Friday , April 16 2021

where to look for still unknown species?

While we are desperately searching for traces of life on other planets, it is estimated that between 83% and 87% of species remain to be discovered on Earth. A new study has examined where they are most likely to meet.

If we are rightly upset rapid extinction of the species, much of life remains unknown to this day. Scientists have counted nearly two millioncash, but we estimate their total number between 3 and 100 million. Quite an amazing number when we thought we had explored every corner of our planet.

Mario Moura and Walter Jetz, two biologists from Yale University, have embarked on mapping places on the planet that will most likely host these unknown species. Therefore, they collected data on 32,000 vertebrates known land areas, including their location, range geographical, historical dates of discovery and other environmental and biological features (body size, temperature, human density, etc.). They then built an extrapolation model where and which species species among the four major vertebrate groups will most likely still be identified.

I wanted to : amphibians and reptiles

« The chances of detection and description are not equal among species, explains Mario Moura. For example, emu, big bird in Australia, was discovered in 1790 shortly after the beginning of taxonomic descriptions of the species. In contrast, a small species of frog Brachycephalus guarani was discovered in Brazil only in 2012, suggesting that there are stillamphibians of this type to find. »

In general, large animals of a wide geographical range are already more likely to be discovered in populated areas. ” The new discoveries these species are likely to be rare in the future », Recognizes Mario Moura. Small animals with limited range and living in less accessible areas, on the contrary, are more likely to have escaped the radar so far. Another surprising factor also comes into play: the number of taxa looking for them. The mammals and birds seem to be in favor of scientists, while amphibians and reptiles they are notoriously neglected.

New species: explore Brazil

Contrary to intuition, the places most likely to house unknown species are those places where biodiversity is already the richest. The tropical rainforests they are known especially for being true ecological niches. Countries like Brazil, Indonesia, Madagascar and Colombia could thus host a quarter of all potential discoveries on their own. Unidentified amphibian species are more likely to be found in neotropes and Indo-Malaysian forests, while reptiles could be found in drier regions such as Australia, Iran, or Argentina. As for mammals, they could hide in Madagascar, where hotspots biodiversity has recently been described.

Why you need to know biodiversity before it disappears

Study, published in the journal Ecology and evolution of nature, has significant limitations because it focuses on only four groups of vertebrates. The bugs, which we know make up the vast majority of the animal world, for example, have not been taken into account. Mario Moura and Walter Jetz therefore plan to expand their map of unknown life to plant, marine and invertebrates in the coming years, in collaboration with partners around the world.

« It is essential to better understand biodiversity before it disappears », Warn the authors. Certain species may indeed bring us untapped environmental or economic benefits (for example, the discovery of new drugs and food supplies), but they can also pose a potential threat of disease or as invasive species.

8.7 million species on Earth, much more to discover …

Article by Bruno Scale published on 25.08.2011

An international scientific team has just estimated the specific richness (or number of species) of our planet, refining previous estimates. It is estimated that about 8.7 million species inhabit Terre. The vast majority of them have not yet been described or even discovered.

How many species exist on our planet? A difficult question that we obviously cannot answer by simply counting the number of species that scientists have described so far. Me discover new species very regularly (about 6,200 a year) and chances are it will continue that way for a long time to come.

The work of an international team led by Camil Mora (University of Hawaii) it consisted in estimating the number of still unknown species by extrapolating from the number already described. Thanks to that modeling, so they could estimate specific wealth of our planet.

So far, estimates, generally based on taxonomist beliefs, have predicted a wealth between 3 and 100 million species. Other estimates related to only a few important groups ( birds,, mammalsetc.), and some of them were based on very controversial calculation methods.

8.7 million species

In a study published on the journal’s website Plos Biology, the model is based on several parameters. Scientists trusted taxa The most famous (birds,, mammalsetc.) from which they have succeeded in extrapolating numerous species by taxon. The frequency of new species discoveries in recent years is also taken into account. These calculations allowed researchers to establish a new estimate: there would be 8.7 million species eukaryotes (and several thousand prokaryotes), of which 6.5 million are terrestrial, while the rest – 2.2 million – are aquatic. An error margin of plus-minus 1.3 million was also determined.

Of this total, 7.77 million are animal species (of which 953,434 have been described) and 298,000 are plants (215,644 described) according to the study list. Then we find 611,000 mushrooms, 36,400 protozoa and 27,500 seaweed (see table above).

Limits of assessment

If the assessment is currently the strongest compared to all previously conducted, the fact remains that it suffers from several weak points. First, what kind? Although the answer seems obvious enough for sexually reproducing organisms – organisms of the same species can reproduce and produce fertile offspring, as defined by Ersnt Mayr, although there are exceptions – it is much less about organisms. asexual.

As the calculation method is based on the extrapolation of the number of species per taxon (genus, family, branch officeetc.), an increase in the amount of taxa would disrupt this assessment. Finally, scientists ’calculations take into account all the taxa and species that have been listed in the past. Frequency new descriptions obviously depends on the amount of species to be detected (the fewer, the harder it is to find), but it also depends on the scientific effort taxonomy. And this factor is not included in the calculations put forward by Camilo Mora and his colleagues.

Furthermore, although the number of species within the most famous taxa – such as mammals – is not accurate (classification error or species not yet detected), the assessment would also be impaired.

According to the authors’ calculations, it would take 1,200 years and about 303,000 taxa to describe a still unknown species. The operation would cost about 252 billion euros. As paleontologists, before them is still a bright future from sincreased extinction rate species, some of which will never be described before theirs extinction.

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