ABSTRACT
Many scientists and philosophers have said something like 'species are the units of evolution' or 'the units of biodiversity'; it is even the title of some well-known books on the subject. This chapter argue that species are real, phenomenal objects rather than objects of any biological theory, let alone of evolutionary theory. Population genetics and evolutionary theory have populations, haplotypes, alleles, trophic nodes, niches and so on, but what they do not have are species. The general characterization of species is that they are the nexus of the coalescence of genes, haplotypes, parent-child lineages and so on, at or about the same level. An instructive example is the discovery by Murray Littlejohn and his advisor of the different species that had previously been called Rana pipiens, the 'leopard frog' of the southern United States. In the traditional view of science, observation is theory-dependent and objects are theoretical.
