Papilio machaon - osmetrium

[John Grehan]

Perhaps the "mechanism" is actually the result of, rather than cause of,
large species. For the sake of another point of view I have rephrased the
sequence (if I have understood this, and I aknowledge that I might have
this confused).

 Species that DON'T limit their competetors access to food all share 
he available food supply. This ecology is compatible with the evolution of:

1): smaller size
2):more eggs and reduced  longevity or flight energy 
3): more flight energy / longevity and reduced ova production


 Species that DO limit competetors access to food. 

The biggest get all the remaining energy, but reduction is offset by large
egg production and good flight ability.

John Grehan