CBSE Class 10 Answered
Variation occurs when one gene in the organism is mutated.If it allows the organism to survive longer than the others in the population without the mutation, it gives the mutated organism a higher chance to pass on its genes. When these genes are passed on, their kids may have the mutation but they will carry the mutated gene. As long as this helps the organism survive it will continue to be passed on to the next generation. After many generations, the mutated trait becomes common which means they have evolved.
Example- For example, a population of long beaks inhabit a particular area. Now, the food can be consumed properly with short beaks. If due to some variations, there may be a possibility that there are some birds with short beaks in that population. So, in the new area, they will survive better and reproduce more which will lead to the evolution of more and new species.