Evolution - Speciation finally observed in the wild?

[tyke]

According to the journal Science, following a 31 year study of Darwin's Finches on the Galapagos Islands, rapid hybridization and speciation has been bserved in the wild after a migrant finch managed to breed successfully and establish a colony.

This, hopefully will provide evidence for those people who declare that speciation has never been observed - well it has now.

The BBC website has a readable outline for the study but it is free to read (after registration) at the Science Journal website.

Let the excuses and the tap dancing begin!!

BBC : Bird seen becoming new species

 

[Strathos]

But they're still finches, call me when they turn into octopuses[/sarcasm]

 

[Radagast]

According to the journal Science, following a 31 year study of Darwin's Finches on the Galapagos Islands, rapid hybridization and speciation has been bserved in the wild after a migrant finch managed to breed successfully and establish a colony.

The question is whether Geospiza conirostris, Geospiza fortis, and the new population are truly three species, or just three subspecies. After all, if they can breed with fertile young, then perhaps they are not different species.

 

[tyke]

The progeny of the observed colony cannot breed with the other species of finches on the islands - as far as I understand it (and I'm definitely no expert on this) this is one of the definitions of speciation.

 

[Radagast]

The progeny of the observed colony cannot breed with the other species of finches on the islands - as far as I understand it (and I'm definitely no expert on this) this is one of the definitions of speciation.

Well, since it turns out that Geospiza conirostris and Geospiza fortis can interbreed, I can't see why the new population shouldn't be able to interbreed with both.

The paper is pointing out that the new population doesn't, but that doesn't mean they can't. And clearly the boundaries of "reproductive isolation" in the Galapagos are fuzzier than has been thought.

With other species, it's common for geographically separated populations, which could interbreed but don't, to be called subspecies.

 

[Saucy]

According to the article:

Due to an inability to recognise the songs of the new males, native females won't pair with this new species.

And in this paper, new genetic evidence shows that after two generations, there was complete reproductive isolation from the native birds. As a result, they are now reproductively - and genetically - isolated. So they have been breeding exclusively with each other over the years.

They can't reproduce not because it's an entirely new species, but they adapted in a way that the mating songs weren't distinguished by the females, so they were entirely isolated. That's completely different than saying it became a whole new species.

 

[tyke]

This new finch population is sufficiently different in form and habits to the native birds, as to be marked out as a new species, and individuals from the different populations don't interbreed.
According to the experts who have been involved for 40 years with these studies, seem to think that they are a new species.

http://This new finch population is...m the different populations don't interbreed.

 

[Radagast]

With other species, it's common for geographically separated populations, which could interbreed but don't, to be called subspecies.

A recent paper in Biological Reviews suggests that all six "species" of Geospiza are actually just one species:

We argue that the six putative ground finch species (genus Geospiza) of the Galápagos Islands represent a dramatic example of Sisyphean evolution that has been confused with the standard model of speciation. The dynamic environment of the Galápagos, closely spaced islands, and frequent dispersal and introgression have prevented the completion of the speciation process. We suggest that morphological clusters represent locally adapted ecomorphs, which might mimic, and have been confused with, species, but these ecomorphs do not form separate gene pools and are ephemeral in space and time. Thus the pattern of morphological, behavioural and genetic variation supports recognition of a single species of Geospiza, which we suggest should be recognized as Darwin’s ground finch (Geospiza magnirostris). We argue that instead of providing an icon of insular speciation and adaptive radiation, which is featured in nearly every textbook on evolutionary biology, Darwin’s ground finch represents a potentially more interesting phenomenon, one of transient morphs trapped in an unpredictable cycle of Sisyphean evolution.

The new study is actually consistent with that.

 

[xianghua]

According to the journal Science, following a 31 year study of Darwin's Finches on the Galapagos Islands, rapid hybridization and speciation has been bserved in the wild after a migrant finch managed to breed successfully and establish a colony.

This, hopefully will provide evidence for those people who declare that speciation has never been observed - well it has now.

The BBC website has a readable outline for the study but it is free to read (after registration) at the Science Journal website.

Let the excuses and the tap dancing begin!!

BBC : Bird seen becoming new species

well, since speciation is only a variation, its not realy evolution.

 

[Shemjaza]

well, since speciation is only a variation, its not realy evolution.

Why? That's all you need for evolution.

Humans are chimps are two variations of the group called ape.

 

[tyke]

well, since speciation is only a variation, its not realy evolution.

I consider this an unsupported assertion unless you provide evidence for your stance.

 

[DogmaHunter]

The question is whether Geospiza conirostris, Geospiza fortis, and the new population are truly three species, or just three subspecies. After all, if they can breed with fertile young, then perhaps they are not different species.

Speciation is always a process of an "ancestral species" evolving into sub-species.
Speciation is a vertical process.

 

[Radagast]

Speciation is always a process of an "ancestral species" evolving into sub-species.
Speciation is a vertical process.

To pick a couple of textbook definitions: "Speciation is the process by which one or more species arises from a common ancestor" and "Speciation is the process by which one or more populations of a species become genetically different enough to form a new species."

The paper by McKay and Zink which I cited earlier suggests that the genus Geospiza does not actually contain more than one true species. If that is so, no speciation has occurred.

Even if you take the currently accepted species boundaries, the population mentioned in the O.P. is not a recognised new species, and therefore its formation cannot be called an instance of speciation.

Indeed, the fact that Geospiza conirostris and Geospiza fortis can interbreed indicates that (going purely by the biological species concept) Geospiza conirostris, Geospiza fortis and the new population are all one species.

To pick a related debate, it has been suggested that the red wolf is a hybrid of Canis lupus and Canis latrans. But it does not follow that the red wolf is a distinct species (Canis rufus). It could be just a subspecies (Canis lupus rufus).

 

[DogmaHunter]

To pick a couple of textbook definitions: "Speciation is the process by which one or more species arises from a common ancestor" and "Speciation is the process by which one or more populations of a species become genetically different enough to form a new species."

Yes. And the sub-species, is the new species.

Even if you take the currently accepted species boundaries,

Well, in truth, there isn't really a clearly defined line which seperates one population from another in terms of "species".

Yes, in a lot of examples, the distinction is rather obvious.
For example, a tiger clearly is a different species then an elephant.

But the closer related the populations are, the lines get blurry.
It kind of depends from which particular angle one is talking.

In some cases, populations that CAN interbreed, but DON'T, will be called different species.
In other cases, the distinction will be reserved for those populations that are genetically incompatible with one another, to produce viable off spring.

Which, by the way, is exactly what we would expect from a gradual process like evolution...

Indeed, the fact that Geospiza conirostris and Geospiza fortis can interbreed indicates that (going purely by the biological species concept) Geospiza conirostris, Geospiza fortis and the new population are all one species.

From one angle, sure.
From another angle, if the two populations CAN interbreed but simply do NOT do it, it is fine to call them different species. After all, if there is NO interbreeding, then it is only a matter of time before they genetically simply won't be able to do so anymore.

Because if they do NOT interbreed (regardless of if they genetically can or not), then they are genetically isolated from one another and their collection DNA will simply diverge further and further as generations come and go.

To a point where they won't be genetically compatible any longer.

And that's the "blurry" line I was talking about: that period where 2 populations CAN interbreed, but don't. After a while, they will still be able to interbreed, but no longer will be able to produce fertile off spring. And after an even longer while, they also won't be able to produce non-fortile off spring either... they will end up genetically incompatible.

That's what genetic isolation inevitably results in.

To pick a related debate, it has been suggested that the red wolf is a hybrid of Canis lupus and Canis latrans. But it does not follow that the red wolf is a distinct species (Canis rufus). It could be just a subspecies (Canis lupus rufus).

A subspecies, IS its own species.

It's not hard....
If species A comes from species B, then A is a sub-species of B.

 

[tyke]

A subspecies, IS its own species.

It's not hard....
If species A comes from species B, then A is a sub-species of B.

I must admit, that's cleared the matter up for me now. Thanks!

How much more evidence do creationists need to accept the ToE as the only viable explanation of animal/plant diversity on the planet???

 

[DogmaHunter]

How much more evidence do creationists need to accept the ToE as the only viable explanation of animal/plant diversity on the planet???

The answer is "none", because while they might say that they need more evidence to accept evolution, what actually goes on is that their dogmatic religious beliefs don't allow them to accept evolution, regardless of the evidence.

I mean, as it stands Evolution theory is already among the most well-evidenced theories in all of science... In terms of evidential support for a theory, it doesn't get a lot more solid then that.

If the mountains of evidence for evolution currently know isn't enough for them, then no amount of evidence will ever be sufficient.

But as said.... it's not a lack of evidence that blocks them from accepting it. It's too much fundamentalist religious nonsense.

 

[Radagast]

Yes. And the sub-species, is the new species.

A new subspecies is not a new species, it is a new subspecies.

For example, a tiger clearly is a different species then an elephant.

Different from a lion, even (lions and tigers can interbreed, but their offspring are sterile). But in this case, there is certainly doubt about whether there is more than one true species of Geospiza.

Consider the tiger again: the Bengal tiger and the Sumatran tiger do not interbreed (they live in different places) but they could. Thus they are classed as two subspecies of Panthera tigris.

After all, if there is NO interbreeding, then it is only a matter of time before they genetically simply won't be able to do so anymore.

That's true enough, but that doesn't seem to have happened to the Geospiza finches yet. McKay and Zink argue that it won't happen, because of the specific circumstances there (including the fact that the island aren't far enough apart to stop interbreeding).

A subspecies, IS its own species.

Read my lips. Panthera tigris is a species, Panthera tigris sondaica is a subspecies. A subspecies is a taxonomic division within a species.

 

[Speedwell]

I must admit, that's cleared the matter up for me now. Thanks!

How much more evidence do creationists need to accept the ToE as the only viable explanation of animal/plant diversity on the planet???

No amount of evidence will convince them. The literal interpretation of Scripture which depends on creationism being true supports a political agenda which they are deeply committed to and won't give up.

 

[Almost there]

This new finch population is sufficiently different in form and habits to the native birds, as to be marked out as a new species, and individuals from the different populations don't interbreed.
According to the experts who have been involved for 40 years with these studies, seem to think that they are a new species.

Or they really want to think that they are a new species. I mean, if I were studying it for 40 years, I'd certainly want to believe that is what it is. But that's just me.

 

[DogmaHunter]

A new subspecies is not a new species, it is a new subspecies.

Dear. Another one arguing against evolution, yet has no idea on how evolution works.

Listen carefully: ever "new" species, is a subspecies of its ancestral species.

It's just the way it is.
Cats don't turn into dogs. Cats produce more cats and sub-species of cats

This is the hierarchical nature of the tree of life.

Speciation is a vertical process.
Homo Sapiens is a primate. A primate is a mammal. A mammal is a vertebrate. A vertebrate is an eukaryote.

Chimpansees and homo sapiens are cousin species.
They are both "sub-species" of the ancestral species they evolved from.
That one is a "sub-species" of the ancestral primate they evolved from.
That primate is a "sub-species" of the ancestral mammal they evolved from.

Etc etc etc.

The alternative is chimps producing humans or cats producing dogs.
And evolution does not work that way.

Different from a lion, even (lions and tigers can interbreed, but their offspring are sterile). But in this case, there is certainly doubt about whether there is more than one true species of Geospiza.

The very fact that one can have debates about if 2 certain populations are the same species or should be viewed as seperate species, is completely expected in an evolutionary context.

Because evolution is a gradual process. So whenever 1 population splits in 2 genetically isolated ones, they gradually start to diverge from one another.

During that period of divergence, they will go through the following phases:
- they still can perfectly interbreed, but don't (for various possible reasons)
- they still can interbreed, but no longer produce viable off spring
- they can no longer interbreed

This is completely within the expectation of evolution theory.
Unlike in a creationistic model, I might add.... if all species were "created" seperatly, I would NOT expect to find populations in any of those 3 phases. I would not expect such blurry lines. In that case, I'ld expect populations either can (and will) interbreed (= the same species) or they can't (= different species).

That's true enough, but that doesn't seem to have happened to the Geospiza finches yet.

Now you're confusing me. So, do you accept evolution theory or not?

Read my lips. Panthera tigris is a species, Panthera tigris sondaica is a subspecies. A subspecies is a taxonomic division within a species.

Yes. It's step 1 in the process of divergence.

Or did you think that a wolf suddenly gave birth to a labrador?