An evolution question

[peter grimes]

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[Ziggy Stardust]

And also the emergence of many new species.

Do you know the ratio?

 

[Domen]

You want new species of complex life to appear in the span of several hundred years?

Yes, it is possible:

"Adaptive radiations often occur as a result of an organism arising in an environment with unoccupied niches, such as a newly formed lake or isolated island chain. The colonizing population may diversify rapidly to take advantage of all possible niches. In Lake Victoria, an isolated lake which formed recently in the African rift valley, over 300 species of cichlid fish adaptively radiated from one parent species in just 15,000 years."

On average one new species per each 50 years.

Do you know the ratio?

See above. During the last 15,000 years in Lake Victoria alone emerged over 300 new species of just one family - Cichlidae.

Which gives us on average 1 new species of Cichlidae family per each 50 years. Just in this one lake.

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We don't get new species of large mammals - they tend to get extinct more often than emerge.

But I imagine that things like for example insects or small fish are evolving quite rapidly.

 

[warpus]

15,000 years, sure.. 100 years, nope, unless we're talking insects, which OP was not talking about, I don't think, it was like a decade ago. I think by now he expects human-dinosaur hybrids to be roaming the countryside.

 

[timtofly]

At least we have proof that computers have evolved into a new species aware of evolution.

 

[Domen]

15,000 years, sure.

But it did not take 15,000 years for EACH single of these species to evolve.

15,000 years ago there was 1 species, now we have over 300 which evolved from that one.

But we don't know exact timeframes - for example 14,900 years ago maybe there were 2, or maybe 3, or maybe 25.

That's why I wrote that 15,000 : 300 = 50 years on average for each of these 300 species to "appear".

Of course such rapid evolution happens only in certain conditions - in this case there emerged a brand new lake to be colonized by fish.

 

[Antilogic]

15,000 years, sure.. 100 years, nope, unless we're talking insects, which OP was not talking about, I don't think, it was like a decade ago. I think by now he expects human-dinosaur hybrids to be roaming the countryside.

Yeah, that OP was a bit... special.

Speciation has been observed, though, in small organisms. We have bacteria that have evolved to consume TNT byproducts and synthetic fibers, neither of which existed before the industrial era.

 

[peter grimes]

I'm no biologist, but I'm fairly certain you can't take the average like this and assume it has anything meaningful to say about cichlid speciation rates.

 

[Borachio]

You mean there's no way of knowing whether the speciation exploded 15,000 years ago in one block, or might be more evenly distributed over that time period?

 

[Ziggy Stardust]

That's not a ratio

 

[Antilogic]

You mean there's no way of knowing whether the speciation exploded 15,000 years ago in one block, or might be more evenly distributed over that time period?

You need more detailed evidence from across the time period to evaluate that. Right now, we have two data points showing.

 

[Borachio]

Isn't it a ratio? I wouldn't know.

I don't understand evolution, though; I do know that.

 

[peter grimes]

That's not a ratio

The ratio is certainly not favorable to organisms that don't benefit from our presence.

 

[Ziggy Stardust]

The ratio is certainly not favorable to organisms that don't benefit from our presence.

I went looking myself, but all I could find in the 3 minutes that I could be bothered was this socialist rag:

http://www.theguardian.com/environment/2010/mar/07/extinction-species-evolve

 

[Domen]

I found an article which says that chichlid evolution in Lake Victoria could in fact be much longer, but it is an old article from 2003:

http://www.geotimes.org/apr03/WebExtra042503.html

On the other hand, a much more recent article - from 2014 - doesn't even mention this theory about a much longer evolution:

http://www.cichlid-forum.com/articles/evol_cich_pt1.php

http://www.cichlid-forum.com/articles/evol_cich_pt2.php

Neither does this article from 2010 put in doubt the theory about extremely rapid evolution of chichlids in Lake Victory:

http://www.nature.com/news/2010/100707/full/466174a.html

It is very probable that mating habits influence the speed of diversification. It seems that each of chichlid females have very narrow mating preferences, but various females have different preferences. So one group will mate only with males with a specific trait, while another groups will choose another trait.

Once they stop interbreeding, two separate species emerge over time. Even though they live in the same lake with not so many natural barriers.

And of course there is also this specialization of roles: insect eaters, leaf choppers, snail crushers and scale scrapers, to name a few.

 

[El_Machinae]

That's not a ratio

It's about 100:1 or 1000:1. A thousand extinct species for each new species made. I'm extrapolating this from the fact that extinctions are currently 100 to 1000 times the historical norm.

 

[Ziggy Stardust]

But I like biodiversity

Then stop consuming.

 

[Domen]

According to:

http://www.mcser.org/images/stories...e vol 2 no 9/N. Cherly Anto Frezina and N.pdf

Millions of biological species constitute the life on earth. The variety of life on Earth and its biological diversity is commonly referred to as ‘biodiversity’. The United Nations declared the year 2010 as the International Year of Biodiversity. New species have been regularly discovered.

Around 8000 new species are identified each year. Most of these newly identified species have not yet classified. It is said that nearly 90% of all arthropods are not yet classified.

Most of these species are newly formed ones due to mutation. These newly formed species helps in maintaining biodiversity as so many species are getting extinct each year. So, modern biodiversity may not be much different from biodiversity 300 million years ago. India, Brazil, Colombia, Ecuador, Peru, Mexico, Madagascar, Zaire, Australia, China, Indonesia and Malaysia are the twelve mega biodiversities in the world. These countries contain most of the species population.

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extinctions are currently 100 to 1000 times the historical norm.

252 million years ago, over the course of 600,000 years, about 97% of all species got extinct:

http://www.nhm.ac.uk/nature-online/...ctions/end-permian-mass-extinction/index.html

201 million years ago, in perhaps as little as 10,000 years, some 84% of all species got extinct:

http://www.nhm.ac.uk/nature-online/...tions/end-triassic-mass-extinction/index.html

Etc., etc., etc.

I don't think that current extinction rates are even close to those historical ones mentioned above.

 

[Ziggy Stardust]

But that doesn't say there are more or as many new species forming.

And your link doesn't make Ziggy more happy

Biologist E. O. Wilson estimated that if current rates of human destruction of the biosphere
continue, one half of all species of life on earth will be extinct by 2100. 30% of all natural species will
be extinct by 2050. He further said that extinctions are occurring about 100 times higher than before

[..]

The period since the emergence of humans has shown a steep reduction in biodiversity. This
reduction is named the Holocene extinction. It is caused due to the destruction of the species’ habitat.

 

[Domen]

Actually during the last couple million years, extinctions have been relatively rare:

http://en.wikipedia.org/wiki/Extinction_event

Graph "Marine extinction intensity during the Phanerozoic" (from 542 to 0 million years ago):

http://upload.wikimedia.org/wikipedia/commons/0/06/Extinction_intensity.svg