The only source of new genetic variation (material) is / are _____ .

Question

BlackTom AI · Accepted Answer

The question asks which option correctly identifies the only source of new genetic variation (material).
Option a: bottlenecks. In reality, bottlenecks reduce genetic variation by drastically shrinking population size, so they do not introduce new genetic variation; they conserve existing variation and can even increase drift effects. Therefore this choice is incorrect.
Option b: mutations. Mutations are changes in DNA sequence that create new alleles and novel genetic variation not present in the population before the mutation occurred. This is the primary source of new genetic material on which evolution acts, making this option correct.
Option c: emergent. This term does not refer to a recognized mechanism of generating genetic variation. It’s vague and not a standard genetic concept for producing new variation, so this is incorrect.
Option d: assortative. Assortative mating affects genotype frequencies by changing which individuals mate with which, thus altering the distribution of existing variation, but it does not generate new genetic variation itself. Hence this is incorrect.
Option e: acquired. Acquired traits (changes acquired during an organism’s life) are not typically heritable and do not create new heritable genetic variation in the germline. Therefore this does not constitute a source of new genetic material, and is incorrect.
In summary, only mutations (option b) introduce new genetic material that can be inherited and acted upon by evolutionary processes. The other options describe processes that alter allele frequencies or variation indirectly or reduce variation, rather than creating new genetic variation.

BIO 181 (001&002) FALL 2025 FA25: Cumulative Exam 4 covers the most important content from Units 1-4: You can do this!!! : ) [Grade is out of 150/900 pts, the same am't of pts for the active learning "easy points" classwork.]

The only source of new genetic variation (material) is / are _____ .

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