Flatfish are strange looking animals that live sideways. One of their eyes has migrated to one side of the fish so that when it lies on its "side" at the bottom of the ocean both eyes point upwards. This is an interesting example of the evolution of a change in development.Fossil relatives of modern flatfish have recently been described and they confirm much of what was surmised about the evolution of these strange creatures. Several bloggers have written about this and it's well worth the effort to read their postings.
Christopher Taylor at Catalogue of Organisms wrote The Ugly Stick in Action.
Ed Yong at Not Exactly Rocket Science wrote 'Missing link' flatfish has eye that's moved halfway across its head.
GrrlScientist at Living the Scientific Life wrote The Mysterious Origin of the Wandering Eye.
Carl Zimmer at The Loom wrote Dawn of the Picasso Fish.
[Image Credit: The drawings are by Georgi Pchelarov from The Classification of Fishes.]
5 comments :
That is really cool. I have never been privy to the flatfish as an example of evolution.
Thanks for sharing.
ScienceNews has two videos showing eye migration in young flatfish.
See: http://www.sciencenews.org/view/generic/id/33976/title/A_wandering_eye
I kind of disagree with the significance that is being attributed to this paper. Certainly what was argued to occur in a single step has been discarded here: a classic “case of saltationism” is no longer valid.
This been said, a step-wise process does not prove natural selection.
Simply put: if X is Y it does not mean that Y is X. A "creative” role for natural selection certainly implies an accumulation of steps, but an accumulation of steps does not imply natural selection. If not we might just as well simply state that evolution= natural selection, since all we have to do is simply adjust our scale of observation (as if magnification in a microscope) to find a step-wise accumulation in any lineage. many of those steps may have been fixed by drift, for instance (in fact the "advantage"of a half-twisted face still remains ambiguous).
It is worth mentioning that only partially twisted flounder can be found in the variation of modern populations, and even sometimes individuals with completely “normal”, non-twisted faces.
Also, a much more arguably non-gradula change is the tendency to twists the face either randomly, always to the right, or always to the left. Changes between these modes, switching from one to the other, can be observed in the phylogeny of flatfishes. That change is a legit, non-gradual “jump”.
Carl Zimmer's article is good....Darwin's own explanation did not involve natural selection alone, but also phenotypic plasticity.
Unfortunately nowadays people are more Darwinian than Darwin...
Interesting. I didn't know that even Darwin flirted with Lamarck's ideas. I can see that the later notice of Mendel's discoveries cleared a lot up.
Dawn of the Picasso Fish
Oddly enough I was prompted to think of Picassofish. Oh well.
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