 To reinforce this point, consider which aspects of an organism can be changed while it remains a member of the same species, and which aspects cannot be changed. The intrinsic reproductive mechanisms within the organisms of a species can be changed, but being part of the same lineage or gene pool cannot be changed. To make this more concrete consider the case of ring species. A ring species consists of a geographic ring of populations such that organisms in contiguous populations can successfully mate, but organisms in populations at distant links in the ring cannot successfully mate. The organisms in distant populations of a ring species have different reproductive mechanisms (Mayr 1963, 512ff.). Suppose Joe is a member of a ring species. Joe could have had a different intrinsic reproductive mechanism than the one he has. Imagine counterfactually that he is a member of a different population of his ring species, namely one with different reproductive mechanisms than those found in his actual population. In this counterfactual situation Joe is still a member of his species so long as we do not remove him from the lineage and gene pool of that ring species. Generally, an organism in a species can have a different reproductive mechanism and still be a part of that species. But an organism cannot be removed from its original lineage and put in another lineage and remain part of the original species. When it comes to species membership, intrinsic mechanisms within the organisms of a species can vary, but certain relations among its organisms cannot vary (Ereshefsky 2010a). (For more critiques of Devitt’s intrinsic essentialism see Barker 2010 and Lewens 2012. For Devitt’s response to those criticisms see Devitt 2021.)