3 events that happened only once in history

[MarkE]

On 14/01/2018 at 10:49 PM, Strange said:

On the evolution of flowering plants, this might be of interest: http://www.bbc.com/news/science-environment-42656306

Pretty interesting! Less (genome) is more it seems. The downsizing of genome of the angiosperms allowed greater CO2 uptake from photosynthesis, maximising their productivity. Just like C4 plants (all grasses, excluding rice) who are higher in efficiency (six times more efficient) than C3 plants.

I guess that "efficiency" is the same reason why C3 grasses are so successful. 

Questioning why ferns and conifers still exist is perhaps in some way like questioning why C4 plants still exist. Isn't nature always looking for higher efficiency and productivity?

Edited January 17, 2018 by MarkE

[CharonY]

Not necessarily, much is also getting into different niches and exploiting them. Otherwise, prokaryotes would be outcompeting eukaryotes as they former are far more genomically streamlined while being metabolically more diverse.

At the same time strategies that are optimized for one condition can fail catastrophically once conditions change. Often, super-optimized populations are vulnerable to perturbations.

[MarkE]

On 17/01/2018 at 11:40 PM, CharonY said:

Not necessarily, much is also getting into different niches and exploiting them.

Eukaryotic animals within that niche have to, because they are in competition with one another.

On 17/01/2018 at 11:40 PM, CharonY said:

Otherwise, prokaryotes would be outcompeting eukaryotes as they former are far more genomically streamlined while being metabolically more diverse

Yes, prokaryotes can't adapt to a different environments the way sexual reproductive eukaryotes can, because prokaryotic asexual reproduction creates identical copies, whereas eukaryotic sexual reproduction leads to more diversity in their genome.

[CharonY]

6 hours ago, MarkE said:

Yes, prokaryotes can't adapt to a different environments the way sexual reproductive eukaryotes can, because prokaryotic asexual reproduction creates identical copies, whereas eukaryotic sexual reproduction leads to more diversity in their genome.

Yet prokaryotes are far more metabolically diverse. It is probably more that multicelluarity allowed the opening of different niches.

[studiot]

I think there was also a question about flowering plants here.

 

If this is the wrong thread I apologise.

 

Try angiosperms

http://www.bbc.co.uk/news/science-environment-42656306

[MarkE]

16 hours ago, CharonY said:

Yet prokaryotes are far more metabolically diverse. 

Is it fair to compare the metabolism of a prokaryotic cell with a eukaryotic cell, and conclude from it that the prokaryotic cell is metabolically more diverse? A eukaryotic cell is part of a multicellular system, in which parts of the metabolism have been taken over, have shifted. An analogy: would you claim that a plant cell's membrane is more robust than an animal cell's membrane because the plant has a cell wall? Well, an animal has a skin that protects all the cells inside the body, which is why it didn't need a cell wall anymore.

Edited January 20, 2018 by MarkE

[CharonY]

If you look at the totality of metabolic diversity in all eurkaryotes and then look at what is in prokaryotes you will find that there is far less around. No need for analogies. Part of the evolution of eukaryotes involved loss of metabolic capabilities.

Edited January 20, 2018 by CharonY

[MarkE]

20 hours ago, studiot said:

I think there was also a question about flowering plants here.

 

If this is the wrong thread I apologise.

 

Try angiosperms

http://www.bbc.co.uk/news/science-environment-42656306

This has already been mentioned by @Strange, but thanks anyway, it was an interesting article.

[squiggle]

On 1/2/2018 at 3:12 AM, MarkE said:

- Ribozyme self-replication happened only once in history, and it’s the ancestor of all eukaryotic life on Earth

- Endosymbiosis that lead to eukaryotic cells happened only once in history, and it’s the ancestor of all multicellular life on Earth

- Two ape chromosomes that fused together into one human chromosome (chromosome 2) happened only once in history, and it’s the ancestor of all human life on Earth

 

What is the reason that these events could only have happened once in history, and will never happen again?

3. We only have evidence of this happening once, but it could have happened numerous times in lineages that died off.