Those of you who have read the posts in this blog's butterfly section know that I am fascinated by the process of metamorphosis, during which a caterpillar creates a chrysalis or cocoon, virtually dissolves into soup, then rearranges those constituent materials into a flying butterfly.
A column by Robert Krulwich at NPR offers a startling take on the process: that caterpillars and lepidoptera are two DIFFERENT creatures that have ?hybridized, and when the caterpillar dies, a butterfly or moth is "reincarnated."
Here's a dangerous, crazy thought from an otherwise sober (and very eminent) biologist, Bernd Heinrich... "[T]he radical change that occurs," he says, "does indeed arguably involve death followed by reincarnation."..The mainstream scientific community totally disagree with this hypothesis and have presented counterarguments, which are elucidated in the column.
"In effect, the animal is a chimera, an amalgam of two, where the first one lives and dies ... and then the other emerges."
What he's saying is, while a moth appears to be one animal, with a wormy start and a flying finish, it's actually two animals — two in one! We start with a baby caterpillar that lives a full life and then dies, dissolves. There's a pause. Then a new animal, the moth, springs to life, from the same cells, reincarnated...
According to this theory, long, long ago, two very different animals, one destined to be wormy, the other destined to take wing, accidently mated, and somehow their genes learned to live side-by-side in their descendants. But their genes never really integrated. They are sharing a DNA molecule like two folks sharing a car, except half way through the trip, one driver dissolves and up pops his totally different successor.
Credit for the butterfly image at the top to TYWKIWDBI reader Jenny at xenotropos.*
Addendum: Reader BJNicholls found an excellent discussion of this topic at Scientific American.
*p.s. - if other readers have original (butterfly or non-butterfly) artwork that they would like to have displayed in this blog (with credit, but without remuneration), please leave a link in the comments. No guarantees, obviously.
Evidently, moths may retain memories they formed during their larval stage. And with some form of functional neural activity persisting across metamorphosis, the idea of death and rebirth is a tough one to sell.
ReplyDeleteSo many insects and animals in other phyla go through larval stages that bear little resemblance to their adult stage, I too am very skeptical of this idea of butterflies being chimera. If there really were composite DNA, then I'd expect that it DNA analysis would point to two different evolutionary lines - is that suggested by anyone? And while I can easily imagine simple cells becoming symbiotic as mitochondria show us with their separate genetics, I can't imagine anything short of a Hollywood fantasy machine accident that would result in a viable chimera of two distinct separately evolved species.
ReplyDeleteThe caterpillar doesn't die. At no time is there a pause where the cells are dead. Reorganization isn't "death" or we'd all have been "dead" as our a ball of cells metamorphosed into an infant Homo sapiens during fetal development.
I drew this in college.
ReplyDeleteAnd it's not what I remembered (is anything ever?)
Actually hesitating even linking to it now.
Thinking back, I just looked at some random images for reference.
So I'm sure it's grossly inaccurate (especially to the community of experts who frequent this blog).
It's definitely the wrong chrysalis for the species (which has also had considerable artistic license taken).
Anyway, my apologies.
I've (hopefully) gotten better in the last 7 years, so maybe it's time to revisit the subject :)
http://www.zia-art.com/junk/flutterby.jpg
I'm very honored that you chose my butterfly painting for your blog. I was having my morning coffee when I saw this load up. It took me about three minutes to go from, "Hey that looks familiar" to "Wait a sec... that's MINE!" :D
ReplyDeleteI painted this for my Mum, who loves butterflies. When we were kids she used to "adopt" monarch butterfly caterpillars and raise them until they were ready to fly away.
My two cents on the cocoon stage? I'd think it may have evolved from some sort of hibernation state. It wouldn't take much to go from "eat as much as you can/hibernate/breed" to "fatten up/hibernate and finish growing while you do it/breed" and finally to "fatten up/cocoon/transform/breed".
Related to this topic is a post at Scientific American blogs today:
ReplyDeletehttp://www.scientificamerican.com/article.cfm?id=insect-metamorphosis-evolution
Here's a link to the Donald Williamson paper mentioned in the post.
http://www.pnas.org/content/early/2009/08/25/0908357106.full.pdf+html
This guy really is suggesting that caterpillars and butterflies are chimera: "I theorize that the first insect to acquire caterpillar larvae did so by hybridizing with an onychophoran, possibly in the Upper Carboniferous period."
I think he's indulging in an educated form of pareidoia myself. The SciAm blog article by Ferris Jabr is very interesting discussion on the origins of metamorphosis.
I've added the SciAm link to the text of the post. Thanks, BJ.
DeleteStan: I didn't know where to post this link which you might (but probably already have) be interested in. This was the first butterfly post I came across.
ReplyDeletehttp://www.nature.com/srep/2012/120809/srep00570/full/srep00570.html
Thank you Ms. Monkey, for a link I had not seen before. In general anyone can contact me by writing a comment on any link (I read every comment), but if you want to communicate without thousands of people reading the content, you can use the email address in my thumbnail bio in the right sidebar: retag4726 (at) mypacks.net
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