Darwin's Flowers: Unraveling an 'Abominable Mystery' | Big Think

Darwin's Flowers: Unraveling an 'Abominable Mystery'
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One of the most famous branches in plant’s evolution is the difference between gymnosperms and angiosperms, which puzzled Darwin.
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Professor Rob Martienssen:

Professor Rob Martienssen leads the plant biology group at CSHL, where he focuses on epigenetic mechanisms that shape and regulate the genome, and their impact on development and inheritance. His work on transposons or "jumping genes" in plants and in fission yeast revealed a link between heterochromatin and RNA interference. His work, along with that of his colleagues, was awarded the “Breakthrough of the Year” by Science magazine in 2002. He has also developed reverse genetics strategies using transposons in maize and Arabidopsis that have become powerful and widely used tools in plant genetics research. He was one of 13 scientists nationwide who was named an HHMI-GBMF Investigator last year.
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TRANSCRIPT:

Rob Martienssen: It’s difficult for any evolutionary biologist to understand some of the arguments against evolution that are in the public domain. I mean, the evidence for evolution is not only overwhelming, but it drives everything that we do.

Goldschmidt famously – who is a famous geneticist once said that nothing in biology can be understood except in the light of evolution. And that’s true. I think we wouldn’t understand as much as we do about the pathways that I described without the evolutionary side of it that makes it all real. Especially in plants. We can rewind the clock of recent evolution by remaking a hybrid, for example, and then seeing how it evolves in the laboratory or in the field and compare that to what we know happened even in recent history. And so evolution is an experimentally tractable topic. I mean, it’s very real.

One of the most famous branches in plant’s evolution is the difference between gymnosperms and Angiosperms. And let me explain what they are. They’re both seed plants so they have seeds, but Angiosperms also have flowers, so whereas gymnosperms have a different sort of reproductive structure or cone. So people will be very familiar with, for example, with cones on pine trees, which are gymnosperms and flowers on, you know, their favorite garden plant. The difference between gymnosperms and angiosperms is very important in evolution because angiosperms were able to somehow radiate into thousands and thousands and thousands of species, whereas, gymnosperms are rather narrow in their species. Also, gymnosperms have very, very large genomes that are largely a component of transposons.

Transposons are pieces of DNA that can move around the genome. And so they, they can move potentially and cause genetic as well as epigenetic changes without having to go through a sexual cross. And most genomes are actually composed mostly of transposons. So, for example, the human genome is about 50 percent transposons and only about five percent genes. The maize genome is even more extreme, it’s about 80 percent transposons and only two or three percent genes. So the bulk of the genome is actually prepared, if you like, for epigenetic change. And this is the area that we work on the most looking at the way in which transposon control, and especially epigenetic transposon control, has influenced the phenotype, the properties of plants over the generations.

Darwin famously referred to the radiation of angiosperms, the generation of thousands of species, as an abominable mystery because it didn’t fit with his gradual change hypothesis of evolution. And we think that maybe some of the explanation lies in this ability to control transposons. But that’s very speculative, but it’s an interesting, interesting thought.

[steveb]

Dobzhansky said; "Nothing in biology makes any sense except in the light of evolution." - not Goldschmidt.
You'd think an evolutionary biologist could've managed to not get both the quote and its attribution wrong.

[ashcapybara]

My concentration level is currently too low to understand this, keep doing great work with genes and stuff!

[Charlie]

The eerie-ness of literally having just finished up an exam about gymno and angiosperms in Bio II is overwhelming me right now...

[erdwaenor]

"Evolution is an experimentably trackable topic. It's very real...!"

Exceptionally wonderful!

[JanjayTrollface]

Great vid! I love how he treats evolution not as absolutely proven fact but as a theory with an undeniable mountain of evidence to back it up.In my mind keeping sight of the facts like that is paramount for real science.

[Volound]

it was theodosius dobzhansky, not whoever you thought it was..

[Wastingsometimehere]

If you don't know something, learn it. Don't just slap "someone must have did that" and walk away. In it's core, that's what creation is. Refusing to learn because it's much easier to walk away.

[libriano]

Good and informative video but the quote "Nothing in Biology Makes Sense Except in the Light of Evolution" is actually from Ukrainian geneticist Theodosius Dobzhansky not Goldschmidt.

[toosinbeymen]

Rob Martienssen's talk is compelling but I doubt many creationists would be swayed. When one is anti science, one's mind is closed to such complexity, IMO.

[humoftheradiator]

Lovely video. Thank you for sharing. :) 

[josephvictory]

Controlling transposons,

This seems an awful lot to suggest consciousness (albeit limited) perhaps this can help us to understand the evolutionary context of placebo effects.

That is, if i understand transposons to be gene types that are influenced by non reproductive conditions.

And that by control we are talking about some sort of non standard feedback loop. Something that isnt just related to environmental factors but perhaps something at the level of consciousness (although a limited definition)

This raises far too many questions and some of them seem to me to raise serious issues with not just evolution but the entire materialistic worldview given just basic leeway.

I think there is probably a much simpler explanation. Corn has developed to be totally dependent on humans to survive in its current form. Its symbiotic with us for survival. Flowers perhaps adapt to insects, some more than others and this diversity is perhaps due in part to the immense diversity of insects that influence them and not any particular genetic flexibility. A stretchy rubberband will remain unstretched if few pull at it.

then again i have absolutley no clue if i even understand anything about this topic beyond what i gleaned from the transcripts.

[dev]

This video wasn't very informative and the interviewed scientist wasn't able to get to any conclusion. Please upload another one about this issue

[miguelsolisbravo]

Nothing to do with the video but, does anyone else think the big think logo is giving us the finger?

[JungleJargon]

Plants have a lot of changes and they remain the kind of plants they are.

[JungleJargon]

An organism can never be what it has no written directives to be. It cannot get different directives out of the thin air.

[Bingusginghs]

To lazy to pay attention. But good job!

[synesthesia]

How about Consciousness is all there is... Everything else is Thought, an Element of reflection to be able to reflect back and ask "What IS Consciousness"? 

[timwoodward]

So lemme get this straight...a transposon is a segment of DNA that floats around the genome of plants and can be transported to other species of plants without interaction (plant-sex/pollination)? That makes no sense at all, I'm going to assume I misunderstood this man. Perhaps someone has a better definition of transposon?

[Neshuah]

interesting vid, but he could use some wig and tan

[JungleJargon]

All of evolution is speculative. Evolution has fallen on its face and it can't get back up!