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Scientists Rebuild Evolution of Dinosaur-Age Mosquito Groups

Publicado em 14 setembro 2021

In the last 37 years, two researchers have been dedicated to telling a story of more than 100 millions of years practically using only a microscope, a tweezer and the well-trained eye. Intensely reviewing the literature on the subject, traveling the world to collect specimens and analyzing others deposited in natural history museums, researchers Sarah Siqueira de Oliveira, currently a professor at the Federal University of Gois (UFG), and Dalton de Souza Amorim, a professor at Ribeiro Preto Faculty of Philosophy, Science and Letters, University of So Paulo (FFCLRP-USP), published the most complete work done to date on a subgroup of the so-called fungus mosquitoes.

A publication, with more than one hundred pages and 128 figures, mostly colored, occupies an entire volume of the traditional Bulletin of the American Museum of Natural History, published since 1881 by the American Museum. The work also makes clear the importance of continuous public funding for science, since it has been supported by several FAPESP projects since 2004.

Between what’s new, the extensive survey led to the description of new species and a new proposal for classifying the Mycetophilidae family, as the group of so-called fungus mosquitoes is known. more than 128 millions of years, and diversifying to the present day, the mosquitoes of the family Mycetophilidae (whose name, in Latin, means that like fungus) have larvae that feed on mushrooms, wood ears, spores and other parts of these organisms that grow on decaying wood.

The researchers looked at a subgroup called Leiinae, originated in the south of the supercontinent Gondwana, which later divided into present-day South America, Africa and Antarctica, India, Australia and New Zealand.

The group, which lived with the dinosaurs uros, one of the five subfamilies and one of the most diverse within Mycetophilidae, with more than 128 described species worldwide. There are at least 2,000 species that still lack description. The new work concluded that the subfamily harbors 37 genera and has some fossils preserved in amber.

*)There was no consensus in the scientific literature about which groups belonged to this subfamily. We chose, then, both in the description and naming of the species to work, and in the evolutionary understanding of the relationships. a very diverse and little-known group in the neotropical region, says Oliveira, who carefully studied more than a thousand specimens to complete the work.

The researcher began studying the evolution of insects while still studying biology, at USP in Ribeiro Preto. At the time, the Biota-FAPESP Program, launched in 1999, was in its early years. There was, therefore, a large amount of material collected to be identified, an opportunity for Oliveira to study fungus mosquitoes. This work had a scientific initiation grant from FAPESP first, between 2005 and 2005.

The research was part of a larger project, Geographic limits and causal factors of endemism in the Atlantic Forest in Diptera, coordinated by Amorim, his advisor, within the scope of Biota. Also as part of this project, the researcher completed her master’s and doctoral degrees.

While the efforts at the undergraduate level were dedicated to identifying specimens collected in the Atlantic Forest and the master’s project focused on a particularly diverse genre, the Doctoral work proposed a broad analysis of the Leiinae subfamily, until then, one of the least studied within the fungal mosquitoes. The latter served as the basis for the current publication, which was expanded with the postdoctoral results, also supported by FAPESP.

Insects are very old groups and many have a worldwide distribution. That’s why, as an advisor, I usually choose topics in which students become world leaders in groups that have few experts. We chose this important group because there was a knowledge gap. And with this work, Sarah assumed a leadership position in the area, says Amorim.

Jurassic Park2006

Becoming an authority on a group of animals that occurs all over the world requires analyzing the specimens personally. Many specimens can be found in the collections of natural history museums, institutions whose mission is to preserve the largest and most diverse possible number of animal, vegetable and mineral specimens.

For his doctorate, Oliveira was in Australia and analyzed the collections of the Australian Museum (AMSA) in Sydney and the CSIRO-ANIC in Canberra; On his way back to Brazil, he stopped to work at the South African museums of Kwa-Zulu Natal (NMSA), Iziko (SAMC) and Pretria (National Collection).

On another trip, he studied still collections from the United States and Canada. In his post-doctorate, part of it with a FAPESP Research Internship Scholarship Abroad, Oliveira spent one period studying the collection of the Natural History Museum in London. She also took advantage of her stay in Europe to visit museum collections in France and Germany.

Between studies in loco and material sent by In correspondence, collections from ten countries were analyzed. Amorim, in turn, collected in Chile, New Zealand, Australia, Costa Rica, California and Nepal, from Brazil as well.

An important part of this work was to bring back to Brazil specimens that they had been collected here, but they did not exist in Brazilian collections. They are very diverse animals in the neotropical region, which originated in southern Gondwana and then spread to the rest of the world. Historically, however, researchers from the countries of the Northern Hemisphere described many Brazilian species until the decade of 1940. A part of the collections has now been repatriated, says the researcher.

In some of the museums, part of the agreement for Oliveira to carry out his studies was to organize mosquito collections, often kept for years without a specialist to identify and organize the material.

Many were single copies or with few units, from very old beyond. These factors often make genetic analysis impossible. However, the study of morphology using a microscope is sufficient to obtain most of the evidence in our work. Furthermore, it is not possible to study the genetic material of fossils and morphology is the source of information that allows them to be included in the system, explains Amorim.

One of the principles of the work of taxonomists such as Oliveira and Amorim is precisely find patterns of sharing characters in the morphology of animals such as wings, legs and other parts that make them unique. In the study published now, characters 128 were used to differentiate genders, such as structures of the head, chest, legs, wings and sexual organ.

To create a classification structure with all genera of the subfamily, the researchers added three tribes to the four existing new ones. The study included 54 known species of fossils, being extinct genres, eight of them with specimens preserved in amber, crystallized form of the sap of trees that gained fame with the film Jurassic Park, from 1993.

The insect that appears in the film, in fact, did not feed on blood as shown, according to Amorim: it is one of the fungus mosquitoes of the family Keroplatidae.

Dinosaurs are always a hit with the public, but few people talk about where they lived, what they ate, what other beings lived around them. Our work shows that in that period there was also this group of mosquitoes flying close to their feet, which ate the fungi associated with forest larvae. At that time, these were basically conifers, different from current tropical forests. We can now glimpse an increasingly complete scenario of the flora and fauna at that time, concludes the researcher.