Sympatric speciation is described as which of the following?

• A. The formation of new species in populations that are geographically isolated from one another
• B. The formation of new species in populations that live in the same geographic area
• C. Speciation due to hybridization and chromosomal changes
• D. Genetic drift causing immediate speciation without isolation

Answer: (B)

Sympatric speciation happens when new species arise within the same geographic area, with reproductive isolation evolving even though there is no physical barrier between populations. This can happen if subgroups start using different resources or habitats (disruptive selection) or if individuals prefer mates from their own subgroup (assortative mating), reducing gene flow between them. In plants, genome doubling after hybridization can also create a new species in the same area, illustrating a mechanism that can operate in sympatry. The key point is that physical separation is not required for speciation in this scenario.

The other descriptions describe different situations: splitting into geographically isolated populations defines allopatric speciation, which is not the scenario here. While hybridization and chromosomal changes can drive speciation, that mechanism is not the defining feature of sympatry on its own. And genetic drift causing rapid speciation without any isolation contradicts the idea that some form of isolation (even in the same area) must arise for distinct lineages to stop interbreeding.