A hybrid zone is properly defined as:

• A. a location where genetic drift is the only evolutionary force acting on a population
• B. a geographic region where two populations of the same species are completely reproductively isolated
• C. a region where members of different species meet and mate, producing at least some offspring of mixed ancestry
• D. an area where a single species is found in isolation from other related species

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of a hybrid zone. A hybrid zone is a geographic area where individuals from two different species or distinct populations meet, mate, and produce offspring that have mixed ancestry. This is a key concept in evolutionary biology and speciation studies.
2. Step 2: Eliminate incorrect options by analyzing their definitions. For example, genetic drift is a random evolutionary force, but it is not the sole defining factor of a hybrid zone. Similarly, reproductive isolation implies no interbreeding, which contradicts the idea of hybrid zones where interbreeding occurs.
3. Step 3: Focus on the correct definition. A hybrid zone is characterized by the presence of hybrids, which are offspring resulting from the mating of individuals from two different species or populations. This means that reproductive barriers are incomplete in this region.
4. Step 4: Consider the ecological and evolutionary significance of hybrid zones. These areas are important for studying gene flow, natural selection, and the processes that maintain or break down species boundaries.
5. Step 5: Conclude that the correct definition of a hybrid zone is 'a region where members of different species meet and mate, producing at least some offspring of mixed ancestry,' as this aligns with the biological and evolutionary understanding of hybrid zones.