[leps-talk] Re: Recent Boston Globe "monarchs are threatened" article

[Patrick Foley]

Mark,

My first point was that no scientist is claiming that Monarchs are 
threatened. The issue is the fascinating and virtually unique 
multigenerational migration of the Eastern NA Monarch. That is due to a 
suite of genetically influenced behavioral traits, which can easily be 
selected against. Indeed, the majority of Danaine populations do not 
show anything close to the migration we are talking about.

The subfamily Danainae has chemically committed itself to eating 
Asclepiadaceae (milkweeds), Apocynaceae and a couple of related tropical 
families. This commitment precedes the migration by tens of millions of 
years, although the Danaine fossil record is spotty. Ackery and 
Vane-Wright (1984, Milkweed Butterflies) lean toward the theory that 
Danauus plexippus and other Danaus species have radiated out from 
Central America/Northern South America during the Pleistocene. Possibly 
as Brower states in his new article in the Encyclopedia of Insects, the 
Monarch tracked the explosion of 108 milkweed species across NA.

I'd like to see someone with more expertise reconstruct the Danaus 
evolutionary history. As for me, I'm heading south for Mexico tomorrow, 
so let the rants ring out! I won't be here to respond.

Patrick
patfoley at csus.edu

The Walkers wrote:

> It seems more intuitive to me that the Monarch is not migrating in 
> order to access the ever precious milkweeds, but that the Monarch has 
> chosen milkweeds because they are are readily available all along 
> their migration path.  I'd say this is one hearty insect indeed, 
> probably one of the most hearty, other than locusts, Vanessa 
> cardui, and cockroaches (but after all, EVERY insect has the potential 
> at any given time of creating a pestilence).  Weed eaters seem to be 
> the best adapted of all the invertebrates.  Migrating weed eaters are 
> the best of the best.  Cardui can basically eat anything along its 
> migration path.
>  
> By the way, do you suppose that there may come a time when the 
> migration path of the Monarch becomes circum-global?  How cool would 
> that be.
>  
> Now the Monarch does make itself vulnerable by clustering so densely 
> during the winter, but then they are just taking the same strategy 
> that the most successful armies of the 2nd millenium used for 
> withstanding their enemies.  Strength in numbers.  Sacrifice the front 
> lines, as long as you can keep throwing out new individuals.  It's 
> kind of like Risk - the team with the biggest army wins.
>  
> I don't know.  It's easy to get worried about the ill environmental 
> effects of human stupidity because we can be quite self-serving and 
> oblivious.  And we are capable of eliminating both species and 
> habitat.  But my guess is that the Monarch is equipped to out-survive 
> mankind.  If we wipe out their overwintering colonies in Mexico, a few 
> of them will go somewhere else, and in a few years you'll have 
> billions again.  If we poison or eradicate all of the milkweed in the 
> U.S., a few of them will adapt to something else, and in a few years 
> you'll have billions again.  I don't think you could successfully 
> eliminate Monarchs even if you tried.  Kind of like the Argentinean 
> ants I'm trying to get rid of in my house.  In that case, I hope I CAN 
> create an extirpation - or better yet, an extinction.  With all of our 
> food stuffs (and my insect collection) tightly sealed, the little 
> bastards have now relegated to eating the silicon sealing around my 
> shower stall.  But just when I think I've gotten the best of them, 
> they come back strong and all the more determined.
>  
> Frogs don't rule the world, but insects do.  When the last human being 
> has planted her face motionless into the ground from whence she came, 
> you can be sure that insects will still be wiggling inside of her.
>  
> Mark Walker.
>  
> Paul Cherubini wrote:
> >Pat Foley wrote:
>  
> > But as we have cleared up several times on this list, the Monarch's
> > Eastern NA migration behavior is a much more fragile thing. Why?
> >1) This kind of migration is not common in butterflies. It
> > apparently requires just the right conditions.
>  
> Fragile?  I'd say quite the opposite...  
>  
> <snippage>
>
> 	
> 	
>
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