الأربعاء، 8 أغسطس 2012

Are butterflies and caterpillars two different organisms?


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."..

"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.  
The mainstream scientific community totally disagree with this hypothesis and have presented counterarguments, which are elucidated in the column.

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.

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