Biodiversity on Earth

How has it changed over time?

Interpretation of Supplied Data

The data provided indicates that the family Angiosperm has the most species encompassed in it, over 400! It also shows that Insets and Mammals also incorporate many different species. The family Insect is made up of approximately 225 species, and mammals almost 150 species.

The families with the lowest amount of species are Gymnosperm and Bivalve. Both only house around 25 species!

The Research Question

Data has sparked the question 'How has biodiversity changed over time?'.

My Claim

Biodiversity has changed dramatically over time, increasing and decreasing, due to the geological and chemical evidence that supports the Permian-Triassic and Cretaceous-Paleogene Extinctions, as well as the Great Oxidation period.

Evidence

There are 3 main evidence points that support my claim:

The Great Oxidation Period: There is extreme geological evidence that a period occurred where Oxygen began to be produced in great numbers. A species of bacteria, called cyanobacteria, mutated and became a photosynthetic life form. Rapid reproduction caused a build-up of Oxygen gas that had not been in the atmosphere before the creation of cyanobacteria. This build-up killed most life forms that were unable to process such high levels of Oxygen, therefore only a few species survived and those species paved the way for Eukaryotic cells, which came very quickly after the influx. Eukaryotic cells found in fossils differentiate very quickly after their creation, which causes diversity to accelerate drastically. This theory is supported by geological evidence such as higher amounts of Carbon Isotopes that were lower in earlier rock forms, as well as isotope changes in Iron and Sulfur. There is also evidence found in the rock that was once under vast ocean, very redox-sensitive metals are found in the composition of studied rocks. It is also supported by the Miller-Urey experiment that proves the atmosphere did not contain high levels of Oxygen.

The Permian-Triassic Extinction: Although it's true happenings are being debated, this extinction was most-likely the result of volcanic activity in the northern countries of Europe and Asia. This volcanic activity caused extreme climate change, oxygen depletion, and acidification. The widespread depletion of Oxygen is what is expected to have caused the extinction of many mammal-like reptiles and ocean organisms. This extinction heavily decreased the amount of biodiversity on Earth. However the biodiversity on Earth increases again in the Age of the Dinosaurs, which were born from those species that survived the extinction. This creates a different form of diversity among organisms, it is not mammal or bacteria that is being diversified, but a completely different life form.

The Cretaceous-Paleogene Extinction: Possibly the most famous extinction, this is caused by a giant meteorite slamming into Earth. It is supported by a layer of clay found world wide that contains high levels of chemicals found in asteroids, meteors, and meteorites. The climate changed dramatically and resulted in ecological disruption. A vast majority of Dinosaurs were killed during this extinction, which decreased biodiversity. Once again the biodiversity changes because new mammals were born from the species that survived the extinction.