Evolution is the theory that organisms change over time. They change to adapt to their surroundings and ultimately they change to survive. This is where the term “Survival of the fittest” come in. Survival of the fittest is the process of natural selection where the ones that were the most adapted to a particular environment survived and those that were not, died.

Charles Darwin created the theory of evolution. Darwin studied plants and animals for nearly 30 years. He then wrote his ideas in his book, origin of species.

The theory of evolution also highlighted that in some way shape or form all organisms are related.

It illustrated that species with similar characteristics are often related for example chimpanzees and humans. These characteristics mean the two organisms often look alike and behave in similar ways.

Sometimes tow organisms may look alike but may be from completely different ancestors. An example for this is sharks and dolphins, which look alike but are not related. Evolutionary trees highlight this


Dolphins have a similar ancestor to the whale but only have a far ancestor to the shark


Natural selection

Natural selection occurs due to a series of steps

  • Organisms show a wide range of variation due to the genes they possess


  • These genes allow them to survive in particular environments, because they survive they are able to pass on their genes


  • The genes passed on to the offspring also allows them to survive


  • Those without the genes are not able to compete for food or shelter and will soon die


  • Over time only certain individuals within a species will exist as they evolve and out compete others


Not everyone agreed with Darwin and many scientists had different views. A key viewpoint was that of Lamarck’s. Lamarck argued that the characteristics used a lot by the organisms would then be developed and passed on to the next generation.



Extinction occurs when there are no more individuals left in a particular species
This can occur due to a number of reasons

Disease – a disease which wipes out a whole species

Predator – a new predator which eats all the prey before they can reproduce

A change in the environment – a change in temperature or climate, may reduce the chances of a particular species of surviving

Competition – competition form another species for food and habitats will cause the other species to die out



Biodiversity is having as many species in a particular environment as possible. This ensures that food chains survive and ensures that we protect the variety of living organisms on this earth

Conservation methods are ways of ensuring that levels of certain species remain high. If they become lower than a certain threshold that species is considered endangered.

There are many ways to protect a species, the simplest way is through education, educating the public about a particular species will increase the awareness and help reduce the aspect, which is causing the decline in numbers

Another way is to start breeding programs, which encourage organism to breed, and thus increasing the population of that particular species,

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