At least 70% of Earth's species are unknown
Although knowledge about the planet's biodiversity is still very fragmented, it is estimated that approximately 1.75 million different species of living beings have been discovered - including microorganisms, plants and animals. The number can impress the most unsuspecting, but it only represents the most optimistic assumptions, only 30% of the life forms on Earth.
Unicamp researcher states that 12 million species remain to be discovered.
by Y. Basset
Mysteries of the Forest: Researchers want to estimate the time and cost to uncover all species on the planet...
"It is estimated that there are another 12 million species yet to be discovered," said Thomas Lewinsohn, professor in the Department of Animal Biology, State University of Campinas (Unicamp), during a presentation that started the 2013 Lecture Series organized by program Biota-FAPESP.
But how to evaluate the amount of ignorance about biodiversity?" For that, we extrapolate, based on the groups of organisms studied to better evaluate the least studied - regions or countries where the organisms are well known and to assess where they are less known. As a rule of three, we arrived at these estimates," he explained.
Latest techniques, according to Lewinsohn, are to use sophisticated statistical formulas based on the rates of discovery and description of new species. Values are adjusted for the existing workforce, that is to say, the number of active taxonomists.
"However, the most important thing to say is: there is no consensus. Estimates can reach more than 100 million unknown species. We do not know the order or magnitude and it is amazing," he continued.
Lewinsohn estimates that to discover all species estimated to exist in Brazil, it would take about 2000 years. "To discover the number of all the world's species would be the same. But we do not have that kind of time," he emphasized.
Some recent techniques of molecular taxonomy, as a DNA barcode, can help speed up the work to identify organisms by analyzing their genetic material. By this method, different DNA strands differentiate species, while in classical taxonomy classification is based on the morphology of living beings, which is much more difficult.
"Can we do this? Yes, but what is the cost?" Lewinsohn questioned. An article published recently in the journal Science found that it would take $500 million to $1 billion a year for 50 years to discover the majority of species on the planet.
Again, the number can scare the unsuspecting, but, according to Lewinsohn, it corresponds to the amount that is spent worldwide on armaments in just five days. "Just in 2011 alone, $1.7 trillion was spent on arms purchases. You need to put things in perspective," he argued.
Many of these unknown species, however, may disappear from the planet even before the man has the time and money to study them. According to data presented by Jean Paul Metzger, professor at the Institute of Biosciences, University of São Paulo (USP), over 50% of the land surface has been transformed by man.
This change in landscape has many consequences and Metzger addressed two of them in the second presentation of the day: habitat loss and fragmentation.
"These are different concepts, which often overlap. Fragmentation is the subdivision of a habitat and can occur when the degradation process occurs at the edges of woodlands. Because the construction of a road, for example, creates isolated patches within the habitat," he explained.
For Metzger, fragmentation is a major threat to biodiversity because it changes the balance between the natural processes of species extinction and colonization. The smaller and more isolated a fragment is, the higher the rate of extinction and the lower the rate of colonization.
"Each species has a minimal amount of habitat it needs to survive and reproduce. We know well what these extinction thresholds are," he warned.
Metzger believes that this threshold may vary according to the configuration of the landscape, that is, the more fragmented the habitat is, the higher the risk of species extinction. As an example, he cited the remaining areas of the Atlantic forest of São Paulo, where 95% of the fragments are less than 100 hectares.
"It is estimated that if 90% of the habitat is lost, we lose 50% of endemic species. In the Atlantic Forest, about 16% of the forest remains.
A mass extinction would be expected, but our record has few cases. Either our theory is wrong, or we are not detecting the extinctions, because species were not even known," said Metzger.
There is, however, a complicating factor: the latency period between the change in landscape structure and change in community structure. While the species with short life cycles can disappear quickly, those with a long cycle life may respond to habitat loss on a centennial scale.
"It creates an extinguishment debt and even if the change in the landscape is interrupted, some species are doomed to disappear with time," said Metzger.
But the good news is that landscapes also regenerate naturally and beyond the rate of extinction thanks to this recovery. The latency period is thus an opportunity for conservation.
"We need to define priority areas for restoration that optimize connectivity and facilitate biological flow between fragments," Metzger defended.
Throughout the 13 years of the Biota-FAPESP, the definition of priority areas for conservation and recovery of the state of São Paulo has been a major concern of researchers.
The results of these studies were used by the state Department of Environment to support public policies, as noted by the program coordinator and professor of Biology at UNICAMP, Carlos Alfredo Joly, the third and last presentation of the day.
"Currently, at least 20 legal instruments, including laws, decrees and resolutions, nominally cite the results of Biota-FAPESP," said Joly.
Between 1999 and 2009, said the coordinator, there was an annual investment of $8 million in the program. This helped fund 94 research projects and resulted in over 700 articles published in 181 journals, including Nature and Science.
The program team also published 16 books and two atlases, described more than 2000 new species, produced and stored about 12,000 species, and made available 35 digitally connected biological collections of São Paulo.
A heavy schedule of future conferences is being planned.
Translated from the Portuguese version by: