What two factors differentiate commensal from native rodents?

The differentiation between commensal and native rodents often relies on physical characteristics and ecological behaviors. In this context, tail length and body shape serve as key distinguishing features.

Commensal rodents, such as the house mouse and the Norway rat, generally exhibit shorter tails relative to their body size compared to many native rodent species. Additionally, the body shape of commensal rodents tends to be more streamlined and adapted for living in close proximity to human environments, while native rodents often have a more diverse range of body shapes suited to their particular habitats. Therefore, tail length gives insights into adaptation to environments—commensal rodents adapting for life alongside humans—and body shape offers clues about their ecological roles.

The other options, while they may suggest differences, do not specifically pinpoint the critical factors used to classify commensal versus native rodents as effectively as tail length and body shape do. For example, color can vary widely among all types of rodents and is not a reliable differentiator, and while habitat is important, it encompasses a broader range that isn’t as focused on physical attributes. Thus, tail length and body shape are the most defining factors in this case.