It has been proven that animals can change at different stages of evolution. This is, because of environmental change and isolation of groups of organisms and this is the main important role in evolution which has caused animals to change and is still changing.
Environmental change is a change in the environment which an organism must adapt to survive. Change of the environment, can be really slow and take time, for example when mountains and deserts form and this will cause some organisms to die and may cause new species to evolve. This could take up to millions of years. Changes in the environment can happen really quickly which are floods, volcanoes and earthquakes. For example, if volcanoes explode in a place where particular organisms are living then they will have to move to a new environment making then to evolve rapidly and adapt to it. …show more content…
The isolation happens when there is something in between that they can't be able to cross. Causes of isolation are like when rivers and mountains form in between them, even when continents split. Organisms can even be separated quickly by heavy waves or tsunami, as it can blow away the organisms leading them to end up in different places.
An example of an animal that has changed, because of isolation are giraffes. In this picture on the left, at top is the common giraffe and at the bottom is a reticulated giraffe. The giraffe used to be the same, but over generations it has changed, because of isolation. It had led them to change their skin, because of the Tana River in Kenya. Therefore the two groups of giraffe have become distinct. When they have been isolation for longer, then the groups will be different from each other.
Giraffe changing over time at different stages of