Sympatric Speciation in the Genomic Era. Both terms are used throughout the paper.
I'm not able to make sense of these terms in the contexts used.
I've also heard the terms 'primary' and 'secondary' gene flow elsewhere on the same topic - are they related?
From the abstract:
However, I argue that genomic studies based on contemporary populations may never be able to provide unequivocal evidence of true primary sympatric speciation, and there is a need to incorporate palaeogenomic studies in to this field. This inability to robustly distinguish cases of primary and secondary divergence-with-gene-flow may be inconsequential, as both are useful for understanding the role of large effect barrier loci in the progression from localised genic isolation to genome-wide reproductive isolation. I argue that they can be of equivalent interest due to shared underlying mechanisms driving divergence and potentially leaving similar coalescent patterns.
From the introduction:
Lastly, I consider whether primary and secondary sympatric speciation represent a mechanistic dichotomy, I suggest that primary and secondary contact can leave a similar genomic signature, when speciation is driven by tightly clustered or large effect loci. Arguably, the advent of affordable population genomic studies should place less focus on whether study systems result from primary or secondary contact and instead focus on the mechanistic aspects of the genomic architecture and making progress in identifying the conditions and processes under which natural and sexual selection can drive speciation, without extrinsic barriers to gene flow.