Question

For natural selection to occur which of them must be true for a population of an organism?
A. The phenotypic variation must be based on genetic variations rather than on varying environmental conditions.
B. The population must be occupying the same niche as another local population.
C. The organism in the population must be capable of sexual reproduction.
D. Food resources must be limited.

Answer 1

Hint: Natural selection (survival of fittest )- In this struggle for existence the individuals who have more favorable variations will enjoy a competitive advantage over the other which have less favorable or unfavorable variations and will survive and reproduce. Variation in the trait is associated with variation in fitness.

Complete answer: Natural selection causes a change in the frequencies of an allele of a population.
It is coupled to increase reproductive success; natural selection makes the population look entirely different from the original speciation.
Sexual reproduction results in variation in genetics but it does not affect natural selection.
Limited environmental resources such as food and space drive natural selection but they are not the reason for occurring natural selection.

Additional information: The theory of natural selection was given by Darwin.
Depending upon the traits favored, natural selection can produce one of the three following.
1. Stabilization, in which more individuals acquire mean character i.e. variation is much reduced
2. Directional change, in which more individuals acquire value other than the mean character value.
3. Disruption in which more individuals acquire peripheral character value at both ends of the distribution curve.

So the correct answer is option A. Phenotypic variation must be based on genetic variations rather than on varying environmental conditions

Note: The sexual reproduction and environmental resources drive natural selection but they are not the reason for natural selection to occur.