George Arun A
01.03.2023
Do You Know How Many Species are there in the Earth?
Global biodiversity:
Global biodiversity is the measure of biodiversity on planet Earth and is defined as the total variability of life forms. More than 99 percent of all species that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 2 million to 1 trillion, of which about 1.74 million have been databased thus far and over 80 percent have not yet been described.
Measuring Diversity
Biodiversity is usually plotted as the richness of a geographic area, with some reference to a temporal scale. Types of biodiversity include taxonomic or species, ecological, morphological, and genetic diversity. Taxonomic diversity, that is the number of species, genera, family is the most commonly assessed type. A few studies have attempted to quantitatively clarify the relationship between different types of diversity. For example, the biologist Sarda Sawhney has found a close link between vertebrate taxonomic and ecological diversity.
Over the past few centuries, human activity including deforestation and urbanization as well as climate change have forced hundreds of species into extinction, with tens of thousands more are currently on the brink of going extinct. But how many endangered species are there right now?
There are currently at least 38,500 species under threat, and over 16,300 species believed to be endangered, according to the International Union for Conservation of Nature (IUCN), the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species.
Based on only 28% of all assessed species, 41% of known endangered species are amphibians, 37% are sharks and rays, 33% are corals, 26% are mammals, and 14% are birds.
Up to 70% of the world’s assessed plants are under threat, and nearly a third of global tree species are facing extinction including well-known species such as magnolias, oaks, maple and ebonies.
In the US alone, the Environmental Protection Agency estimates there are currently over 1,300 endangered or threatened species.
Some of the most critically endangered species include rhinoceros due to rampant poaching, orangutans as result of deforestation for palm oil, and vaquitas, the smallest and most endangered marine mammal in the world with only nine individuals left.
While it’s difficult to pinpoint the exact number of endangered species, it’s undeniable that the rate of extinction is accelerating at unprecedented rates. We are losing the same amount of species within 20 years as we did over the whole of the last century.
In a 2020 analysis published in the journal Proceedings of the National Academy of Sciences, scientists have identified 515 species with populations below 1,000 and about half of these had fewer than 250 individuals remaining. There are also 388 species of land vertebrates with populations under 5,000 individuals, 84% of them live in the same regions as the species with populations under 1,000, creating the conditions for a domino effect where close ecological interactions of species on the brink tend to move other species towards extinction.
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