Does it matter whether the larvae of one fruit fly species have hairy backs while those of another are smooth? Well, for scientists who believe both species descended from the same ancestor population, it could perhaps be taken as an example of evolution in action. The genetic causes for these particular differences, however, clearly show that no Darwinian processes were involved.
An international team of biologists has teased out the genetic underpinnings of fruit fly larval hairs. The researchers found that the presence or absence of hairs resulted from “many subtle-effect substitutions in regulatory DNA,” not in genes.1 These minor changes were labeled “evolution in action,” but the study results actually show just the opposite. The variations in larvae hairs show at least two genetic features that only make sense if they were purposefully designed creations.
Publishing in the journal Nature, the researchers compared larvae of the very common fruit fly Drosophila melanogaster, which has tiny hairs, with a related hairless variety namedDrosophila sechellia.1 The researchers reverse-engineered the genetic differences between the two species and measured the incremental, as well as total, effects on larval hair production caused by various DNA base substitutions.2
First, the researchers found that reducing the production of these tiny hairs only required the subtle alteration of a handful of DNA sequences that were not genes but were regulatory DNA called “enhancers.” They also found that thousands of DNA bases close to the hair-producing genes were exactly the same between the two species. The differences occurred within a 500-base region that they termed the “focal region.”….
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