Convergent Evolution Upends Honeyeaters' Taxonomy

grrlscientist writes in with a beautiful piece of science, beautifully explicated. The poignant bit is that the birds in question are all extinct. "Every once in awhile, I will read a scientific paper that astonishes and delights me so much that I can hardly wait to tell you all about it. Such is the situation with a newly published paper about the Hawai'ian Honeyeaters. In short, due to the remarkable power of convergent evolution, Hawai'ian Honeyeaters have thoroughly deceived taxonomists and ornithologists as to their true origin and identity for more than 200 years."

Comments

Re:Why still depend on observation?

[Daniel Dvorkin]

Another poster, who is probably a biologist, gave two very good answers to your question; as a bioinformatician, I'll give a third. You're right that DNA doesn't lie, but we can have a damn hard time figuring out what it's trying to tell us. There is no universally agreed-upon method for reconstructing phylogenetic trees from sequence data -- Google on "phylogenetic algorithm" to see the enormous number of methods that people have come up with, and what an active area of research this continues to be. Also, the Linnaean taxonomic system, obviously, was not designed with modern genetics in mind, and trying to shoehorn phylogenetic data into this system (which is pretty much what everybody does, even if they're not happy about it) can lead to bizarre results. Until we have what everyone agrees is really a gold standard method for reconstructing ancestral trees, this is the way it's going to be.

Re:Predictive power of evolution!

[lilomar]

Thank you for making this post. It's good to see that someone out there understands this basic concept. Although, as a sister post notes, we do have a pretty good idea as to the cause of gravity.

Law of gravity: Objects attract each other according to their mass and the square of the distance between them. (F = GMm/R^2)

Theory of gravity: Gravity is caused by the interaction of gravitons at the quantum level, making gravity one of the basic forces.

Notice that theories describe the how and why of things, laws make concrete facts about the way things are.

Neither scientific laws or scientific theories (not to be confused with traffic laws or layman's theories, which describe different things entirely) are above being revised. In the case of laws, becoming more precise as our instruments become more precise, for instance, I believe that the universal gravitational constant (G, above) has been changed at various times as we are able to get better measurements. Theories, are often refined, partially revised, or scrapped altogether, often, we will use different theories depending on the model we are using (once again, scientific model, not like a car model, or like a car in general, get your analogies away from me! ;-) ).

The most important distinction between laws and theories, is that laws can be proven: measure the gravitational pull between two masses, if it fits the formula, voila! Gravity still works as predicted, the aprocralypse is not upon us yet. Theories, however, can only be disproven, you can say, "Gravitons cannot be the cause of gravity, here is my evidence, which the theory doesn't explain," but you cannot say, "Here is my proof that gravitons cause gravity." (you can try to get proof, but at most you will have a very strong correlation, which, as every slashdotter is fond of pointing out, does not prove causation.

"But," you say, "that means that everything we know could be a lie!" To which I reply, "Yes, yes it does, but that is unlikely, because most theories that actually have a name, have been shown to correlate with the facts very, very consistently, and although this doesn't prove causation, it's a pretty good indication that most of science is true."