Tag: selection and evolution

The 'Big Five' mass extinctions include the Ordovician-Silurian, Late Devonian, Permian-Triassic, Triassic-Jurassic, and Cretaceous-Paleogene. The Permian-Triassic is often cited as the most severe.

The Precambrian is a vast span of time preceding the Cambrian period, consisting of the Hadean, Archean, and Proterozoic eons.

The Permian-Triassic extinction event, often called the Great Dying, was the most severe extinction event in Earth's history. It resulted in the loss of approximately 96 percent of all marine species and about 70 percent of terrestrial vertebrate species.

The Cretaceous-Tertiary (K-T) extinction event is widely known as the fifth mass extinction, but historical classifications sometimes grouped the Cretaceous-Palaeocene boundary as synonymous with the K-T boundary. Since both B and C refer to the same geological transition, D is the correct choice.

Australopithecus species were primarily herbivorous, feeding on fruits, leaves, and other plant matter. While they may have occasionally scavenged, they are not characterized as hunters using stone weapons, which is a trait associated with later Homo species.

Extinction is the complete demise of a species. It takes place when all individuals of a species die out. Extinction has occurred throughout the history of life on Earth. It is the ultimate fate of all species. It has been estimated that 99.9% of all species that have ever lived on Earth are now extinct. The causes of extinction are many and highly variable. They vary from environmental changes brought about by events such as floods, volcanic eruptions, or meteorite impacts, to fluctuations in sea level or climate, to competition between species.

When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out. The process is a completely natural part of evolution. But sometimes extinctions happen at a higher and a faster rate than usual. Factors such as large body size, small population, and position at a higher trophic level favour extinction. Fear of extinction of species from tropical forests is at the rate of 2-5 species/hr.

The Galapagos islands are known for their large number of endemic species and were studied by Charles Darwin during the second voyage of HMS Beagle. His observations and collections contributed to the inception of Darwin's theory of evolution by means of natural selection. The islands are located in the eastern Pacific Ocean, near the west coast of South America.