If you accept microevolution

[jamesmorlock]

Simply because they are identical.

Consider an analogy:

Imagine that you can travel across the universe by walking. You have an infinite amount of time to do this, but you must make your journey by taking small steps. You have no destination, but you can go anywhere and you must never stop walking.

A thousand years pass. Where are you now? Further.
A million years pass. Where are you now? Even Further.
A billion years pass. Where are you now? Far, far away.

For every iteration of time, you will have traveled further and further. It is inevitable, for every small step takes you further. It is not possible to not travel far.

Microevolution is the small step. Macroevolution is the collective of small steps over a large period of time.

When walking for billions of years, how can you not be far away from your starting point?

[nygreenguy]

Conventionally, "macroevolution" in biology means evolution at or above the level of speciation. You can have indefinite amounts of microevolution without speciation ever occurring, so accumulated microevolution need not lead to macroevolution.

This is incorrect. When enough "microevolution" happens, the two sets of organisms are different enough that Biologists, somewhat arbitrarily, draw a line and call them two different species. What distinguishes one species from another is the quantity of microevolution. In other words, to use another analogy, 1 + 1 + 1 + 1 + 1 = 5. If you add up enough ones, you can't avoid reaching 5. If you add up enough micro-evolution, you get a new species.[/quote] Ok, if you add it up to infinity, perhaps. They could also just become extinct.

However, its generally not arbitrary. Most often it is from genetic incompatibility. The incompatibility isnt necessarily from a set number of differences. IOW, 2000 base pair differences isnt necessarily what makes 2 populations different enough to be incompatible. There has to be something specific about the changes which create the incompatibility.

[sfs]

Nothing prevents mutations from happening, but natural selection prevents most mutations with phenotypic effect from sticking around in the population, since they are usually deleterious

. Not quite. Most are nuetral; neither advantageous nor deleterious. Some are negative. And a few are beneficial; those are the ones that drive evolution.

Most mutations with phenotypic effect are not neutral.

There is no reason in principle why organisms should be viable beyond a certain mutational distance from existing species

.Why not? A mutation is a mutation. How does the mutation know how many previous mutations have happened?

If the first mutation makes the organism slightly worse, and the second makes it slightly worse again, and so on, eventually the organism won't do too well.

Whether too many mutations to a genome leads to a dead organism or to a new species is an empirical question(*), not one to be settled by analogies to space travel.

It is, and it's one that has been settled by empiricism; which is why the Theory of Evolution (ToE) is the foundation of modern Biology.

Yes, I know that. So? That doesn't make the original claims true.

At this point in our knowledge of Biology, we know that ToE is correct, and there is no such Biblical barrier, as well as we know anything in science.

We know that because we have strong evidence for common descent, not because we can determine from first principles what the effect of a large number of mutations will be on an organism.

Do try to pay attention to what is actually being argued, rather than just shooting off anti-creationist barbs.

[sfs]

But, yes it does hold.... since 'macro-evolution' is the accumulation of small changes.

Conventionally, "macroevolution" in biology means evolution at or above the level of speciation. You can have indefinite amounts of microevolution without speciation ever occurring, so accumulated microevolution need not lead to macroevolution.

Really??? Care to prove that claim??

No, I don't think I can prove it, but there's no reason in principle why a species should need to split. In a small, stable environmental niche, why would speciation occur?

If that was true, then, how do you explain ring species?

I explain ring species the usual way: partial geographic isolation of subpopulations, with accumulating genetic change (driven by selection or drift) leading to incompatibility between some subpopulations. Why do you ask? I never suggested that microevolution doesn't produce macroevolution, just that it doesn't have to.

[sfs]

In other words, to use another analogy, 1 + 1 + 1 + 1 + 1 = 5. If you add up enough ones, you can't avoid reaching 5. If you add up enough micro-evolution, you get a new species.

There are two problems with your analogy, and they represent the misunderstandings that I'm trying to correct. First, quite often evolution is not adding 1 + 1 + 1 + 1 . . , but rather adding 1 + 1 - 1 + 1 - 1 - 1 + 1 . . . That is, evolution often represents small wobbles (either in allele frequency or in phenotype) around a nearly stable point. For example, the Grants' work on finches showed beak length being driven by selection toward larger beaks, and then back toward smaller, and to larger again, and so on, depending on the weather that year.

Second, new mutations only have a decent chance of fixing in the population if they are neutral or beneficial. Once an organism has reached a local fitness peak, however, there are no more beneficial mutations to make, so only neutral ones will accumulate. Now it may be that some selectively neutral mutations will have enough functional effect that the organism can gradually change visibly, but probably not to any great degree: most aspects of an organism are well adapted to its environment, and any change will be deleterious. So new mutations will not keep adding to old ones; purifying selection prevents them. Now there are various mechanisms for overcoming that conservative tendency, but it is not as simple as random mutations accumulating freely.

[Autodidact]

Conventionally, "macroevolution" in biology means evolution at or above the level of speciation. You can have indefinite amounts of microevolution without speciation ever occurring, so accumulated microevolution need not lead to macroevolution.

This is incorrect. When enough "microevolution" happens, the two sets of organisms are different enough that Biologists, somewhat arbitrarily, draw a line and call them two different species. What distinguishes one species from another is the quantity of microevolution. In other words, to use another analogy, 1 + 1 + 1 + 1 + 1 = 5. If you add up enough ones, you can't avoid reaching 5. If you add up enough micro-evolution, you get a new species.

Ok, if you add it up to infinity, perhaps. They could also just become extinct. [/quote] They could, and they probably will; after all, 99% of all species that have ever existed are now extinct. All that I'm saying is that a sufficient quantity of micro-evolution, by definition, produces speciation. Just as 1 + 1 + 1 + 1 + 1 = 5, by definition.

However, its generally not arbitrary. Most often it is from genetic incompatibility. The incompatibility isnt necessarily from a set number of differences. IOW, 2000 base pair differences isnt necessarily what makes 2 populations different enough to be incompatible. There has to be something specific about the changes which create the incompatibility.

Well, when two populations get different enough, they either no longer interbreed, or can no longer interbreed, so they are called different species. That's all a species is, a segregated breeding population.

[Autodidact]

Nothing prevents mutations from happening, but natural selection prevents most mutations with phenotypic effect from sticking around in the population, since they are usually deleterious

. Not quite. Most are nuetral; neither advantageous nor deleterious. Some are negative. And a few are beneficial; those are the ones that drive evolution.

Most mutations with phenotypic effect are not neutral.

There is no reason in principle why organisms should be viable beyond a certain mutational distance from existing species

.Why not? A mutation is a mutation. How does the mutation know how many previous mutations have happened?

If the first mutation makes the organism slightly worse, and the second makes it slightly worse again, and so on, eventually the organism won't do too well.

And thus will go extinct, at which point all of those mutations lose their relevance.

Whether too many mutations to a genome leads to a dead organism or to a new species is an empirical question(*), not one to be settled by analogies to space travel.

It is, and it's one that has been settled by empiricism; which is why the Theory of Evolution (ToE) is the foundation of modern Biology.

Yes, I know that. So? That doesn't make the original claims true.

Which original claims?

At this point in our knowledge of Biology, we know that ToE is correct, and there is no such Biblical barrier, as well as we know anything in science.

We know that because we have strong evidence for common descent, not because we can determine from first principles what the effect of a large number of mutations will be on an organism.

No, it is because it is empirically supported. Science doesn't work from first principles, for the most part, but from empirical observation.

Do try to pay attention to what is actually being argued, rather than just shooting off anti-creationist barbs.

what is it that you are arguing?

I don't think making some mainstream uncontroversial descriptions of the state of modern Biology can really be considered an anti-creationist barb. Believe me, when I shoot off some anti-creationist barbs, you'll know it.

[Goat]

Nothing prevents mutations from happening, but natural selection prevents most mutations with phenotypic effect from sticking around in the population, since they are usually deleterious

. Not quite. Most are nuetral; neither advantageous nor deleterious. Some are negative. And a few are beneficial; those are the ones that drive evolution.

Most mutations with phenotypic effect are not neutral.

There is no reason in principle why organisms should be viable beyond a certain mutational distance from existing species

.Why not? A mutation is a mutation. How does the mutation know how many previous mutations have happened?

If the first mutation makes the organism slightly worse, and the second makes it slightly worse again, and so on, eventually the organism won't do too well.

And thus will go extinct, at which point all of those mutations lose their relevance.

Actually, what probably would happen is that the specific organism that has so many bad mutations probably won't out compete the members of it's own species with out those mutations, and therefore would not reproduce. This is the filter of 'natural selection'. Most extinctions are because the organism either could not keep up with environmental changes, or was out competed by a competing species... or it could be the species changed so much it no longer the same species.

[sfs]

If the first mutation makes the organism slightly worse, and the second makes it slightly worse again, and so on, eventually the organism won't do too well.

And thus will go extinct, at which point all of those mutations lose their relevance.

Actually, no, it won't. In reality, the deleterious mutations will occur and then be weeded out by natural selection (as Goat has pointed out). That's the point: you're ignoring natural selection.

Which original claims?

Start with the original claim that large amounts of microevolution necessarily produces macroevolution.

At this point in our knowledge of Biology, we know that ToE is correct, and there is no such Biblical barrier, as well as we know anything in science.

We know that because we have strong evidence for common descent, not because we can determine from first principles what the effect of a large number of mutations will be on an organism.

No, it is because it is empirically supported. Science doesn't work from first principles, for the most part, but from empirical observation.

So your claim is that we know that there is no barrier to indefinite genetic change based on empirical evidence, but not based on empirical evidence for common descent? That's the only meaning I can take from your response. Okay, just what empirical evidence are you talking about, that isn't based on common descent, show that?

Also, note that it was the claim that we can know from first principles that there is no barrier to indefinite genetic change that I was disagreeing with. Like when you wrote in another recent post, "All that I'm saying is that a sufficient quantity of micro-evolution, by definition, produces speciation." If something is true by definition, then it is true from first principles, not based on empirical evidence. So do we know that sufficient microevolution necessarily produces macroevolution based on empirical evidence, or based on definitions?

I don't think making some mainstream uncontroversial descriptions of the state of modern Biology can really be considered an anti-creationist barb. Believe me, when I shoot off some anti-creationist barbs, you'll know it.

The odds are good that, if you're disagreeing with a biologist, then what you're describing is not mainstream, uncontroversial biology.

[nygreenguy]

However, its generally not arbitrary. Most often it is from genetic incompatibility. The incompatibility isnt necessarily from a set number of differences. IOW, 2000 base pair differences isnt necessarily what makes 2 populations different enough to be incompatible. There has to be something specific about the changes which create the incompatibility.

Well, when two populations get different enough, they either no longer interbreed, or can no longer interbreed, so they are called different species. That's all a species is, a segregated breeding population.

This is what the discussion is about. The amount of difference needed can vary greatly.

[nygreenguy]

Second, new mutations only have a decent chance of fixing in the population if they are neutral or beneficial. Once an organism has reached a local fitness peak, however, there are no more beneficial mutations to make, so only neutral ones will accumulate.

Without additional information, this statement isnt exactly correct. This first presumes there IS a peak. This all depends on the heterogeneity of the fitness of the genotypes. Secondly, there must not be much selection pressure. If you are a tillman person, you may not this this is ever a possibility while grime leaves a bit of space for reduced selective pressure.

Also, if there is a "fitness peak" (theorized, not actual) then its hard to say if its a true peak. We only get peaks when we reach the biological limit of evolution in that environment. It a borderline argument to incredulity.

We can also have epistasis which can supplement existing genes in order to alter the fitness landscape.