Abstract
I analyse how disputes about species delimitation have (and have not) changed with the advent of genome-scale data and the rapid proliferation of computational methods for using genetic and genomic datasets. Implementation of the multi-species coalescent (MSC) has promised to bridge the old divide between phylogenetics (above the species level) and population genetics (within species). Debates about the value of these new methods have included claims about whether MSC-based methods inevitably over-split species. Arguments about these claims reflect persistent disagreement about the sufficiency of the General Lineage Concept and the necessity of (some version of) a Biological Species Concept (or another view about species). I argue that simulation studies of MSC-based species delimitation demonstrate that the General Lineage Concept, on its own, does not suffice for species delimitation. This does not mean that species are not 'real'. It does mean that some empirical cases are genuinely ambiguous. The power of computational methods for analysing genome-scale data has accelerated the discovery of ambiguous cases.