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