At least 1, species of beetle fell to the ground, of which lived only on a single tree species. Many scientists believe the 30 million number is far too high. Later estimates arrived at figures under 10 million. In , scientists used a technique based on patterns in the number of species at each level of biological classification to arrive at a much lower prediction of about 8. But most estimates of global biodiversity overlook microorganisms such as bacteria because many of these organisms can only be identified to species level by sequencing their DNA.
After compiling and analysing a database of DNA sequences from 5 million microbe species from 35, sites around the world, researchers concluded that there are a staggering 1 trillion species on Earth. But, like previous estimates, this one relies on patterns in biodiversity, and not everyone agrees these should be applied to microorganisms. Most — and possibly all — insect species are the victim of at least one or more species of parasitic wasp. These lay their eggs in or on a host species think of the movie Aliens, if the aliens had wings.
Researchers suggest that the insect group containing wasps may be the largest group of animals on the planet. I have no doubt we can catalogue all of life, and it would be useful, but we don't have the luxury of time.
You can do a lot of protection even in the absence of knowledge. To reduce the time it takes to name the world's species, Dr Costello and colleagues recommend more taxonomists to be employed, increased financial support and international coordination in the scientific community to share expertise. Professor Georgina Mace, from the Centre for Population Biology at Imperial College London, welcomed the analysis but also questioned whether we really need to know the names of all species.
She added that with sensible sampling, conservationists could prioritise groups of species that are disappearing in the places most under threat. The levels of investment needed to name all the species is very modest, in global terms, said Professor Ken Norris, director of centre for Agri-Environmental research at Reading University. He added that many species play important functional roles in the way Earth works and the life support systems they provide.
Billions required to save nature. Some species physically look almost exactly the same as other species they are called sibling species. And this can have real-world consequences. I estimate that distinguishing a Queensland fruit fly scientific name Bactrocera tryoni , a major fruit pest, from one of its many closely related but harmless sibling fruit fly species, would be impossible for all but a few well-trained entomologists. But being able to accurately distinguish these species matters a lot in the real world when it comes to biosecurity and developing international trade.
It is almost always the case that species that are siblings in an anatomical sense are also very difficult to distinguish genetically; they very often have the same DNA barcode sequences, or overlapping sets of DNA sequences.
Government quarantine services often contract our scientists to develop protocols for distinguishing quarantine threats from harmless local species. We manage a collection of more than 12 million specimens, almost all of them from Australia. We have the vast majority of named Australian insect species in the collection, plus tens of thousands of unnamed species.
Unnamed species belong to a wide range of groups such as mosquitoes that bite humans, and innocent native beetles that look just like major timber and grain pests native to our overseas trading partners.
Often species wait in the collection for decades before study. A PhD student and I are in the process of naming an entire new lineage of flower pollinating insects in the collection, from specimens found in a remote corner of Western Australia 35 years ago. One of a new lineage of flies about to be formally named. Image credit — Xuankun Li. To gain a more precise answer, the authors examined the categories into which all species are grouped.
Scientists lump similar species together into a broader grouping called a genus, similar genera into a still broader category called a family, and so on, all the way up to a supercategory called a kingdom.
See photos of species classification in National Geographic magazine. There are five kingdoms: animals, plants, fungi, chromists—including one-celled plants such as diatoms—and protozoa, or one-celled organisms. Worm's team estimated the total number of genera, families, orders, classes, and phyla—a designation above class—in each kingdom. That's a relatively easy task, since the number of new examples in these categories has leveled off in recent decades.
Using complex statistics, Worm and colleagues used the number of genera, families, and so on to predict Earth's number of unknown species, and their calculations gave them a number: 8. The new study "takes a hugely clever approach, and I think it's going to turn out to be a pretty important study," said Lucas Joppa , a conservation ecologist at Microsoft Research, the research branch of the software giant.
But Dan Bebber , an ecologist at the environmental group Earthwatch Institute, said the study relies on improper statistical methods. The study team used a method called linear regression to calculate the number of Earth's species. But Bebber thinks this method is the wrong one for the data, and that the team should have used a technique known as ordinal regression.
Overall, formally categorizing a new organism is a lot more complicated than discovering one, study co-author Worm said. Scientists must compare their specimen to museum samples, analyze its DNA, and complete reams of paperwork.
Most scientists "will describe dozens of species in their lifetime, if they're really lucky. Unfortunately, extinction rates have accelerated to ten to a hundred times their natural level, Worm added. See "Extinctions Overestimated by Percent?
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