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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."
There have been debates over the taxonomy of odd creatures (with similarities to other known creatures) forever. Sometimes simple physical resemblence just doesn't really tell the tale. Of course, evolution producing similar looking/behaving birds is nothing new either (just look at how similar African parrots and South American parrots are to one another).
The really great debates come when zoologists get into trying to classify an animal that looks like (or behaves like) two DIFFERENT known creatures. One of my personal favorites is the Red Panda. The bottom of its body and claws look like a bear's (you can see it clearly in this picture) and it eats only bamboo, just like a Giant Panda. But the rest of it looks like a raccoon. This cute little furball finally had to be given its own unique family, because no one was quite sure where to put the little bastard. And it's still debatable if it truly deserves its own family.
SJW: Someone who has run out of real oppression, and has to fake it.
I realize that in this case (being dead for 200 years) it is more difficult, but why don't they _just_ use DNA sequencing to determine the classification of animals?
Observation (of both behaviour and appearance) is influenced by the observer and is variable. Two people never see the same thing the same way. Ask a man and wife what colour the living-room couch is and you will get two different answers! =)
The DNA sequence will never lie, and that sequence will tell us FAR more about common evolutionary traits then our eyeballs will.
"The price good men pay for indifference to public affairs is to be ruled by evil men." ~Plato (427-347 BC)
Ah, thanks for the kind invitation to join your discussions. i wish i had more time to do so, but alas, i have only a few hours per day of internet access, so i spend most of that time looking for papers to write about and answering emails as well as publishing my essays and images. but i will try to make more of an effort to comment here now and again!
I was always impressed by the similarities between sharks, dolphins, and icthyosaurs. Similarly, there's a phenomenal similarity between the flying reptiles such as the pterodactyls and bats with finger bones modified with flaps of skin to make wings. There's also the similarities between various species of gliding tree mammals, the flying squirrels and lemurs and the like. One can also talk of amazing developments with marsupials which had armored herbivores similar to a rhino and carnivores like a leopard-form. (and let's not forget that a Triceratops is built awfully similar to a rhino down to the armored hide, horns, and heavy, stocky legs.) All of these from obviously unrelated lines of descent converging on similar forms to satisfy ecological niches. If I recall correctly, there's also a type of fish that developed a false-placenta for live-birthed young -- it's not a true placenta because it isn't a placental animal but it serves the same purpose. I believe this fish was in the extended shark family.
The other thing that really amazes me is how the theory of evolution makes certain predictions that you'll simply not see contradicted. For example, there's the general rule that animals will adapt existing limbs for various purposes so you might see a rodent develop forelimbs into wings but you will not see a rodent sprout brand new wings from its back while retaining the previous four limbs. Even the weirdest body parts you can find can be seen to be modifications, not wholly new structures sprung forth from nothing. You won't see a bird suddenly come with three eyes or an elephant with a cyclopean eye or a cat with eight legs like a spider (barring genetic defects that will be unable to reproduce).
What's also amazing is how the lines between species get blurry. The old definition is that two populations are split as a species when they cannot interbred and create viable offspring. But we've seen from zoos that populations that don't mix in the wild can produce viable offspring such as ligers, tygons, then there's the blonde grizzlies that are a hybrid of grizzly and polar bear that did occur in the wild... All of these animals come from common ancestors if you go back far enough and it makes you wonder just how freely genes could be traded back and forth with the right technology and a proper understanding of genetics.
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