A PHYLOGENETIC ANALYSIS OF THE WHISTLING AND WHITE-BACKED DUCKS (ANATIDAE, DENDROCYGNINAE) USING MORPHOLOGICAL CHARACTERS

A phylogenetic analysis of the eight species of whistling-duck (Dendro cygna) and the White-backed Duck (Thalassornis leuconotus) was perform ed using 68 characters of the skeleton, trachea, and natal and definit ive integument. Three shortest trees were found, each having a length of 91 and a consistency index of 0.766 (excluding uninformative charac ters). Monophyly of Dendrocygna + Thalassornis was supported by three unambiguous synapomorphies, and monophyly of Dendrocygna by eight unam biguous synapomorphies. The three shortest trees supported two major c lades within Dendrocygna, each supported by three synapomorphies: (1) D. autumnalis + D. viduata; and (2) the other six species of Dendrocyg na. Within the latter, the three shortest trees defined two groups: (1 ) D. guttata + D. arborea (supported by three synapomorphies); and (2) an unresolved trichotomy (supported by one unambiguous synapomorphy) involving D. eytoni, D. bicolor, and the clade D. arcuata + D. javanic a (the last two united by three synapomorphies). A majority-rule conse nsus tree of 1000 bootstrapped replicates confirmed all of the branche s common to the three equally parsimonious trees. All species of Dendr ocygna and (especially) Thalassornis were highly autapomorphic. Mappin g of selected ecomorphological parameters on the trees revealed evolut ionary patterns in body mass, egg mass, relative clutch mass, and divi ng habit, with lesser trends in preferred nest site, perching habit, a nd diel activity pattern. A phylogenetic classification of the group i s presented and related systematic and biogeographic issues are discus sed.