A combination of factors, I think. Clearly, less myoglobin. Mass-specific respiration rates of white flight muscle are much lower than pink flight muscle.
But the white muscle is also generally WAY smaller than the pink muscle, and from crude visual inspection I'd say there's quite a bit of variation in white muscle - the most extreme cases tend to be in the short-winged crickets, which never grow more flight muscle.
The main thinking is that in formerly pink-muscled insects, the muscle gets histolyzed so the protein can be diverted into reproduction, but then at the same time, histolyzed muscle would require much less energy for maintenance, so there are energy savings as well.
I think the grad student in our lab is eventually going to have to do some microscopy work. For the time being, she's characterizing mitochondrial function.
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But the white muscle is also generally WAY smaller than the pink muscle, and from crude visual inspection I'd say there's quite a bit of variation in white muscle - the most extreme cases tend to be in the short-winged crickets, which never grow more flight muscle.
The main thinking is that in formerly pink-muscled insects, the muscle gets histolyzed so the protein can be diverted into reproduction, but then at the same time, histolyzed muscle would require much less energy for maintenance, so there are energy savings as well.
I think the grad student in our lab is eventually going to have to do some microscopy work. For the time being, she's characterizing mitochondrial function.