padfield wrote:
Outbreeding confers genetic strength. Butterflies that breed in relatively localised colonies will benefit from genetic exchange between nearby colonies. In principle, either males or females or both could wander from their birth colony in search of others in which to breed, but in practice females get mated early and are then egg-bound. Flying in search of another colony in which to lay her eggs (so the next generation would outbreed) would be energy intensive, because eggs are heavy to fly with. Thus, it makes more sense for the males to have this instinct built into them.
Yer, I think your right there and that is sort of what I thought after I had posted.
padfield wrote:EDIT : Thinking about it, the fact that males can ensure outbreeding in the same generation, while females can only ensure outbreeding for the subsequent generation (assuming they are mated soon after emergence) might be sufficient on its own to answer the question, without worrying about the energy expenditure of flying egg-bound.
So, male "A" mates with female "A" who stays at the site. Male "A" moves to a new site and mates with female "B" resulting in genetic exchange and outbreeding.
IF I have interpreted this right, it possibly suggests the females are not moving - or very little amusing conditions and the site are suitable. So, that it begs the question about colonising new sites. I would expect there is some movement in the females possibly caused by environmental change and certain genetic triggers. I remember something about that with saprophytic beetles when they run out of dead wood to feed on.
It also makes me think about the maximum carrying capacity or threshold of a site and at what point does a site or patch become over crowded - resulting in dispersal(?). I don't expect answers, these are just thoughts that are going though my mind.
The fact females get mated early raises another thought:
Would an un-mated female, say from a site where there are few males, be more likely or able to disperse and fly further in search of males?
Something tells me she probably wouldn't bother.
That then comes on to the size of the thorax or wing muscles. Have females got larger thorax or wing muscles, therefor they have the potential to fly further - I think so.
Crispin