A PHYLOGENETIC ANALYSIS OF MODERN POCHARDS (ANATIDAE, AYTHYINI)

A phylogenetic analysis of modern pochards (Aythyini) was performed us ing 99 characters of the skeleton, trachea, natal plumage, and definit ive integument. Three shortest trees were found (length = 148; consist ency index for informative characters = 0.68) which: (1) placed Marmar onetta as the sister group to other members; (2) defined a basal clade comprising as sister groups Rhodonessa caryophyllacea + Netta rufina and N. peposaca + N. erythrophthalma; and (3) defined as the sister gr oup to the preceding clade all other pochards, in which the three redh eads (Aythya valisineria, and the sister species A. ferina and A. amer icana) are the sister group to the mutually monophyletic white-eyes (A , australis, A. innotata, and the sister species A. nyroca and A. baer i) and scaup (in order of increasingly close relationship, A. novaesee landiae, A. collaris, A. fuligula, A. marila, and A. affinis). The thr ee shortest trees differed only in the topology among the white-eyes. These nodes, and that supporting the sister relationship between N. pe posaca and N. erythrophthalma, were the only nodes not conserved in a majority of bootstrapped replicates; Bremer (decay) indices provided s imilar assessments of empirical support. Evolutionary trends in body m ass, clutch size, preferred nest site, diel activity pattern, and biog eographic patterns are evaluated in the context of this phylogenetic h ypothesis. Quantitative comparisons with previously proposed phylogene tic hypotheses, particularly that of Johnsgard, are made using constra ined searches based on these data, and a revised classification of the Aythyini is proposed.