 Interestingly, another major area in which biological individuality has played a large role is in debates over the nature of  species.  That is, many philosophers of biology maintain that species are properly construed as individuals. Species, often referred to as “units of evolution”—groups of organisms that evolve in a unified way—are nonetheless rarely seen as units of selection. In Elisabeth Lloyd’s terminology (see the entry on  units and levels of selection),  this is presumably because species are rarely seen as replicators/reproducers or vehicles/interactors but are commonly seen as beneficiaries of evolution by natural selection. In addition to sorting out whether species are individuals and what sort of units of evolution (if any) they might be, there are many-decades’ worth of papers trying to characterize the species concept, whether in terms of interbreeding, phylogeny, morphology, ecology, or some other set of characteristics. Here, as in many other areas of the philosophy of biology, there have also been arguments for a pluralistic approach.