Knowing when a species should be declared extinct is a longstanding dilemma for biologists. In fact, an international study concluded that: There are more than 500 “lost” species; that is, it is not known for certain whether they continue to exist or not..
Species such as Sir David’s long-billed echidna (Zaglossus attenboroughi), ivory-billed woodpecker (prince of campephilus) and Baiji or Baiji (Lipotes vexillifer) remain in limbo as it is not certain that they continued to exist, but it has not been possible to confirm their extinction.
official definitionExtinct“In the International Union for Conservation of Nature (IUCN) Red List: “When there is no reasonable doubt that the last individual of a species has died“, which in most cases is difficult to verify.
A taxon is assumed to be extinct. extensive studies failed to record any individuals during their historical range in known and/or expected habitat, at appropriate times (daily, seasonal, annual).
A few decades ago it was proposed that a species be classified as extinct if it was not observed for 50 years. However, this proposal was not widely accepted. simple natureand conservation institutions are now a more cautious approach before declarations of extinction.
There are many cases where species declared ‘extinct’ are rediscovered decades or even centuries later.. For example, two species of Coelacanth, (Latimeria limestone) Y (Latimeria menadoensis), Miles’ Thief Frog (Kraugastor spindle) or a bird, black-browed chatter (Malacocincla perspicillata), declared extinct and ‘rediscovered’. And second, in the case of an endemic songbird from Borneo, it was observed again two years ago, 172 years after it was considered extinct.
‘False alarm’ problem
These cases – and others – undermine the validity and reliability of a strict ’50 years’ criterion. But at the same time, Early declaration of a species’ extinction could have detrimental consequences for conservationbecause a key habitat for the species in question may no longer be protected.
Same way, Ongoing ‘false alarms’ could undermine public empathy and the study authors note that it undermines confidence in the veracity and seriousness of extinction as a label.
Researchers reviewed information on 32,802 species on the IUCN Red List of Threatened Species and Detected 562 lost species. Their findings were published in the journal ‘Animal Conservation’.
The Red List classifies 75 of these 562 lost species as “probably extinct,” according to Simon Fraser University (SFU) biodiversity professor and co-author Arne Mooers. And he adds that as the extinction crisis worsens, the existence of many species with uncertain conservation status may become increasingly problematic.
Initially, the authors of the study identified 1,674 species extinct with more than 10 years of last observation. But they found this Of these, 57 were recently rediscovered.causing the disappearance of a total of 1,617 species (602 amphibians, 584 reptiles, 102 birds and 329 mammals).
The next step was to eliminate all species with a last observation date of less than 50 years, leaving a final central specimen with the aforementioned 562 lost species (137 amphibians, 257 reptiles, 38 birds and 130 mammals).
Tropical countries, hardest hit
It appears when a total of 311 species of terrestrial vertebrates have been declared extinct since 1500. 80 percent more species thought to be lost than declared extinct. Most of these missing animals were last seen in countries such as Indonesia (69 species), Mexico (33) and Brazil (29).
Although not surprising, this Concentration in a few countries important to researchers. “The truth is that This is alarming given that most of the species lost are in mega-diverse tropical countries, where the most extinctions are expected in the coming decades.“The study’s lead author, says Tom Martin of Paignton Zoo in England.
Gareth Bennett, an undergraduate at SFU who does most of the data matching, hopes this simple study will help make missing species “a focus of future research.”
The authors acknowledge that future study effortscritical points“defined as places where the existence of many particular species is suspected.
They note that more funding will be needed to support such fieldwork for hotspots to rediscover lost species or to remove reasonable doubt that a particular missing species really still exists.
Reference work: https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/acv.12788
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