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.

Advertisements

2 thoughts on “Genetics suggests unexpected origins of hummingbirds

  1. Joe G

    Hi, DNA does not determine the overall form of a bird. DNA has sequences that control and influence development but no one has ever discovered that DNA determines what will develop. Most DNA has to do with producing proteins required for day-to-day sustaining of the cells. Only a small % have something to do with controlling and influencing development.

    And we don’t know what the original birds were. But if you have any evidence that genetic changes to Therapsids can produce a bird that would be Nobel Prize worthy.

    How are you defining “evolution”?

    1. Hi Joe, thanks for commenting!

      “Hi, DNA does not determine the overall form of a bird. DNA has sequences that control and influence development but no one has ever discovered that DNA determines what will develop.”

      Not entirely sure what you mean by this. You agree that DNA influences development, but seem to be insinuating that there are more important factors out there.

      “Most DNA has to do with producing proteins required for day-to-day sustaining of the cells. Only a small % have something to do with controlling and influencing development.”

      Come to think of it, I’ve never seen numbers on this. Do you have a reference that I could read? It would be interesting to learn if someone has assessed this, and for which organisms they’ve sussed it out. My guess is this is largely limited to a few model organisms like yeast and fruit flies.

      “And we don’t know what the original birds were.”

      This depends on how you define a “bird”, but we do have some ideas based on the fossil record.

      “But if you have any evidence that genetic changes to Therapsids can produce a bird that would be Nobel Prize worthy.”

      Therapsids are thought to be on the mammal side of the tree of life. I assume you mean dinosaurs? There have been at least some studies in which scientists have manipulated bird embryo gene/protein expression that result in more dinosaur-like embryos.

      “How are you defining “evolution”?”

      I’m defining it more-or-less like any biologist would: changes in gene allele frequencies over time, which often corresponds to changes in phenotype over time.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s