Question

What are Variations? How are they important for species?

Answer 1

Variations are usually the variations occurring in DNA sequences of an organism. These variations make an organism different from another organism. They are indispensable for natural selection. Variations occurring in species help to adapt to the environment. Some variations are caused by recombination between homologous chromosomes during meiosis, random mating and random fertilization.

Complete answer:
Variation occurs during sexual reproduction. It is important for evolution.
Variation is helpful in better survival of an organism.
When variation accumulates continuously over a time, then it leads to speciation.
Even variation causes genetic drift where the same species themselves get distanced.
Useful variations are passed to organisms from one generation to next generation, which is a requisite for the adaptation of an organism.
Variations provide every organism with individuality.
Variations compose the raw materials for variation.
They make individuals better suited in struggle for existence and survival of the fittest.
They allow breeders to provide improvement of races of useful animals and plants for lesser input, faster growth, better yield and enhanced resistance.
Variations do not allow species to be static. Species become gradually modified with time and form new species with time.
Variations (discontinuous) provide new traits in the organisms.
They also aid in the prevention of extinction of species.
Neutral variations cause pre-adaptations to the organism, which are extremely helpful in the survival against sudden and new changes in the environment. Example is resistance against a new pesticide.

Note:
There are two major classes of variations. They are continuous variation and discontinuous variation. Continuous variation is where different types of variations occur at continuity. Example is hair color. Discontinuous variation is where different variations are discrete qualitatively. Example is blood group. Some causes of variation are due to DNA mutation by alteration of genes in a population. Example is leaf modification in plants.