BILL #6: “How and why species multiply” by Peter and Rosemary Grant

| 23 Comments

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The sixth BILL is a visit with two of the biggest names in evolutionary biology, a couple of scientists who have undertaken one of the great long-term studies in recent scientific history. They are Peter and Rosemary Grant, whose work was the subject of the Pulitzer Prize-winning book The Beak of the Finch by Jonathan Weiner.

BILL the sixth is “How and why species multiply”, a tag-team lecture by Peter and Rosemary Grant presented as part of the Darwin’s Legacy course at Stanford University in 2008.

The lectures comprise a wide-ranging, engaging, and accessible introduction to the findings that emerged from the Grants’ three decades of research in the Galapagos archipelago. A book by the same title has just been released by Princeton University Press.

Don’t be put off by the length of the YouTube video; Peter begins his lecture at :14, Rosemary starts at :48 and finishes at 1:14, so the actual lecture is an hour. The remaining time is a panel discussion/Q&A that I haven’t previewed. Rosemary’s excellent lecture can stand alone, so feel free to start at :48 to enjoy a clear and engaging account of the influences of song and size on genetic variation and speciation. She ends with a nice summary of the whole lecture.

As usual, tips and comments are below the fold. Recommendations for future BILLs should be sent to the BILL czar (BILL at pandasthumb dot org) or can be left in the comments.


Peter, beginning around :13

  • Introductory comments on pre-Darwin ideas of speciation (pretty good ones). Then a more modern version from Muller.
  • Woodpecker finch using a tool. “But the beak itself is a tool.”
  • Two-sided coin: development of the beaks, and environment (factors favoring speciation)
  • Genes affecting beaks. Work with Cliff Tabin and Arkhat Abzhanovat at Harvard Medical School. “They’re the geneticists. We’re not.”
  • Finch genes injected into chicks.
  • Commenting on the two genes shown (so far) to underlie beak variation. “Implies that there is variation within a species that then becomes transformed into a difference between a species. In what? Either in the genes - we don’t think so - but in the genetic control of their expression, the regulators of these genes.”
  • Natural selection minimizing competition for food and minimizing interbreeding between related species.
  • Looking for “intermediates” on various islands of the Galapagos archipelago.
  • “Bizarre” feeding habits of some finches, including drinking the blood of boobies instead of eating the bugs that drink the blood of boobies. “This bird … has simply shortened the food chain.”
  • “It’s never been settled by humans, and I think you can see why.” Pictures of the field station.
  • On evidence for natural selection across generations: “Our result was anticipated by Darwin.”
  • “The island had been converted… and the direction of selection had changed.”
  • The long view…ought to follow a pattern. Selection oscillates in direction repeatedly, and not just once.
  • But found the opposite recently. Why? There had been a character displacement.

Rosemary, beginning at :48

  • How is genetic variability maintained? With oscillating selection we expect genetic variability to be “gradually eroded.” But it’s not. And… what is the barrier to interbreeding between species? Answers are related.
  • Short answer: song and morphology.
  • Experiments using museum specimens to test ability to discriminate members of one species. Mating with a stuffed museum specimen. [laughter]
  • Rosemary knows the “lyrics” of the songs; listen for muesli
  • A fascinating story of a song that became “rusty” when a bird was injured in the 1970s and has been inherited like that since then.
  • Lorenzian imprinting!
  • Hybrids: are they viable? Fertile? Yes. So there is some gene flow between species. There is no genetic incompatibility; the species are kept separate by song. Barriers are pre-mating barriers.
  • G. scandens and G. fortis appear to be converging genetically. But… hybrid fitness is episodic.
  • A separate example where hybridization does not happen. Why not? Harassment: “…just whipped in and beat the living daylights out of them.” Difference accounted for by size differential.
  • Hybridization has been common in the finch populations, and maintains genetic variation.
  • Finch population in Galapagos are “long before the points of genetic incompatibility.” How long? About 30 million years.
  • Episodic introgression can be a “rapid route to change” analogous to “artificial selection”
  • Does this happen in the wild? Yes, it is “very general.”
  • “Neither species nor environments are static entities, but dynamic, and constantly changing. To conserve species and their environments, we must keep them both capable of further change.”

23 Comments

Thanks for this Steve. It’s a wonderful presentation of the early stages of speciation.

This is great Steve. This is very similar to the presentation that first caused me to question the details of speciation as it had been presented to me by my textbooks and teachers in years of biology classes.

I hope that everyone who participated in or observed the discussion we have been having here on speciation will watch this … maybe more than once.

Do so with an open and unbiased mind, and with an ear to discerning what the Grants are really revealing from their evidence. While they are certainly cognizant of their audience and those who provide funding for their studies (not a bad gig I’d say) they are pretty forthright and honest about what can and cannot be concluded from the evidence they have collected.

As you noted above, one pertinent observation is that genetic incompatibility wouldn’t take place until 30 million years of complete separation (that would be without any of the type of hybridization they observed).

Did you also note the subtle comment by Rosemary at the end of her section that the “Tree-of-Life” is really better described as a web?

I read their book years ago. YEC does not have a complaint with trivial selection options for changing creatures. Whether true or not.

yet it makes a bigger point about the logic and case made by Darwin or modern researchers.

Finch beaks changing is not evidence for the great claims of evolution of mice to manatees. Its only a line of reasoning. Even if true it still would only be a line of reasoning and NOT a conclusion from “scientific’ investigation.

Confidence that evolution is true or likely because of selection going on within some species etc is not from science. Its only a reasoning. A hunch.

FM wrote:

“As you noted above, one pertinent observation is that genetic incompatibility wouldn’t take place until 30 million years of complete separation (that would be without any of the type of hybridization they observed).”

Actually, that’s not what she said. She said that in birds. on average, thirty million years of divergence will result in complete reproductive isolation. It can happen much faster. It happened faster in one bird population. It happened faster in the human/chimp split. Complete reproductive isolation can occur by many mechanisms, then by definition you have a new species. Now what do you think could ever prevent this from happening eventually? The evidence is clear that it has happened millions of times in evolutionary history. Deal with it.

Whether it’s 30 million years or “much faster” (like what … 1 million years?) we’re still talking about a theoretical period of time that is conveniently (at least for evolutionists) well out of what is empirically observable.

The only way biologists can claim to have observed “speciation” is by redefining the word species. Did you watch the panel, discussion after the talk? Peter spent several seconds explaining the simple conventional definition of species (true genetic reproductive isolation) … then rambled for several minutes trying to re-define what “species” has come to mean in order to pacify a belief in the institutionally accepted theory.

I can just imagine the conversation these two have in the privacy of their hotel room after a talk like this . .

Rosemary - “Seriously honey when do you think they will figure out what we’re really saying”

Peter - “As long as there’s two or more academics in the room I think were safe . . none of them will risk publicly asking the questions they must be thinking to themselves. Eventually the herd will turn but in the mean time I’m sure enjoying the speaking fees, book royalties, and free lunches…”

fittest meme said:

Whether it’s 30 million years or “much faster” (like what … 1 million years?) we’re still talking about a theoretical period of time that is conveniently (at least for evolutionists) well out of what is empirically observable.

So tell us, fittest meme, tell us why believing that God magically poofed everything into existence using magic is more believable than species evolving over the course of 3.75 billion years.

The only way biologists can claim to have observed “speciation” is by redefining the word species.

So what evidence do you have to support your own personal definition of “species”? I mean, besides blatant lying, and quotemining.

I can just imagine the conversation these two have in the privacy of their hotel room after a talk like this:

*catty inanity snipped*

So, being a snide, willfully ignorant idiot for Jesus not only makes you smarter than all of those stupid, evil scientists put together, but, it also grants you the superpower of mind-reading?

Oh, wait, no, you can’t read minds: you’re just insulting and degrading your betters because they aren’t deliberate idiots for Jesus like you are.

FM, your confusion about the concept of speciation has already been discussed more than it should have. Now that you are using your ignorance for bashing and trolling, you can continue embarrassing yourself (and whatever religion you profess) on the Bathroom Wall.

This comment has been moved to The Bathroom Wall.

This comment has been moved to The Bathroom Wall.

This comment has been moved to The Bathroom Wall.

This comment has been moved to The Bathroom Wall.

This comment has been moved to The Bathroom Wall.

Whether it’s 30 million years or “much faster” (like what … 1 million years?) we’re still talking about a theoretical period of time that is conveniently (at least for evolutionists) well out of what is empirically observable.

This is just wrong. Empirically wrong.

We’ve seen speciation occur a lot faster than 30 million years. Look at dogs and wolves. They can and do occasionally exchange genes. But how often does that occur in nature? How many dashunds are mating with wolves and vice versa.

Same thing with domestic cats and their middle eastern wild cat ancestors.

Or with corn and its wild progenitor, Teosinte.

Or with wheat and its wild ancestors, some of which are still around.

Or with Tunisian and Madeirian mice.

In all these cases, from historical and archaeological evidence, we know when the split occurred. Somewhere between 12,000 and 6,000 years ago depending on the speices.

In the case of Madeirian and Tunisian mice, somewhere in the last 500 years.

You don’t need complete reproductive isolation for speciation to occur. You just need it to be rare enough so that there are two separate and diverging gene pools.

And you also don’t have to see something in real time to recognize the consequences of it having occurred in the past.

raven said:

We’ve seen speciation occur a lot faster than 30 million years. Look at dogs and wolves. They can and do occasionally exchange genes. But how often does that occur in nature? How many dashunds are mating with wolves and vice versa.

Same thing with domestic cats and their middle eastern wild cat ancestors.

Or with corn and its wild progenitor, Teosinte.

Or with wheat and its wild ancestors, some of which are still around.

Or with Tunisian and Madeirian mice.

In all these cases, from historical and archaeological evidence, we know when the split occurred. Somewhere between 12,000 and 6,000 years ago depending on the speices.

In the case of Madeirian and Tunisian mice, somewhere in the last 500 years.

You don’t need complete reproductive isolation for speciation to occur. You just need it to be rare enough so that there are two separate and diverging gene pools.

You’re absolutely right Raven, if you consider speciation to have occurred when pre-mating barriers limit gene flow to being “rare.” Unfortunately, by this definition you would have to classify Australian Aborigines and Scandinavian Caucasians to be different species. Obviously some better definition of species is needed.

The 30 million year reference was what Rosemary Grant said was the average time divergent populations of birds must be kept reproductively isolated before true genetic incompatibility was achieved. The Grant’s research indicated that the different “species” of Galapagos Finches showed no genetic incompatibility even after a supposed 8 million years of radiation on the archipelago. They continued to witness hybridization occurring (“rare” in the context of their observation period but very common in the context of 8 million years). It was their conclusion that this “introgressive hybridization” was what provided genetic diversity to different populations and thus maintained the finches capability of producing enough phenotypic variation to survive environmental changes.

The Grant’s study of Galapagos finches is probably the most complete and extensive study of natural population divergence available in the scientific literature. If you have a comparable set of data on the other examples you present, and it shows something contradictory to their findings, please post references.

I’m particularly surprised that you considered domestic dogs and wolves to be separate species. It’s pretty well known that they are not. While a dachshund may not mate with a wolf directly because of pre-mating barriers it is well known that an in-vitro cross would produce a reproductively viable offspring. This however, would not be the only way that wolf and dachshund genes could end up coming together. It is entirely conceivable that a small wolf/husky mix could mate with a large dachshund/beagle mix and thus in 2 generations the genes would be “naturally” mixed.

As Rosemary indicated in her presentation plant and animal breeders regularity re-introduce ancestral genes into their domesticated varieties for various purposes.

I would suggest that the empirical evidence for the examples you list would actually show very similar findings to the Grant’s. “Speciation” is only achieved if one defines species in the evolutionists preferred subjective and ambiguous way. If a more objective (and thus scientifically testable) distinction of post-mating genetic incompatibility is used then no speciation has occurred.

I suppose speaking the truth on a subject that Professor Matheson selected will again get me sent to the Bathroom Wall. I would have though a professor would be more interested in participating in discussion and teaching rather than just insulting and censoring those whose interpretations of the evidence contradict his own. Dr. Matheson is acting more like a Pharisee protecting the institutionalized belief system of evolution than the follower of Christ he claims to be … (http://sfmatheson.blogspot.com/p/about.html).

Come on brother Steve, use your God given knowledge, position and influence to pursue the truth where ever it leads … not obscure it.

Unfortunately, by this definition you would have to classify Australian Aborigines and Scandinavian Caucasians to be different species.

Not at all. Australian aborigines and northern Europeans live together and exchange genes often. There are a lot of mixed race people in Australia these days.

In terms of human history and lifespan, the separation between the two populations wasn’t very long.

The most isolated human gene pool turns out to be the Bushmen of South Africa, estimated to be something like 90,000 years old. There is speculation that if they had stayed separated for another few 100,000’s of years, they might have speciated. That isn’t going to happen either. There are a lot of mixed Bushmen, Africans, and Europeans. It turns out that Bishop Desmond Tutu has a Bushman ancestor.

creationist:

I’m particularly surprised that you considered domestic dogs and wolves to be separate species. It’s pretty well known that they are not.

That is false, not true. Some biologists consider dogs and wolves to be the same species. Others do not. There is no agreement.

Janice Koler-Matznic:

The vast majority of biologists, except the molecular DNA types, do not consider the domestic dog, Canis familiaris, a subspecies of the gray wolf, Canis lupus. This name change and lumping of the two was proposed by Wilson and Reeder in the checkist Mammals of the World, and has subsequently been picked up by those who don’t seriously consider the implications of arbitrarily “wipeing out” a species on paper. Recently, the subspecies designation is becoming more frequent in the literature, especially in genetics The vast majority of biologists, except the molecular DNA types, do not consider the domestic dog, Canis familiaris, a subspecies of the gray wolf, Canis lupus. This name change and lumping of the two was proposed by Wilson and Reeder in the checkist Mammals of the World, and has subsequently been picked up by those who don’t seriously consider the implications of arbitrarily “wipeing out” a species on paper. Recently, the subspecies designation is becoming more frequent in the literature, especially in genetics.

The species concept is fuzzy. This is because species are fuzzy. While two populations will diverge during speciation, there is always going to be cases where it’s questionable whether two populations are subspecies or separate species.

Nice try Raven. However, this guy is not here for an adult conversation. I would recommend responding t=o him only on the bathroom wall.

“Speciation” is only achieved if one defines species in the evolutionists preferred subjective and ambiguous way. If a more objective (and thus scientifically testable) distinction of post-mating genetic incompatibility is used then no speciation has occurred.

That isn’t the definition of a species. Post-mating genetic incompatibility is not the criterion for differentiating two species. It never has been.

There are many defintions of a species because the concept is fuzzy. It is fuzzy because reality is fuzzy. Even so, that has never been one of the many definitions.

You are just making things up. Lying.

Mammal species might be fuzzy, since they have hair. But reptiles don’t have hair, so they ain’t fuzzy. :p

Nice try Raven. However, this guy is not here for an adult conversation. I would recommend responding t=o him only on the bathroom wall.

Oh. OK, not that I’m going to spend any more time on this. He does seem to do what all creationists do. Lie a lot. He is just making it up as he goes along.

BTW, troll we have seen an example of rapid post-speciation incompatiblity. It is rare but that is because it is a rare event.

wikipedia:

In 2008 a speciation gene causing reproductive isolation was reported.[24] It causes hybrid sterility between related subspecies.

Time to Move The Goalposts. And Play Wack-A-Mole.

FM, the reason your comments get sent to the BW is because you are engaging in what I consider to be trolling, i.e., the repetition of a single point, relevant or not, accurate or not, ad nauseum. In your case, the “point” is your own confusion about the concept of speciation. You are apparently unwilling to read up on the subject; if you did, you would learn that there are several different (sometimes overlapping) conceptions of “species.” I personally cannot understand how someone who understands that fact could continue to harp on the topic, and I especially cannot understand how a person of integrity could continuously and repeatedly use their ignorance to level accusations against “evolutionists.” But that’s what you’re doing.

I also consider it to be dishonest to refer to the moving of uninteresting bickering to the BW as “censorship.” Your view may differ, but now you know where I stand. Unlike you, I will not play the religion card here. And unlike you, I do not enjoy the protection of anonymity. Please do not bother to post any further comments on the BW policy.

If you want your comments to avoid the BW, then demonstrate more of a tendency to read and understand the science and less of a tendency to engage in inane repetition and blanket accusation. The place to start, I would suggest, is with a more informed understanding of species concepts. With that in hand, you will be better prepared to discuss the meaning and implications of the topics explored by the Grants and others.

And since you profess to be eager to learn, I recommend this 2007 minireview as a nice place to start in understanding the genetics of speciation. The Wikipedia page on species concepts is a great overview of the use and history of species concepts.

Steve,

Thanks for the link. Other posters here would be wise to study the article.

Steve,

Thanks for posting their lecture. I was fortunate to have heard them twice in 2009; once at Columbia University where one of those in attendance was Columbia journalism professor Jonathan Weiner, and the other at a Linnean Society of New York meeting. While they are now both professors emeritii, I believe they are still continuing their research, with the most able assistance of former students and postdocs.

Sincerely,

John

@ FM - You would do well to heed Steve’s advice. Instead of your ongoing creotard trolling, please learn something about biology for once, via the online resources Steve has indicated.

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This page contains a single entry by Steve Matheson published on October 26, 2011 3:15 PM.

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