A short break from our Prum et al. 2015 series
as we take a peek at the origin of flamingos and other basal neognath birds, which we’ll look at in greater depth tomorrow in part 3.
flamingos, like Phoenicopterus (Fig. 1), have been difficult to nest in bird cladograms. Flamingos seem to stand alone. Bird expert Gerald Mayr 2004 quoted Sibley & Ahlquist (1990), who wrote flamingos are “among the ‘most controversial and long-standing problems’” in phylogenetic analysis.
Cracraft (1981) made a luke-warm suggestion for stork affinities. Other bird experts, Olson and Feduccia (1980) liked stilts and avocets as relatives. They also suggested that flamingo-like Palaelodus (Figs. 2, 3) ‘may have occupied a more duck-like swimming niche than do typical flamingos’, The Galloanseres (chickens + ducks invalid clade) was considered, perhaps based on the long-legged duck Presbyornis.
Prum 2015 and others before them nested the flamingo, Phoenicopterus, with the flightless grebe, Rollandia (Fig. 1). And now (hopefully) you see what I mean when I say, DNA does not recover testable or valid relations over long phylogenetic distances.
the large reptile tree, (LRT, 1026 taxa) nests the flamingo with the similarly proportioned, hook-beaked seriema, Cariama sisters to the terrestrial birds of prey, represented today by Sagittarius, the secretary bird. Here (Fig. 2), based on a long list of shared traits, it is possible to see how flamingos could gradually arise from seriemas.
Mayr 2004 wrote:
“A recent molecular analysis strongly supported sister group relationship between flamingos (Phoenicopteridae) and grebes (Podicipedidae), a hypothesis which has not been suggested before. Flamingos are long-legged filter-feeders whereas grebes are morphologically quite divergent foot-propelled diving birds, and sister group relationship between these two taxa would thus provide an interesting example of evolution of different feeding strategies in birds.”
grebes are quite similar to loons, like Gavia (Fig. 2), which nests with terns and penguins in the Prum et al. tree AND in the LRT. (Wow! That’s a rare happenstance!)
Then Mayr 2006
found a taxon that had been around awhile Palaelodus ambiguus (Figs. 3–5), that morphologically linked flamingos to grebes. Mayr reports, “Since both grebes and †Palaelodidae are aquatic birds which use their hindlimbs for propulsion, it is most parsimonious to assume that the stem species of (Pan-)Phoenicopteriformes also was an aquatic bird which used its hind limbs for propulsion in the water (Mayr 2004). Palaelodus has “derived skull features of flamingos with leg adaptations for hindlimb propulsion found in grebes.”
In the LRT
stork-like Palaelodus (1.5m tall) nests with Rhynchotus, a tinamou. Like Rhynchotus, Palaelodus appears to be fully volant.
70 characters and 17 suprageneric taxa later, Mayr 2004 wrote:
“Previously overlooked morphological, oological and parasitological evidence is recorded which supports this hypothesis, and which makes the taxon (Podicipedidae + Phoenicopteridae) one of the best supported higher-level clades within modern birds. It is more parsimonious to assume that flamingos evolved from a highly aquatic ancestor than from a shorebird-like ancestor.” Do you see the fatal flaw here?
Mayr employed 17 suprageneric taxa,
rather than generic taxa, even though his museum has a long list of bird skeletons in its collection. The Mayr 2004 cladogram is very poorly supported with most nodes failing to attain a Bootstrap score over 50. But it did nest Gavia with Phoenicopterus and grebes. Mayr also notes a parasite common to both grebes and flamingos alone among birds. Mayr did include tinamous in his analysis. So, I suppose character scoring is to blame here. Mayr’s hypothesis of relationships (Fig. 5) appears to be untenable. Many other taxa are closer to all three in morphology.
G. Mayr wrote via email upon seeing this cladogram:
“Hmm, to me the trees make little sense. If Palaelodus results within palaeognathous birds, many characters must be incorrectly scored. Furthermore, this exemplifies the pitfalls of laerge-scale cladistzic analyses.
this reply reflects the general view of PhDs. Large scale analyses, as readers know, test more possibilities, giving each taxon more opportunities to nest wherever they most parsimoniously fit.
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Mayr G 2004. Morphological evidence for sister group relationship between flamingos (Aves: Phoenicopteridae) and grebes (Podicipedidae). Zoological Journal of the Linnean Society. 140 (2): 157–169. doi:10.1111/j.1096-3642.2003.00094.x. ISSN 0024-4082.
Mayr G 2006. The contribution of fossils to the reconstruction of the higherlevelphylogeny of birds. Species, Phylogeny and Evolution 1 (2006):59–64.
Mayr G 2015. Cranial and vertebral morphology of the straight-billed Miocene phoenicopteriform bird Palaelodus and its evolutionary significance. Zoologischer Anzeiger – A Journal of Comparative Zoology. 254:18–26.
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Olson SL, Feduccia A 1980a. Relationships and evolution of flamingos (Aves: Phoenicopteridae). Smithsonian Contributions to Zoology 316: 1–73.