what is variation?why is it necessary
Answers
Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population. ... Genetic variation is advantageous to a population because it enables some individuals to adapt to the environment while maintaining the survival of the population.
Variation is important for any species because it allows the species to adapt to a changing environment.
Also, the presence of diseases and parasites maintains variation in a species, particularly those associated with blood groups.
The first response of a species confronted with environmental changes, such as climate change, is to shift its range. So a species could move poleward, or to higher altitudes. When that does not work variations help individuals survive in harsher conditions, and adapt to the changes.
A problem at present is that global warming is happening fast and many species have already been reduced to smaller populations. This reduces the available variation, making the species less adaptable. This can also happen if the range gets broken up, and individuals in one area can no longer breed with those in another.
The variations that help resist parasites persist in a population. Say most individuals are vulnerable to a particular parasite, but there is a small number resistant to it. These individuals have an advantage and increase in numbers until they are enough to keep the parasite from spreading. This will allow vulnerable individuals to avoid infection and survive. When the parasite adapts to the resistant strain, they often loose the ability to infect some other strain, and so it goes.