Genetics suggests unexpected origins of hummingbirds

Caprimulgiformes is a group of night- and twilight-active (nocturnal–crepuscular), mostly insectivorous birds found on every continent except Antarctica. It includes birds with such colorful names as nightjars, oilbirds, potoos, frogmouths and owlet-nightjars. In addition to their activity times and diet, they tend to have weak legs and some species can even echolocate, using sonar to catch their prey.

Given their tendencies to be active in the dark, you might mistake them for owls. Indeed, these birds share certain features with owls, including rather drab-colored plumage and large eyes to improve light perception in the dark. However, biologists don’t think these are owls, a conclusion supported by both anatomy and DNA. Owls, as indicated by the representatives Tyto and Strix in the phylogeny below (towards the top), have DNA more similar to things like toucans, trogons and eagles than to Caprimulgiformes.

image_3326_2e-Avian-Tree-of-Life

Instead, Caprimulgiformes have DNA that is extremely similar to swifts and, of all things, hummingbirds! In fact, the DNA of hummingbirds and swifts is more similar to that of owlet-nightjars than the DNA of owlet-nightjars is to other Caprimulgiformes. The next most similar species are frogmouths, and this is followed by potoos and oilbirds. This means that multiple kinds of Caprimulgiformes are more genetically similar to swifts and hummingbirds than they are to each other!

Below are the results from a study on bird DNA that compared >390,000 letters of DNA from 198 species of birds [1]. You can see hummingbirds and swifts (Apodiformes) nested within the greater group of Caprimulgiformes (in brown; Strisores).

image_3326_1e-Avian-Tree-of-Life

While swifts do have some strong similarities to Caprimulgiformes, including having weak legs, insectivorous diets and often hunting at dusk, hummingbirds seem hardly at all like these dark-dwelling birds. Hummingbirds have a very distinct mode of flying, hovering while their wings beat at extremely rapid rates, allowing their specialized beaks to feed on the nectar of flowers. Plus they’re quite colorful to boot!

Despite this, their DNA robustly tells the surprising story that hummingbirds are related to things like oilbirds, pootos, and nightjars, and therefore may have evolved from an ancestor that was drab in coloration, and fancied hunting insects towards nightfall. Once again, DNA points to evolution in ways that may seem baffling, while also showing the amazing replicative power of the theory.

Questions for Creationists
If hummingbirds look so dissimilar to Caprimulgiformes, why is their DNA so similar to these birds? Why don’t all Caprimulgiformes have DNA more similar to each other than they do to swifts and hummingbirds? If DNA helps determine the overall form of a bird, why don’t Caprimulgiformes have DNA more similar to owls than swifts and hummingbirds? If these birds all descended from the same ‘kind’, wouldn’t that imply that swifts and hummingbirds all evolved drastically different anatomy since the 6,000-10,000 years assumed by the Young Earth Creationism model? Could nightjars, oilbirds, potoos, frogmouths and owlet-nightjars all represent different ‘kinds’? If so, why would the Creator create kinds that are so similar to one another?

References

1. Prum, R. O., Berv, J. S., Dornburg, A., Field, D. J., Townsend, J. P., Lemmon, E. M., & Lemmon, A. R. (2015). A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature, 526(7574), 569.

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