Final answer:
Syndactyly is a non-adaptive variation because, unlike adaptations such as a cheetah's speed or a platypus's webbed feet which have evolved to improve survival, syndactyly does not confer an advantage or increase fitness in a particular environment.
Step-by-step explanation:
Syndactyly is an example of non-adaptive variation because it does not provide any apparent advantage or improved fitness for survival in a particular environment. Unlike the streamlined shapes in both fishes and mammals like whales that allow them to better maneuver in water, or wings in insects and birds that have evolved to enable flight, syndactyly, which is the fusion of digits (fingers or toes), does not result from natural selection promoting survival in a specific habitat. Instead, it is typically a random, non-adaptive genetic occurrence. Adaptive variation, on the other hand, occurs when a heritable trait enhances an organism's ability to survive and reproduce in its present environment. For instance, the platypus's webbed feet are an adaptation for swimming, and a cheetah's impressive speed is an adaptation for chasing prey. These traits have evolved over time because they provide a survival advantage in the organism's environment, thus being passed on through generations. Syndactyly does not fulfill such a role; it is a developmental anomaly without significant adaptive value.