Very few doctorates have influenced an area of Brazilian science as much as the one completed at Harvard University by São Paulo zoologist Paulo Emílio Vanzolini. After working alongside biologists who were exploring the formation and diversification of species from an evolutionary perspective, Vanzolini returned to Brazil in 1951 advocating concepts that revolutionized Brazilian zoology and that are still used to understand biodiversity today. Vanzolini argued that it was vital to study species not only through isolated specimens, which had been the approach until then, but also by looking at the distribution of populations of one same species across time and space. He later proposed that the marked diversity of animal species in the Amazon Region was the result of the geographic isolation of animal populations prompted by climate changes that took place thousands of years ago. According to Vanzolini, during eras when the climate was colder and drier, forests would fragment and form islands of plant life – called refugia – where animals were able to survive and form new species.
Although this perspective, like any other, has revealed its limitations over time, it can still be useful. “The refugia alone were not responsible for these patterns of biological diversity,” underscores Célio Haddad, professor at the Universidade Estadual Paulista (Unesp) in Rio Claro. In his opinion, phylogenetic, climatic, and geological questions should generally be examined jointly if the formation and diversification of species are to be properly understood. “The same idea or hypothesis can be used in different contexts,” says biologist João Alexandrino, professor at the Federal University of São Paulo (Unifesp). In early May of this year, one of Alexandrino’s students began analyzing the genetic diversity of populations of a species of tree frog found in the Atlantic Forest and in the fields of southern Brazil, Argentina, and Uruguay. After examining the diversity patterns suggested by preliminary findings, Alexandrino advised the young man to read an article that Vanzolini had published in 1981, in which he proposed the concept of vanishing refugia, according to which forest islands could suffer fragmentation and thereby force less specialized species to adapt to open environments.
“The refugia approach was innovative at the time it was presented, and it guided several generations of researchers,” observed Hussam Zaher, director of the University of São Paulo (USP) Zoology Museum, which Vanzolini headed for three decades as tenured director, appointed by former São Paulo governor Carvalho Pinto. “Refugia were talked about for a long time,” says Zaher. The director says he believes that Vanzolini’s greatest merit as a scientist was that he introduced Brazil to the “modern synthesis” – which consolidated the work of Theodosius Dobzhansky in genetics, of Ernest Mayr in zoology, and of George Simpson in paleontology – and encouraged its adoption here. Vanzolini studied under Mayr and Simpson at Harvard, already a center for modern science back then. Dobzhansky, who also spent time at Harvard, paid four visits to Brazil and played a valuable role in the training of the country’s first geneticists. Vanzo, as he liked to be called, was used to keeping company with intellectuals: his great-grandfather translated the six books of Roman poet Lucretius’ De rerum natura (On the Nature of Things) from Latin to Italian and his grandfather was in the habit of sending interesting Brazilian animal species to museums in Europe. In an interview given to zoologist William Ronald Heyer, Vanzolini said he learned English by reading Shakespeare’s plays in the original.
The so-called refuge theory was introduced by German geologist Jürgen Haffer in the journal Science in 1969. Haffer showed that there was a higher concentration of populations of different species of toucans in areas that had received more rainfall. Three years earlier, the British ornithologist Reginald Moreau had highlighted the influence of climate alterations and refugia on the distribution and differentiation of bird populations in Africa, but he did not go much farther than this. Around the same time, Vanzolini and a former Harvard colleague, Ernest Williams, did a study on the geographic variation and distribution of a species of lizard of the genus Anolis in the Amazon Region, which could be explained by climate variations; they published their paper one year after Haffer. In an interview with Pesquisa FAPESP in 2012, Vanzolini reported that his and Williams’ research was “a practical example of what Haffer had posited from a theoretical perspective. It’s nothing more than a [conceptual] model that can in fact be replicated in other regions.”
In 1970, the year his study of Anolis came out, Vanzolini acknowledged that it takes more than the biologist’s point of view to understand the distribution of animal populations in Brazil’s forests. “I’ve been studying the evolutionary patterns of South American lizards for 20 years. Although I had already refined the theory in 1951, my research always proceeded very slowly because there was paleoclimatic information missing, until I was able to rely on the outstanding geographical assistance of Aziz N. Ab’Saber, some six or seven years ago. After this new data was obtained, the research started flowing and I’ve attained rewarding results,” he wrote in a funding application submitted to FAPESP in 1970. “I feel I am ready to take on research of a broader scope, that is, an overall study of the speciation patterns of South American lizards on the whole.”
Applications and limitations
“You can’t deny that the refuge model, as he preferred to call it, applies to part of our fauna,” says zoologist Miguel Trefaut Rodrigues, professor at USP. Today, brejos de altitude – Caatinga moist forest enclaves found on hilltops surrounded by open fields, especially in the Northeast – are “the most consistent evidence of refugia,” he says. These brejos de altitude are still areas of climate stability, which favors the diversification of species. “Each brejo has a unique set of fauna, but being a brejo is not enough to make it a refuge.” In 1980, on the only expedition that Rodrigues and Vanzolini took together, the former, then a doctoral candidate, and the latter, his advisor, went to northern Bahia to gather specimens in the municipality of Caatinga do Moura, which Vanzolini believed to have been a refuge. “It was only 10 years after this trip,” says Rodrigues, “that I realized that the area of climate stability was really in the highlands near the Diamantina Plateau.”
Vanzolini liked to travel but he hardly ever engaged in field collection, arguing that he wasn’t any good at it. But in his own way, he was always adding precious material to the museum’s collections. Whenever he went somewhere, he would spread the word that he had a bag full of coins with him and was interested in buying animals. “Among the 400 lizards of the genus Tropidurus that he bought from a bunch of kids in Cocorobó, Bahia, I found six specimens of a new species,” says Rodrigues.
From 1967 to the mid-1980s, through the Ongoing Expedition to the Amazon Region, Vanzolini and other researchers from Brazil and abroad visited unexplored areas along the region’s main rivers, sailing in two boats, which were the first to be funded by FAPESP: the 11.5-meter-long Lindolpho R. Guimarães and the 18-meter-long Garbe. In April of that same year, Paraguassú Éleres, a naval construction researcher, completed a report on the building of these two boats. He had designed them and oversaw their construction at Oriximiná, Pará (1965), along with Paulo Vanzolini (the rare photographs of the boats shown in this article are from his collection; the full text of Éleres’ report and the travel diary of Vanzolini and other zoologists who visited the Amazon Region are available on the magazine’s site, in Portuguese).
The concept of a refuge does not always apply. In a study published in March 2013, Tiago Porto and Luis Rocha, of the Federal University of Bahia (UFBA), and Ana Carnaval, of New York University, determined that the distribution of the populations of 14 species of different animal groups – spiders, harvestmen, scorpions, amphibians, birds, lizards, and mammals – does not coincide with the refuge areas as previously identified. Moreover, in the past 20 years, genetic and molecular analyses have indicated that most animal species likely formed about 11 million years ago rather than during the geological period known as the Quaternary, which was only one million years ago, as Haffer, Vanzolini, and scientists from other continents had suggested. “There is indeed evidence that forests shrank during the Quaternary but this was essentially a time of species extinction, because it was relatively short,” observes Zaher. “The evolutionary processes that led to the formation of most species are much older.”
Nor do the latest approaches account for everything. Geographical obstacles like rivers can favor the isolation and differentiation of species of mammals, birds, and insects, but sometimes they are irrelevant. In short, as stated by researchers from the Federal University of Rio Grande do Sul (UFRGS) and the Botanical Institute of São Paulo in an article released in March 2013, South America’s biological diversity reflects a complex space that is the result of climatic, geological, and biological influences, for which there is as yet no single explanation.
Read the article The freedom of the bohemian about Paulo Vanzolini’s musical work.
VANZOLINI, P.E. Paleoclimas e especiação em animais da América do Sul tropical. Estudos avançados. v. 6, no. 15, pp. 41-65, 1992.
PORTO, T.J. et al. Evaluating forest refugial models using species distribution models, model filling and inclusion: a case study with 14 Brazilian species. Diversity and Distributions. v. 19, pp. 330-40, 2013.
TURCHETTO-ZOLET, A.C. et al. Phylogeographical patterns shed light on evolutionary process in South America. Molecular Ecology. v. 22, pp. 1,193-213, 2013.