The Phylogeny of the Alcidae

-An estimate of the phylogeny of 22 extant and 1 extinct species of the Alcidae was determined from compatibility analyses of 33 cladistic characters of the skeleton, integument, and natural history. The puffins were found to be a sister-group to all other alcids. Cerorhinca was found to be a puffin. The auklets were found to be a sister-group to the remaining species. Brachyramphus was found to represent a phyletic line separate from that including the other murrelets. Cepphus was found to be a member of the phyletic line including Endomychura and Synthliboramphus. Alle was found to be a sister-group of the auks. A compatibility analysis of muscle characters of Hudson et al. (1969) yielded a phylogenetic tree in agreement with that found using my data. The relationships among Cepphus and the murrelets were found to need further study. A classification based on these results is suggested. It is recommended that the recent merging of genera by the A.O.U. (1982) be accepted, that Cyclorrhynchus be merged with Aethia, and that Pinguinus be merged with Alca. Received 25 Ianuary 1984, accepted 3 December 1984. THEAlcidae, a distinct group of marine, wingevidence that sandgrouse are charadriiforms. propelled diving birds, have been classified Although current evidence indicates that the during the past 150 years (literature reviewed composition of the Charadriiformes is close to by Sibley and Ahlquist 1972) with the loons that proposed by Wetmore (1930), future reso(Gaviidae), grebes (Podicipedidae), diving pelution of the higher relationships of birds may trels (Pelecanoididae), and penguins (Sphenisshow this conclusion to be oversimplified. cidae). The modern consensus is that they are Given that the Alcidae are charadriiforms, members of the Charadriiformes (Wetmore there is still a question of their affinities within 1930, Mayr and Amadon 1951, Kitto and Wilthe order. Most authors have suggested that alson 1966, Storer 1971, Sibley and Ahlquist 1972, cids are most closely related to gulls (Storer Stegmann 1978, Strauch 1978, Cracraft 1981); 1960, Kozlova 1961). Ahlquist (1974) reported however, a few recent authors (Verheyen 1958, that the isoelectric focusing in polyacrylamide Gysels and Rabaey 1964) have disputed this (IFPA) patterns of egg-white proteins of Uria opinion. The assumed monophyly of the Cha"shows an unmistakable likeness to those of radriiformes is based on their sharing a comgulls." Evidence that the ancestor of the alcids plex of character states (Zusi 1974, Strauch may have been more like a shorebird has been 1976), but it never has been tested by a phyreported by Stettenheim (1959), Hudson et al. logenetic analysis of the orders of birds. Fur(1969), and Stegmann (1978). However, bethermore, the limits of the order still are uncause there is considerable evidence that Droresolved. Storer (1956) and Sibley and Ahlquist mas is closely related to the Lari (Strauch 1978, (1972) presented evidence that the loons also Sibley and Ahlquist in press), a shorebird-like may be charadriiforms (but see Cracraft 1982). common ancestor of alcids and larids may not Olson and Feduccia (1980) asserted that the flaconflict with earlier ideas. Strauch (1978) and mingos (Phoenicopteridae) are closely related others (Stegmann 1978, Cracraft 1981) were unto Charadriiformes, and Olson and Steadman able to identify the closest relatives of the al(1981) presented evidence that Pedionomus is a cids. On the basis of DNA-DNA hybridization charadriiform. Maclean (1967) and Fjeldsa studies, Sibley and Ahlquist (in press) found (1976) argued that sandgrouse (Pteroclididae) that the Alcidae and Lari are sister-groups. are charadriiforms, but their evidence and conThe Alcidae are distinguished among chaclusions have been challenged by Olson (1970) radriiform birds by their compact form, short and Strauch (1979) and are not supported by wings, and feeding habits (Coues 1868). Some the findings of Kitto and Wilson (1966). Sibley of the characteristics (sternum long and narrow and Ahlquist (in press), however, have new with long, rounded metasternum; wing bones 520 The Auk 102: 520-539. July 1985 521 July 19851 Phylogeny of the Alcidae flattened) used to define them (Verheyen 1958, Zusi 1974) may be related to their marine and diving habits; others (large supraorbital grooves, basipterygoid processes absent in adults, anterior toes fully webbed, hind toe absent) are found in other charadriiform birds. Strauch (1978) found the Alcidae to be a monophyletic group defined by twisting of the brachial tuberosity of the coracoid so that it does not roof the triosseal canal and by lack of a lateral synsacral strut. Coues (1868) used nostril feathering, bill form, and presence or absence of crests to divide the Alcidae into three subfamilies: Alcinae (Pinguinus, Alca), Phaleridinae (Fratercula, Lunda, Cerorhinca, Ptychoramphus, Cyclorrhynchus, Aethia), and Urinae (Synthliboramphus, Endomychura, Brachyramphus, Cepphus, Alle, Uria). Beddard (1898) used the number of rectrices, relative size of the right and left liver lobes, leg muscle formula, and form of the syrinx to divide the alcids into two families: Fraterculidae (Cerorhinca, Lunda, Fratercula) and Uriidae (all other genera). Shufeldt (1901), summarizing a series of papers on the osteology of the alcids (1888, 1889a-d), decided that Beddard's two families represented two subfamilies. Shufeldt (1889d) thought Alle closest to the auklets and Uria closest to the Laridae. Dawson (1920) used egg characteristics supplemented by other characters to divide the alcids into five families: Aethiidae (Alle, Ptychoramphus, Cyclorrhynchus, Aethia), Cepphidae (Cepphus), Alcidae (Uria, Alca, Pinguinus), Fraterculidae (Cerorhinca, Lunda, Fratercula), and Synthliboramphidae (Synthliboramphus, Brachyramphus, Endomychura). Storer (1945a) used pelvis and leg morphology supplemented by plumage, soft-part, egg, and breeding characters to divide the alcids into seven groups, which he later (1960) designated as tribes: Alcini (Uria, Alca, Pinguinus), Cepphini (Cepphus), Brachyramphini (Brachyramphus), Plautini (Alle), Aethiini (Ptychoramphus, Cyclorrhynchus, Aethia), Synthliboramphini (Endomychura, Synthliboramphus), and Fraterculini (Cerorhinca, Lunda, Fratercula). Storer (1952) suggested that Alle might be closest to his Alcini and that Cepphus was closer to the ancestral stock of the family than was Uria. Earlier, Storer (1945b) thought Brachyramphus the most primitive genus of alcid. Verheyen (1958) classified the Alcidae into four subfamilies: Fraterculinae (Cerorhinca, Lunda, Fratercula), Alcinae (Pinguinus, Alca, Uria, Cepphus), Plautinae (Alle), and Aethiinae (the remaining genera). Yudin (1965) thought that there probably were two phyletic lines in the Alcidae but found insufficient grounds on which to divide them. He suspected that similarities in the jaw musculature of puffins and auklets were due to "parallel development." In a study of the wing and leg musculature, Hudson et al. (1969) found that the puffins differed markedly from other alcids, were probably the most primitive living alcids, and were closest to Ptychoramphus, among the genera studied. They found that Brachyramphus was not particularly close to any other genus, but was closer to Uria and Alca than to Cepphus, other murrelets, auklets, or puffins; and they found Cepphus to be closest to Uria and Synthliboramphus. Several authors (Storer 1945b, Sealy 1972, Binford et al. 1975, Jehl and Bond 1975) have concluded that among the murrelets Endomychura and Synthliboramphus are quite similar and that both are distinct from Brachyramphus. It has long been agreed that the puffins (Cerorhinca, Lunda, Fratercula), the auklets (Ptychoramphus, Cyclorrhynchus, Aethia), and the auks (Uria, Alca, Pinguinus) are clusters of closely related species. The relationships among the murrelets (Brachyramphus, Endornychura, Synthliboramphus), the relationships of Cepphus and Alle to other alcids, and the relationships among all of these groups have been debated, however. I reexamined the relationships among the species of the Alcidae using a modern, objective method to evaluate the characters on which the estimate of phylogeny is based. I examined skins and skeletons of each living species of alcid. A complete composite skeleton and several unassociated bones of Pinguinus also were examined. Integument characters for Pinguinuswere obtained from Ridgway (1919). Natural history data were taken from the literature (Storer 1945a, Kozlova 1961, Sealy 1972, Simons 1980, Terres 1980). Natural history data for Pinguinus were obtained from Bengtson (1984). Character names follow Howard (1929), Bock and McEvey (1969), Zusi and Jeh1(1970), and Strauch (1978). A set of 33 cladistic characters was devised for the 22 extant and 1 extinct species studied. Primitive states were determined using other charadriiform birds, particularly the Lari, as outgroups (Strauch 1978). Character compatibility analysis employing the program CLINCH 5 (written by K. L. Fiala) was used to find the largest set of mutually compatible characters 522 J. G. STRAUCH, JR. TABLE1. Character-state trees for the Alcidae.