Debates about the ontological status of species have traditionally been divided into two camps: advocates of Hull's individuality thesis, and its critics. In this talk, I avoid the dualism of opinions by defending a form of pluralism. According to this view, all of the following statements are true: (1) some species are individuals but not kinds; (2) some species are kinds but not individuals; and (3) some species are both individuals and kinds.

To argue for these theses, I delineate three models of speciation. Model 1 is the familiar case in which there is a strong positive correlation between resemblance and relatedness. Since related organisms are similar, organisms belonging to a single lineage also form a robust kind. Species-individuals are therefore species-kinds and both ontological forms coincide.

In Model 2, resemblance is negatively correlated with relatedness. Organisms of the same kind resemble one another but do not constitute a single individual because they are the scattered parts of distinct lineages. If any species were to approximate this scenario, ontological categories would drift apart and individuals and kinds would not coincide.

In Model 3, there is no correlation between resemblance and relatedness. Some organisms form kinds, but members of such kinds are not the parts of an individual lineage. As a consequence, species-kinds and species-individuals do not coincide and ontological categories again become dissociated. Some details about microbes support the relevance of this model.

My conclusion is that the ways in which species happened to evolve explain their ontological status.