Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 83 (8942 total)
29 online now:
AZPaul3, PaulK, ssope, Thugpreacha (AdminPhat), vimesey (5 members, 24 visitors)
Newest Member: John Sullivan
Post Volume: Total: 863,625 Year: 18,661/19,786 Month: 1,081/1,705 Week: 333/518 Day: 9/88 Hour: 1/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Definition of Species
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 134 of 450 (570858)
07-29-2010 8:52 AM
Reply to: Message 133 by Huntard
07-29-2010 8:19 AM


Re: Not even tangential to the original direction.
Huntard writes:

Well, it's your example, so you're free to let them appear by magic. In nature though, they would appear through mutations.

Mutations have nothing to do with natural selection or survival of the fittest...which is what I am talking about.

If you have another theory of evolution please be sure to share that with us.


This message is a reply to:
 Message 133 by Huntard, posted 07-29-2010 8:19 AM Huntard has responded

Replies to this message:
 Message 135 by Huntard, posted 07-29-2010 9:02 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 136 of 450 (570869)
07-29-2010 9:27 AM
Reply to: Message 135 by Huntard
07-29-2010 9:02 AM


Re: Not even tangential to the original direction.
Migration, genetic drift and selection all decrease biodiversity. If your theory of mutations has the capacity of increasing biodiversity please share that with us?

This message is a reply to:
 Message 135 by Huntard, posted 07-29-2010 9:02 AM Huntard has responded

Replies to this message:
 Message 137 by Huntard, posted 07-29-2010 9:36 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 138 of 450 (570874)
07-29-2010 9:52 AM
Reply to: Message 137 by Huntard
07-29-2010 9:36 AM


Re: Not even tangential to the original direction.
Huntard writes:

It's not my theory. It's the normal ToE. I suggest reading up on that if you want to find out about mutations.

If you are relying on mutations to solve your evolutionary dilemmas, this doesn't help with the problem given. A mutant gene, as in the example given, leaves no indication of ancestry or lineage. P, Q, and R, in the example, offer no trace as to who the parent was. Was it a fish, was it a bird was it a plane? Dunno....


This message is a reply to:
 Message 137 by Huntard, posted 07-29-2010 9:36 AM Huntard has responded

Replies to this message:
 Message 139 by Huntard, posted 07-29-2010 10:02 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 140 of 450 (570879)
07-29-2010 10:06 AM
Reply to: Message 139 by Huntard
07-29-2010 10:02 AM


Re: Not even tangential to the original direction.
No, but genes X, Y and Z do.

No because X, Y, Z are unrelated to lineage or to species identification.


This message is a reply to:
 Message 139 by Huntard, posted 07-29-2010 10:02 AM Huntard has responded

Replies to this message:
 Message 141 by Huntard, posted 07-29-2010 10:09 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 142 of 450 (570884)
07-29-2010 10:18 AM
Reply to: Message 141 by Huntard
07-29-2010 10:09 AM


Re: Not even tangential to the original direction.
No they're not, you said so yourself in the example. A, B and C all have the X,Y and Z genes, as do all the rabits.

We know that some modern fish have X,Y,Z. These will have mated with fish which don't have X,Y,Z. (As in B or C's mate.) Most common ancestors therefore are unlikely to have X,Y,Z. We cannot therefore use X,Y,Z to determine lineage.

Hence you can't apply this to rabbits.


This message is a reply to:
 Message 141 by Huntard, posted 07-29-2010 10:09 AM Huntard has responded

Replies to this message:
 Message 143 by Huntard, posted 07-29-2010 10:27 AM Big_Al35 has not yet responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 146 of 450 (572168)
08-04-2010 9:36 AM


Species Definition
The traditional definition of species is as a group of organisms capable of interbreeding and producing fertile offspring. Advances in genetics could offer a more precise genome sequenced definition of species. Segments of the genome could be used to define existing species and assist in identifying new species.

This might be an arbitrary system but it would be far more accurate and effective amongst known living species. eg no one would doubt that a polar bear and a brown bear are different species but they can interbreed and produce fertile offspring. The genome sequencing definition of species would allow us to identify the species, the hybrid, parentage and lineage. Hence this system has to be the preferred system of definition in the modern age.

In the previous comments we had the example that P,Q,R makes a rabbit a rabbit. No other species would contain P,Q,R because if it did it would be a rabbit. Thus we could use the genome sequence of P,Q,R to define a rabbit. This however, does not help us with history. If the rabbits had evolved from a rabbit like creature then this system of defining species would start to come into question. A rabbit like creature might contain say P,Q only. If on the other hand we follow the ID philosophy we can adopt the like begats like ideology. eg P,Q,R always leads to P,Q,R except in the case of tragic abnormalities and mutants.


Replies to this message:
 Message 147 by Blue Jay, posted 08-04-2010 11:24 AM Big_Al35 has responded
 Message 148 by Dr Jack, posted 08-04-2010 11:38 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 149 of 450 (572272)
08-05-2010 5:51 AM
Reply to: Message 148 by Dr Jack
08-04-2010 11:38 AM


Re: Species Definition
Mr Jack writes:

To me, this is not surprising, because as I alluded to in my introduction, the concept of a species predates modern biology. The simple fact is that in the light of evolutionary understanding the concept of species is a shaky one as best, perhaps applicable if you view a single snapshot of time, but fundamentally flawed on a longer timescale.

Earlier in this debate...see the off topic posts after message 87....we kind of established that the ancestors of modern fish were infact ancient fish. This idea that the usual definitions of species can't be applied in this case are therefore simply not true. I am suggesting that the normal definitions of species ie (similar behaviour, type etc and interbreeding and possibly even DNA) are still useful in this case and no snapshot in time is required.

Other cases we can debate but this is one case where any definition of species would be adequate. We are even using the term fish for the ancient fish and not some other word. That in itself is a clue.

Ofcourse we don't have access to ancient DNA and therefore the newer models for species definition have limited applicability. This might change with advances in technology.


This message is a reply to:
 Message 148 by Dr Jack, posted 08-04-2010 11:38 AM Dr Jack has responded

Replies to this message:
 Message 150 by Dr Jack, posted 08-05-2010 6:02 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 151 of 450 (572274)
08-05-2010 6:10 AM
Reply to: Message 147 by Blue Jay
08-04-2010 11:24 AM


Re: Species Definition
Bluejay writes:

I argue that the only reason to use the methodology you espouse is because it satisfyingly parcels things into convenient packages of information that sound nice to you. But, it isn’t any more accurate or correct than any other proposed methodology, and it severely restricts the number of people who can do it.

I am not the one advocating the newer definitions of species. Scientists working in the field are actively doing this as it gives significant advantages. And yes I do like convenient parcels and packages. Why not.

As regards the expensive equipment and the restrictions on people, I am happy for them to continue to use the older or existing definitions of species. For the vast majority of people these older models work perfectly adequately.


This message is a reply to:
 Message 147 by Blue Jay, posted 08-04-2010 11:24 AM Blue Jay has responded

Replies to this message:
 Message 167 by Blue Jay, posted 08-05-2010 10:31 AM Big_Al35 has not yet responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 152 of 450 (572275)
08-05-2010 6:27 AM
Reply to: Message 150 by Dr Jack
08-05-2010 6:02 AM


Re: Species Definition
Mr Jack writes:

"Fish" is not a species. "Fish" is not even a genus, a family, an order, a class or a phylum. (And "Fish" is certainly not a clade!)

If you reject the word fish, I am guessing you will reject the word shark (also not a species). Here is a link showing that we cannot establish the species of shark in the fossil records in most cases due to lack of information ->http://www.elasmo-research.org/education/evolution/earliest.htm

If I can't use the word fish...and I can't use the word shark...there are no other words to use as we don't have enough data. These creatures date back 400 million years. I think it's safe to assume that the modern sharks came from these ancient sharks.


This message is a reply to:
 Message 150 by Dr Jack, posted 08-05-2010 6:02 AM Dr Jack has responded

Replies to this message:
 Message 153 by Dr Jack, posted 08-05-2010 6:34 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 154 of 450 (572279)
08-05-2010 6:51 AM
Reply to: Message 153 by Dr Jack
08-05-2010 6:34 AM


Re: Species Definition
I don't reject the word "fish", I pointed out it isn't a species! It's also not terribly biologically useful because it's paraphyletic.
Shark is better (if you're willing to include the rays as well) because the Elasmobranch group appears to be a monophyletic clade.

It's still not a species though so, again, I find myself wondering what it's relevance to our current discussion is?

The point I am making is that any definition of species must be based on a snapshot in time and that snapshot in time must be now. We don't have enough data for any other period of time. We then have no choice but to apply today's snapshot in time to the ancient fossil records. We must classify the ancient species against known species of today. Anything else does not make sense.

eg..if we found a fossil and then declared it a missing link between the bears and cats...and then further established it as a new species this would be absurd. We simply don't have enough data.


This message is a reply to:
 Message 153 by Dr Jack, posted 08-05-2010 6:34 AM Dr Jack has responded

Replies to this message:
 Message 155 by Huntard, posted 08-05-2010 7:04 AM Big_Al35 has not yet responded
 Message 156 by Dr Jack, posted 08-05-2010 7:05 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 157 of 450 (572300)
08-05-2010 8:34 AM
Reply to: Message 156 by Dr Jack
08-05-2010 7:05 AM


Re: Species Definition
So, according to you, we should shoe-horn any, and all, extinct animal into a currently extant species? Really?

No...your putting words into my mouth. I never said this. The best we can do is to identify living species and the known extinct species (like the dodo). Fossils that don't fall into the known categories/species would need another system. I don't know what this system would be...I am not a paleontologist or biologist.

But we can't just make up ad hoc species and lump these fossils under that category. It couldn't be defined as a species under any of our definitions anyway. We don't have access to the DNA, we don't know their behaviour and we can never know if they could interbreed. It has become an exercise in futility.

Paleontologists must discuss extinct organisms using some new criterion but they should never evangelise this new methodology to the proletariat as their new system has no basis in fact.


This message is a reply to:
 Message 156 by Dr Jack, posted 08-05-2010 7:05 AM Dr Jack has responded

Replies to this message:
 Message 158 by Huntard, posted 08-05-2010 8:48 AM Big_Al35 has responded
 Message 159 by Dr Jack, posted 08-05-2010 9:10 AM Big_Al35 has not yet responded
 Message 169 by Blue Jay, posted 08-05-2010 10:57 AM Big_Al35 has not yet responded
 Message 175 by RAZD, posted 08-05-2010 9:09 PM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 160 of 450 (572312)
08-05-2010 9:12 AM
Reply to: Message 158 by Huntard
08-05-2010 8:48 AM


Re: Species Definition
Huntard writes:

The "known extinct species" include every fossil ever found.

I see a huge difference between the dodo and the TRex in terms of our knowledge of the creatures. The dodo was known to man. TRex never was. I think we even have stuffed dodos in museums. Also the behaviour of dodos has been documented extensively. We can safely say that that was a species.

TRex is a mystery. All we have are movie images and directors imaginations to go on. If you found two TRex half skeletons I think you would be hard pushed to even show that it was the same animal. You would have no idea if they could interbreed and their behaviour is unknown.


This message is a reply to:
 Message 158 by Huntard, posted 08-05-2010 8:48 AM Huntard has responded

Replies to this message:
 Message 161 by Huntard, posted 08-05-2010 9:16 AM Big_Al35 has responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 162 of 450 (572321)
08-05-2010 9:32 AM
Reply to: Message 161 by Huntard
08-05-2010 9:16 AM


Re: Species Definition
Huntard writes:

I would be, the experts, not really, no. With half a skeleton I predict a 100% sure identification.

Again I must refer you to a link that I already supplied in another debate about the differences between lions and tigers.

Ok here is one link from potentially many that supports my claim that the differences are hard to distinguish.

I think you will agree that lions and tigers are different species, yet they have almost identical skeletons.


This message is a reply to:
 Message 161 by Huntard, posted 08-05-2010 9:16 AM Huntard has responded

Replies to this message:
 Message 163 by Huntard, posted 08-05-2010 9:37 AM Big_Al35 has not yet responded
 Message 168 by Percy, posted 08-05-2010 10:35 AM Big_Al35 has responded
 Message 176 by Theodoric, posted 08-05-2010 9:24 PM Big_Al35 has not yet responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 164 of 450 (572328)
08-05-2010 9:43 AM
Reply to: Message 161 by Huntard
08-05-2010 9:16 AM


Re: Species Definition
Huntard writes:

So? Also, there is quite a lot known about the behaviour of T. Rex.

We don't even know if TRex was a top predator or just a scavenger.


This message is a reply to:
 Message 161 by Huntard, posted 08-05-2010 9:16 AM Huntard has not yet responded

Replies to this message:
 Message 165 by caffeine, posted 08-05-2010 9:48 AM Big_Al35 has not yet responded
 Message 166 by jar, posted 08-05-2010 10:10 AM Big_Al35 has not yet responded

    
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 170 of 450 (572359)
08-05-2010 11:05 AM
Reply to: Message 168 by Percy
08-05-2010 10:35 AM


Re: Species Definition
Percy writes:

So why do you perceive it to be a significant problem for learning a lot about, say, T-Rex if we're actually mistaken in thinking our fossils represent a single species? Even if they are multiple species they're still extremely similar.

Yes, that's right...there maybe multiple TRex species. I don't disagree that a lot can still be gleaned from the fossil evidence. However, a lot cannot be gleaned from the fossil evidence. eg we don't know if the TRex was a predator or a scavenger. With living species it's very easy...we have access to them and can analyse their behaviour.

We have already discussed three potential definitions of species;
1) genome sequenced definition of species
2) interbreeding definition of species
3) behaviour, diet, appearance, environment based definition.

1 is I believe the newer definition but not yet officially established.
TRex fails to achieve species classification by all three definitions.


This message is a reply to:
 Message 168 by Percy, posted 08-05-2010 10:35 AM Percy has responded

Replies to this message:
 Message 172 by jar, posted 08-05-2010 11:42 AM Big_Al35 has not yet responded
 Message 173 by Percy, posted 08-05-2010 3:20 PM Big_Al35 has not yet responded
 Message 179 by caffeine, posted 08-06-2010 5:48 AM Big_Al35 has responded

    
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2019