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Can the spot within a spot be explained by Turing's reaction-diffusion mechanism of morphogenesis?
The Turing-Murray theory is certainly that pretty much all patterns result from reaction-diffusion, but I've never seen it applied specifically to ladybirds, where most studies have focussed on the genetics of the forms.
The Harlequin has a multiple-gene system which is also thought to code for the extent of the variation, while the extent of melanisation is also partially determined by environmental factors, particularly the temperature during development - I found a pupa outside on th 9th Dec last year, which hatched into a succinea individual which was so dark there was virtually no orange on it
Record your ladybird sightings!
I am currently reading about EvoDevo in the book by Sean Carroll*. On p.123, the Turing mechanism is discounted in favour of one based on genetic switches.
* Endless Forms Most Beautiful ISBN 978-1-84916-048-3
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