In the context of evolution by natural selection, natural selection cannot occur without which of the following conditions?

• A. Individuals acquiring beneficial traits during their lifetime and passing them to offspring
• B. Gene flow between two populations through migration
• C. Random changes in allele frequencies due to genetic drift in a small population
• D. Heritable variation among individuals that leads to differences in survival and reproduction

Answer: (D)

Verified step by step guidance

1. Understand the concept of natural selection: it is a process where individuals with certain heritable traits tend to survive and reproduce more successfully than others, leading to changes in allele frequencies over generations.
2. Identify the key conditions required for natural selection to occur: there must be variation in traits among individuals, these traits must be heritable (passed from parents to offspring), and these traits must affect survival or reproduction.
3. Analyze each option given in the problem to see if it meets these conditions: acquiring traits during a lifetime (not heritable), gene flow (movement of alleles but not a requirement for natural selection), genetic drift (random changes, not selection).
4. Recognize that the essential condition for natural selection is heritable variation that influences survival and reproduction, because without this, natural selection cannot act on the population.
5. Conclude that the correct answer is the presence of heritable variation among individuals that leads to differences in survival and reproduction, as this is the fundamental requirement for natural selection.