Explain sympatric speciation and provide an example of a non-geographic barrier that can drive it.

Explain sympatric speciation and provide an example of a non-geographic barrier that can drive it.

• A. Speciation occurs within the same geographic area; barriers include polyploidy in plants or niche differentiation leading to assortative mating
• B. Speciation occurs due to a predator introducing selection pressure
• C. Speciation occurs when a physical barrier like a river prevents gene flow
• D. Species diverge because of different mating seasons in different areas

Answer: (A)

Sympatric speciation happens when new species arise in the same geographic area, with reproductive isolation created by barriers that don’t involve physical separation. A key non-geographic barrier is polyploidy in plants, where chromosome doubling produces individuals that can only mate with other polyploids, giving them immediate reproductive isolation from the diploid population. Another non-geographic route is ecological differentiation that leads to assortative mating: subgroups exploit different resources or habitats and preferentially mate with others sharing their ecological traits, so gene flow between the groups drops even though they live in the same area. This combination of occurring in the same location and arising from non-geographic barriers is why this description fits sympatric speciation well.

Sympatric speciation happens when new species arise in the same geographic area, with reproductive isolation created by barriers that don’t involve physical separation. A key non-geographic barrier is polyploidy in plants, where chromosome doubling produces individuals that can only mate with other polyploids, giving them immediate reproductive isolation from the diploid population. Another non-geographic route is ecological differentiation that leads to assortative mating: subgroups exploit different resources or habitats and preferentially mate with others sharing their ecological traits, so gene flow between the groups drops even though they live in the same area. This combination of occurring in the same location and arising from non-geographic barriers is why this description fits sympatric speciation well.