**True species are reproductively isolated, meaning they only interbreed with each other and produce viable offspring. This can be due to geographic isolation, or it can be due to certain appearances or behaviors that enable the members of a species to recognize each other.

¥¥ We may say 'members' of a species can interbreed, but this word is not mentioned in the question. That leads us to our answer, i.e. species are reproductively isolated.

Interbreeding:
Interbreeding refers to the ability of individuals within a species to mate and produce fertile offspring. This is a defining characteristic of true species. If two individuals from different populations can successfully reproduce and their offspring can also reproduce, then they are considered to be part of the same species. On the other hand, if individuals from different populations cannot produce viable offspring, they are considered to be separate species.

Sharing the same niche:
A niche refers to the specific role or position that a species has in its environment, including its interactions with other species and its use of resources. While it is not a requirement for true species to share the exact same niche, they often occupy similar ecological roles. This can be seen in cases where closely related species have similar diets, habitats, or behaviors. However, it is important to note that two species can have overlapping niches without being the same species.

Feeding on the same food:
Feeding on the same food source is not a defining characteristic of true species. Many species may have different diets and still belong to the same species. Variation in diets can be observed even within a single species, as individuals may have different preferences or access to different food sources. Therefore, while some species may share the same food source, it is not a requirement for them to be considered true species.

Reproductively isolated:
Reproductive isolation is a crucial aspect of defining true species. It refers to the inability of individuals from different species to produce viable offspring. Reproductive isolation can occur due to various factors, such as differences in mating behaviors, physical incompatibilities, or genetic barriers. When reproductive isolation prevents gene flow between populations, it can lead to the divergence of traits and the formation of distinct species over time. Therefore, if individuals are reproductively isolated and cannot produce fertile offspring, they are considered separate species.

In summary, while interbreeding and reproductive isolation are key criteria for defining true species, sharing the same niche and feeding on the same food are not necessary characteristics. Species can have different ecological roles and diets while still belonging to the same species.