Molecules vs. morphology in bird phylogeny: Prum et al. 2015 part 2

Yesterday we looked at the basal bird taxa in both the LRT (morphology) and Prum 2015 (molecules/DNA). Today that continues with Prum’s Neoaves.

Prum et al. 2015 clade 3: Strisores
Derived from a sister to screamers and megapodes, the clade, Strisores, includes nightjars, potoos, and arising from owlet nightjars, the apodiformes (= swifts + hummingbirds). In other words, this clade includes several aerial insect-eaters with a wide, short, hooked rostrum and the hummingbirds, which have a narrow, long, not-hooked rostrum.

The skull and skeleton of Apus apus,

Figure 2. The skull and skeleton of Apus apus, the Common Swift. Note the big eyes, like an owl, and hooked beak, like an owl.

In the LRT
(subset Fig. 4) hummingbirds arise from similar taxa with a narrow and long rostrum, like the sea gull, Chroicocephalus. By contrast, swifts and their kin arise from the birds of prey clade all with a short, hooked rostrum. Swifts, like Apus (Fig. 2) are most closely related to owls. Perhaps that is why the owlet nightjars nest with them (they have not yet been tested). Googling: owlet nightjar reveals that the skull is very much like that of the tested swift, Apus with the same big eyes, like an owl, only in swifts they eyeballs are not so exposed.

The swift clade
includes such supreme masters of the air that the feet are reduced and seldom used except for perching. That they should arise from dirt-pecking, ground-dwelling chicken-like taxa that run around and rarely take flight, does not make sense when looking for a gradual accumulation of traits. The better relationship is with falcons (some of the fastest of all flyers) and owls (some of the quietest of all flyers), as recovered using morphology.

Prum et al. clade 4: Columbaves
this clade derived from a sister to the swifts, is divided between cuckoos and their kin (turacos and bustards) and pigeons and their kin. Among the bustards, the Kori bustard (Ardeotis lori) is the largest extant flying bird native to Africa.

Figure 2. Ardeotis skull. Note the ridge at the posterior cranium. Compare to figure 3, the heron skull is similar.

Figure 2. Ardeotis skull. Note the ridge at the posterior cranium. Compare to figure 3, the heron skull is similar.

By contrast, the LRT, based on morphology,
widely separates cuckoos and pigeons. Cukoos and the Kori bustard both nest with herons. Pigeons, like Columba, nest with wrens and dippers.

Figure 4. Subset of the LRT focusing on birds.

Figure 4. Subset of the LRT focusing on birds.

A reader asked about
Pandion, the osprey. Here it nests between falcons and owls + swifts.

References
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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