A Contrarian View of Species Discovery
Posted by Richard Conniff on January 30, 2013
In case you missed it, a paper in this week’s Science takes a contrarian look at the rate at which species are going extinct, the number of species remaining to be discovered, and the availability of expert taxonomists capable of describing them. Here’s part of a report from Rachel Nuwer in The New York Times:
In a paper published in Science, the team delivers good news in three-fold. Taxonomy, or the branch of science concerned with classifying and naming species, is thriving, they write. The number of species left to discover and name are not as daunting as some estimates indicate, they add, and extinction rates are not as bad as conservationists may assume. With these factors in mind, nearly every species on the planet could be discovered within the next 50 years if current trends continue.
“The real crux is that actually we can discover most species before the go extinct,” said Mark Costello, an associate professor at the Leigh Marine Laboratory at the University of Auckland and the paper’s lead author. “Things are not as bad as we thought: there are fewer species than we thought, and efforts to find and name them are greater than we thought.”
Recent biology graduates may recall their freshman professors lamenting the end of the art of taxonomy. In Britain, the House of Lords published a report in 2008 indicating that this old science had reached a “point of crisis.” The demand for taxonomists has declined in North America and Europe, concerned parties warned, and a growing emphasis on biomedical and molecular science is elbowing them out of university departments.
“A couple of decades ago, people in the U.K. and elsewhere were saying taxonomists are going extinct faster than species,” Dr. Costello said. “But this is an old paradigm taken for granted, and nobody checked the numbers.”
Dr. Costello and his colleagues first picked up on this inaccuracy while compiling a global biodiversity database. Much to their surprise, they found that three times as many people were actively identifying new species over the last decade than had done so in earlier years. Quite a few of these people were working from home addresses, suggesting that they are high-level amateurs who pursue taxonomy as a hobby rather than a profession.
Currently, around 16,000 papers announcing new additions to the tree of life come out each year. Most of these findings represent arthropods, the group that dominates global biodiversity and includes crustaceans and insects; mollusk discoveries are also plentiful.M. J. Costello A close-up of soft coral in the Philippines.
The number of such papers has increased significantly over the last decade, especially in up-and-coming biological hot spots like South America and Asia that house a significant proportion of the globe’s undiscovered biodiversity. “Even if things have stayed the same in the Northern Hemisphere, they’re growing rapidly in the Southern Hemisphere and Asia,” Dr. Costello said. “Maybe older professionals are not aware of all the young people coming up through the system, especially if they’re based in other countries.”
From there, the researchers decided to take a closer look at how many species currently occupy the planet (not including bacteria). We already know of about 1.5 million of them. As for the unknowns, recent past estimates have varied by orders of magnitude, from two million to 100 million. Dr. Costello and his colleagues rounded up the latest papers that combine empirical data, extrapolated rates of discovery and the latest statistical models for terrestrial, marine, arthropod and plant species. Collectively, those papers indicate that two to eight million species have yet to be discovered.
Lastly, the researchers tackled the question of extinction rates. Other papers estimated that one-hundredth of a percentage point to 5 percent of species are going extinct each decade. If scientists assume a worst-case scenario — 5 percent of species lost every 10 years — then half of the planet’s biodiversity will be gone in the next 150 years. “We were quite surprised to find that the extinction numbers being thrown around also vary widely, even more so than the number of species people think are on earth,” Dr. Costello said.
Recent, more realistic estimates indicate a loss of less than 1 percent per decade, however, in which case the rate of finding and describing species would greatly outpace extinction rates. Nailing down this last unknown is tricky, however. The risk of extinction varies between animals, and climate change, habitat destruction and the wildlife trade may exacerbate future extinction trends. What is more, the speed of discovery may slow as the pool of yet-to-be-described species dwindles — like finding that last, well-hidden Easter egg.
Taking all of this into account, Dr. Costello and his colleagues hope that an international community will emerge to coordinate the many shoestring endeavors currently dominating the discoveries. An expenditure of $500 million to $1 billion could provide a 10-fold increase in global taxonomic efforts, they estimated, tidying up all species descriptions by 2060.
All of this may lead one to ask why researchers care so much about discovering and naming species in the first place. As elements are to chemistry and particles are to physics, species are the most basic metric in ecology. “The first thing we want to do when we start exploring a natural environment is name species,” Dr. Costello explained. “Once the species are defined, we have a baseline from which we can then build up more knowledge.”
“And, we’re just a curious species ourselves, so this is all a part of exploring our own world to understand what lives with us,” he said. “It’s a simple way of saying, let’s understand nature.”