For ecologist Raul Costa Pereira, from Unicamp, calling São Paulo a stone jungle is not just a force of expression. Used to doing fieldwork in lush ecosystems such as the Pantanal, Pereira is preparing to explore the biodiversity that hides in São Paulo houses —in a flower vase, in the corner of the room or in the cracks of a tile.
“We normally use binoculars and field pants to study ecological relationships. I want to see what it is possible to do in pajamas and socks indoors”, joked the researcher in a conversation with Folha.
The idea will receive an investment of R$ 570 thousand from Instituto Serrapilheira, a private non-profit organization that finances Brazilian scientists with innovative projects. Although there are already some surveys on the fauna of birds and other larger animals that can be found in parks, squares and other areas of the Brazilian metropolises, the ecologist’s work has slightly different objectives: to find tiny shapes, but still very important, of biodiversity.
“Let’s look more at the micro, basically at arthropods”, he explains, referring to the most diverse group of invertebrates, which includes ants, spiders, beetles, mites and a multitude of other creatures. The “micro” of the analysis also includes the spatial delimitation: Pereira wants to investigate how the habits of each residence influence the presence of different species in it.
“I have an interest in what you might call the ecology of individuals,” he says. “We tend to put several individuals of the same species, such as a type of fish or bird, in the same box. But when we look at us humans, individuality is wide open, and I think it’s possible to see how this reverberates and becomes a driving force for the diversity of these micro-ecosystems that are naturally dependent on us.”
It is possible to think, for example, of the interior of a house as a habitat that houses a miniature food chain, including small herbivores, such as certain ants, and the predators that feed on them (say, spiders), and so on. Details such as the presence of plants, small areas with flowerbeds or lawns, the type of floor in the house, lighting, ventilation, etc. are able to influence which species will form these chains.
But another important variable is the habits of humans in each house, he points out. “Will we have the same species in the home of someone who is vegan, who only eats processed food and who eats practically all meals outside the home? As we are the key species in these environments, all this will make a difference.”
Many of our animals that the researcher intends to study are difficult to see, either because of their size or because of their habit of frequenting little corners that are not accessible to human hands and eyes. To get around this detection problem, the project will adopt environmental genomics techniques. This means that even the dust accumulated in a carpet can undergo a DNA analysis capable of capturing the species that have passed through there, even if larger and more visible remains of them have already disappeared.
Another important tool will be stable isotopes — variants of atoms such as carbon, which appear in all organic molecules, which help to estimate the origin of the food that a given animal consumes. The idea is to investigate, for example, what happened in places where invertebrates depended on the constant presence of food discarded by humans to eat — until they ran out of this “self-service” with the arrival of social distance caused by the Covid-19 pandemic. . This is the case of Unicamp itself, where the researcher normally works.
In addition, the idea is to sample São Paulo houses that take into account the city’s regional and socioeconomic diversities — more wooded neighborhoods or just asphalt and concrete, periphery and downtown, and so on. It will be possible to cross this geographic data with the arthropod surveys to understand how one thing influences the other.
Someone more skeptical might think that hardly anything more interesting than simple ants and cockroaches will show up in a survey like this. Pereira disagrees. “The first step is to open up, throw the net and see what’s next”, he compares, using a fisherman analogy. “I think there can be good and bad surprises, including the presence of some species that, in theory, would only appear in well-preserved places.”