William Morse  wrote or quoted:

> I thought Hamilton originally suggested his rule to answer the question 
> of how a feature like the toxicity of monarch butterflies could evolve. 
> 
> This feature has nothing to do with reciprocity. It might not be considered 
> altruism by most, but in fact is, since being toxic doesn't help an 
> individual at first - the individual will still be killed by the 
> predator.The predator is likely thereafter to avoid the species - so it is 
> only after the toxicity gene has spread that it provides any advantage to 
> the bearer. The initial benefit has to be to other individuals who are 
> likely to share the gene - i.e. kin. Note here that the benefit does not 
> have to be only to kin - in the monarch butterfly example the benefit would 
> be to all monarch butterflies -  the benefit to kin only has to exceed the 
> cost to the individual. 

Conventionally (i.e. if you avoid species level selection), then
spatialisation is important.

I.e. it would really matter that a predator who had a toxic monarch
for breakfast would be likely to be avoiding relatives for lunch
and dinner - by virtue of the fact that they are in the same vicinity.

Without spatialisation, benefit would accrue equally to all monarchs -
and the costs would be paid only by those with the gene - a result 
which is bound to be a net loss for them in the competiton between them.

If you permit species-level or group level explanations, toxic monarchs 
are no puzzle at all, of course.
-- 
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