Analysis of 309 strains suggests that the genus Escovopsis originated about 56.9 million years ago, but did not begin interacting with modern mutualistic ants until roughly 38 million years ago—challenging the idea that these groups arose simultaneously.
A group of fungi once thought to be harmful parasites of ant associated fungi may play a far more complicated role in nature. A study published in the journal Communications Biology and supported by FAPESP suggests this because the fungi appeared about 18 million years before the ants they are linked to today.
The findings come from an analysis of 309 strains from the fungal genus Escovopsis collected across eight countries in the Americas. Researchers examined parts of the fungi’s genomes, along with their physical traits, geographic range, and evolutionary relationships. This approach allowed them to trace how Escovopsis became associated with leafcutter ants over the past 38 million years. The analysis shows that Escovopsis first emerged around 56.9 million years ago.
“Our main hypothesis is that they emerged associated with ancestral groups of fungus-growing ants and then began to coexist with the current leafcutter ants 38 million years ago. Another possibility is that they lived in a different context during those initial 18 million years, outside of their association with ants, as leaf colonizers or degrading organic matter, for example,” explains Quimi Vidaurre Montoya, the first author of the study.
Vidaurre Montoya conducted the study as part of his postdoctoral research with a fellowship from FAPESP at the Institute of Biosciences of São Paulo State University (IB-UNESP) in Rio Claro, Brazil.
Leafcutter ants (subtribe Attina) cultivate fungi for food. According to a recent study by the group published in the journal Science in 2024, this mutualistic relationship is thought to have emerged 66 million years ago.
“Our current work is on Escovopsis, a genus of fungi that isn’t cultivated by ants, but is present in the colonies of some species of farming ants and can kill some of their cultivars. Because of this, it’s portrayed as a ‘parasite,’ when in fact only one of 24 species is known to cause infection in the fungus cultivated by ants,” Montoya explains.
The study is part of a project supported by FAPESP through the FAPESP Research Program on Biodiversity Characterization, Conservation, Restoration, and Sustainable Use (BIOTA-FAPESP), coordinated by André Rodrigues, a professor at IB-UNESP and a researcher at the Center for Research on Biodiversity Dynamics and Climate Change (CBioClima), which is one of the Research, Innovation, and Dissemination Centers (RIDCs) supported by FAPESP.
Adaptations
The researchers report that Escovopsis gradually developed physical and biological changes over long periods of evolution, likely helping it reproduce more efficiently and survive within ant nests. Most of these adaptations involved the vesicles that generate conidia, the structures responsible for asexual reproduction.
“The vesicles change from a globular shape in species closer to the common ancestor to a cylindrical shape in more recent species. These changes may have been responses to barriers imposed by the ants or their symbiotic fungi,” Montoya says.
Physiological data indicate that the growth rate, number of vesicles, and production and viability of conidia gradually increased as the genus diversified. Species with cylindrical vesicles may grow faster than those with globular structures. The thinner, elongated vesicles of more recent species produce considerably more viable conidia than older groups with globular vesicles.
“Apparently, there’s a coevolution between ants, symbiotic fungi, and Escovopsis. We don’t know if they evolved to become parasites or if they’re opportunists that feed on debris and can eat what remains when the system as a whole collapses. But if it were a specialized virulent host, as part of the literature assumes, it would destroy the system regardless of whether it was in equilibrium or not,” Montoya says.
Little-known fungi
This study is an offshoot of broader work on the genus Escovopsis that began during Montoya’s doctoral studies. He received a scholarship from FAPESP to conduct research under the guidance of Rodrigues. Montoya also completed an internship at Emory University in the United States.
At the time, Montoya analyzed the two largest existing collections of these fungi: the IB-UNESP collection, which was collected and maintained by Rodrigues’s group, and the Emory collection, which was maintained by Professor Nicole Marie Gerardo, Montoya’s supervisor abroad.
One of the first results of that effort was the description of two new genera previously classified as Escovopsis. Two others discovered in that work are still in the process of being described. Montoya and Rodrigues also led the description of 13 new species of Escovopsis, with ten more in the process of being described.
“These fungi are still poorly understood from physiological and ecological points of view. Therefore, it’s premature to treat them all as parasites. Our studies suggest that they have other functions and can live in relative harmony in colonies,” Montoya believes.
According to the researcher, only the Escovopsis weberi species has been proven to cause infections in fungi cultivated by ants. Experiments by his group and others show that several strains did not kill the fungi in the presence of these insects.
In vitro experiments that support the claim of parasitism disregard the fact that the affected fungi rely on ants for protection. Therefore, evaluating the effect of Escovopsis on mutualistic fungi without ants and their hygiene behaviors, which act as a social immune system, would not make sense.
“Some more virulent fungi are immediately removed by ants when inoculated into the colony. In experiments with Escovopsis, however, they don’t give it much importance,” the researcher says.
The Life of Earth
https://chuckincardinal.blogspot.com/
No comments:
Post a Comment
Stick to the subject, NO religion, or Party politics