Evolutionary implications of synapomorphic wing-molt sequences among falcons (falconiformes) and parrots (psittaciformes)

Abstract

I examined over 4500 specimens to investigate the evolutionary significance of molt sequences as related to systematic relationships of falcons and parrots. Nodes of molt among the medial primaries (p4-p6) and at s5 among the secondaries, followed by bidirectional replacement from the node within each tract, was confirmed for most or all taxonomic groupings of both falcons and parrots, with the exception of the Kakapo or Owl Parrot (Strigops habroptila), which appears to replace its remiges in sequences similar to those of most other birds. Initiation of primary molt varies between p4 and p5 in falcons and between p5 and p6 in parrots, including within species, suggesting that the node's position may be fluid within a defined area along the alar tract. The coincidence and consistency of these molt sequences in parrots and falcons but in no other order of birds suggests that molt sequence may be a synapomorphic (shared) character state, supporting recent molecular evidence that the Falconiformes and Psittaciformes are sister taxa. A more ancestral molt sequence in Strigops may suggest that it split from other parrots prior to a Falconiformes-Psittaciformes divergence or it may indicate reversion to a primitive character state in response to the species' unique nocturnal and ground-dwelling habits. The results of this analysis further suggest that synapomorphic wing-molt sequences can be used as an indicator of systematic relationships in birds and that molt sequence is perhaps controlled by a neurological process more fixed than timing, extent, and geographic location of molts. © The Cooper Ornithological Society 2013.