Amazonetta

Abstract: We studied the phylogenetic relationships of four duck genera endemic to South America: Brazilian teal Amazonetta brasiliensis, spectacled duck Speculanas specularis, crested duck Lophonetta specularioides, and four species of steamer ducks Tachyerespatachonicus, T. leucocephalus, T. pteneres, T. brachypterus. Genetic divergence within and among species was compared using population-level sampling of the mitochondrial DNA (mtDNA) control region, supplemented with three additional mtDNA genes and six independent nuclear loci from one individual of each species and a variety of outgroup taxa. The monophyly of these four morphologically divergent South American genera was strongly supported. Within this clade, Amazonetta and Speculanas were supported as sister species in all analyses, but different gene regions yielded conflicting or ambiguous results for Lophonetta and Tachyeres. This lack of resolution resulted from little informative variation in nuclear loci and high levels of homoplasy in the mtDNA control region. Control region sequences from the four Tachyeres species fell into two distinct clades. In one clade, T. patachonicus and T. leucocephalus share a set of closely related haplotypes (≤0.6% sequence divergence); while no identical haplotypes were shared between species, the control region phylogeny was insufficiently resolved to either support or reject reciprocal monophyly. The second clade, ~1.7% divergent from the first, comprised haplotypes of the Falkland Islands species T. brachypterus and a captive individual of T. pteneres. These distinctive South American ducks likely experienced two bouts of rapid diversification, thus making analysis of their phylogenetic relationships difficult. Incomplete lineage sorting, founder effects, and perhaps introgression likely have contributed to obscuring the relationships among steamer ducks.

Abstract: The Brazilian duck (Amazonetta brasiliensis) is abundant in the northern plains of the state of Apure, where its natural habitat has been modified by the building of dikes (Ramia 1972, Ojasti 1973, Pacheco et al. 1977). It is often found in agricultural areas but is not considered a pest to crops (G6mez 1979, Madriz 1979). The objective of this study was to document the food habits of the Brazilian duck in the periodically flooded savannahs of Apure, Venezuela.

Abstract: We constructed a phylogeny for the dabbling ducks (tribe Anatini) based on cytochrome-b and ND2 mitochondrial gene DNA sequences. This phylogeny differed in sev- eral important respects from a morphological phylogeny developed by Livezey (1991), in- cluding the distinctiveness of the blue-winged ducks from other dabbling ducks, the inclu- sion of the genus Tachyeres and exclusion of Callonetta from the subtribe Anateae, and the lack of support for Mareca as a genus separate from Anas. Characters from three other data sets showed greater consistency with the molecular topology than with the morphological topology. The molecular phylogeny divides the dabbling ducks into four distinct groups: (1) four South American genera, including Amazonetta, Lophonetta, Speculanas, and Tachyeres; (2) the Baikal Teal (Anas formosa); (3) the blue-winged ducks and allies; and (4) a large clade including wigeons, pintails, mallards, and several teal lineages. An examination of the dis- tributions of species in light of the phylogeny indicates relatively little biogeographic struc- ture. Geographic origin for most internal branches is ambiguous using several reconstruc- tion methods. We suggest that the high dispersal ability of birds (especially dabbling ducks) has important implications for recovery of branches using molecular systematics. Received