{"id":125159,"date":"2012-08-22T10:00:40","date_gmt":"2012-08-22T13:00:40","guid":{"rendered":"http:\/\/revistapesquisa.fapesp.br\/?p=125159"},"modified":"2015-11-27T13:20:32","modified_gmt":"2015-11-27T15:20:32","slug":"a-theory-endures","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/a-theory-endures\/","title":{"rendered":"A theory endures"},"content":{"rendered":"

\"090-093_Vanzolini_esp50\"<\/a>Developed more than 40 years ago by the German geologist J\u00fcrgen Haffer and, indirectly, by Brazilian zoologist and samba musician Paulo Vanzolini, the Refuge Theory, associating the Amazon region\u2019s biodiversity with periods of arid climate and geographic isolation, was declared obsolete on numerous occasions over the years by various other researchers. In the words of one of Vanzolini\u2019s own songs, however, the theory \u201cgot over\u201d this setback and, after being brought somewhat up to date, is now seen as valid within various research circles \u2013 valid not only in the sense of explaining the emergence of species in the Amazon region, but also the emergence of those in the Atlantic Forest, where the theory\u2019s principles have also been applied.<\/p>\n

Settled snuggly into his favorite armchair in one of the upper rooms of his home in Aclima\u00e7\u00e3o, an old neighborhood on the south side of the city of S\u00e3o Paulo, Vanzolini, now 88, claims not to have come up with any theory at all: \u201cIt was just some work I did with an animal species. What I did ended up being a concrete example of what Haffer had proposed from a theoretical viewpoint. It\u2019s nothing more than a model \u2013 a conceptual one \u2013 that can be replicated, even in other regions.\u201d In 1970, one year after Haffer presented his theory in an article published in the journal Science, Vanzolini and the American researcher Ernest Williams published a study of nearly 300 pages about the emergence of a species of lizard of the genus Anolis without making a single reference to the Refuge Theory.<\/p>\n

Haffer, a geologist who had studied the geographic distribution of bird species in the Amazon region, advanced the theory that changes to the region\u2019s vegetation accompanied naturally-occurring climatic shifts during a given period in geologic history. This process dispersed the species\u2019 various points of origin, isolating some of them in ecological refuges where they lived separated from the others. These relentless climatic changes effectively pulverized the forests of the Amazon region. The resulting patches of forest, separated by barren areas, set the stage for the development of new species and sub-species. Three developments likely occurred in these areas: the defining or evolution of new species, the extinction of certain other species, and the adaptation of others that managed to survive the changes to their ecosystems without undergoing significant genetic mutation.<\/p>\n

\"Anolis

estra\u00eddo do artigo vanzolini & williams, 1970<\/span><\/a> Anolis chrysolepis<\/em>, the species that served as a basis for Vanzolini\u2019s general understanding of the process of speciation in the Amazonestra\u00eddo do artigo vanzolini & williams, 1970<\/span><\/p><\/div>\n

Less-defined patches of forest<\/strong>
\nIn an 2005 interview with the newspaper Folha de S\u00e3o Paulo, Haffer stood by his Refuge Theory, but not without suggesting some corrections to how his work should be approached: \u201cIt\u2019s likely that these patches of rainforest during the dry periods were larger and far less-defined than those on many of the maps that illustrate the location of the refuges in the pluvial tropical forest.\u201d Haffer died in 2010 at the age of 77.<\/p>\n

One of the criticisms of Haffer\u2019s theory that has been presented over the years has come from Vanzolini, whose objection relates precisely to where Haffer claims the Amazon region\u2019s barren areas were situated, as well as to the fact that evidence of these areas has never been firmly established. According to Haffer, however, many erroneous interpretations to his refuges idea have been presented over the years: \u201cOur data show climatic shifts occurring at least on a localized and roughly regional basis. Of course, extensive expanses of pluvial forest, all very ancient, have always existed in the Amazon.\u201d<\/p>\n

Research groups from S\u00e3o Paulo have conducted studies over the past few years on the emergence of new species in the Atlantic Forest that have buttressed the theory that was proposed towards the end of the 1960s. At least Vanzolini\u2019s idea and that of his German colleague can still be considered valid or at least of sufficient interest to reanimate the controversy that surrounds it.<\/p>\n

The two men became friends around 1970 after exchanging correspondence about their respective studies. Vanzolini likes to say that Haffer, besides being a first-rate scientist, showed generosity. \u201cAnd, like every good German,\u201d adds Vanzolini, \u201che couldn\u2019t pass up a beer.\u201d Vanzolini recalls that he received the article from the German scientist by mail after finishing his article with Williams. \u201cErnest thought they had pulled a fast one on us,\u201d says Vanzolini about their reaction to the publication. Vanzolini was soon in touch with Haffer, who immediately put aside a research project in South Africa to go to Brazil for an in-depth look at Vanzolini\u2019s lizard refuges.<\/p>\n

Different times and new research follow more or less the same course. In a 2008 article about the sauba ants of the Amazon published in the journal PLoS One, Brazilian and American scientists proposed a kind of re-examination of the Refuge Theory. According to Maur\u00edcio Bacci Jr., a biochemist at S\u00e3o Paulo State University in Rio Claro, the huge explosion in the diversity of ants in the Amazon region occurred despite the geographic barrier created when the region\u2019s rivers were being formed. Bacci explains that this extraordinary diversity in sauba ant species is a recent phenomenon that occurred approximately two million years ago. Ant nests may have migrated throughout the region through the river system by floating atop plants.<\/p>\n

Genetic research points to another important process besides the Refuge Theory \u2013 one that predates it \u2013 involving the transformation of the landscape of the Amazon that was a determining factor behind the diversity of the region\u2019s ant species. Fifteen million years ago, before the Amazon river was formed, the rise in sea level led to an influx of the oceans\u2019 waters into the region which, according to scientists, led to the isolation of certain swathes of land mass that eventually became islands. This fragmentation of the ecosystem would then be further brought to relief with the formation of the refuges. According to this study, the great upswing in diversification of ant species occurred some 8 to 14 million years ago.<\/p>\n

\"Now

l\u00e9o ramos<\/span>Now in his 88th year, Paulo Vanzolini is pessimistic about the preservation of the Amazonl\u00e9o ramos<\/span><\/p><\/div>\n

The theory of areas isolated in the Amazon for a certain period may \u2013 while bearing in mind its limitations \u2013 help explain much of the diversity of the Atlantic forest. Cinthia Brasileiro, an expert in ecology at the Federal University of S\u00e3o Paulo (Unifesp), supports the claim that a number of speciation areas, veritable centers for the manufacture of species, must have existed in the region between the states of Bahia and S\u00e3o Paulo.<\/p>\n

The refuge hypothesis as applied to the Atlantic Forest arose from the evaluation of genetic data on two species of frog. The study of phylogeography (the mapping of the genetic diversity of a species over time) shows that some areas of the forest remained covered and had a more or less stable climate for millions of years. These areas underwent neither periods of extensive draught nor excessive cold temperatures. There is also no evidence of dramatic changes in sea level in these areas.<\/p>\n

Over the past 12 million years, however, a number of refuges existed along the coast of Brazil. One of these probably developed in the area between S\u00e3o Sebasti\u00e3o and Cananeia in coastal S\u00e3o Paulo. When, for example, the area\u2019s surrounding sea-level declined, drylands emerged that later became forested for longer periods, thereby enabling these regions to sustain an influx of different species. This is how the speciation process that Vanzolini and Haffer imagined occurred in the Amazon region.<\/p>\n

Regardless of whether the theory that has been advanced is entirely valid, it is clear that phenomena such as fragmentation, isolation, climate change and environmental stability are constant factors behind the development of new species. This is but another way to say that the debate surrounding the refuges question is now more pertinent than ever. With human activity at once accelerating climate change and diminishing the forests in many parts of the world, a process may well be in place \u2013 one that may be invisible to us \u2013 that is running counter to the speciation process also underway. The consequences of these developments remain uncertain.<\/p>\n

Topics such as climate change and an extinction of biodiversity leave Vanzolini quite pessimistic about preservation of the Amazon region\u2019s ecosystem, a region he came to know so well through decades of 3-month expeditions conducted just about once a year. \u201cThe Amazon is done,\u201d Vanzolini laments, \u201cThere\u2019s a lot of cattle and soybean there, but the people of the Amazon \u2013 who have to survive \u2013 are also the ones most interested in increasing these kinds of economic activities.\u201d<\/p>\n

Scientific articles<\/em>
\nHAFFER, J. e PRANCE, G. T. Impulsos clim\u00e1ticos da evolu\u00e7\u00e3o na Amaz\u00f4nia durante o Cenozoico: sobre a Teoria dos Ref\u00fagios da diferencia\u00e7\u00e3o bi\u00f3tica<\/a>. Estudos Avan\u00e7ados<\/strong>, 16, (46), 2002.
\nSCHULTZ T. R. e BRADY, S.G. Major evolutionary transitions in ant agriculture.<\/a> Proceedings of the National Academy of Sciences of the USA<\/strong>, Early Edition (March 24, 2008).
\nVANZOLINI, P. E. and WILLIAMS, E. E. South American anoles: the geographic differentiation and evolution of the Anolis chrysolepis species group (Sauria, Iguanidae).<\/a> Arq. Zool<\/strong>, 19 ( 1-2): 1-176, 1970.<\/p>\n

From our archive<\/strong>
\nThe work of a lifetime<\/a> –<\/em> Issue 175 \u2013 September, 2010
\nImperiled sanctuaries<\/a> –<\/em> Issue 129 \u2013 November, 2006
\nA treasure on the banks of the S\u00e3o Francisco River<\/a> –<\/em> Issue 57 \u2013 September 2000<\/p>\n","protected":false},"excerpt":{"rendered":"A lizard from the Amazon region reinforces a German geologist\u2019s position ","protected":false},"author":112,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[1237],"tags":[209,200],"coauthors":[417],"class_list":["post-125159","post","type-post","status-publish","format-standard","hentry","category-biology-special-2","tag-biology","tag-environment"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/125159","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/112"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=125159"}],"version-history":[{"count":0,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/125159\/revisions"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=125159"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=125159"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=125159"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=125159"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}