Data from: A phylogenetic analysis of geese and swans (Anseriformes: Anserinae), including selected fossil species

A phylogenetic analysis of modern and selected fossil geese and swans was performed using 165 characters of the skeleton, trachea, and natal and definitive integument. Five shortest trees were found (length = 318; consistency index for informative characters = 0.634), which differed only in details of relationships among three species of Branta. The trees supported (1) +Cnemiornis as sister group to other taxa analyzed; (2) a sister group relationship between the moa-nalos of Hawaii and other geese and swans; (3) Cereopsis as sister group of Anser, Branta, Coscoroba, and Cygnus (contra Livezey, 1986, Auk 103:737--754); (4) monophyly of Anser, Branta, and +Geochen and confirmation of generic monophyly of each; and (5) Coscoroba as sister group to Cygnus. Selective exclusion of fossil taxa from the analysis variably affected inferred relationships and had substantial impacts on computational efficiency. Some nodes were not robust to bootstrapping: (1) nodes relating species groups within Anser, Cygnus, and +Thambetochen and (2) the node uniting Anser, Branta, Coscoroba, and Cygnus relative to Cereopsis. Bremer (decay) indices indicated similar differences in relative support for nodes. Skeletal characters were comparatively important in establishing higher order relationships, whereas integumentary characters were critical for lower order inferences. Constrained analyses revealed that other proposed phylogenetic hypotheses entailed variable penalities in parsimony. The shortest tree(s) was considered with respect to selected ecomorphological attributes (e.g., body mass, sexual size dimorphism, clutch size) and biogeography, and a revised phylogenetic classification of the geese and swans is proposed.本研究基于骨骼、气管以及雏鸟与成鸟的被皮系统共165个性状，对现生及部分化石雁类和天鹅类开展了系统发育分析（phylogenetic analysis）。本次分析共获得5棵最简约树，树长为318，信息性状的一致性指数为0.634，各树的差异仅体现在黑雁属（Branta）3个物种间的亲缘关系细节上。分析结果支持如下结论：（1）已灭绝的克奈米雁属（Cnemiornis）为本次分析中其余类群（taxon）的姊妹群（sister group）；（2）夏威夷摩阿纳卢雁类（moa-nalos）与其他雁类和天鹅类构成姊妹群关系；（3）蜡嘴雁属（Cereopsis）为雁属（Anser）、黑雁属（Branta）、扁嘴天鹅属（Coscoroba）与天鹅属（Cygnus）的姊妹群，该结论与Livezey 1986年发表于《Auk》第103卷737–754页的研究结果相悖；（4）雁属、黑雁属以及已灭绝的盖肯雁属（Geochen）均为单系群（monophyly），且各属的单系性均得到验证；（5）扁嘴天鹅属为天鹅属的姊妹群。在分析中选择性剔除化石类群，会对推导得到的亲缘关系产生不定向影响，并对计算效率造成显著影响。部分分支节点在自举检验（bootstrapping）中未表现出较高支持稳定性：其一为涉及雁属、天鹅属以及已灭绝的坦贝托肯雁属（Thambetochen）内物种类群间亲缘关系的节点；其二为将雁属、黑雁属、扁嘴天鹅属与天鹅属聚合为相对于蜡嘴雁属的支系的节点。Bremer衰变指数（Bremer decay indices）同样反映出各节点间相对支持度的差异。骨骼性状在构建高阶支系的亲缘关系时相对关键，而被皮性状则对低阶类群的亲缘关系推断至关重要。约束性分析结果显示，其他已提出的系统发育假说在最大简约法（parsimony）框架下会产生不同程度的罚分。本研究结合部分生态形态学特征（如体重、性大小二态性、窝卵数）与生物地理学信息对最简约树进行了综合评估，并提出了修订后的雁类与天鹅类系统发育分类方案。