Which statement best describes sympatric speciation?

• A. Speciation without geographic separation
• B. Speciation with geographic separation
• C. Hybridization without isolation
• D. Reproductive isolation due to different diets

Answer: (A)

Sympatric speciation is speciation without geographic separation. The defining idea is that new species arise within the same area, so gene flow is reduced by factors other than physical barriers—such as disruptive selection within the population, differences in mating preferences, or genetic changes like polyploidy in plants. That makes the statement about speciation occurring in the absence of geographic separation the clearest description.

The other options describe scenarios involving geography or mechanisms that don’t by themselves capture the core idea. Speciation with geographic separation is allopatric, where a physical barrier splits populations. Hybridization without isolation doesn’t inherently describe the process leading to fully separate species in the same space. Reproductive isolation due to different diets points to an ecological cause of isolation, which can occur in sympatry but doesn’t state that geographic separation is absent—the defining feature remains the lack of a geographic barrier.