DWise1 writes:
Why do you emphasize "variation within a kind"? The implication is that that disagrees with evolution. Why do you think that?
Well, let me try to sort this out. You think the KIND keeps changing until it could eventually be called another Kind? No? Isn't that what the ToE implies?
No, that is not what the ToE implies. The kind does not become a different kind, but rather over the generations it can diversify into new sub-kinds,
all of which are still of the original kind. The image is that of a branching tree; all the new branches are still part of the original branch. In evolution, every organism reproduces after its own kind, especially among eukaryotes (what protista do can get pretty weird).
The scientific term that describes this is
nested clades, cladistics being the discipline of classifying species. You can read "clade" as being a "kind". A clade will have descendent clades. All descendent clades will be nested within the parent clades. An everyday analogy would be a computer's directory tree structure in which each directory could have any number of child subtrees, but each directory (except for the root directory) will have one and only one parent directory. At no time does a directory jump from one directory subtree to another (symbolic links in UNIX/Linux do not count) and at no time does the addition of directory subtrees change what the entire directory structure is.
For more information on clades and cladistics, look at RAZD's
Message 363.
I'm trying to say that the genome of any given Kind can't change, that all the change, all the variation we see of cats and dogs and whatnot, is all confined within the limits of the genome for the Kind and it cannot produce anything but what's in that genome.
I think that you're a bit off about genomes. There is not one single genome for all the different species and subspecies within a kind. Each species has its own genome, as does each subspecies. Those genomes are very similar, but still different; the more closely related (ie, more recently split off from its parent species) the more similar those genomes will be. And the more remotely related (ie, split off from a much earlier generation) the less similar they will be. IOW, how similar the genomes of two species are depends on how long ago (AKA "how many generations back", since number of generations equals time) they had shared a common ancestor.
So while the first generation of a kind had its own genome from which all its descendent species derived theirs, there is no such thing as a kind having one single genome. A kind contains a collection of the genomes possessed by all its species.
Even mutations can only change within the structure of the genome, replacing segments of DNA with other sequences, usually to the detriment of the organism, ...
I'll skip asking what you mean by "mutations", since we appear to be talking about the same thing. To many, "mutation" means something that went wrong during the development of an embryo (eg, thalidamide babies), but that would have nothing to do with evolution since that phenotype mutation would not be inheritable. Or something had damaged the DNA drastically causing great physical deformities, which again would have nothing to do with evolution since the individual's chances of survival and reproduction would be very small. Rather, the only mutations that are of any interest are the genetic changes that can be inherited. And those changes are few and well understood (See
Mutation).
In the case of a base insertion or deletion within a gene, then that would shift the sequence and code for an entirely different amino acid sequence. I cannot think of how this could not be detrimental. If I'm not mistaken, I think that this is one way that a gene becomes recessive.
In the case of a point mutation, a single codon would have changed. That could or could not code for a different amino acid. The amino acid requirements within a protein's sequence depends on the site within the protein. Some sites require a specific amino acid, so changing that would disable the protein. Some sites require a particular type of amino acid, so changing that amino acid may or may not affect the protein. Many sites will accept any amino acid, so changing the amino acid there will have no effect. Also, a point mutation could cause a different protein to be produced, such as a gene for lysozyme having mutated to instead produce alpha-lactalbumin, which is used in the production of milk. So this type of mutation could be detrimental, but it might be beneficial instead and it's rather likely to be neutral.
If a sequence is duplicated, then that will likely result in the duplication of a gene. This is where those multiple alleles come from. And multiple alleles also allow an organism to continue producing a protein even after some of the alleles have mutated to produce a different protein (eg, we continue to produce lysozyme along with alpha-lactalbumin). Though if the insertion is in the wrong place, then it could cause problems.
In short, mutations of the genome are not always detrimental, but can instead be neutral or even beneficial. The detrimental mutations will be selected against, undoubtedly mostly through spontaneous abortion when the embryo proves to be nonviable -- much more than half of all fertilizations result in spontaneous abortions. Most of the mutations that are inherited would be either neutral or beneficial.
... , but even assuming it sometimes produced something viable it could still only be within the template determined by the genome. That's the genetic boundary of the Kind.
Yes, mutations to the genome will be within the framework of the genome. And the changes to the genome that are more likely to keep the organism viable are the small ones. But that does not prevent the addition or modification of traits in the genome, ones that can change the genetic boundaries of the kind. Remember, those genetic boundaries are the union of all the individual genomes of all the various species and subspecies within that kind.
Or to mix test pilot and post office metaphors, envelopes are meant to be pushed.
And otherwise I argue that the processes of evolution that form new varieties, at least where this comes about by the splitting of populations into daughter populations, tends toward the LOSS of genetic variability or diversity, so that any series of population splits will create interesting new variations or phenotypes BUT at the ssame time with the loss of genetic diversity.
Certainly, natural selection works to diminish the variability of a population as the better adapted individuals tend to survive and propagate while the less well adapted don't. But natural selection is only part of the story, since there are processes that work to increase genetic variability, such that the net effect is a balance between diminishing and increasing variability, a balance that can teeter either way or maintain an equilibrium. Many factors come into play, all of which are analyzed in the highly mathematical science of population genetics.
Since that is the trend brought about BY evolution through these processes, you can see that ultimately there will be a point where no further evolution or variation is possible. Which is the opposite direction from what the ToE postulates and needs.
No, that is the trend brought about by
natural selection, which is only one part of evolution. What the ToE postulates and needs is
both increased variation and natural selection.
Our different views here are driven mainly by the time frames that we allow. It takes time for genetic variability to accumulate within a population. Because of your YEC beliefs, you only allow a very short period of time, about 1,000 years, for all this evolution to take place (your "variation within kinds"). Because of that, you need to imagine that the original breed pairs representing each basic kind come preloaded up front with all the genetic variability that that kind will need to create all the species that it needs to. Your model does not even begin to allow any time for the processes that will increase variability.
Since I am not constrained by your YEC assumptions, my model allows for the time that is needed for variability to increase, plus natural selection and speciation don't have to proceed at anything approach the break-neck speed that your model demands. In my model, life is allowed to simply do what life does naturally: survive and reproduce. And what life does naturally in the form of populations of organisms is really what evolution is all about.
SO; genetically you can't get variation beyond the limits determined by the genome, and phenotypically you are always going to be spending genetic variability as you develop new breeds, variations, races, or "species."
There is no such thing as "
he genome", but rather each individual species and subspecies has its own genome.
Genomes change, which means that their limits change too.
Genetic variability increases as well as decreases. It's dynamic, not static.
No I believe evolutionists think that variation is openended, and that the genome can be altered by mutations, that you can go on getting variations in phenotypes indefinitely.
I feel that I'm seeing a mixing up of genotypes and phenotypes. I'll take a chance and assume that you know their definitions (and that you've not invented some unique new definitions that nobody else has ever heard of). The genotype describes the genetic characteristics of the individual. The phenotype describes the individual's physical characteristics. The genetic information in the genotype is used to create and operate the phenotype. The genotype in eukaryotes is created through recombination and mutation, but is not subject to selection. The phenotype is subject to selection, so it is indirectly through the phenotype that the individual's genotype is selected or not. It is the genotype that is inherited, not the phenotype. Variability is about the genotype, not the phenotype.
It is interesting to note that there is no one-to-one correspondence between the genotype and the phenotype. Small changes in the genotype can translate to large-scale changes in the phenotype, or large-scale changes in the genotype could translate to very small changes in the phenotype, or no change at all. You can't really predict it, though we may be learning to slowly.
"What's to stop microevolution from becoming macroevolution?" is the nave question asked all the time here.
No, that's not at all nave. In fact, your own model not only answers that question, but it absolutely demands that microevolution naturally becomes macroevolution given enough time (ie, enough generations). Without that, your model completely falls apart.
More on that in my reply to your
Message 354.
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