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“Evolution is governed by a relatively small number of genes”

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passion vine butterfly/Durrell Kapan

In “Butterfly Study Sheds Light On Convergent Evolution: Single Gene Controls Mimicry Across Different Species” (ScienceDaily, July 21, 2011), we learn:

For 150 years scientists have been trying to explain convergent evolution. One of the best-known examples of this is how poisonous butterflies from different species evolve to mimic each other’s color patterns — in effect joining forces to warn predators, “Don’t eat us,” while spreading the cost of this lesson.[ … ]

Now an international team of researchers led by Robert Reed, UC Irvine assistant professor of ecology & evolutionary biology, has solved part of the mystery by identifying a single gene called optix responsible for red wing color patterns in a wide variety of passion vine butterfly species.

[ … ]

“Biologists have been asking themselves, ‘Are there really so few genes that govern evolution?'” Reed said. “This is a beautiful example of how a single gene can control the evolution of complex patterns in nature. Now we want to understand why: What is it about this one gene in particular that makes it so good at driving rapid evolution?”

Steady on. That gene had that effect in a “wide variety of passion vine butterfly species” so close that they are capable of “crossbreeding.”

Would someone like to try this explanation of convergent evolution of wing patterns on the Monarch and Viceroy species of North America, where

The resemblance is not the result of a close genetic relationship. The Monarch (Danaus) and the Viceroy (Archippus) belong to different subfamilies of the order Lepidoptera (butterflies and moths).(5) Their habits are also very different. The Monarch migrates over three to five generations between summer sites in the northern United States and Canada, and overwintering sites in Mexico. The Viceroy, which is territorial, overwinters in its home environment at the first and second growth stages (instars) of the caterpillar, in a form of hibernation (diapause).

The caterpillars are not at all similar. The Viceroy caterpillar resembles a bird dropping; the Monarch is striped orange, yellow, and black, with horns on both the head and tail.

That’s where the bar is set for convergent evolution.

Incidentally, the Viceroy does hybridize, but neverwith the Monarch, rather with other Canadian butterflies that belong to the same family but look very different from itself:

The pupae are irregularly shaped. All of our species hybridize to some extent because they are so closely related. Some of these hybrid forms have been given varietal names.

Most admiral species are dark with a distinctive white band, but several, such as the Viceroy (Limenitis archippus) and the Red-spotted Purple (Limenitis arthemis astyanax) mimic other butterflies that are distasteful to birds.

– Butterflies of Canada

Why do many students of butterflies doubt Darwinism?

If the mimic butterflys are not distasteful then why would this not teach the birds to eat the real distasteful ones? Just musing? I agree there must be some law going on here in the creation of these creatures. yet its my conclusion that danger coloured critters are not seen as distasteful but rather frighten away predators by their boldness. The colours just insist that creatures note their boldness. Robert Byers
Just so story: The butterfly developed mimicry so that birds would leave it alone. Mung
Convergent evolution occurs where there is a selective advantage to converge. For instance, in the case of those butterflies: One is poisonous and one is not. Therefore, the non-poisonous one would have a selective advantage to look similar to the poisonous one. A bird which sees the fraud could mistake it for the real thing, resulting in the bird leaving it alone. A poor similarity would result in the fraud being less effective- but from a distance or to an animal with poor sight, it would still be left alone. TaslemGuy
Genes may influence development. They do not determine it.
Yes, this point is often overlooked. Indeed the looseness of relationship between genotype and phenotype may prove to be one of the reasons that populations adapt so well. Elizabeth Liddle
of related note: Here is a excellent new DVD which recently came out on the 'miracle' of Butterflies; Metamorphosis: The Beauty & Design of Butterflies - movie trailer http://www.youtube.com/watch?v=AZk6nZGH9Xo Metamorphosis: The Beauty & Design of Butterflies trailer - DVD is available for purchase now - for more information visit; http://www.illustramedia.com bornagain77
No one knows what makes a butterfly a buttefly. Genes may influence development. They do not determine it. Joseph

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