The basic unit of evolution is

Industrial melanism in the peppered moth $(Biston \text{ } betularia)$ is an example of:

The concept that species have changed over a long period of time is known as:

Snakes do not have legs because:

In some animals,different groups develop similar structures in the same direction due to adaptation for similar needs. What is this process called?

The evolution of higher taxonomic groups such as new classes,new orders,etc.,is known as: