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Wings not lost, just hidden in some insects
The mealworm beetle (Tenebrio molitor).
[Image courtesy of Takahiro Ohde]
The only limbs that can grow upon a modern insect's back are wings and wing-like structures, and they only appear on the second and third segments of an insect's thorax--between their head and their abdomen. However, some insects in the fossil record seem to have wing-like "pads" on many of their non-winged body segments.
Now, researchers show that two of these "pads" on the mealworm beetle, Tenebrio molitor, can sprout wing-like appendages when the expression of a certain gene is decreased. Takahiro Ohde and colleagues performed experiments with the beetles and discovered that decreasing the activity of their Hox gene caused wing-like structures to grow from otherwise wingless parts of their bodies.
Apparently, these beetle body parts still have a mechanism for wing development that can be turned on to grow new limbs. These regions have not been lost over evolutionary time, according to the researchers; they've only been altered to allow for a variety of different insect body designs. In fact, other species of insects might still have the potential to grow wings from non-winged segments of their bodies too, they say.