[leps-talk] Monarch question

[Paul Cherubini]

Woody Woods wrote:
> 
> Regarding heritability of migratory strategies, it might be worth mentioning
> that there are Monarchs in Costa Rica that are considered a separate
> subspecies, Danaus plexippus megalippe, thought by Vane-Wright and Ackery not
> to interbreed with D. plexippus plexippus. I must say that they are
> indistinguishable to me even with the subtle markers these authors mention,
> though I am no expert there. 

Chris Durden has suggested there are subtle phenotypic differences between
the year round breeding populations of monarchs that exist in the lowlands of
Mexico and the migratory monarchs of the northern USA and Canada.

One difference he has noted is that the former has white apical spots 
near the tips of the forewings whereas the latter has consistently orange
apical spots.

However, I have found that very roughly 1 in every 200 migratory monarchs
from the northern USA also has the white apical spots.  For example, all three
monarchs in the picture below were collected in Iowa in September during
the fall migration from overnight aggregation sites:

http://www.saber.net/~monarch/apical.jpg

Paul Cherubini

 
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