The largest unit within which gene flow can readily occur is a a. population. b. species. c. genus. d. hybrid.

Verified step by step guidance

1. Step 1: Understand the question. The question is asking for the largest unit within which gene flow can readily occur. Gene flow is the transfer of genetic variation from one population to another. If an individual migrates into a new population and reproduces, its genes are incorporated into the new population's gene pool.
2. Step 2: Review the options. The options are a) population, b) species, c) genus, and d) hybrid. A population is a group of individuals of the same species that live in the same area and interbreed. A species is a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. A genus is a rank in the biological classification (taxonomy) above species and below family. A hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction.
3. Step 3: Evaluate each option in relation to the concept of gene flow. Gene flow can occur within a population, as individuals can interbreed. Gene flow can also occur between different populations of the same species, as they are capable of interbreeding. However, gene flow is less likely to occur between different species, as they are usually not capable of interbreeding. Gene flow is even less likely to occur between different genera, as they are even less likely to be capable of interbreeding. Hybrids, being the result of interbreeding, do not represent a unit within which gene flow can occur.
4. Step 4: Choose the correct answer. The largest unit within which gene flow can readily occur is a species, as it includes all individuals capable of interbreeding.
5. Step 5: Verify your answer. Gene flow is the transfer of genetic variation from one population to another. This can occur within a species, as different populations of the same species can interbreed. Therefore, the correct answer is b) species.