Q. 2. Why is variation beneficial to the species but not necessarily for the individual?
Variations are beneficial for the survival of the species. Populations of organisms fill well-defined places in the ecosystem, using their ability to reproduce. However, these places can change because of reasons beyond the control of the organisms and could even wipe out the entire population. However, if some variations were to be present in a few individuals in these populations, there would be some chance for them to survive.
For example - If there were a population of bacteria living in temperate waters and suppose the water temperature was to be increased by global warming. Most of these bacteria would die, but the few heat resistant variants would survive and grow further. Variation is thus useful for the survival of species over time.
Certain adaptations are preadaptations which have no immediate benefits to the individual. However, such variations remain in population. Whenever, there is a drastic change in the environmental preadaptations present in some of the members of population allow them to survive, grow and regain the earlier size of the population therefore, we can say that variations are not only beneficial to individuals but may also be useful to the species
Species is a collection of organisms which is on a large scale. As the individual is single and may not get benefits but species are in large no. that is why the get benefit.