Alcatrazes reveals hidden natural wealth .

A group of biologists from Unicamp unravels the mysteries of the flora found on the coasts of the 'Brazilian Galapagos'

Approximately 35 kilometers off the coast of São Sebastião, on the northern coast of São Paulo, an untouched natural paradise fills the imagination of local residents and draws the attention of those who frequent the famous beaches of Maresias and Juquehy. With 67,4 hectares, the Alcatrazes Archipelago Wildlife Refuge is the largest fully protected marine conservation unit in the South and Southeast Regions and the second largest in the country, behind only the Abrolhos National Park in Bahia. The environmentally protected area comprises five main islands – Alcatrazes, the largest, has approximately 190 hectares (the equivalent of 266 soccer fields) – and the entire marine environment.

Home to an exuberant biodiversity, its great potential for scientific research has earned it the nickname “Brazilian Galapagos”, a reference to the archipelago studied by Charles Darwin, considered the world’s leading living laboratory of biology. Alcatrazes is recognized for its importance as a breeding ground for seabirds, especially the large frigatebird nest located on the mainland side of the main island. According to the area’s management plan, prepared by the Chico Mendes Institute for Biodiversity Conservation (ICMBio), the estimated population of frigatebirds exceeds 10 individuals, which live in balance with other species of reptiles, amphibians, insects and arachnids, not to mention marine fauna.

A group of researchers from the Biology Institute (IB) at Unicamp is working to uncover a layer of the archipelago that has yet to be explored: the flora that inhabits the islands' coasts. The vegetation in these locations is intriguing not only because of its high specificity – according to the researchers, coordinated by Professor Fábio Pinheiro, there are between 260 and 300 endemic plant species on Alcatrazes Island alone – but also because of the species that have not yet been identified, either because studies of this type have less visibility or because of the difficulties in accessing the site. So far, the group has discovered two new species of bromeliad and rediscovered a species of begonia that had not been recorded for over a hundred years.

The research carried out on site is essential to strengthen the work of environmental preservation agencies and contributes to keeping alive species that tell part of the region's natural history. These species, due to their isolation and unique nature, are already under threat of extinction when identified.

Isolated by nature

Geological formations like Alcatrazes are extremely old, dating back to the Precambrian period, which began with the formation of the planet itself, about 4,5 billion years ago, and lasted until about 540 million years ago. In German, they are called Inselbergs , a term meaning "island mountain," hills formed by large, single rocks, usually composed of granite, that stand out in the middle of the flat landscape. Corcovado Mountain, where the Christ the Redeemer statue stands, and Urca Mountain, which makes up Sugarloaf Mountain, in Rio de Janeiro, offer famous examples of Inselbergs . "These are formations that predate the separation of the continents, predating the origin of terrestrial plants," explains Pinheiro. "We usually say that Inselbergs didn't just appear. They've always been there."

Even when located in areas near forests, the physical characteristics of innselbergs make the biodiversity found there distinct from that of their surroundings. This is due to their altitude, the characteristics of the rocky soil, and the difficulty of access for animals, such as pollinators and predators of the local flora, making them unique habitats. In the case of maritime innselbergs , both isolation and environmental conditions become even more pronounced. "They [ maritime innselbergs ] suffer greatly from wind, high salinity, and isolation itself," says Gabriel Sabino, a doctoral student and member of the group.

These characteristics affect the factors that determine the evolution of plant species in places like Alcatrazes. Pinheiro uses a comparison between the island and Morro da Urca, where access by small animals, such as marmosets and various insects, is facilitated by the proximity to the ground. “Our hypothesis is that, on the island, there is a greater relaxation of the defense resources that plants develop against predators, such as thorns and poisonous leaves,” he comments. To measure how much isolation has changed the species on the island, it was necessary to look at the marks that the passage of time has left on the phylogenetic structure of the place, that is, how the species found there have related to each other throughout their evolution. This became possible thanks to an interesting aspect of the island: the rock formation was once connected to the continent.

Up to 20 to 15 years ago, during the planet's last glacial cycle, sea levels were between 120 and 150 meters lower than today, and the shoreline extended up to 500 kilometers into the current ocean. Thus, prehistoric animals and humans could reach it on foot. After the rise in sea level, isolation occurred, and the hill transformed into an island. According to researchers, this process has occurred several times throughout history, alternating between periods of connection and isolation. This means it is possible to make comparisons between the flora of Alcatrazes and that of continental inselbergs . And the research group did just that in a study published in the Journal of Vegetation Science.

Island of surprises

Fifteen inselbergs in the Atlantic Forest region were studied : six marine inselbergs – including the islands of the Alcatrazes Archipelago, Queimada Grande Island, located between Itanhaém and Peruíbe on the southern coast of São Paulo, and Cagarras Island, near Ipanema beach in Rio de Janeiro – and nine continental inselbergs, such as some hills also in Rio de Janeiro, Minas Gerais, and Espírito Santo. Based on the collection of floristic and phylogenetic data of plants found in these locations, researchers can project how closely related the species are to each other within the same environment, and whether the islands and the mainland share species.

According to the publication, a total of 753 plant species were recorded, with particular emphasis on the orchid family ( Orchidaceae ); the bromeliad family ( Bromeliaceae ); the asteraceae family ( Asteraceae ), which includes sunflowers and chrysanthemums, for example; and the fabaceae family ( Fabaceae ), which produce pod-shaped fruits. It is noteworthy that only 11% of the species appeared in both types of Inselbergs , while 72% inhabited only one of the two environments. Biologists highlight that, despite the high degree of uniqueness, they were able to verify similarities within the group of maritime Inselbergs and others within the group of continental ones, even though the distance between some islands and some land hills was smaller. “Generally, what is expected is that those that are closer will be more similar. But that is not what happens,” points out Vitor Kamimura, a postdoctoral researcher and also a member of the research team. Kamimura cites the example of Cagarras Island, located only 5 kilometers from the beach, but whose flora bears more resemblance to that of Alcatrazes than to that of Morro da Urca itself. The latter, in turn, has more similarities to the Inselbergs of Minas Gerais.

Another important finding: the phylogenetic structure of marine inselbergs proved to be more clustered, meaning that the species formed more relationships with each other throughout their evolution, becoming more closely related than the species on the mainland. Kamimura explains that this occurs because isolation allows species to dispense with competition among themselves, favoring the coexistence of plants with more similar functions and characteristics. "They need to compete more with the extreme environment than with each other," he details. Alcatrazes Island was the marine inselberg studied with the largest number of recorded species, between 260 and 300 species.

This aspect is also repeated when comparing species that coexist on islands and on the mainland. Raphael Silva, a master's student and member of the team, conducted this analysis with specimens of Brazilian peppertree ( Schinus terebinthifolia ), black pitanga ( Eugenia sulcata ), and Chiococca alba , a plant from the Rubiaceae family related to coffee. Due to the period of connection during the last glacial period, these species occur in both environments. However, due to isolation, there was a greater flow of genetic information between the island species compared to those on the mainland. "The effect of sea level rise was much greater on these species," says Silva.

Studying the flora of Alcatrazes offers a unique experience for Unicamp researchers. “Being on the island makes us feel like explorers, true naturalists,” comments Sabino. Throughout the studies, the group discovered two new endemic bromeliads. Tillandsia alcatrazensis was named in honor of the archipelago, and Tillandsia uiraretama was named in reference to how the Tupi people called the place: “uira,” meaning “bird,” and “retama,” meaning “place of.” According to the researcher, both bromeliads have larger flowers and different colors from the closest continental species, Tillandsia geminiflora . The scientists were also surprised to rediscover Begonia larorum , a begonia species last recorded 104 years ago and now found in a difficult-to-access location. “It [the begonia] is like a symbol of the island and of our exploration work,” says the researcher, noting that other plants identified may yet be described as new species, including an anthurium and one from the Asteraceae family , the same as daisies.

Uncovering the flora of Alcatrazes, however, represents only one frontier of the research. Undergraduate research student Giovana Narezi, for example, is studying the fungi found on the roots of a species of orchid on the island. Narezi also identified a greater diversity among the specimens found on the island when compared to those on the mainland. “In Alcatrazes, we found around 40 genera of fungi per plant, while on the mainland there were only 20 to 30 genera,” she explains. Another important area for researchers concerns the pollinators that inhabit the area and the strategies used by the flowers to attract them. “The more we study, the more we realize that we still know very little about such a peculiar system,” reflects Sabino.