Question

which of the following can typically decrease genetic variation?
toxins
predator - prey relationships
competition
new habitat
disasters
increased food supply
retry

Explanation:

To determine which factor decreases genetic variation, we analyze each option:

• Toxins: Can harm organisms, but don't directly reduce genetic variation (may affect survival but not genetic diversity's root cause like bottleneck).
• Predator - prey relationships: Drive natural selection, which can increase variation as traits favorable against predators are selected (e.g., camouflage variations).
• Competition: Leads to natural selection for competitive traits, increasing variation (e.g., different feeding strategies in competitive environments).
• New habitat: Introduces new selection pressures, often increasing variation as organisms adapt to new conditions (e.g., new food sources, climates).
• Disasters: Events like natural disasters (e.g., earthquakes, floods) can cause a population bottleneck. A bottleneck occurs when a large portion of the population is killed, and only a small, random subset survives. This random subset has less genetic variation than the original population, so disasters typically decrease genetic variation.
• Increased food supply: Reduces selection pressure, allowing more genetic variants to persist (as resources are not limiting survival), so it increases or maintains variation.

Answer:

disasters