Question

Decide which examples are most likely to increase variation or decrease variation. Some examples could do both.

Which of the following could possibly increase genetic variation indirectly?

toxins

predator-prey relationships

competition

new habitat

disasters

increased food supply

Answer 1

Short answer: All of them could possibly increase genetic variation under some circumstances — but several can also decrease variation. Brief notes on mechanisms:

- Toxins — could increase variation indirectly if they act as mutagens (raising mutation rate) or if they impose selection that maintains multiple resistant/susceptible genotypes (balancing selection). They also often reduce variation by removing susceptible genotypes.

- Predator–prey relationships — can increase variation via frequency‑dependent selection or coevolution (rare prey types or different defenses are favored), or by promoting niche divergence. They can also reduce variation through strong directional selection.

- Competition — can increase variation by driving disruptive selection or character displacement (different morphs/specializations), or by promoting speciation. It can also reduce variation if one type outcompetes others.

- New habitat — can increase variation by offering new niches and relaxed constraints, allowing diversification and accumulation of new mutations as the population expands. But colonization often causes founder effects that initially reduce within‑population variation.

- Disasters — typically decrease within‑population variation (bottleneck). Indirectly they can increase genetic divergence between separated survivor groups or set up new selective regimes that lead to later increases in variation, but their immediate effect is usually loss of variation.

- Increased food supply — tends to increase variation by allowing larger population sizes (reducing drift and preserving variation), by relaxing selection against some alleles, and by enabling expansion into new niches.

So which “could possibly increase” — all six, depending on context; disasters are the most likely to reduce variation immediately, while increased food, new habitat, predator–prey, competition, and toxins are more plausibly sources of increased variation in many scenarios.