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Author Topic:   Is evolution of mammals finished?
MartinV 
Suspended Member (Idle past 3932 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 76 of 213 (386406)
02-21-2007 1:46 PM
Reply to: Message 71 by Chiroptera
02-20-2007 5:40 PM


Re: Weird.

You also haven't explained why you find the conception of a vaguely defined, unobservable "spirit force" to be reasonable.

I agree with the idea of Robert Broom. Might be it is not reasonable but I don't force you to agree with it. You have your random mutation, natural selection, empty niches.


…the strange course of the history of life on the earth appears to admit of but one explanation – that it has been brought about by spiritual agencies and that the production of man has been the chief purpose of it all. Though man as we see him to-day may be regarded as a very disappointing result of all these millions of years of evolution, we must not consider human evolution quite finished. Physically man may change very little in the next 10,000,000 years, but mentally and morally it seems possible he may evolve almost into a new being.

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derwood
Member
Posts: 1457
Joined: 12-27-2001


Message 77 of 213 (386410)
02-21-2007 2:25 PM
Reply to: Message 75 by MartinV
02-21-2007 1:38 PM


Re: So, back to mammalian evolution
Well, it has been a while, I admit, but I do remember 'debating' him here, and that is definitely what he claimed here:

"There is also no evidence that macroevolution is still in progress, a view proposed by Robert Broom who claimed that a new Genus has not appeared in the past two million years. "

The above is taken form:

THE CASE FOR INSTANT EVOLUTION
By
John A. Davison
Professor Emeritus of Biology

[NOTE - Davison is NOT nor was he ever an Emeritus Professor]

But yeah, you got me VMartin - I guess I just don't know Davison's claims at all....


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RAZD
Member
Posts: 19809
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 78 of 213 (386437)
02-21-2007 5:27 PM
Reply to: Message 74 by MartinV
02-21-2007 1:18 PM


Re: Marine K-T extinctions and opportunity

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

Might be the more you repeat it the more you are convinced it to be true.

The fossil evidence is that at every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in. There is nothing to be "convinced" about the fact of evidence that shows they were successful at surviving and breeding at every generation. Surviving and breeding are the only requirements to being "fully adapted" to their environment. If they had not been "fully adapted" they would have gone extinct without resulting in whales.

Yet when all of them from Pakicetus, Ambulocetus etc.. were so "fully adapted" why all of them disappeared? Ambulocetus looks like crocodile - why we don't find him today?

Because they continued to evolve and the natural selection within the populations were towards the more aquatically adapted individuals within the populations. Thus the population gradually shifted from one to the next.

You seem to think of these species as fixed types populating pre-history in lumps, but every individual is a transitional species, every generation is different from the generation before.

Change happens.

No other branch from Pakicetus has evolved that survived till today? Is it possible that on the cladogram nothing except whales live nowadays (exceopt fully marine mammals)?

The ones that were fully adapted to the environment they were in at every stage of their development from land to water the whale ancestors continued to breed and survive because - at every stage of their development from land to water the whale ancestors - they were fully adapted to the environment they were in.

Crocodiles were also fully adapted and are fully adapted even today I suppose.

Of course - they continue to breed and survive. That doesn't mean they were able to exclude other fully adapted species from surviving and breeding.

The only difference between today and the period following the K/T extinction event is that there was more opportunity after the extinction event for more diverse populations to survive.

Enjoy.

Edited by RAZD, : reworded end

Edited by RAZD, : fully adapted


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MartinV 
Suspended Member (Idle past 3932 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 79 of 213 (386841)
02-24-2007 2:40 AM
Reply to: Message 78 by RAZD
02-21-2007 5:27 PM


Re: Marine K-T extinctions and opportunity

Of course - they continue to breed and survive. That doesn't mean they were able to exclude other fully adapted species from surviving and breeding.

Yet something happened. Once crocodiles and ambulocetus lived together in estuaries. Ambulocetus became the whale. His niche remained empty. Some other species should evolve to fill the emptied niche.

Edited by MartinV, : No reason given.


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MartinV 
Suspended Member (Idle past 3932 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 80 of 213 (386844)
02-24-2007 2:45 AM
Reply to: Message 77 by derwood
02-21-2007 2:25 PM


Re: So, back to mammalian evolution

Robert Broom who claimed that a new Genus has not appeared in the past two million years.

According Robert Broom no new mammalian Order appeared in the past 30 million years and no new Genus appeared in the past two million years.
What contradictionu do you see?


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Alan Fox
Member (Idle past 86 days)
Posts: 32
From: France
Joined: 06-14-2006


Message 81 of 213 (386852)
02-24-2007 7:11 AM
Reply to: Message 80 by MartinV
02-24-2007 2:45 AM


Re: So, back to mammalian evolution
MartinV writes:

According Robert Broom no new mammalian Order appeared in the past 30 million years and no new Genus appeared in the past two million years.

Do you have a reference for these remarks by Broom?

Others have already pointed out that Orders and Genera are taxonomical classification terms which are convenient but arbitrary.


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RAZD
Member
Posts: 19809
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 82 of 213 (386858)
02-24-2007 9:01 AM
Reply to: Message 79 by MartinV
02-24-2007 2:40 AM


Re: Marine K-T extinctions, opportunity and eco-niches
Once crocodiles and ambulocetus lived together in estuaries. Ambulocetus became the whale. His niche remained empty. Some other species should evolve to fill the emptied niche.

What makes you think the "niches" were\are (a) a singular property and (b) empty? It is not an on-off situation:

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

quote:
In ecology, a niche is a term describing the relational position of a species or population in an ecosystem. More formally, the niche includes how a population responds to the abundance of its resources and enemies (e. g., by growing when resources are abundant, and predators, parasites and pathogens are scarce) and how it affects those same factors (e.g., by reducing the abundance of resources through consumption and contributing to the population growth of enemies by falling prey to them). The abiotic or physical environment is part of the niche because it influences how populations affect, and are affected by, resources and enemies.

The description of a niche may include descriptions of the organism's life history, habitat, and place in the food chain. According to the competitive exclusion principle, no two species can occupy the same niche in the same environment for a long time.


Strictly speaking there is no such thing as an "empty niche" because the niche is defined around the species: no species no niche.

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

quote:
The issue of what exactly defines a 'vacant niche' and whether they exist in Ecosystems is the subject of some considerable controversy. It is important to understand that the subject is intimately tied into a much broader debate on whether ecosystems can reach equilibrium, where they could theoretically become maximally saturated with species. Given that saturation is a measure of the number of species per resource axis per ecosystem, the question becomes: is it usefull to define unused resource clusters as niche 'vacancies' or not?.

When a species becomes extinct there is no "vacant house" waiting to be filled, rather there is opportunity within the environment for any aspect of the former species niche to be adapted by another species. The former species no longer patrols the "boundaries" of its niche, so it can be encroached from any side. No one species will adapt all of the aspects of the former niche, just the ones beneficial to it.

When a species goes extinct (singular rather than mass extinction event), this is because aspects of it's niche are being coopted by other species - taken over - to the extent that it is no longer able to survive and breed.

Conversely, when a mass extinction event occurs, the boundaries between former niches are obliterated along with the species that went extinct - they no longer patrol the boundaries. This creates opportunity for surviving species to define new boundaries using whatever available resources are beneficial to it for survival and breeding.

There are more opportunities - for the survivors - after a mass extinction event, but there are opportunities in any environment. The species\individuals best able to take advantage of opportunities will continue to survive and breed.

Some other species should evolve to fill the emptied niche.

All that is needed is for surviving species to take parts of it. No single species is required to take over {all of it}.

This is also true where you have a species evolving away from a former habitat - say from shallow water to deeper water habitat - there is opportunity for surrounding species to coopt parts where the evolving whale species no longer is adept at defending it's borders - extreme shallow water - as it is better able to survive and breed in other -new- areas of its "niche" (which also evolves around it).

"Niche" is a plastic amoeba kind of matrix around a species. The more there are in an environment the less opportunity there is for any one to move out of its area; conversely, the less there are in an environment the more opportunity there is for one to move into new - for it - areas.

Enjoy.

Edited by RAZD, : clarity at the end


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we are limited in our ability to understand
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RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

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RAZD
Member
Posts: 19809
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 83 of 213 (386859)
02-24-2007 9:05 AM
Reply to: Message 81 by Alan Fox
02-24-2007 7:11 AM


Re: So, back to mammalian evolution
Welcome to the fray Alan Fox.

Others have already pointed out that Orders and Genera are taxonomical classification terms which are convenient but arbitrary.

And some have mysteriously "disappeared" ... because they have been reclassified into other existing taxons.

Curiously no individuals disappeared - or devolved - when the classifications went the way of the Dodo ...

Enjoy.

Edited by RAZD, : added devolved


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we are limited in our ability to understand
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RebelAAmericanOZen[Deist
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to share.

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MartinV 
Suspended Member (Idle past 3932 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 84 of 213 (386876)
02-24-2007 11:33 AM
Reply to: Message 83 by RAZD
02-24-2007 9:05 AM


Re: So, back to mammalian evolution

And some have mysteriously "disappeared" ... because they have been reclassified into other existing taxons.

They didn't disappeared. As our knowledge increase we reclassify some organisms. We know more on relationiships between different organisms. Statement that higher classification doesn't exist as such is curious one - I suppose only darwinists use such a notion of "classification". Classification is no way some human invention, it exists and many branches of science - not darwinism of course - do not doubt it. Chemistry knows "acids", "proteins", "alcohol" etc (Even DNA and RNA could be considerred as classification). No one consider these classification to be something artificial. No one claim that only "chemical components" exists and all rules above them that classify chemical compouds are arbitrary. No one doubt about proteins or RNA to be something "arbitrary".

So there is no reason to doubt that wolfs, giraffes, beasts(carnivora), rodents and whales exist in order only to support darwinistic gradualism.


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Quetzal
Member (Idle past 3976 days)
Posts: 3228
Joined: 01-09-2002


Message 85 of 213 (386881)
02-24-2007 12:15 PM
Reply to: Message 69 by Chiroptera
02-20-2007 2:46 PM


Re: Weird.
Chiro,

One of the things that Martin appears to be claiming (and that I'm not sure has been addressed) is that competitive exclusion would preclude any adaptive radiation following the K/T extinctions, although it's really hard to follow his train of thought. IOW, because there were aquatic predators which survived the event, they would have already been in an advantageous position to exploit the newly-available resources, so any "latecomers" like the proto-whales would necessarily be unable to move in.

Obviously, there are several holes in this argument. For instance, we see successful invasions of exotics all the time (cf, European red squirrel (Scurius vulgaris) losing out to the introduced American grey squirrel (Scurius carolinensis) in the UK - even though S. vulgaris was already in place and exploiting the available resources). Now, admittedly, this is not "evolution" writ large, but it does show that no matter how full a system is, someone is often capable of horning in on the neighbors.

Secondly, competitive exclusion strong enough to preclude adaptive radiation would only be possible in a highly constrained or bounded ecosystem - which quite obviously the post-K/T-extinction world was not. It was an amazingly empty world, not only in terms of biodiversity, but in terms of sheer numbers of individuals. Picture a closet stuffed with clothes. Remove 75% of them. Lots of room for new articles, n'est-ce pas?

Another point that Martin brings out is a bit harder to explain. Why didn't the existing surviving aquatic predators match the "explosive" radiation of the terrestrial mammals - to the point that nothing else could play in their sandbox? Partly this is an insoluable problem - we simply don't know all the parameters of what makes one lineage more "adaptable" than another. We can speculate a lot, based on modern species dynamics, but the specifics would be pure guesses. In any event, since Martin appears to be fixated on sharks for some reason, their big Golden Age was the Carboniferous - 45 families of sharks appear in this period (compared to about 40 families plus the rays that are here today). Whether this order could have radiated post-K/T or not, the fact is they didn't - at least not to the extent that would have prevented some other lineage(s) from moving in to "shark niches". Same goes for the crocodillians.

I don't know whether this helps or confuses the issue even more. AZPaul3 alluded to niche construction as one reason the proto-whales could have made the transition from land to water without being excluded, and I would add niche partitioning as another (if you weren't previously aware, I'm a biodiversity "dynamic disequilibrium-ist").


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Fosdick 
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Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 86 of 213 (386884)
02-24-2007 12:56 PM
Reply to: Message 63 by RAZD
02-19-2007 8:43 PM


Re: Marine K-T extinctions and opportunity
RAZD wrote:

You typically seem to think survival is an all or nothing situation at every juncture. It isn't. The world is gray.

What survived is what survived, and it may have had as much to do with luck as anything when the asteroid hit.


I do agree with this. The K-T extinction certainly was a stroke of bad luck for life on Earth, but disasters like this one, or worse, occurred fairly often over geologic time. The world is gray, and luck in the form of random coincidence is an operative. Given this grayness and randomness in the course of biological evolution here on Earth, I have to conclude that the evolution of human consciousness was manifestly too gray and too lucky to have occurred anywhere else in the universe. I used to go along with Isaac Asimov's contention that the probability of extraterrestrial civilizations was 1.0. But eventually I had to agree with S. J. Gould that there were just too many gray and random events ocurring in the course of biological evolution on Earth to expect that organic evolution should follow the same course on any other planet. (Thus the foolishness of SETI.)

—HM


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RAZD
Member
Posts: 19809
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 87 of 213 (386889)
02-24-2007 1:33 PM
Reply to: Message 84 by MartinV
02-24-2007 11:33 AM


arbitrary classifications
They didn't disappeared. As our knowledge increase we reclassify some organisms. ... Classification is no way some human invention, ...

You contradict yourself: if they were non-arbitrary there would be no re-drawing of the lines.

Classification is arbitrary. What {groups} are used is arbitrary, what names they are given is arbitrary.

What is not arbitrary is the hierarchy of relationships based on common ancestor populations, but every classification before and after speciation branches is totally arbitrary on where the lines are drawn.

So there is no reason to doubt that wolfs, giraffes, beasts(carnivora), rodents and whales exist ...

But the names we give them and where we draw the lines on the tree of life are arbitrary.

Classifications are useful for discussions, but the world\universe does not rely on them for the existence or behavior of life.


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we are limited in our ability to understand
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MartinV 
Suspended Member (Idle past 3932 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 88 of 213 (386894)
02-24-2007 2:36 PM
Reply to: Message 86 by Fosdick
02-24-2007 12:56 PM


Re: Marine K-T extinctions and opportunity

Given this grayness and randomness in the course of biological evolution here on Earth, I have to conclude that the evolution of human consciousness was manifestly too gray and too lucky to have occurred anywhere else in the universe.

The evolution of human was inevitable - all previous evolution served only as a mean to this outcome. Luck and chance has nothing to do with it. As John Davison observed in his Manifesto - the course of phylogeny might be as inevitable as course of ontogeny.

Evolution now is finished. It's over.


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MartinV 
Suspended Member (Idle past 3932 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 89 of 213 (386896)
02-24-2007 2:55 PM
Reply to: Message 85 by Quetzal
02-24-2007 12:15 PM


Re: Weird.

It was an amazingly empty world, not only in terms of biodiversity, but in terms of sheer numbers of individuals. Picture a closet stuffed with clothes. Remove 75% of them. Lots of room for new articles, n'est-ce pas?

It depends what exactly you remove. If you remove 75% animals from each species I would say nothing happens - remaining individuals will geometrically fill niches. According previous information 85% of marine Orders survived K/T. So diversification of life remain partly unaffected after K/T in the Ocean.


Why didn't the existing surviving aquatic predators match the "explosive" radiation of the terrestrial mammals - to the point that nothing else could play in their sandbox?

That's the question. Why crocodiles and sharks didn't occupy emptied niches? Why after Ambulocetus left estuaries no other mammals entered it again?

It's not only the problem of the land-sea transition of mammals. Eocene lavish on curious mammalian forms. One should suppose much more niches at that time as nowadays. Neverthenless climate was warmer so why we didn't observe in reptiles realm "adaptive radiation" too? While Pakicetus became through Ambulocetus fully marine whale, crocodiles seems to be in stasis (occupying the same niche as Ambulocetus).

One should really take into concideration possibility that something like "internal factors" hindern reptiles evolve after K/T period even though niches were emptied for them too.


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MartinV 
Suspended Member (Idle past 3932 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 90 of 213 (386900)
02-24-2007 3:22 PM
Reply to: Message 87 by RAZD
02-24-2007 1:33 PM


Re: arbitrary classifications

Classifications are useful for discussions, but the world\universe does not rely on them for the existence or behavior of life.

Of course they exist. Even animals recognise them in order to mate themselves, to recognise what to hunt and what to avoid. It's a weird opinion that cats learn to avoid german shepard, bulterier, canis lupus etc and that they do not make some generalization of canidae family. It's a matter of survival to make such classification for them I would say (no-verbal classification of course).

Generalization (to decept other, to pretend to be a member of different group of classification) is even darwinistic explanation of allegedly effectiveness of mimicry.


What is not arbitrary is the hierarchy of relationships based on common ancestor populations, but every classification before and after speciation branches is totally arbitrary on where the lines are drawn.

Because common ancestor does not exist only darwinistic classification is arbitrary. All the others classifications tend to describe animal reality finding out "substance" "essence" of animal diversity and unity via classification. Like in chemistry - they also do not classify chemicals how they evolved but what they really are, what characteristics they have.


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