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You went too far on that limb. The ocean Ph level doesn't have much to do with CO2 levels. It has everything to do with the rate of change of CO2 levels. If
by btilly 7y ago
You went too far on that limb.
The ocean Ph level doesn't have much to do with CO2 levels. It has everything to do with the rate of change of CO2 levels.
If you raise the CO2 level fast, the ocean turns acidic. If you raise it slowly, deposits of lime on the bottom of the ocean dissolve and Ph remains constant.
While CO2 has been much higher than the present, the rate of change is unprecedented.
Also evolution is a lot slower than you think. A change in Ph over millions of years could readily be adapted to by evolution. Over 20, not so much.
- Mikeb85 7y agoEvolution through natural selection happens much quicker than that. Sure, fish walking on land progression takes awhile, but otherwise it's pretty quick. https://www.sciencemag.org/news/2019/05/evolution-brings-extinct-island-bird-back-existence https://www.sciencemag.org/news/2019/05/evolution-brings-ext... As for the crabs, some of them still develop hard shells. They'll reproduce and the soft-shelled ones won't. So whatever it is that causes harder shells will persist.
- btilly 7y agoEvolution has a fast mode and a slow mode. The fast mode is that if there is enough genetic diversity in the population that a subset have a combination of traits that suffices, natural selection quickly will reduce the genetic diversity and all of the survivors will have those traits. The advantage of sexual reproduction is that much of the genetic diversity is retained and gets to recombine in interesting ways allowing the next challenge to be addressed. The slow mode is that if overcoming a barrier requires random mutations to produce new traits, it takes many generations for that to happen. The current pH allows some to survive and others not to. But with projected future pH levels, none will be able to survive. Therefore natural selection will select out the entire population as there isn't enough time for a new set of traits to evolve.
- achillesheels 7y agoWhat about nylonase?
- btilly 7y agoThe rate of potential mutation in a species is tied to the reproduction rate. Evolution in bacteria can therefore happen much more quickly than in larger organisms. Evolution in viruses is quicker still. (The flu that comes around each year is noticeably evolved from last year's one. In particular it is bred to avoid triggering immune system responses to recent flu variants.) Crabs can't evolve at anything like the rate of bacteria.
- achillesheels 7y agoSo you predict extinction instead of adaptation or rather speciation (new cell lines resilient in a new environment which form a distinctly new genome)?
- btilly 7y agoOn current projections of ocean acidification, extinction is inevitable for this type of crab. The only news here is that they have actually been measured to be impacted at rates that they were predicted to be impacted. The overall conclusion of what will happen is not changed.
- achillesheels 7y agoThis is where I would disagree with your belief that mutations are caused by replication rates rather than environmental feedback responses. The bandwidth of environmental sampling of larger species such as these crabs permits greater adaptability in near-future generations. I speak specifically to metabolizing de novo proteins in this novel environment which promote cellular replication stability, ie survival, eg enteric coatings. I think you presuppose climate change is a disaster in your extinction judgment rather than a transient response to human industrialization.