Updated: Jun 1, 2020
When people think of evolution they think of a simple creature becoming more complex one, which to a degree is correct but is not always true, evolution works in necessity.
For example take the Kakapo a flightless parrot from New Zealand, their ancestors could fly but because at the time there where no predators on the island (cats and dogs have gotten to the island but the New Zealand government is taking steps to protect the Kakapo). They lost the ability to fly as they had no need to escape predators.
Another example is the Olm a cave Salamander, because they live in complete darkness they have no need for sight so over time their eyes became under developed and have left them blind.
The loss of flight and sight might seem like a step backwards but because they no longer needed these abilities so evolution got rid of them.
There are several types of evolution.
Is when animals that don't have a common ancestor to each other but evolve to behave or have similar attributes to each other such as ants and termites. Ants are in the Hymenoptera order so they
are related to Bees and Wasps and Termites are in the Blattodea order they are distantly related to Cockroaches.
Even though they are not related they both live in colonies with individuals doing a set jobs, they are both ruled by a queen that is the mothers to all the individuals in the colony, they create their own nests or mounds but Termites tend to make more advanced mounds Ants (Convergent evolution) compared to Ants such as the Wood ants.
Is when when animals are related but do not look as though they are an example would be the Hyrax, Hyraxes are related to the Elephant. Even though the Hyrax looks like a rodents and are found in trees and scurrying between rocks and the Elephant is the largest land mammal they are both related even though they couldn't look more different.
Is when the males and females look different in some cases the males and females can look like they are from 2 different species a good example of this is the Elephant seal the males can be more than 4 times the size of the females.
Normally happens after a mass event that kills a large number of a species population. This happened to Cheetahs about 10,000 years ago when they almost became extinct. So many cheetahs died that their genetic variations have shrunk to such an extent that their evolution has almost came to a stop. Genetic variations are important for animals to change, adapt and evolve. Favourable genetic variations are passed onto the next generation, they control everything from the colour of your eyes to your ability to deal with infection.