EVOLUTION

Extinction and Speciation

Extinction and Speciation

Extinction

ExtinctionExtinction is where a whole species is wiped out. There are a number of reasons why this can occur:

  • changes to the environmental over a geological period
  • the introduction of new predators
  • the introduction of new diseases
  • better competitors
  • one catastrophic event like a huge volcanic eruption
  • due to the cyclical nature of speciation

As dead as a dodo

One of the most popular examples of recent extinction is the dodo. They were large, flightless birds native to Mauritius. When humans arrived on the island in 1638 they brought with them a lot of animals, like dogs, cats and pigs, who plundered the birds’ nests and killed their young. Humans began not only to destroy the Dodo’s habitat but quickly over hunted them because they were very easy prey being slow and unafraid of people. Eighty years later the dodo had been wiped out.

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Speciation

Speciation refers to the process in which a new species arises.

ExtinctionIsolation is one such way. This is where two populations of the same species become separated geographically, for example by a desert or a large body of water. This prevents the groups from mating with each other on a regular basis thereby causing speciation.

The African elephant is one example of speciation through isolation. It has always been seen as a single species however scientists have discovered that due to geographical isolation the elephants located in West Africa are in fact a different species to the savannah elephants. And yet another species, the forest elephants, can be found living in Central Africa.