Evolving spots


Here's what seems to be a relatively simple problem in evolution. Within the Drosophila genus (and in diverse insects in general), species have evolved patterned spots on their wings, which seem to be important in species-specific courtship. Gompel et al. have been exploring in depth one particular problem, illustrated below: how did a spot-free ancestral fly species acquire that distinctive dark patch near the front tip of the wing in Drosophila biarmipes? Their answer involves dissecting the molecular regulators of pattern in the fly wing, doing comparative sequence analyses and identifying the specific stretches of DNA involved in turning on the pigment pattern, and testing their models experimentally by expressing novel gene constructs in different species of flies.

gompel et al.

The particular gene of interests is calledl yellow (y), which is required for the production of black pigments (why is a gene for black pigments called yellow? Because genes are often named for their effect when mutated. Break the yellow gene with a mutation, and the resulting mutant animal can't make dark pigments, and looks yellowish.) Yellow is normally turned on at a low level everywhere in the fruit fly wing, pigmenting the wing an overall light gray. In D. biarmipes, there is an additional patch of elevated yellow expression in one corner of the wing. What activates this gene in just that one place?

Continue reading "Evolving spots" (on Pharyngula)


What activates this gene in just that one place?

Duh! The intelligent designer! Or, as Frankie S. might say, “It’s witchcraft, wicked witchcraft…”

Pardon me for pointing out the obvious, PZ, but a fly with dark spots on its wings is still a fly.

You can rest the defense of mutation/selection in microevolution.

If you come up with observed or experimental evidence that mutation/selection can turn a single celled organism into a fly (with or without dark spots on its wings) then I’m all ears.

Good luck.

DaveScot, are you not the one that claims that Amoeba dubia, a one celled organism, contains all the genetic information for all life on earth?

Your statement of

DaveScot Wrote:

If you come up with observed or experimental evidence that mutation/selection can turn a single celled organism into a fly

only would work in your world

In the real world we would need billions of steps of mutation and time for natural selection to eventually get a fly from a common ancestor of even your beloved Amoeba dubia.

Creationist Arguments, in Summary:

Wilberforce, 1860: Verily I say, evolution is utterly wrong.

Philip Johnson, 1980s: Microevolution is true, but Macroevolution is wrong.

Behe, 1990s: Micro and Macro are true, except for a few select kinds of Macro.

The reader can draw whatever conclusions his intelligence allows.

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This page contains a single entry by PZ Myers published on February 10, 2005 7:49 PM.

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