Will DNA analysis let us define "species" more precisely? What should the rule look like?

Question

I am an amateur birder. Over the last decade or so, I have heard of more than 15 new species in NA, only one of which might have been newly discovered. The rest were split off from some existing species on grounds that sometime seemed arcane or subjective (such as "less than 20% of the respective populations interbreed")

Answer 1

There you have the problem - the idea of 'species' is a fairly arbitrary one, and is generally based on those arcane and subjective factors. Genetics may or may not be helpful; it all comes back to the definition of what a 'species' constitutes. There's lots of haggling over the details, especially in birds, where the 'lumpers' and the 'splitters' have been waging a noisy contest for a long itme now, with the advantage shifting back and forth semi-randomly. I'm afriad your life list will fluctuate throughout your life regardless of your skill at spotting new birds, based solely on the periodic meetings of the nomenclature committee (or whatever the group is that makes these determinations).