How much variation in a population

[gbrooks9 (George Brooks)]

@Lynn_Munter

What? Why would you think this? In the beginning of the domestication process, you would be dealing with a small and fairly homogeneous population which had not differentiated much from wolves or from each other.

@Lynn_Munter

Oh for goodness sake.

My starting premise is that “on average”, all species have an average propensity to form Ring Species. I’m well aware that this is just an assumption. But for now it’s a handy starting place.

Second, a Ring Species is created by pockets of genetic exchange, moderately bound by de facto separation of sub-populations (by geographic impediments, or by sheer distance as an impediment ) limiting the free exchange of genetic information).

Third, in view of the second point above, the creatures we call dogs today seem significantly Less likely to create a Ring Species event, than the creatures our ancestors called dogs many thousands of years ago (think about the first dogs brought to Australia by humans?). So what is the difference between the original Dogs and the Dogs of the modern period?

Fourth, based on our understanding of Ring Speciation, the difference appears to be that the constellation of genetic site that affect “Reproductive Compatibility” is much more thoroughly mixed in the modern canine population than it was before human breeding efforts began in earnest.

Epilogue: If you don’t think dogs were ever good candidates for Ring Speciation, I would respect that view. And I probably would agree with that conclusion without much resistance.

My prior “compare/contrast” discussion was my awkward attempt to discuss how an “average” population of mammals could become extraordinarily unlikely to trigger a Ring Species event if human intervention could so persistently effect a mixing of genetic factors (Alleles!) - - with the unintentional artifact that mating pairs which (generation after generation) demonstrated their high reproductive compatibilities would, by definition, make it increasingly difficult to find mating pairs that were less reproductively compatible.

Lynn, I think you will find that you and I are pretty much on the same page on the topic of Ring Species. I only ask you and others to consider what it would mean for a population to, mathematically speaking, be especially resistant to forming Ring Species events.

[gbrooks9 (George Brooks)]

@Lynn_Munter

Before you get too much more wound up on this, I thought it was clear he knows ring species are a thing, he just doesn’t think ‘ring speciation’ is a verb. Since he has more biology expertise than either of us, don’t play the role you were just criticizing when it was nonlin and swamidass in the other thread.

@Lynn_Munter

You are obviously more compassionate and willing to discuss the nuances than our dear friend, sfmatheson. Instead of just complaining about the verb form of what I freely admit is a neologism… he seemed intent on dismissing the whole topic of my discussion.

Frankly, I think he and I would enjoy each other’s company via skype, discussing the day’s class on Evolutionary topics. Oh, maybe not at first. But inevitably so.

I am quite well aware of his professional reputation. And I have no intention of comparing him to the regular cast of the “usual suspects” who just can’t accept a biological fact when they bang their toe into one. I would encourage you not to conclude that I am such a suspect either.

Ben went off the rails. And without much investigation, sfmatheson has concluded that I must have said or written something particularly stupid. And yet nobody seems quite able to put their finger on exactly what it was that I wrote that was stupid. Not even Ben. That’s why I provided a re-hash of our earliest postings on the matter in a thread that is now (mercifully) closed.

When an error is identified, I am usually pretty quick to accept my frailty in contributing to that error. But when no facts are being offered, and all that is being hurled around is innuendo and invective, I think you have already found me tediously resistant. My favorite part of the tedium was when I demonstrated that even Ben had to agree (in veiled language) there were not enough alleles in the first one-celled creatures to ever make a Whale. Instead of just plainly admitted it, he concocted a pretty wild explanation that by asking Ben a rhetorical question, it somehow proved that I was a dumb about Haploidy and Diploidy (FN - see footnote at bottom).

But let’s not digress any further. **I think the topic of an “Anti-Ring Species” (that’s an awful name, isn’t it?) does help some audiences understand what exactly makes a Ring Species even possible. And those things that can go together to make a Ring Species, can also be kept separate, making a Ring Species most difficult to create.

I believe centuries of intensive dog breeding by humans unintentionally provided the antidote to those factors that would ordinarily contribute “to the Formation of a Ring Species” (aka, “to Ring Speciation”).
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FOOTNOTE **
Haploidy and Diploidy: Yikes! How about these words for awkwardness. Look at these topic
non-euphonious usages!:

o Haplodiploidy - Wikipedia < Haplo - Di - Ploidy … wowzers!
o Ploidy - Wikipedia
o The evolution of Haploidy and Diploidy - ScienceDirect

It makes me a little nostalgic for a phrase like “Ring Speciation” !!! Ha!

[sfmatheson]

@gbrooks9

You write that there is no such thing as “ring speciation”

Yep. And there isn’t. There’s speciation and the stages of divergence that lead to it. “Ring speciation” is nonsense. A “ring species” did not undergo “ring speciation” as though that’s a distinct process.

[Lynn_Munter]

@gbrooks9

My starting premise is that “on average”, all species have an average propensity to form Ring Species. I’m well aware that this is just an assumption. But for now it’s a handy starting place.

Is it? Biologically, I have no idea what such a propensity would consist of. I think ring species occur after sufficient time and genetic divergence in a broad and differentiated enough environment.

@gbrooks9

Third, in view of the second point above, the creatures we call dogs today seem significantly Less likely to create a Ring Species event, than the creatures our ancestors called dogs many thousands of years ago (think about the first dogs brought to Australia by humans?). So what is the difference between the original Dogs and the Dogs of the modern period?

This may be the crux of the matter here. The difference between the original dogs and the dogs of the modern period is that modern dogs have spent more time diverging from each other. The first Australian dogs were not very different from original non-Australian dogs. But modern Australian dingoes are very different from most modern dogs!

@gbrooks9

Fourth, based on our understanding of Ring Speciation, the difference appears to be that the constellation of genetic site that affect “Reproductive Compatibility” is much more thoroughly mixed in the modern canine population than it was before human breeding efforts began in earnest.

This sounds like nonsense to me. I see the point you are trying to make, but you might be able to make it better if you took the course others have suggested.

@gbrooks9

Epilogue: If you don’t think dogs were ever good candidates for Ring Speciation, I would respect that view. And I probably would agree with that conclusion without much resistance.

Let me be specific: I don’t think nearly enough time has elapsed for dogs to become a ring species. That is not to say that they could not become one, a million or two years down the road.

@gbrooks9

mating pairs which (generation after generation) demonstrated their high reproductive compatibilities would, by definition, make it increasingly difficult to find mating pairs that were less reproductively compatible.

This could apply just as easily to evolution in general; there is nothing about artificial selection which makes this more likely.

@gbrooks9

I only ask you and others to consider what it would mean for a population to, mathematically speaking, be especially resistant to forming Ring Species events.

You raise an interesting question, but I don’t think the way you have applied it to dogs, specifically, holds up the way you thought it would. I think the rarity of ring species in the natural world speaks to the obstacles to be evaded along the path.

@gbrooks9

I think the topic of an “Anti-Ring Species” (that’s an awful name, isn’t it?) does help some audiences understand what exactly makes a Ring Species even possible. And those things that can go together to make a Ring Species, can **also be kept separate, making a Ring Species most difficult to create.

Again, I think it would help your case if you had a firmer grounding in biology. I have pointed out a great many points you have been off about so far. I don’t think dogs are an anti-ring species, if such a thing exists. But I will not have much more time for point-by-point disagreement on this topic, especially since it seems to be approaching diminishing returns.

Thanks for your considerate words and replies!

[gbrooks9 (George Brooks)]

@sfmatheson

Yep. And there isn’t. There’s speciation and the stages of divergence that lead to it. “Ring speciation” is nonsense. A “ring species” did not undergo “ring speciation” as though that’s a distinct process.

@sfmatheson,

I think it would have been useful to have spelled out your objection to the term “Ring Speciation” to begin with, rather than to attack the term in a way that would confuse others into thinking you didn’t think Ring Species was valid terminology.

I’m not going to fall on my sword on a neo-logism like “Ring Speciation”. But there is a certain economy to the phrase. But out of respect for your preferences, I have been trying to frame my thoughts along the use of phrases like these:

“lead to a Ring Species event” or the more plain “lead to a Ring Species”, or “create a Ring Species”.

But I wonder if you are being a little too fastidious about the general concept. You write: “A ‘ring species’ did not undergo ‘ring speciation’ as though that’s a distinct process.”

I agree with you completely that the processes involved are not distinct. But the resulting situation sure seems distinct to me. I will confess that it was only last year that I had ever heard of Ring Species. [< is that how we would write it when there is more than one Ring Species? It gets pretty dicey when we start trying to use the plural forms of Species and Ring Species.]

I had no idea that there was even one such Ring Species, let alone a handful of them - - or a larger handful of those cases where the population is not quite yet a Ring Species. Certainly the concept of the Ring Species should be much more discussed and celebrated. It’s quite amazing to consider that even in North America we have the humble Florida and Alaska Rabbits so strikingly exhibiting Reproductive Incompatibility and the phenotypical differentiations that almost inevitably come from such incompatibilities.

One YEC fellow tried to dismiss the whole idea of a Ring Species by saying that artificial insemination could ‘probably’ reverse the process. I’m not quite sure how he expected to disprove the evolution of the whale with an argument like that.

Dr. Matheson, if you have recommendations for any journal articles that discuss the details of genetic sites/alleles that most closely influence a subject’s “Reproductive Compatibility”, I would be most eager to follow up on reading them!

Respectfully & Sincerely,

George Brooks

[sfmatheson]

@gbrooks9

if you have recommendations for any journal articles that discuss the details of genetic sites/alleles that most closely influence a subject’s “Reproductive Compatibility”

Not sure what exactly you mean, and really will never understand why you capitalize words so often. Here are some basic reviews of speciation genes, most of which are genes that somehow influence reproductive isolation.

Speciation genetics: current status and evolving approaches
Speciation genes (chapter from Encyclopedia of Evolutionary BIology
The genes underlying the process of speciation

[gbrooks9 (George Brooks)]

@Lynn_Munter

Is it? Biologically, I have no idea what such a propensity would consist of. I think ring species occur after sufficient time and genetic divergence in a broad and differentiated enough environment.

@Lynn_Munter

I think you are starting to invest too much time in micro-analyzing my every sentence. Your posts are now starting to look like Ben’s… where he rips into each and every sentence or two … counting the warrior’s coup against his opponent. I object to the approach out of hand. I will never attempt to respond to all those paragraphs you have laid out. I have no plan to even read all of that.

But as a demonstration of sincerity I will respond to your first … and with considerably robust discussion! I quote your response (above) to my discussion of the biological propensity for a population to create a Ring Species.

You seem most skeptical that there is much to think about. But let me give you an example of what I mean by using the Wiki illustration for the Larus Gulls:

Let’s accept the premise that there are 7 distinct “pockets” of gull populations. And because of the progressive nature of geographical distances, acting as impediments to a free exchange of genetic factors between pockets, we might be able to calculate some kind of “Index of Difference” between the gene pool of sub-groups (2) and (4) and between sub-groups (2) and (6).

As the distance between sub-groups increases, the Index of Difference (however it might be calculated) should also increase… but only in reference to the gradient as defined by “Norway heading East” vs. “Britain heading West”, right?

In the polar map image, sub-group (7) is pretty darn close to sub-group (1), and even sub-group (6) isn’t too terribly far from (1) - - when compared to how far (6) is from (2) going in the opposite direction.

But historical developments do have their consequences. And the spread of the population appears to have anchored itself in Scandinavia, and extended itself further and further East. I’m sure there is an interesting story behind that progression.

The whole point of the diagram is to show how geography has influenced the growing genetic differences between sub-group (1) and sub-group (6) and/or (7). A comparison on these sub-groups should produce the highest mathematical calculation of “Index of [Genetic] Differences”.

But let’s ask some hypothetical questions: What if there was an affordable way to install feeding stations in key areas of the Arctic Polar region? Feeding stations that would attract members of some of these sub-groups? And what if we could control how many birds we could attract by carefully calibrating proximity of the feeding stations to the various concentration of population members, and by how much food was deposited at the various stations.

TEST QUESTION: What percentage of a sub-group would have to be enlisted, and how many sub-groups (and even what specific sequence of sub-groups) in order to introduce the genetic information of the “Westerly” populations in sufficient volumes into the “Easterly” populations to stabilize the genetic trend towards increased genetic differences to virtually ZERO?

The process would be analogous to installing “air pipes” of various diameters from one sub-group to another … allowing a set percentage of one group to begin exchanging genetic variance with a group that it ordinarily never mated with. At what percentages would the exchange even be noticeable? And at what percentages would the exchange be sufficient to prevent any further mathematical differentiation… but not to reverse the process?

And then, what percentage would be required to reach the tipping point of genetic exchange… where we could forecast than in 400 years, or a 1000 years, that groups (7) and (1) could once again mate and produce offspring? Finally, what percentages would have to be in play where all significant differences in “Reproductive Compatibility” were eliminated? … where (7) and (1) - - though they may look a little different - - essentially displayed the very same level of compatibility as groups (2) and (3), or (3) and (4), and so on?

So here’s the structure for the above questions to be asked. But this is just a prelude. The two serious questions to be answered by all this time and money invested is:

A) What genetic sites most closely affect “Reproductive Compatibility”? What process, or protein, or other elements prevents two individuals that look the same from producing fertile offspring? And what are the elements that allow 2 individuals that look different to still produce fertile offspring?

B) Having all this bounty of mathematical detail, we could certainly create an “Index of Propensity” (I would call it the Munter Index!).

^^^ The Munter Index <<<< !!!
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It would be the mathematical measurement of the tendency for a population, divided into “n” groups, to create terminal populations that cannot produce fertile offspring! This would be quite an accomplishment!

But wait, there’s more! (I’ll be selling apple peelers in my next thread!.)

If we discover the answers to Question (A), and create a benchmark using the Gulls (or some other convenient animal group), we would then be able to apply the formula, using identical “Quantities n”, and forecast which groups (with their current genome) is least likely to create a Ring Species, and which groups are most likely to create a Ring Species!

Needless to say, there would be considerable standard deviations to cope with… and it would probably take an awful lot of sampling to get anywhere near a helpful measurement. But theoretically it would be possible. And it would demonstrate what I think many professionals would believe is the very heart of Evolutionary science:

. . . . what does it take to effect changes in Reproductive Compatibility, and what are the time frames for the process?

We would have the mathematical explanation for why some populations (like Lions and Tigers) seem to look very different, but still have some rudimentary Reproductive Compatibilities. The ultimate reason for Lions and Tigers looking so different is that the originators of their respective populations headed into different ecological niches.

Tigers headed into the tropical areas of India. Lions headed into the savannah regions of Africa. And the combination of Drift and Selection produced stripes on tigers and social living on Lions. But all this was not enough to break their Reproductive Compatibility. We call them two different species for practical reasons … or out of courtesy to our elders. But it seems clear that Lions and Tigers, together, would not qualify as a Ring Species. They just “get on” way too well!

While other populations of other creatures might look much more alike … they have stopped being able to breed with members of the other group many eons ago. And today, we still cannot answer exactly why.

In recent months, we have had at least 2 YEC-like participants insist that Speciation was not real, and that even it was, it would not lead to dramatic differences in animals (like Bears vs. Lions). But once we crack the math on Reproductive Compatibility, I think objections like those will become a dead thing from the past.

[gbrooks9 (George Brooks)]

@sfmatheson

Not sure what exactly you mean, and really will never understand why you capitalize words so often. Here are some basic reviews of speciation genes, most of which are genes that somehow influence reproductive isolation.

Speciation Genetics: current status and evolving approaches
http://rstb.royalsocietypublishing.org/content/365/1547/1717

Speciation genes (chapter from Encyclopedia of Evolutionary Biology
https://nature.berkeley.edu/blackmanlab/Blackman_Lab/Publications_files/SpeciationGenes_EoEB.pdf

The Genes underlying the process of speciation
http://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(11)00002-4
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[END OF QUOTE]

My mother never understood why I loved upper case letters either. Believe me, the Administrators here at BioLogos had to basically invoke a threat of lobotomy to get me to stop capitalizing whole words. It is such a great joy too type words like UNICEF, or “Man from UNCLE” … because my old friends the upper case letters get to come out and say hey!

But back to important matters! I very much appreciate these links! And no doubt others will … as they go back through the archives!

Thanks again!
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
HERE ARE THE LINKS AGAIN … SO THEY DON’T
GET BURIED IN THE BODY OF THE POSTING
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Speciation Genetics: current status and evolving approaches
http://rstb.royalsocietypublishing.org/content/365/1547/1717

Speciation genes (chapter from Encyclopedia of Evolutionary Biology

SpeciationGenes_EoEB.pdf

The Genes underlying the process of speciation
http://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(11)00002-4

[Lynn_Munter]

@gbrooks9

I think it would have been useful to have spelled out your objection to the term “Ring Speciation” to begin with, rather than to attack the term in a way that would confuse others into thinking you didn’t think Ring Species was valid terminology.

I was going to let this detail go unremarked, but as it appears you have not gone back to look at the post which began the issue, let me present it to you here with a little bold added for emphasis.

@sfmatheson

But that’s just not a useful comparison. There is no such thing as “ring speciation” and so there is nothing that could be its “opposite.” Dogs have been driven by selection to vary dramatically in morphology and other traits, but the forms (breeds) are reproductively compatible. Okay. And then there are examples of strong selection driving actual speciation. And then there are examples like ring species, in which the speciation has occurred, but stepwise, with the steps still visible.

Your conclusion that @sfmatheson did not believe in ring species was unwarranted from the start.

@gbrooks9

I think you are starting to invest too much time in micro-analyzing my every sentence.

I apologize that you feel I was being unnecessarily detailed in my previous response to you. It was not particularly fun for me to feel I had to be that detailed, and I’m afraid I may have been a little short with you as a result, for which I am sorry. But I had only just read the following statement of yours, and I didn’t want to risk being too vague about everything you were wrong on.

@gbrooks9

When an error is identified, I am usually pretty quick to accept my frailty in contributing to that error. But when no facts are being offered, and all that is being hurled around is innuendo and invective, I think you have already found me tediously resistant.

Thanks for the response to my first point, I appreciate all the effort you are going to to keep this discussion a positive one!

[gbrooks9 (George Brooks)]

@Lynn_Munter

Your conclusion that @sfmatheson did not believe in ring species was unwarranted from the start.

@Lynn_Munter

I think your analysis of that sentence is a little corrupted by your bias. Here is what I read as a “unit” of thought:

He quoted me:
“I thought it would be helpful if I brought in the Ring Species discussion. The whole thrust of my point is that dogs, as a breed, represents the very opposite of Ring Speciation.”

And his response was:

"But that’s just not a useful comparison. There is no such thing as “ring speciation” and so there is nothing that could be its “opposite.”

You see, the quote he chose, and his description of my quote was not merely that he didn’t like the made up phrase “Ring Speciation”… he rejected the whole concept, from beginning to end.

He didn’t like the words I chose.
He didn’t like the idea that there was something that could be opposite of the Propensity to create Ring Speciation.

I didn’t see a single thing that I could use to redeem my expectations regarding how the discussion was going to go.

And so I took his words at face value: Not only doesn’t he like the phrase, he doesn’t even accept the premise.

So, I reject your assessment of what I was justified to believe.

It seems pretty obvious to me that if there are genes that seem to control the progress of speciation, then it would also be true that configurations of those genes could encourage or discourage speciation.

My hypothesis was that protracted human intervention in breeding can affect the configuration of those genes. And in a calmer moment, with the full benefit of some shared preliminary discussion, I would think that you and he would also accept this hypothesis.

But perhaps I’m being overly optimistic.

What’s really more important is when you are going to get off my back? I did you a huge favor by not reading your monster of a posting. Whenever I see that pattern of paragraphs, I know there’s way too much energy behind the writings… Ben, Eddie and one fellow who will go unnamed were notorious for that style of posting.

I decided that I didn’t want my perception of your writings to be too colored by a moment of excitement. And based on your last post, I was correct in my decision.

So maybe we can get back to discussing Variation in Populations, yes?

[Lynn_Munter]

Whoops, fixed the monster bold; that was unintentional.

Consider me off your back and out!

[benkirk (Benjamin Kirk)]

@gbrooks9

I think it would have been useful to have spelled out your objection to the term “Ring Speciation” to begin with, rather than to attack the term in a way that would confuse others into thinking you didn’t think Ring Species was valid terminology.

I don’t see anyone but you being confused, as the objection was substantive and spelled out clearly.

[benkirk (Benjamin Kirk)]

@Donald

I understand that evolution in sexually reproducing species takes place with the variation already present within the population, but for how long? That is, if there were no supply of new mutations also contributing to the variation, how far could evolution go?

Hello Donald,

I think that a bathtub metaphor may be helpful.

Roughly, if evolutionary mechanisms have a bathtub full of existing heritable variation (aka polymorphism) to act upon for diploid organisms like us, new mutations add only a single drop of new water (one-millionth) to that bathtub each generation. This does not hold true for haploids such as bacteria.

So if mutation magically stopped tomorrow, this tiny ratio suggests you wouldn’t know it by looking at the products of natural selection and drift for thousands of generations.

(10 hr later) To add more, the water in the bathtub is reduced by inbreeding.

Some examples from humans: the child of first cousins would have a bathtub that is 7/8ths full. The child of a brother and sister would have a bathtub that is 3/4ths full.

Interestingly, we have many strains of fully inbred lab mice (repeated brother x sister matings) that essentially have empty bathtubs. They wouldn’t survive more than a generation or two in the wild.

[benkirk (Benjamin Kirk)]

@gbrooks9

Oh, Stephen, seeing as how you didn’t even know Ring Species was “a thing”

George, ring species isn’t a thing. It’s multiple things, as “species” in this term is plural, not singular.

This is the source of only some of your confusion.

[gbrooks9 (George Brooks)]

@benkirk

I don’t see anyone but you being confused, as the objection was substantive and spelled out clearly.

@benkirk,

So what you are trying to tell me and the world is - - that if we took, say, all land mammal populations, placed n the same geographic circumstances, would on average, display exactly the same propensity to create a Ring Species?

That there is no way to configure chromosomes so that some populations might be less likely, and other populations are more likely?

You are going to double-down on this assertion? The King of Alleles? You are telling me that shifting key Alleles around won’t make a bit of difference ?

Ha.

[sfmatheson]

@gbrooks9

So what you are trying to tell me and the world is - - that if we took, say, all land mammal populations, placed n the same geographic circumstances, would on average, display exactly the same propensity to create a Ring Species?

I missed that. He wrote that? Heh. No, he didn’t.

@gbrooks9

That there is no way to configure chromosomes so that some populations might be less likely, and other populations are more likely?

Huh? What does this even mean?

These writings are gibberish. I know @benkirk understands evolution, so I know you are misunderstanding him. Maybe trade one hour of typing for one hour of reading?

[gbrooks9 (George Brooks)]

@sfmatheson

I know @benkirk understands evolution, so I know you are misunderstanding him. Maybe trade one hour of typing for one hour of reading?

@sfmatheson:

Yes, agreed. @benkirk understands evolution. He understands a lot (!) about Evolution.

But I could say the exact same thing as someone else… and if I say it, he is just as likely to say “George doesn’t know what he’s talking about.”

As to the issue of “gibberish” . . . I don’t quite understand the objection. We all talk about evolution in all its nuances and subtleties. But as soon as I end a sentence with the phrase " less likely to create a Ring Species" - - all of a sudden, nobody knows what I’m talking about.

Looks like I’m going to have spend more time talking about Ring Species then. I think it’s the window to the education of a very confused Evangelical audience.

Postscript: Let’s assume everyone knows what a Ring Species is. It takes various time intervals for them to occur, and each case differs in terms of the genetic factors involved. So what would it take to undo the Trend of Ring Species formation? What would it take to stop a Ring Species from forming? And how would these inhibiting factors be quantified?

Please note the effort I am using to avoid the dreaded neologism: “Ring Speciation”.

[sfmatheson]

@gbrooks9

So what would it take to undo the Trend of Ring Species formation?

Extinction would work. Specifically local extinction of one or more of the populations that make up the ring. Then the two halves of the ring might diverge and there’d be no more ring. Not very interesting.

Or you could undo the ring by somehow allowing a lot more gene flow between the two ends of the ring. Maybe that would cause the two ends to become reproductively un-isolated, and then poof there’s no more ring species but just a set of varying adjacent populations.

I hope that these answers help you see that there’s really nothing extraordinary about the “formation” or maintenance of ring species. They are nothing more than sets of adjacent (geographically) populations that differ to a big enough extent that when you’ve gone a few steps away from any particular population, you discover reproductive incompatibility. For some reason, you seem to think there’s something bigger than that going on. I really don’t understand what you’re trying to say or to ask.

@gbrooks9

What would it take to stop a Ring Species from forming?

I think that high gene flow between neighboring populations will make it harder, since the only interesting thing about a ring species is, well, speciation along a gradient. And I think that ring species occurrences require large geographical ranges for the total collection of populations, not only to keep gene flow from homogenizing everything but for a gradient of adaptation (perhaps due to varying habitats) to exist across the range of the set of populations.

@gbrooks9

And how would these inhibiting factors be quantified?

Dunno. Why would they need to be? Given the rarity of this phenomenon, I think only modeling could get at the question, but I’m afraid I don’t see why the question is interesting or important.

[gbrooks9 (George Brooks)]

@sfmatheson

Or you could undo the ring by somehow allowing a lot more gene flow between the two ends of the ring. Maybe that would cause the two ends to become reproductively un-isolated, and then poof there’s no more ring species but just a set of varying adjacent populations.

@sfmatheson

Perfect! Indeed, this is where my interest lies. Which genetic factors have the most affect on diffusing the trend towards formation of a Ring Species?

Evangelicals frequently ask where can we go to see Evolution happening right now? And I’ve never actually read anyone making the suggestion that they could see the genomes of the Alaska Rabbit and the Florida Rabbit to see exactly what transpired that formed a new species!

We know it “happened relatively recently” because we still have the Minnesota Rabbits who can breed with the other sub-groups.

And what is the Biblical test for species or kinds? Right here:

Gen 1:24
And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.

Gen 1:25
And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.

I am reaching the conclusion that these may be the two most momentous texts in Genesis (after “Let there be Light”).

In the 24th verse, God said, “Let The Earth Bring Forth…” and only in the 25th verse does God repeat the same concept, but saying God was also involved in the process. When God triggered a storm so that his favored by win a battle, the Bible could as just as easily said: “And the water vapors gathered together to create the storm … And even God gathered the vapors together to create the storm…” God’s providence and God’s natural processes are of a single piece.

But we’re still not done with these verses. The text tells us that the animals “. . .bring forth the living creature after his [his/their] kind[s]…”

So: is the Alaska Rabbit and the Florida Rabbit of a kind? Apparently not! For they are unable to bring forth any generations!

But what about the Alaska Rabbit-v-Minnesota Rabbit … versus …
the Minnesota Rabbit-v-Florida Rabbit? Well, these must be Two Kinds . . . because they are “bringing forth” new generations.

“Yes, yes,” the YEC’s might say, “but how can it be two kinds if the Minnesota Rabbit is parenting both generations?”

The Bible does not answer this question exactly. But it does say that “kinds” are able bring forth new generations.

[sfmatheson]

@gbrooks9

Which genetic factors have the most affect on diffusing the trend towards formation of a Ring Species?

That question doesn’t make any sense to me. A ring species is just a series of populations. “Diffusing the trend” just isn’t coherent.