A long snouted rainforest weevil: by using data taken from beetle populations, the researchers have estimated that there are significantly less species living on the planet – only 5.5 million.
Credit: iStockphoto
SYDNEY: How many species share our planet? According to a recalculation by an international research team, the number is significantly lower than we thought - only around 5.5 million.
While that may sound like a lot, this number pales in comparison to previous species estimates, which varied widely from 30 million to over 100 million species.
In fact, the new study, appearing in the journal The American Naturalist, shows that there is less than 0.001% chance that the frequently cited previous estimate of 30 million could be true.
Adding certainty
The new estimate, which is particularly timely in the International Year of Biodiversity, takes into account plants and animals but, like previous studies, it excludes bacteria - a group that has been notoriously difficult to quantify.
"Everyone keeps redoing the information and coming up with different answers," said Andrew Hamilton of Melbourne University's School of Land and Environment and lead author of the study.
"So we came at it from a different perspective. Rather than saying 'there are so many species,' we've included how certain or uncertain we are in our estimates."
New model
Previous studies that used averages or point estimates made it impossible to determine the precision of a particular estimate, said Hamilton.
But by using probability-modelling techniques, the ecologists were able to come up with estimates that factor in the probability of the original data being accurate.
This type of model is widely used in financial risk assessments, but has rarely been applied to ecology.
Counting beetles
The model used by Hamilton and his team focusses on the numbers of tropical arthropods - the group that includes animals such as insects, arachnids and crustaceans.
Anthropods are thought to be the most diverse group on the planet. They are also the group that is believed to have the most yet-unidentified species.
By looking at all of the beetles that live on a single tree species in Papua New Guinea, the researchers were able to extrapolate their numbers to a global scale.
Where's your editor?
So, instead of propagating good science, and giving the article a title that correctly implies that the study is also subject to errors and peer review, you go ahead and give the impression that this is a final and complete truth, with no further clarification possible. It gives an air of definitiveness, where there should be none. I thought for a second I was reading Cosmo, not Cosmos. Shame.
journalism
editors chose the titles.
i concurr...
spot on!
Scientific method at it's best!
This article is a steaming pile of bovine excrement. The best these reasearchers came up with is a strikingly good example of bad statistics. You simply cannot extrapolate what species the collective environments of the world may contain from what beetles land on a single tree on a single island.
So then what?
Would you rather have a group of researchers count every single animal on the planet?
Compromise
I think that sampling from many different locations would have been more appropriate.
Why not, Noah did it.
:D
90%
Remind me not to risk my millions - I think I'd be a little disappointed with the results. Or does money work in a totally different way to Nature?