Striking example of avatars evolving together among local communities

An 'avatar' is a local population of a species in a local community; it is the local embodiment of the group - the tangible representative that interacts with avatars of other species (Damuth, 1985). In this issue of New Phytologist, Anderson & Johnson (pp. 533-540) report on a striking story of avatars evolving under the influence of one another in diverging communities. Previously, Anderson & Johnson (2008) reported on a species of long?tongued fly, Prosoeca ganglbaueri, which seems to have co?evolved locally with a species of Scrophulariaceae, Zalusianskya microsiphon. In the area studied, the fly gets much of its nectar from this one plant; the scroph is even more specialized in being pollinated almost exclusively by this one fly. The fly's average tongue length varies among sites from 20 to 50 mm, and the scroph's average floral tube length covaries from 19 to 55 mm. The positive covariation is strong and significant even after taking into account factors such as body size and elevation. Furthermore, the variation is a geographic mosaic rather than being clinal. The fly and the scroph together have undergone extreme divergence among populations within their respective species.