Tuesday, July 7, 2015

Differing forms in Apatura ilia

Following on from Arcadian Emperor's photos below, can any clever person tell me what determines the preponderance of one form over the other - it's not something that occurs in any of the UK resident butterflies (is it?), but is very common in some tropical species that occur in up to five different forms in some cases. Presumably they're only identified as belonging to the same species by breeding them up.

Is it purely a genetic blue eyes, brown eyes sort of thing, ie do clytie forms tend to have clytie progeny, or is there an environmental factor involved? Your comments and any relevant links would be appreciated. 


irisscientist said...

Derek. No genetics is not the only determining factor. Spring and summer broods of the same A.ilia ssp (see Akio Masui's book) very often posses differing colourations. In essence summer broods posses significantly more orange (more clytie) than the spring (more ilia) specimens. This subject matter is touching on parts of my research work. My current evidence currently points to one of two possible explanations. Differing lighting conditions (between the months) significantly effects the perception of essential visual mating signals. Specimens therefore increase their chances of mating by increasing the contrast against their environment. For references please take a look at Thery (2001) "Forest Light and its influence on Habitat Selection" and also Shashar (1998) "Polarization of Light in a Tropical Rain Forest". The other explanation is due to the regulation of temperature effecting the release of essential wing compounds. I hope this helps?

Derek Longhurst said...

Many thanks, yes it does. I somehow thought it couldn't just be one or the other. I guess Araschnia levana has mastered the trick most effectively, with totally different spring and summer forms.