Question

Why is the variation beneficial to the species but no necessarily for the individual ?

Answer 1

Species occupy well-defined spaces in the ecosystem, called niches, by increasing their population through reproduction. These niches in the ecosystem may change upon time, even drastically, which are not in control of these organisms occupying the space. The changes, such as an increase in temperature, may cause a threat to the survival of the species in that niche. If the species have variations within the population, some of the variants might be able to cope with the change, thus having a survival advantage. Thus, these variants will survive, leaving behind the individuals in the population with no desirable variation. Thus, these variants help in the survival of species. But, not all variations are beneficial for individual organisms.