Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 76 (8908 total)
Current session began: 
Page Loaded: 05-20-2019 4:45 AM
22 online now:
caffeine, Heathen, PaulK, Tangle (4 members, 18 visitors)
Chatting now:  Chat room empty
Newest Member: WeloTemo
Happy Birthday: Percy
Post Volume:
Total: 851,620 Year: 6,657/19,786 Month: 1,198/1,581 Week: 20/393 Day: 3/17 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
1
2Next
Author Topic:   Is evolution of mammals finished?
RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 6 of 213 (383787)
02-09-2007 7:49 AM
Reply to: Message 1 by MartinV
02-08-2007 4:50 PM


Does modern researches support such "outdated" ideas? In my opinion yes - here is the chart from 2005 that clearly support Broom observation that all mammalian orders aroused in Eocene:

What is an "order" and how is it different from "family" and "genus" or other classifications?

To discuss this we need to know what the delineations are eh? Are they real or are they arbitrary assumptions?

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 1 by MartinV, posted 02-08-2007 4:50 PM MartinV has not yet responded

Replies to this message:
 Message 8 by PaulK, posted 02-09-2007 8:23 AM RAZD has responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 16 of 213 (384004)
02-09-2007 6:47 PM
Reply to: Message 8 by PaulK
02-09-2007 8:23 AM


trees, forests, and bushes
Order is above Family, which is above Genus. (There are a confusing array of subclassifications but that's the basic situation).

Which is "above" species ... (whatever "above" means here).

But what is the real difference between them? At what point does a change from the difference between species and genus become the difference between genus and family, etc?

There is no weak and wavering rule (to say nothing about hard and fast) regarding these classifications, no relation of "genus" > m "non-arbitrary speciations"(1), "family" > n "geniations" etc.

(1) where "non-arbitrary speciations" means divergence into two or more daughter populations that are non-arbitrary because they don't interbreed, versus "arbitrary speciation" which is species classification in time lumps (and we don't know if they are really non-breeding due to lapsed time between populations).

All classifications above species are really arbitrary human impressions of how much difference they include, how many different species are involved and the time frames involved.

One could also group species by {time lumps} from common ancestors - every species that is descended from a common ancestor population in the last 10 million years (say) are in the same genus, all those that are descended from a common ancestor population in the last 30 million years (say) are in the same family, all those that are descended from a common ancestor population in the last 90 million years (say) are in the same order, etcetera, ...

... and you would end up with a similar arrangement of species into genus and family and order etcetera, but one much less susceptible to the arbitrary ego of man.

"Why are there no new orders" is the basic question of this thread, and to answer that properly one needs to know how "order" is\was defined -- and the answer is that it was done rather arbitrarily for the convenience of humans studying the ancestry of life.

There are no new "orders" because we have not chosen to reorder or re-evaluate these divisions, NOT because evolution has stopped.

This is also part of why creationists don't understand "macro"evolution, but that's a horse of a different collar.

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 8 by PaulK, posted 02-09-2007 8:23 AM PaulK has not yet responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 19 of 213 (384139)
02-10-2007 8:20 AM
Reply to: Message 17 by Hyroglyphx
02-09-2007 10:42 PM


Re: Evolutions precipice versus Creations Blank Stare
I believe there is a limit on the speed of beneficial evolution that hits a wall, which thus, would render evolution on a macro scale impossible. In other words, there is a cost substitution problem associated with the possible variables of allelic expression through genetic drift.

First your strawman only lists one way of changing the frequency of alleles, thus it is incomplete and does not constitute any kind of answer.

Please define "macro"evolution - so we can be sure we are (a) talking about evolution and (b) we are talking about the same thing.

Also define "micro"evolution just to be sure we are talking about something different.

It should be easy eh?.

I asked the same question of Oliver on Why Evolution is science and he fluffed off with:

Message 198
Micro, as in variation and adaptation.
Macro, as in complete change fronm one creature into another.
Thanks..

Which neither addresses time frame nor degree of change involved. My answer to him is at Message 200, and you can feel free to respond there or to dodge the question.

What is the "macro"evolutionary change from Genus to Family? Family to Order? When does it occur? What is different about those levels of change and the one from Species to Genus?

What do the classifications of species into different "Genus" "Family" "Order" etcetera groupings really mean?

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 17 by Hyroglyphx, posted 02-09-2007 10:42 PM Hyroglyphx has not yet responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 35 of 213 (385807)
02-17-2007 9:06 AM
Reply to: Message 34 by MartinV
02-17-2007 8:51 AM


Re: Marine K-T extinctions
... but somehow there was no selective drive into the sea.

There ... is ... no ... drive ...

Evolution is NOT driven, it is a response to opportunity.

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 34 by MartinV, posted 02-17-2007 8:51 AM MartinV has responded

Replies to this message:
 Message 36 by MartinV, posted 02-17-2007 1:26 PM RAZD has responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 37 of 213 (385841)
02-17-2007 2:16 PM
Reply to: Message 36 by MartinV
02-17-2007 1:26 PM


Re: Marine K-T extinctions and opportunity
... birds responded to opportunity and filled "emptied niches" in the environment.

Or re-filled niches that had been vacated by other birds (birds being older than the K/T event). It seems most of the birds that survived were aquatic (there was a thread that discussed this, can't find the link), and that birds today are descendants of those survivors.

Yet they were unable to "respond to new opportunity" and to fill "emptied niches" as succesfully as mammals did.

But opportunities are not just environmental, they also involve the available variations within the populations and behavioral patterns (such as being aquatic versus terrestrial birds).

Crocodiles somehow did not react to changing environment at all ...

They did. Those that survived were adapted to the environment they were in, and thus able to survive within it. They did not need to change to be adapted to that environment. They then radiated out into similar environments that had been vacated.

The question is whether they could have benefited by moving into a substantially different environment. The crocodile today is a shore feeder, and adaptation to full water life would mean giving up some of that ability. There is also the issue of warm-blooded versus cold-blooded and both being air breathers -- this would have limited the crocodile ability to dive in deep water and actively pursue prey compared to a warm-blooded competitor (or a cold-blooded water breather). This would limit the ability of crocodilians to become like whales. Evidence for this is also in the areas where crocodiles live -- only where there is warm and relatively shallow water.

Note that the similar shore environment further north is occupied by the seals and other Pinnipeds - further evidence of the benefit of warm-bloodedness - and that these are intermediate between crocodiles and whales for diving ability.

You also talk about proto-whales competing with sharks, and note that sharks diversified into many species - including herbivores.

From an evolution standpoint it doesn't really matter what the species - or how many - fill a niche, just that they do so in sufficient quantity and ability to survive and breed. There are many birds that eat the same basic seeds and live in the same basic areas - one doesn't always drive the other out (or to extinction). We see oscillations - give and take - between different species (ie like galapagos finch beaks).

Whether there are 10 shark species or 9 shark species and one whale species filling the same general habitat amounts to the same result in the end.

Opportunity = available niche, available ability, available behavior patterns.

Enjoy.

Edited by RAZD, : added pinnipeds


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 36 by MartinV, posted 02-17-2007 1:26 PM MartinV has responded

Replies to this message:
 Message 38 by MartinV, posted 02-17-2007 3:48 PM RAZD has responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 41 of 213 (385865)
02-17-2007 6:13 PM
Reply to: Message 38 by MartinV
02-17-2007 3:48 PM


Re: Marine K-T extinctions and opportunity
Yet according Nature 2005 crocodiles have warm-blooded ancestors.

It comes down again to opportunities:

http://www.adelaide.edu.au/adelaidean/issues/5501/news5550.html

quote:
"It turns out that all of these advanced cardiovascular features are valuable for today's crocodiles, enabling them to bypass the lungs and hold their breath for longer periods," Professor Seymour said. "Crocodiles typically remain hidden under water until their prey comes near, then they lunge and often drown their victims. Warm-bloodedness is not suited for this type of sit-and-wait hunting, because of a high metabolic rate and a need to breathe often.

"When I looked at the palaeontology of crocodiles, a consistent picture appeared-the earliest ancestors of crocodiles were definitely not sit-and-wait predators. Instead, many had long legs and some ran around on only two legs. These were obviously highly active, terrestrial predators which would have been well served by warm-bloodedness and a four chambered heart.

"Between 200 and 65 million years ago, the crocodilian lineage diversified into more than 150 genera in all kinds of habitats from land-based to fresh water and the ocean," he said.

"Only one relatively small group that were aquatic and sat and waited for food to come to them managed to survive until today. All the rest became extinct about 65 million years ago with the big extinction when most of the dinosaurs died out," he said. "The cold-bloodedness that this group evolved may have been a factor that saved it."


When the mass extinction occurred the ancestors of today's crocodiles had already taken the opportunity to be cold-blooded again to augment their behavior pattern of ambush predation.

Those that were deep sea predators or warm-blooded predators were killed in the mass extinction, leaving those niches open for later animals to take the opportunities available.

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 38 by MartinV, posted 02-17-2007 3:48 PM MartinV has responded

Replies to this message:
 Message 45 by MartinV, posted 02-18-2007 8:18 AM RAZD has responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 46 of 213 (385932)
02-18-2007 9:53 AM
Reply to: Message 45 by MartinV
02-18-2007 8:18 AM


Re: Marine K-T extinctions and opportunity
Warm-blooded predators were superseded by other warm-blooded mammalian predators and cold-blooded reptilian predators.

You are lumping two things together: survival of the K/T extinction event and radiation after that event. Fitness to survive the extinction event does not translate into fitness for the niches evacuated by that event.

If you have warm-blooded predators filling the niche before, having taken the opportunity to evolve to fill that niche, then it is logical that the same niche would be filled by warm-blooded predators after the niche again becomes available.

What was the disatvatage of this warm-blooded predators to be replaced by another ones ...

They couldn't survive the K/T extinction event.

(it is claimed by darwinists that warm-blooded feature was one of the reason of succesfull mammalian radiation during Eocene)?

That is radiation to fill available niches AFTER the K/T event. There were no animals in those niches then, so they were up for grabs by whatever came along that could take advantage of the opportunity.

Warm blooded just means that they have higher levels of energy available, whether they were reptiles, birds or mammals. That higher energy translates to increased fitness.

Evolution does not say that it HAD to be mammals that filled the niches, just that the animals that did so were better fit to take advantage of the opportunities. Mammals just happened to be the ones in the right place at the right time with the right equipment at that moment.

Just like dinosaurs happened to be the ones in the right place at the right time with the right equipment after the previous mass extinction event.

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 45 by MartinV, posted 02-18-2007 8:18 AM MartinV has responded

Replies to this message:
 Message 54 by MartinV, posted 02-19-2007 2:49 AM RAZD has responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 48 of 213 (385962)
02-18-2007 2:06 PM
Reply to: Message 42 by Lithodid-Man
02-18-2007 12:35 AM


Crocodiles and Dinosaurs?
We have seen where dinosaurs were once thought to be cold-blooded and now are considered to be warm-blooded. Where birds are now thought to be descended from dinosaurs (or are dinosaurs).

Now we have evidence of a remnant of warm-blooded adaptation in the hearts of crocodiles:

http://www.adelaide.edu.au/adelaidean/issues/5501/news5550.html
(also nature article and others)

Do you know of any thoughts on the line of crocodiles being another surviving branch of dinosaurs, even though they reverted to cold-blooded behavior, due to this heart issue?

It seems to me that the hearts of dinosaurs being soft tissue and not preserved in fossils would make this a possibility, but I am not sure of the rest of the lineage\cladistics issues.

Comment?

(perhaps this should be a new thread, although this would make it about a "new" order of dinosaurs?)


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 42 by Lithodid-Man, posted 02-18-2007 12:35 AM Lithodid-Man has not yet responded

Replies to this message:
 Message 49 by Chiroptera, posted 02-18-2007 2:18 PM RAZD has responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 50 of 213 (385968)
02-18-2007 3:33 PM
Reply to: Message 49 by Chiroptera
02-18-2007 2:18 PM


Re: Crocodiles and Dinosaurs?
So both are surviving dinos. Thanks. That means that crocs are not (strictly speaking) cold-blooded reptiles eh?

I found this abstarct:
I also found an old Pharygula article

Saw both of those when googling the warm-hearted crocs.

During the Permian, the therapsids were the most dominant land form. Then the PT extinction event (the worst that is known) allowed the archosaurs to become dominant; the extinction event that marked the end of the Triassic allowed one particular branch of the archosaurs, the dinosaurs, the opportunity to become dominant, and the the KT extinction then allowed one particular branch of the therapsis, the placental mammals, to once again reclaim their ancestor's place as the dominant land form.

Several changes in the pecking order eh? So much for directed evolution.

Or did the therapsids somehow recover their lost "spirit"?

LOL.

Thanks.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

This message is a reply to:
 Message 49 by Chiroptera, posted 02-18-2007 2:18 PM Chiroptera has responded

Replies to this message:
 Message 51 by Chiroptera, posted 02-18-2007 3:38 PM RAZD has responded

RAZD
Member
Posts: 19839
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 6.0


Message 52 of 213 (385976)
02-18-2007 5:08 PM
Reply to: Message 51 by Chiroptera
02-18-2007 3:38 PM


Re: Crocodiles and Dinosaurs?
okay, common ancestor older than croc\dino ...

... so how old is the warm-blooded heart? We have this feature in therapsid\mammals, crocs\archosaurs and bird\dinos ... is it the same heart or were there several evolutions of a 4-chambered heart?

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

quote:
The metabolism of archosaurs is still a controversial topic.
  • 4-chambered hearts. Mammals and birds have 4-chambered hearts. Non-crocodilian reptiles have 3-chambered hearts,
  • How does that archosaur phylogeny match up with the synapsids?
    http://en.wikipedia.org/wiki/Synapsid

    Do we go back to amniotes to get to the heart of this?
    http://en.wikipedia.org/wiki/Amniote

    quote:
    Amniota
  • Class Synapsida - Mammal-like "reptiles"
  • Class Sauropsida - Reptiles
  • But some reptiles are 3-chambered.


    Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
    compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

    This message is a reply to:
     Message 51 by Chiroptera, posted 02-18-2007 3:38 PM Chiroptera has not yet responded

    RAZD
    Member
    Posts: 19839
    From: the other end of the sidewalk
    Joined: 03-14-2004
    Member Rating: 6.0


    Message 63 of 213 (386138)
    02-19-2007 8:43 PM
    Reply to: Message 54 by MartinV
    02-19-2007 2:49 AM


    Re: Marine K-T extinctions and opportunity
    Yet cold-blooded reptiles could survive quite well.

    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.

    We don't know if niches were really so empty.

    They don't have to be empty for there to be opportunity. I'm sure that when you go shopping for food you don't wait until the store is empty -- you know there is sufficient opportunity to buy what you want or something close enough that you can eat.

    Early whales were predators (you noted the jaw of one was like a crocodile eh?). That changes the balance with other predators - wary coexistence is more common than fighting every encounter. Perhaps the early whales survived and thrived because they were hunting rather than being the hunted.

    In the warm climate of Eocene I do not see the advantage.

    Strangely the world doesn't require your ability to see the advantage for it to have happened. Life is not limited by your inability to see.


    Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
    compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

    This message is a reply to:
     Message 54 by MartinV, posted 02-19-2007 2:49 AM MartinV has responded

    Replies to this message:
     Message 65 by MartinV, posted 02-20-2007 5:21 AM RAZD has responded
     Message 86 by Fosdick, posted 02-24-2007 12:56 PM RAZD has not yet responded

    RAZD
    Member
    Posts: 19839
    From: the other end of the sidewalk
    Joined: 03-14-2004
    Member Rating: 6.0


    Message 72 of 213 (386289)
    02-20-2007 6:15 PM
    Reply to: Message 65 by MartinV
    02-20-2007 5:21 AM


    Re: Marine K-T extinctions and opportunity
    ... they entered environment with fully adapted predators ...

    How do you enter something you are already part of? What do you mean by "fully adapted" - able to survive and breed? Anything else is meaningless because that is all that is required. But this also applies just as strongly to the whale ancestors as to your list of predators.

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

    The only difference between them and the other animals was that generation by generation their environment was a little bit more in the water and a little less on the land.

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

    There were opportunities presented by the environment, opportunities presented by the variations in genetics of their population group and opportunities presented by their behavior.

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

    Evolution does not occur in sudden shifts in individuals, it does not occur within individuals. Evolution is a process of change over time within a population. Those that are better able to survive and breed are the ones that have greater opportunity to survive and breed while those that are NOT better able to survive and breed have less opportunity to do so.

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

    ... yet there was enough space and nurture for them too.

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

    All development subsequently was a matter of "internal factors" .

    No "internal factors" required. It's like walking down the road. One step at a time gets you there. You don't reach a point where you suddenly need a mythical "internal factor" to take another step.

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

    Enjoy.


    Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
    compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

    This message is a reply to:
     Message 65 by MartinV, posted 02-20-2007 5:21 AM MartinV has responded

    Replies to this message:
     Message 74 by MartinV, posted 02-21-2007 1:18 PM RAZD has responded

    RAZD
    Member
    Posts: 19839
    From: the other end of the sidewalk
    Joined: 03-14-2004
    Member Rating: 6.0


    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


    Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
    compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

    This message is a reply to:
     Message 74 by MartinV, posted 02-21-2007 1:18 PM MartinV has responded

    Replies to this message:
     Message 79 by MartinV, posted 02-24-2007 2:40 AM RAZD has responded

    RAZD
    Member
    Posts: 19839
    From: the other end of the sidewalk
    Joined: 03-14-2004
    Member Rating: 6.0


    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


    Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
    compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

    This message is a reply to:
     Message 79 by MartinV, posted 02-24-2007 2:40 AM MartinV has not yet responded

    RAZD
    Member
    Posts: 19839
    From: the other end of the sidewalk
    Joined: 03-14-2004
    Member Rating: 6.0


    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


    Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
    compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


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

    This message is a reply to:
     Message 81 by Alan Fox, posted 02-24-2007 7:11 AM Alan Fox has not yet responded

    Replies to this message:
     Message 84 by MartinV, posted 02-24-2007 11:33 AM RAZD has responded

    1
    2Next
    Newer Topic | Older Topic
    Jump to:


    Copyright 2001-2018 by EvC Forum, All Rights Reserved

    ™ Version 4.0 Beta
    Innovative software from Qwixotic © 2019