I keep seeing and hearing that a particular species is 60% or some percent extinct. My question would be how was the total number of living species ever calculated. For example say dolphins. How would anyone ever know the number of dolphins alive at a particular time. At least for us we have a registered census but what is it for these species?
In: Earth Science
You estimate it from the numbers that you’re actually seeing. It’s a fairly common statistical technique to derive total populations from a limited sample set of it, and it’s fairly accurate. In addition, if you know that you’re seeing 60% fewer of a particular species than you were a few years ago, it’s reasonable to assume that the species as a whole has also declined by that sort of level–it’s extremely unlikely that 60% have decided to simultaneously go into hiding.
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