[rockarage]

Read the companion website, the authors cherry-picked their findings, good thing they link to another independent study:

https://elifesciences.org/articles/48224

“Surprisingly, we find that frequently observed adaptive substitutions at two sites, 111 and 122, are lethal when homozygous and adult heterozygotes exhibit dominant neural dysfunction. We identify a phylogenetically correlated substitution, A119S, that partially ameliorates the deleterious effects of substitutions at 111 and 122. Despite contributing little to cardiac glycoside-insensitivity in vitro, A119S, like substitutions at 111 and 122, substantially increases adult survivorship upon cardiac glycoside exposure.”

Essentially the study found 2 mutations (substitutions at 111 and 122) give the treatment fruit fly(Drosophila ) an immunity to milkweed poison(cardiac glycosides), the mutation has a lethal side effect: it causes a neural dysfunction that kills the treatment fly(adult heterozygotes). A third mutation(A119S) is immediately needed to correct the side effect. If we are being honest an adaptive walk is essentially impossible for the Monarch. An honest critic refutes the Whiteman Laboratory & NYTimes assertion that an adaptive walk occurred.

[redofrac]

Could you explain how the need for two mutations refutes the idea of an adaptive walk? The elife article just seems to suggest that walk may have been a more complex process.

[inkaudio]

Not two, but three mutations. The first & second induced mutations gives the fruit fly immunity to the poison but the mutations are also lethal, which means the fly could not survive long enough for the third needed mutation to occur in an adaptive walk. The third mutation is like a stabilizer of the first & second mutation, it does not give immunity. In the test all three mutations are needed simultaneously for the fly to have the immunity and survive, that is not an adaptive walk, that is incredible engineering. So essentially you can engineer a monarch butterfly, but an adaptive walk is impossible in this case. (Writing on the go, may edit later)

[ceejayoz]

> A third mutation(A119S) is immediately needed to correct the side effect.

Or, that third mutation came first.

[inkaudio]

These are sequential, it could not have naturally.