungi are completely dependent on ants to survive in arid environments, laying the foundation for the advanced agricultural system practiced by leaf-shearing ants today.
"Ants domesticate these fungi in the same way humans domesticate crops," Schultz said. "Unusually, we can now determine when higher ants first cultivated higher fungi."
编译自/SciTechDaily