So the question to you would be: do you think humans have reached the end of the road if they have made these varieties but have not made a new species?
The end of the road isn't reached until all genetic possibilities have been exhausted. Human beings have a lot of genetic diversity left as far as I can see.
Well, I'd go with genetic drift except I keep finding out there seems to be some way I'm not getting genetic drift. I can't make sense out of the definition "random sampling." The best I can do with it is random selection which implies a random change in the look of a population over time in the direction of a homogeneous subpopulation within the population. Best I can do with the concept. But if it's anywhere in the ballpark then it's one of those "subtractive" processes like a population split that I keep saying can eventually form new races or subspecies and does so by losing alleles for traits other than those that are coming to characterize the new subpopulation.
I think you may be making more of it than is necessary.
Genetic drift doesn't care about how a species looks, survives or mates, etc.
It is SO unnecessary and confusing and a waste of time to say such things.
Think of a population and then have half that village population killed by a volcanic eruption: those that survive do so because they were not there at the time, not by any special trait of their own compared to those that perish. It's like a lottery with some winners and some losers.
Those that survive are the parents of the next generation. What alleles they have would not confer an advantage to survive another eruption.
That is in many ways quite similar to the population splits I've been talking about, being a random selection of alleles without any regard to fitness, except all the genetic stuff survives rather than dying as in drift.
So I'd agree that the changes aren't due to any selection pressure on the traits themselves, but due to a random favoring of some traits. ...
I would not say "favoring" as that implies some intrinsic value to the survivors compared to the victims that doesn't exist.
The word "random" is supposed to take care of that implication. Could say "selection" again but that has the same implication. I can't think of a word for the phenomenon that wouldn't have that implication.
Consider everyone flips a coin and the heads then form a subpopulation and the tails form a second subpopulation -- the mix of alleles available in each population is a purely random distribution of those in the parent population, based only on what the individuals that got heads had and what the individuals that got tails had.
Isn't that what I said? I understand the process, what is apparently needed as a more neutral term and I can't come up with one.
... But I think you are overlooking the fact that the initial dividing into small bands as they spread out in itself will bring about new allele frequencies that would already affect the look of the band over time with or without additional genetic drift.
But that IS genetic drift -- the "small bands" would not necessarily have the allele distribution of the parent population, but whatever alleles they have become the pool of alleles for their descendants.
This is what I've been describing forever, but apparently you haven't noticed. If genetic drift randomly destroys individuals it's not quite the same, although I have thought it similar enough to say so, and HBD disagreed. In any case the small bands would DEFINITELY not have the allele distribution of the parent population but completely different allele frequencies, which is how the new traits emerge.
How is that selective pressure "demonstrated" as you claim it is though? I don't see any need for selective pressure at all. ...
Perhaps a misunderstanding -- I said that there was no apparent selective pressure.
It seemed clear you said it was demonstrated but I'll have to check later.
... Why wouldn't the new allele frequencies created by the initial formation of the band of migrants be enough to explain it?
Same old alleles different frequencies, still not enough to be that different from the parent population to account for the world wide variation seen.
I'm absolutely certain it is, just as you all think not, and there really isn't any proof one way or the other. You imagine mutations making the big differences, where's the evidence?
Changes would be due to mutations and genetic drift, so that things like skin color and eye color and hair color and hair curliness\straightness etc would vary from one population to the other.
All that is built into the human genome, new traits emerging when new allele frequencies favor it.
These mutations, while not necessarily selected do still mean that the mutations can be tracked from population to population, and from that analysis determine the general paths of migration of the exploratory populations.
What's being tracked is built-in allelic possibilities, called mutations from the ToE belief in mutations.
Not up to looking at a link right now. (The Human Journey: Migration Routes )
Yes, like the finches' beaks are adapted to the foods they eat, like that large-headed lizard has adapted to a particular food its stronger jaws can handle, and so on. But the question I keep raising is how you know the creature genetically changed to adapt to the environment when striking changes can occur simply from the new allele frequencies caused by an isolated small population? ...
Except when they exceed the range provided by the previous alleles, and when genetic analysis shows mutations at specific locations: this is increasingly being done, and the evidence to date has been that mutations make new alleles (modify old ones) rather than it just being a selection of existing alleles.
What evidence? The evidence is that mutations accomplish very little of use to any organism. Just consider that all jar and PaulK could come up with in their recent posts are the sickle cell example, which offers a protection against malaria at the cost of sickle sickness and death, wonderful gift of mutation. And that other familiar one, can't think of it right now. WONDERFUL track record for mutations. There is NO evidence that mutations are the source of healthy alleles, some flukes where their errors manage to do something useful, but very rare flukes.
... In that case the creature would simply find the appropriate food or other accommodation in the environment and adapt simply by using the characteristic it already has for the task it's best suited for ...
Which is the same in the case of mutations, the only difference is that mutated alleles have the potential to be beneficial in ecologies that the old ones have less advantage in.
That is purely an article of faith. There is no reason whatever that "old" alleles in new combinations can't bring out new beaks or other features. And really, somebody should discuss the logistics of adding a mutation to the collection of alleles. It has to be beneficial, it has to show up in the reproductive system where it can be passed on, multiple copies of it have to be distributed for it to become expressed in the phenotype etc. Those that do get distributed in the population tend to be disease factors. Wonderful. Meanwhile the existing alleles are already in the system and have useful functions.
The black pocket mice for example - being black by mutation they could then take advantage of the lava beds where black was beneficial compared to tan.
That's the only example anyone can come up with. Raises some questions about how mutations manage to show up for the occasion.
... One thing that makes me think this is that even on different islands the environments aren't different enough to force a genetic change. ...
In this you would be wrong. The ecologies of the different Galapagos islands varies from lush to arid (wiki):
quote:
The islands are famed for their vast number of endemic species and were studied by Charles Darwin during the voyage of the Beagle. ...
Weather changes as altitude increases in the large islands. Temperature decreases gradually with altitude, while precipitation increases due to the condensation of moisture in clouds on the slopes. There is a large range in precipitation from one place to another, not only with altitude, but also depending on the location of the islands, and also with the seasons.
On the larger islands, the pattern of generally wet highlands and drier lowlands impacts the flora. The vegetation in the highlands tends to be green and lush, with tropical woodland in places. The lowland areas tend to have arid and semi-arid vegetation, with many thorny shrubs and cacti, and almost bare volcanic rock elsewhere.
The differences between islands has caused the tortoises, finches and other species (plant and animal) to evolve in different ways,
A general statement won't do it. You need specifics. Such variations don't preclude there being enough range of possibilities for the different traits brought out by different allele frequencies to find a niche.
... Some change over generations probably as the subspecies continues to prefer its food or other qualities of its niche, but all toward elaborating the main characteristic that was already brought out by the new alleles frequencies due only to the population split.
Well that is basically how selection and adaptation works - organisms evolve to take advantage of the opportunities provided by their traits and their ecology, and different populations in different ecologies become differentiated by different adaptations. But there is not much variation available from just inherited alleles, so without new alleles from mutations there would be a coalescing of genotype\phenotype into a stasis population rather rapidly (a generation or two) on an isolated island with a small population.
Pure theory, no evidence. There's LOTS of variation available from the many alleles for the many genes that govern different traits.
In most cases there would already be enough variability for a great range of changes and adaptations in any of the small populations we've been talking about. Mutation is hardly ever needed for adaptations. ...
Your claim, no evidence that this is the case.
Yes, against YOUR claim that also has no evidence but is nothing but an endless restatement of the theory.
The smaller the population the smaller the gene pool of possible variations on alleles you can have, and the more you need mutations to have variation. Your hypothesis seems to run into itself: first you claim a small population reduces the available alleles dramatically and this brings out rare alleles to cause differentiation, then you claim there is enough allele variation "for a great range of changes" ... which requires a lot of alleles. Or mutations.
Great range in the larger population, enough to get for instance many separate populations of finches with different beaks. Eventually if they kept on losing alleles in various selection processes they'd run out of diversity, but if they've found their niche they can just stay there, further change not being needed.
The proof of all this really is the fact that when diversity IS depleted there is NOTHING that comes along to recover it. Where are your otherwise so plentiful mutations then? And on a desert island you aren't going to get migration to save the day either.
... And again I go back to the situations where a handy mutation or set of mutations would save a genetically endangered species like the cheetah and it simply doesn't happen ...
Except that mutation does not occur on demand or in response to any need of any organism. You really should know this by now, with the hundreds of times you must have been told by now.
Oh I know it, but I wonder about the evo people who so often talk as if mutation just shows up as needed and yet there is the cheetah and other endangered species to prove all that optimism wrong. Supposedly it may already be in circulation disguised as just another allele, but how would you know it WASN'T just another allele? Mutation is ASSUMED, not proved.
However, when species do recover from the brink of extinction, it is not through the loss of alleles -- that is what took them to the brink -- but through new random mutations that happened to provide a benefit. In other words, species that have recovered disprove your hypothesis. So rather than species on the endangered list (of which the Cheetah is an extreme example) we should be looking at species that have recovered from being endangered:
Humpback Whales No Longer Endangered - Nature
'Teddy bear' no longer endangered
Gray Wolf no longer endangered? - American News
First Fish That’s No Longer Endangered: Freshwater Species of the Week
and of course we have the History of the Bald Eagle
Excuse me, but those creatures recovered by growing their population when factors endangering them were removed. The elephant seal also has recovered in that sense, despite its genetic impoverishment. Without being given the information about their genetic situation, however, there's no way to say if any on that list also have a healthy enough genome to have recovered genetically as well as in numbers, but population growth doesn't by itself prove anything about their genetic health.
You are ASSUMING recovery involving mutation, you've offered no evidence of it.
... and yet this idea that mutation is the source of new genetic material to widen a creature's range of possibilities is always included in these scenarios, clung to as if it were reality.
So tell me Faith, how did species that were endangered due to low numbers of alleles available to the breeding population -- your end scenario for species due to continual loss of alleles as they form species and subspecies and varieties ... -- how do they recover?
Where does the genetic material, the alleles, come from to enable a species to recover?
They don't recover from genetic depletion, RAZD, they don't. If they remain healthy enough nevertheless they may recover population, but not genetic diversity.
In the ideal world originally created there would never have been any danger, just endless variations of beautiful living things, but this world is shot through with disease and death and if you want to save living things you have to keep them from becoming genetically impoverished.
But the processes I'm talking about I assume would have operated in the original world too, taking creatures out along interesting lines of variation until they run out of variability, but not being threatened by any of that. In THIS world, however, they are threatened, but the point of my argument is that it proves there is a built-in limitation to variation of each Kind and that macroevolution is impossible. The only argument against it really is all those phantom mutations the ToE conjures up.
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