Phenotypic divergence in two sibling species of shorebird: Common Snipe and Wilson's Snipe (Charadriiformes: Scolopacidae)

Natural selection and social selection are among the main shapers of biological diversity, but their relative importance in divergence remains understudied.  Additionally, although neutral evolutionary processes may promote phenotypic divergence, their potential contribution in speciation is often overlooked in studies of comparative morphology.  In this study, we investigated phenotypic differentiation in two allopatric shorebirds: the Palearctic Common Snipe Gallinago gallinago and the Nearctic Wilson’s Snipe G. delicata.  Specimens of Common Snipe (n = 355 skins, n = 163 skeletons) and Wilson’s Snipe (n = 403 skins, n = 141 skeletons) in natural history collections, were examined to quantify differences in skeletal and external measurements, and measures on wing and tail plumage variables.  The species did not differ in skeletal variables except for the relatively larger sternum of the Common Snipe.  The two species do not differ in multivariate wing size or shape (pointedness).  Pre...