Researchers map the epic evolution of a 'ring species'

May 25, 2014
This image shows a West Siberian greenish warbler (P. t. viridanus). Credit: Darren Irwin, University of British Columbia.

The Greenish Warbler, long considered an idealized example of a single species that diverged into two as it expanded its range, has a much more checkered family history than biologists previously realized.

Ring species are a continuous loop of related populations, each adapted to its local environment, with two terminal populations in the loop meeting but now unable to mate. But an in-depth genomic analysis published today in Nature by University of British Columbia researchers reveals that the Greenish Warbler's genetic migration through central Asia involved periods of geographic separation and hybridization.

"We've shown that the evolution of ring species is much more complex than the smooth and continuous divergence envisioned by the classic model," says UBC zoologist Miguel Alcaide, the paper's lead author.

"If you view the ring of Greenish Warbler subspecies as a river, over the years the flow of populations has experienced periods of isolation—as if forming ponds during a draught—which accelerated genetic differences. This would have been interspersed with periods of flooding, or rapid exchange between populations. Interbreeding after range expansion has been, however, much more restricted among neighboring populations exhibiting substantial differences in morphology and behavior."

This image shows an East Siberian greenish warbler (P. t. plumbeitarsus). Credit: Darren Irwin, University of British Columbia.

Originally expanding out of southern Asia, subspecies of greenish warbler have diverged around the expanse of the Tibetan plateau over thousands of years, with two distantly related populations meeting again in the north, in central Siberia. Since early observations in the 1930s, biologists have thought the terminal sub-species incapable of mating. The new analysis shows that small regions of the western Siberian genome can be found in some of the eastern Siberian birds, indicating some successful hybridization between those forms.

"Given the new genomic evidence for historical breaks in gene flow, it's remarkable that traits such as plumage and song show such gradual change around the ring," says UBC researcher Darren Irwin, senior author on the paper and an expert who has studied greenish warblers since the 1990s.

"And despite the small amount of between the most distantly related forms in central Siberia, they remain highly distinct in songs, plumage and genomic patterns."

Greenish warblers were thought to have evolved from a single ancestral population that gradually diverged into two new species as it expanded northwards around the Tibetan plateau (grey arrows). Cutting-edge genomic approaches now show that at least two ancestral populations generated the current ring distribution (black arrows). The two populations met in northern India, where they extensively interbreed (bi-directional black arrows), and in central Siberia, where interbreeding is rare. Circles indicate 'dead ends' for gene flow. Credit: Miguel Alcaide, University of British Columbia.

"Overall, despite the complex patterns of gene flow, the Greenish Warbler still has the central characteristics of a ring species: two mostly distinct populations connected by a chain of populations in which traits and genes change progressively from one species to the other," says Irwin.

Explore further: Songbirds may have 'borrowed' DNA to fuel migration

More information: Paper: Genomic divergence in a ring species complex, DOI: 10.1038/nature13285

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User comments : 12

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JVK
1 / 5 (3) May 26, 2014
Re: "If you view the ring of Greenish Warbler subspecies as a river, over the years the flow of populations has experienced periods of isolation—as if forming ponds during a draught—which accelerated genetic differences."

If you view these subspecies as if they were a subspecies of any other vertebrate, the differences could be compared to those of white-throated sparrows in the context of the epigenetic effects of biparental feeding on nutrient-dependent pheromone-controlled ecological adaptations manifested in morphological and behavioral phenotypes. However, if you would rather view the differences as if they resulted from evolution via mutations and natural selection rather than view the similarities, which exemplify biological facts, do not read: http://www.pnas.o...abstract It is a factual representation of biophysically-constrained ecological adaptations.
Captain Stumpy
5 / 5 (3) May 29, 2014
: http://www.pnas.o...abstract It is a factual representation of biophysically-constrained ecological adaptations
@jk
YOUR model includes mutations, jk!
from the abstract
a chromosomal polymorphism (ZAL2/2m) is known to segregate with a behavioral phenotype
from Kris Wetterstrand, M.S. - Scientific Liaison to the Director for Extramural Activities, National Human Genome Research Institute, NIH
regarding ...polymorphism, mutations, etc. In the most literal sense, polymorphism means multiple forms. So a DNA polymorphism, simply put, is a difference between sequences. Mutation is the process by which changes are made. So, yes, you can think of mutation and polymorphism as equivalent. Genome changes due to "nutrient-dependent pheromone-controlled ecological adaptation" would have evolved because of natural selection acting on differences that original arose because of mutation.
JVK
1 / 5 (2) May 29, 2014
Moths do not mutate into butterflies. http://dx.doi.org...omms4957

The creation of a new pheromone blend is nutrient-dependent.

Kris Wetterstrand is not well-informed, and appears to be touting the pseudoscientific nonsense that is still being taught to unsuspecting students.

Mutations and amino acid substitutions are not the same. The epigenetic landscape is linked to the physical landscape of DNA in organized genomes via nutrient-dependent amino acid substitutions that differentiate cell types in individuals of species from microbes to man. Mutations perturb the protein folding that amino acid substitutions use to create and stabilize novel functional structure.
JVK
1 / 5 (2) May 29, 2014
Striking lack of diversity in prehistoric birds http://www.scienc...4911.htm

In the context of the misrepresentations by Ms. Wetterstrand of how biolophysically-constrained biodiversity arises via mutations, it appears that prehistoric birds waited to mutate into the extant species of today.

Does anyone know what they might have been waiting for? Does anyone think they were waiting for moths to mutate and become butterflies that the birds could see better.

If so, bird predation of butterflies might have caused the butterflies to mutate like the fawn-to-peppered colored moths that supposedly mutated due to bird predation.

But wait... birds must have mutated after the moth-to-butterfly mutations, not before, or there would be more diversity among the prehistoric birds in the fossil record.

It's all so confusing as to seem like only a very poorly concocted story, which is what evolutionary theory is.

Ecological variation leads to adaptations!
Captain Stumpy
5 / 5 (1) May 29, 2014
Mutations and amino acid substitutions are not the same
@jk
try re-reading that, illiterate-one. he never said that. it said
So, yes, you can think of mutation and polymorphism as equivalent
it also said
Genome changes due to "nutrient-dependent pheromone-controlled ecological adaptation" would have evolved because of natural selection acting on differences that original arose because of mutation
which ONLY CONFIRMS what you said here when I asked
DOES your model make any changes to the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element?
This is a yes or no answer
to which you answered
YES!
--Thanks for asking
THEREFORE arguing AGAINST mutation (and evolution) is arguing AGAINST YOUR OWN MODEL, and therefore you cannot use YOUR model as proof supporting the argument that mutations don't exist a YOUR model is supporting evidence that Mutations and evolutions DO exist!

Captain Stumpy
5 / 5 (1) May 29, 2014
Mutations perturb the protein folding that amino acid substitutions use to create and stabilize novel functional structure
@jk the illiterate one
so NOW YOU ARE SAYING that YOUR OWN MODEL cannot be a part of evolution because it causes mutations? again with the circular logic: IF it is proof of evolution BECAUSE it causes mutations THEN it cannot also be proof against mutations
Given that you continually post the same nonsense against mutations (specifically) and evolution (because it includes mutations as well as other effects) then by proof of your posts and re-verified above:
You MUST be ignorant of the lexicon in your field
you MUST be having issues with comprehension
YOU cannot be pushing KNOWN SCIENCE

MORE proof supporting mutations:
http://phys.org/n...lts.html

also in comments: PROOF that YOUR MODEL CAUSES MUTATIONS per your own admission in your own words
Captain Stumpy
5 / 5 (1) May 29, 2014
Kris Wetterstrand is not well-informed
@jk
more proof that you either ignored the information posted, you are illiterate and your translator didn't give you all the data, or you are ignoring relevant data which disputes your pseudoscience BELIEF (which you normally do) and since you've failed out of college, then I would assume (supported by the evidence above and in other posts) that you have severe issues with anyone of authority or who has an education as you feel threatened by their success and intimidated by your own failures.

read that again
Kris Wetterstrand, M.S. - Scientific Liaison to the Director for Extramural Activities, National Human Genome Research Institute, NIH
given that you are a clarified lab tech who would not even be eligible for the above position given your lack of education, how do you justify your libelous remark? (other than through your fear and intimidation)

so NIH, the Human Genome project and I agree... and you are still confused
JVK
1 / 5 (2) May 29, 2014
Two fixed differences among 597 amino acids drive a valine to alanine polymorphism that distinguishes morphological and behavioral phenotypes in white throated sparrows. In a clear indicator of what a single amino acid substitution can do, estrogen receptor 1 (ESR1), which is the gene that encodes estrogen receptor alpha (ERa), is most closely associated with what appears to be different nutrient-dependent hormone-organized and hormone-activated adult behavioral phenotypes.

A valine to alanine substitution also distinguishes a modern human population that arose during the past ~30K years from ancestral populations. The climate change, dietary change, and disappearance of the Neanderthals at the same time suggest nothing other than a nutrient-dependent pheromone-controlled ecological adaptation, which was modeled in the mouse.

Ms. Wetterstrand could clarify herself, but it is idiotic to say that my model causes mutations when it exemplifies ecological adaptations in all species.
anonymous_9001
5 / 5 (2) May 30, 2014
In a clear indicator of what a single amino acid substitution can do, estrogen receptor 1


What process was responsible for that substitution? If it's anything described by Shapiro, it's still classified as a mutation.
Captain Stumpy
5 / 5 (2) May 30, 2014
but it is idiotic to say that my model causes mutations when it exemplifies ecological adaptations in all species
@jk
you like to call educated people "idiot minions"... I now find it hilarious that you are calling yourself an idiot. very fitting.

your model DOES cause mutations, or did you already forget that conversation? remember.. I asked
DOES your model make any changes to the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element?
This is a yes or no answer
to which you answered
YES!
--Thanks for asking
so, drawing from your own words AGAIN...
IF it is idiotic to say that your model causes mutations
it is idiotic to say that my model causes mutations
AND you say yourself that your model causes mutations
YES!
--Thanks for asking
THEN one can only conclude, per your own words and conclusions, that YOU are an IDIOT!
this is your own logic and in your own words, jk.

JVK
1 / 5 (2) May 30, 2014
In a clear indicator of what a single amino acid substitution can do, estrogen receptor 1


What process was responsible for that substitution? If it's anything described by Shapiro, it's still classified as a mutation.


Therein lies a problem:
I wrote: "A valine to alanine substitution also distinguishes a modern human population that arose during the past ~30K years from ancestral populations. The climate change, dietary change, and disappearance of the Neanderthals at the same time suggest nothing other than a nutrient-dependent pheromone-controlled ecological adaptation, which was modeled in the mouse."

You want the mouse-to-human model to be considered in the context of mutations and natural selection that somehow lead to the evolution of biodiversity. I want it to be considered in the context of biological facts that link ecological variation to ecological adaptations in species from microbes to man.

I think we have reached an impasse.

anonymous_9001
5 / 5 (2) May 30, 2014
The mouse model you cite says nothing of DNA-level changes. It concerns expression changes. Those are not synonymous and the way you write implies you think they are.