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"Surprising" Convergent Genetic Evolution in Insects

What are the odds that two genes would independently converge on a similar DNA sequence? Well, they're so low that molecular systematists make one of their ground rules the supposition that any two genes that have molecular homology MUST have shared a common ancestor. The odds of two genes independently arriving at the same sequence are simply too low.

Yet sometimes that's exactly the conclusion that evolutionists are forced to draw. In the past here on ENV, we've covered this problem for Darwinian biology -- called convergent genetic evolution. Now, a new paper from Science, titled "Parallel Molecular Evolution in an Herbivore Community," finds many parallel, convergent genetic similarities between various insects that are resistant to the effects of cardenolides, a toxic compound produced by plants to prevent other organisms from feeding upon them:

Numerous insects have independently evolved the ability to feed on plants that produce toxic secondary compounds called cardenolides and can sequester these compounds for use in their defense. We surveyed the protein target for cardenolides, the alpha subunit of the sodium pump, Na+,K+-ATPase (ATP?), in 14 species that feed on cardenolide-producing plants and 15 outgroups spanning three insect orders. Despite the large number of potential targets for modulating cardenolide sensitivity, amino acid substitutions associated with host-plant specialization are highly clustered, with many parallel substitutions.

(Ying Zhen, Matthew L. Aardema, Edgar M. Medina, Molly Schumer, Peter Andolfatto, "Parallel Molecular Evolution in an Herbivore Community," Science, Vol. 337:1634-1637 (September 28, 2012).)

These systems were so similiar that they were forced to conclude that the same genes experienced duplications and then experienced the same amino acid changes independently in widely different organisms: "Thus, in addition to parallelisms in gene copy number and at the level of individual amino acid substitutions, we also observe parallel evolution of expression patterns for ATP?1 duplicates arising in distantly related taxa."

An article on this paper at Science Daily, Far from Random, Evolution Follows a Predictable Genetic Pattern, reports widespread convergent genetic evolution in very diverse groups of insects:



The gene sequences in these "distantly related insect species" independently evolved highly similar sequences:


Sure, if they assume that Darwinian evolution is correct then the necessary conclusion is that it must be "predictable." Is this what they expected, however? Not at all. As one scientist quoted in the same article said: "Is evolution predictable? To a surprising extent the answer is yes."