Question

sympatric speciation
○ occurs when a new species emerges from a population in the absence of a geographical barrier.
○ is impossible, because the populations of a species must be isolated from one another for speciation to occur.
○ is always a result of polyploidy.
○ occurs only in plants.

Explanation:

To solve this, we analyze each option based on the definition of sympatric speciation:

• Option 1: Sympatric speciation is defined as the formation of a new species from a single ancestral species while inhabiting the same geographic region (no geographical barrier). This matches the definition.
• Option 2: Sympatric speciation is possible (e.g., through polyploidy in plants or other mechanisms like sexual selection, habitat differentiation in animals), so this is incorrect.
• Option 3: While polyploidy is a common cause in plants, sympatric speciation can occur via other means (e.g., sexual selection, habitat differentiation), so it's not "always" due to polyploidy. Incorrect.
• Option 4: Sympatric speciation can occur in animals (e.g., cichlid fish in lakes) as well, not just plants. Incorrect.

Answer:

A. occurs when a new species emerges from a population in the absence of a geographical barrier.