Molecules vs. morphology in bird phylogeny: Prum et al. 2015 part 3

Earlier and the day before we looked at basal euornithine taxa in two cladograms: one recovered from DNA analysis (Prum et al. 2015), and one from morphology (the large reptile tree or LRT, 1026 taxa). Today we’ll look at a few more Prum et al. clades.

Prum et al. clade 5: Gruiformes
These are the rails and cranes and kin: sun grebes (Heliornis), fluff tails (Sarothrura), water rails (Rallus), ocellated crakes (Micropygia), swamp hens (Porphyrio) all in one clade. In the other clade are the shorter trumpeters (Psophia) and limpkins (Aramus), and the taller crowned cranes (Balearica) and cranes (Grus).

In the LRT
only three of the last four are presently included. Psophia nests with roadrunners and cuckoos, but close to Crex, another type of rail, all derived from basal neognaths including the birds of prey clade. Aramus nests at the base of cranes, like Grus, but also terns, sea gulls, hummingbirds, penguins, pigeons and kingfishers, which is in itself quite a mixed bag of taxa—all with a long straight bill, which is not a unique trait among neognaths.

Prum et al. clade 6: Aequorlitornithes
According to Prum et al. “The Aequorlitornithes is a novel, comprehensive clade of waterbirds, including all shorebirds, diving birds, and wading birds. Within this group, the flamingos and grebes are the sister group to shorebirds, and the sunbittern and tropicbirds are the sister group to the wading and diving birds.” This is such a big clade with 18 taxa nesting distinct from 26 others that it needs to be dissected a bit more. Like so:

Aequorlitornithes clade a1: flamingos (Phoenicopterus) and grebes (Rollandia).

In the LRT: flamingos nest with the birds of prey, like the Cariama. Grebes have not been tested, but they look a great deal like loons. In any case, yesterday we looked at the untenable match between grebes and flamingos.

Aequorlitornithes clade a2: thick-knees (Burhinus), plovers and kildeers (Charadrius), oystercatchers (Haematopus), avocets (Recurvirostra).

In the LRT: none of these taxa have been tested at present.

Aequorlitornithes clade a3: plains wanderers (Pedionomus), lily trodders (Jacana), painted snipes (Rostratula), godwits (Limosa), turnstones (Arenaria), waders (Tringa).

In the LRT: none of these taxa have been tested at present.

Aequorlitornithes clade a4: buttonquails (Turnix),  pratincoles (Glareola), murres or guillemots (Uria), sea gulls (Chrococephalus), terns (Sterna) and skimmers (Rhynchops)

In the LRT: murres nest with penguins from clade b1 (see below). Sea gulls nest with hummingbirds (we’ll look at this in more detail tomorrow) and these were sisters to storks. Basically sea gulls were short-legged neotonous storks. Hummingbirds were descendants of Eocypselus, both were tiny neotonous sea gulls with an ancient lineage.

Aequorlitornithes clade b1: sunbitterns (Eurypyga), tropicbirds (Phaethon), loons (Gavia), penguins (Spheniscus).

Figure 1. The tropic bird (genus: Phaethon) in vivo.

Figure 1. The tropic bird (genus: Phaethon) in vivo. At sunset, in silhouette, some people seeing this bird with such long slender tail feathers thought it was a basal pterosaur. 

In the LRT: sunbitterns nest with similar wading storks from clade b3 (below). Loons nest with terns from clade a4 (above). Penguins nest with murres in clade a4, but a node or two apart form loons and terns. Tropicbirds, like Phaethon (Figs. 1,2), nest with barbets and toucans in the LRT.

Figure 2. The skull of the tropic bird, Phaethon rubricauda, most closely related to the barbets in the LRT.

Figure 2. The skull of the tropic bird, Phaethon rubricauda, most closely related to the barbets in the LRT. Note the posteriorly drooping maxilla, a key trait in this clade that also includes hornbills and toucans. 

Aequorlitornithes clade b2: petrels: albatrosses (Phoebastria), storm petrels (Oceanites , Pelagodroma and Oceanodroma,) fulmars (Fulmarus), shearwaters (Puffinus), petrels (Pterodroma), and diving petrels (Pelecanoides).

In the LRT: only one tube nose, Macronectes, has so far been tested. The presence of a tube nose on the rostrum of all these taxa makes this a probable monophyletic clade.

Aequorlitornithes clade b3: storks (Ciconia) maribou storks (Leptoptilos), frigate birds (Fregata), gannets (Morus), darters or snake birds (Anhinga) cormorants (Phalcrocorax), ibises (Theristicus), tiger heron (Tigrisoma), blue herons (Ardea), bitterns (Ixobrychu), hamerkops (Scopus), shoebills (Balaeniceps) and pelicans (Pelecanus).

In the LRT: hamerkops, shoebills and pelicans also nest together. Storks nest apart from herons and also apart from hamerkops and kin. The ibises nest at the base of spoonbills and ducks, sisters to hornbills and toucans. The rest have not yet been tested.

Prum et al. (6 co-authors) 2015. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature 526:569–573. online


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