DRIVER OF SPECIATION? “Specialization also need not by itself be the driver of speciation. In the sword-bill-pollinated clade of passionflowers…specialized pollination is not the driver of speciation but instead the precondition for successful species persistence in small populations, which then adapt locally and evolve into separate species.”
http://rspb.royalsocietypublishing.org/content/281/1795/20142004.short