Mind boggling Monarch Butterfly life cycle

[Skeptic Ginger]

Nova had a program on the Monarch Butterfly migration the other night.
The Incredible Journey of the Butterflies

I knew they migrated across the continent for winter, and that is amazing enough. But I had no idea the trip north took 4 generations and the trip south was accomplished by that 4th generation alone. This is just totally weird.


Monarch Life Cycle

These are the four stages in the life cycle of the Monarch Butterfly [egg, caterpiller, chrysalis, butterfly]

The total time frame for one butterfly's life cycle (one generation) is about 6-8 weeks . . . egg, caterpillar, chrysalis, butterfly. It grows inside the egg for about 4 days. It then munches milkweed and grows as a monarch caterpillar (larvae) for about 2 more weeks. The caterpillar's life inside the chrysalis (pupa) lasts about 10 days and its wonderful life as an adult butterfly lasts from 2 - 6 weeks.

February/March - hibernating monarchs in Mexico and southern California reawaken, become active, find a mate, begin the flight northward and lay their eggs. Finally they die. These special monarchs have lived about 4-5 months through the long winter.

March/April -the 1st generation monarchs are born -egg, caterpillar, chrysalis, adult butterfly;

May/June - the 2nd generation is born - egg, caterpillar, chrysalis, adult butterfly;

July/August - the 3rd generation is born - egg, caterpillar, chrysalis, adult butterfly;

Sept/Oct - the 4th generation is born - egg, caterpillar, chrysalis, adult butterfly . . . but THIS generation does not die. It MIGRATES south and lives 6-8 months in Mexico or Southern California. They begin awakening and mating in February/March of the NEXT SPRING, and then lay their eggs! Withered and tattered from their migration and hibernation . . . they finally die.

 

[I Ratant]

In a normal summer, the Monarchs pass thru here, many ending up on radiator grills and windshields.. Those that evolved to fly higher get past the barriers of the freeways.
The past two summers, due to "unusual climatic conditions" possibly related to warmth and lack of humidity , they've been as scarce as hen's teeth around here!
Bees are nearly non-existent also.
The trees are full of flowers, but the pollinators just aren't here!

 

[Holler Hoojer]

Nova had a program on the Monarch Butterfly migration the other night.
The Incredible Journey of the Butterflies

I knew they migrated across the continent for winter, and that is amazing enough. But I had no idea the trip north took 4 generations and the trip south was accomplished by that 4th generation alone. This is just totally weird.


Monarch Life Cycle

I'm a great fan of the Monarch. I follow the spotting reports every spring. I grow milkweed in my yard and watch for caterpillars (ugly buggers!). I plant all sorts of butterfly-favored flowers and am even lucky enough to have an area in the woods behind the house where several kinds come to mate (though no Monarchs). But, I am dumbstruck that somehow the Monarchs have that "long generation" that overwinters. How the heck did that ever evolve? I loved the show.

 

[Skeptic Ginger]

...But, I am dumbstruck that somehow the Monarchs have that "long generation" that overwinters. How the heck did that ever evolve? ....

And how the heck is it genetically coded for?

 

[Holler Hoojer]

I hadn't even thought of that. Is there some sort of indexing, or just an external trigger, or something more complex? That would be interesting to learn.

 

[Skeptic Ginger]

If I were going into genetic science, I think that would be an excellent genome to study.

 

[Dancing David]

And how the heck is it genetically coded for?

I am not sure that over wintering needs to be coded for, following the sun angle to avoid frost might be all that is neeeded.

Since they are very quiet and still while they over winter (compared to foraging and mating), it takes a lot less energy to just hang there on a tree.

So my guess is that they might have coding to follow the sun angle, then they just hang out during the winter.

Still very cool. I love them and have had a butterfly gardden when I can.

PS :For those who want a kick butt annual, asclepias curassavica rocks!

It is high in the toxic chemicals and the nectar is very attractive,
http://images.google.com/images?hl=en&q=asclepias curassavica&um=1&ie=UTF-8&sa=N&tab=wi

 

[Skeptic Ginger]

DD, did you not notice what genetic pattern we were talking about? These butterflies take 4 generations migrating north. Then the 4th generation lives 5 times longer, migrates the entire southward journey and ends up in one of two locations, Mexico or So CA where they over-winter and the cycle starts again. Every 4th generation has a different life cycle than the previous 3.

And in one experiment, researchers moved a number of southward migrating butterflies ~1,000 miles east and released them. After a short period going south, they reoriented to the southwest and made it to their destination in Mexico. So the genetic code in that 4th generation is specific to a destination, not merely a north south phenomena.

 

[Dancing David]

Sceptigirl, did you even consider I am aware of the phenomena. So please be sure to make up some stuff when there is a simpler explanation.

Sun angle is sufficient. It triggers the flight north and the flight south.

Yes, they even fly over the ocean.

 

[shandyjan]

Sceptigirl, did you even consider I am aware of the phenomena. So please be sure to make up some stuff when there is a simpler explanation.

Sun angle is sufficient. It triggers the flight north and the flight south.

Yes, they even fly over the ocean.

I think the code was in relation to the 4th generation? Absolutely fascinating, thanks for the post Sceptgirl!

 

[IndridCold]

I've always found metamorphosis fascinating.

 

[Dancing David]

I think the code was in relation to the 4th generation? Absolutely fascinating, thanks for the post Sceptgirl!

The made up stuff of sceptigirl's is that I am in any way disagreeing with her.



There are a lot of google hits and monarch and sun angle if you care to look.

So I don't care that the fouth generation is different. Because it is genetically the same as the first through third. (Except the second, third and fourth are in my backyard.)

Whoopeee.

1. Code for sun angle to turn off mating and patrolling behaviors.
2. Code for point head south by position of sun on horizon at sunrise.
3. Possible terrain responses.
4. Code to turn back on mating and patroling behaviors.
5. Code to point ass towards the sun based on sun's position.

What is so magic about the fourth generation? Nothing. They are less toxic than the second generation. They are not patrolling and mating until the code is activated for them to restart the cycle.

I love monarchs and what they do. I get sad every year when the patrolling stops and the what I call the 'stall gliding' begins. They glide higher and higher into a breeze from the south, they reach about fifty feet and off they go.

BTW the painted lady (vanessa cardui) does a similar thing each year as well by over wintering in warmer climes and then coming back north. Nothing so spectatcular as the monarch.

 

[Dancing David]

I've always found metamorphosis fascinating.

It is hard to imagine that the nerve system of the adult is embedded in the larva.

 

[Third Eye Open]

I know... I add nothing to the discussion.

 

[Dancing David]

Is that a Viceroy or a Monarch?

 

[Skeptic Ginger]

Sceptigirl, did you even consider I am aware of the phenomena. So please be sure to make up some stuff when there is a simpler explanation.

Sun angle is sufficient. It triggers the flight north and the flight south.

Yes, they even fly over the ocean.

Make up stuff? Whatever...

Getting back to your post: "I am not sure that over wintering needs to be coded for, following the sun angle to avoid frost might be all that is neeeded."

Tell me how the sun angle explains the genetic coding for different life cycle lengths every 4th generation. And how does the Sun angle direct the species to move West when they were unnaturally moved East by the researchers?

 

[Dancing David]

I am not going to argue with you, I aid what i thought was coded for, you are having a made up argument with yourself.

Read what I wrote in this post
http://www.internationalskeptics.com/forums/showpost.php?p=4552284&postcount=12

I know you miss Claus, but I am not going to stand in for him in one of your imaginary arguments with your self.

I am not here to argue with you, I stated what i feel is most likely coded for why not discuss that?



Since you got stuch, here is what I wrote

1. Code for sun angle to turn off mating and patrolling behaviors.
2. Code for point head south by position of sun on horizon at sunrise.
3. Possible terrain responses.
4. Code to turn back on mating and patroling behaviors.
5. Code to point ass towards the sun based on sun's position.

 

[kellyb]

I am not going to argue with you, I aid what i thought was coded for, you are having a made up argument with yourself.

Read what I wrote in this post
http://www.internationalskeptics.com/forums/showpost.php?p=4552284&postcount=12

I know you miss Claus, but I am not going to stand in for him in one of your imaginary arguments with your self.

I am not here to argue with you, I stated what i feel is most likely coded for why not discuss that?



Since you got stuch, here is what I wrote

How could that make them live so much longer, though?

 

[Dancing David]

That is great question, the time a monarch spends in patrolling and breeding is rather extensive during the time not spent in over wintering. Males tend to patrol for nectar sources and females (associated with nectar sources), females tend to patrol for larval food sources.

Females tend to avoid males, and males tend to pursue females. The mating itself involves the male ‘narcing’ up the female with hormones and then they carry the female while they mate. The female then lays eggs on larval food sources.

So there is a lot of time spent on patrolling and mating behaviors. From wing nocks (it is amazing how much of a wing can be missing) I know that some imagoes (adults) can live 6+ weeks and even longer.

The causes of wear and tear upon adults are evident storms, mildew, birds, battering by winds and other things.(Cats, kids with nets.) The larvae are very prone to being preyed upon by other insects, as are the adults by praying mantises.

Now as to my guesses as to why the over wintering populations live longer.

Hmmm, I am thinking that maybe (please note this is speculative) it has to do with
1. Lack of mating. (Commonly vulnerability for predation.)
2. Fewer encounters with severe thunderstorms.
3. Lower metabolism in the over wintering phase.
4. Other than the migration, less time spent flying.

But there certainly can, could and probably is some genetic component involving estivation/torpor.

 

[IndridCold]

The wings and everything. Just one more reason I love evolution.