Natural species, causal profile and multiple constitution

It is possible to conceive of the identity of a natural species in terms of its causal profile. Such a conception corresponds better to science than two other possible options. The identity of a natural species is not determined by a single causal role 1) because a species can have several causal roles and functions, and 2) because certain functions are shared by different species. Furthermore, as a general rule, the microstructuralist thesis is not correct: the identity of certain natural species is not determined by their microstructure. It is true that if chemical substances A and B have the same microstructural composition, then a sample of substance species A belongs to the same species as a sample of substance B. However, the opposite implication does not hold. The fact that a sample A belongs to the same species as sample B does not guarantee that A and B have the same microstructural composition. Indeed, some macroscopic natural species can be "multi-constituted" or "multiconstituted" by different microscopic structures.