* The ability to reproduce and create fertile offspring. This is the defining characteristic of a species.
* Similar physical characteristics. While there can be variations within a species, they share fundamental physical traits.
* Similar genetic makeup. Individuals of the same species share a large percentage of their DNA.
* The ability to interbreed. This is closely related to the first point, but it emphasizes the potential for reproduction.
* Similar ecological requirements. Members of the same species tend to occupy similar habitats and have similar food sources.
It's important to note that individuals within a species can have variations in appearance, behavior, and other traits due to genetic diversity.
