Lesson 5 of 30

3. Biodiversity

Overview

  • The variety and variability of life on Earth is biodiversity. Typically, biodiversity is a measurement of genetic, species, and ecosystem variability. The terrestrial biodiversity in the region of the equator, owing to the warm climate and high primary productivity, is generally greater.

  • Biodiversity is not uniformly spread on Earth, however, it is rich in the tropics. Such ecosystems of tropical forests occupy fewer than 10 percent of the surface of the planet. It also compensates for about 90 percent of the world ‘s species.

  • Marine s biodiversity in the Western Pacific, with the lowest sea surface temperatures, along with the mid-latitudinal band in all oceans is generally the present in highest numbers. There are latitudinal gradients in species diversity. Biodiversity usually tends to cluster in hotspots. It has been increasing over time but will be likely to slow in the future.

Biodiversity Changes

  • Usually, mass extinction triggers drastic environmental changes. There is an estimated extinction of over 99.9% of all species that have ever been living on Earth. It represents more than five billion species. The total number of Earth species numbers vary from 10 to 14 million, with about 1.2 million recorded, and over 86 percent not yet described.

  • In May 2016, scientists have recently announced that there are actually 1 trillion species with just a thousandth of one percent described on Earth.  The total amount of related DNA base pairs on Earth is estimated at 5.0 x 1037 and weighs 50 billion tonnes. 

  • In contrast, the total mass of the biosphere has been estimated to be as much as 4 TTC (trillion tons of carbon). In July 2016, scientists prescribed identifying a set of 355 genes from the Last Universal Common Ancestor (LUCA) of all organisms existing on Earth.

  • The Earth’s age is about 4.54 billion years. At least 3,5 billion years ago, the earliest unchallenged evidence of life on Earth started to solidify in the Earth during the Eoarchean Era, replacing the earlier molten Hadean Eon. The 3.48 billion-year-old sandstone discovered by Western Australia includes microbial layer fossils.

  • Graphite of 3.7 billion years aged meta-sedimentary rocks located in the west of Greenland is another early physical evidence of biogenic substances. More recently, “remains of biotic life” were found in Western Australia in 4.1 billion-year-old rocks in 2015.  As per one of the researchers, “If life arose relatively quickly on Earth .. then it could be common in the universe.”

  • Since the beginning of life on Earth, five mass extinctions have contributed to significant and unexpected declines in biodiversity. Additionally, many small events. A rapid rise in biodiversity was detected during the Cambrian explosion (last 540 million years) in Phanerozoic eon — which was the first to establish the majority of multicellular phyla.

  • Repeated mass losses of biodiversity are classified as events of mass extinction in the next 400 million years. Rainforest collapse caused significant loss of life for plants and animals in the Carboniferous rainforest. The worst was the 251 million years old Permian – Triassic Case of Extinction; it took 30 million years to rebound for vertebrates.

     
  • The current, the Cretaceous–Paleogene extinction event, occurred 65 million years ago. It has subsequently attracted more attention than others as it resulted in the extinction of the non-avian dinosaurs.

  • Since before the emergence of humans, biodiversity has started to decline and genetic diversity has been destroyed. The decline is partly due to human activities, particularly habitat loss, named the Holocene extinction. On the other side, the impact of nature on human well-being is defined in a variety of ways.

  • United Nations in 2011-2020 had proclaimed a United Nations Biodiversity Decade. According to a 2019 Global Assessment Report that IPBES released on Biodiversity and Ecosystem Services, 25 percent of animals and plants species as a consequence of human activities are threatened with extinction.
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