News speciation

Redefining species: Nuclear vs. mitochondrial genes in birds

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From Geoffrey E. Hill at The Scientist:

What defines a species? Because the boundaries between species can appear so fluid, pursuing such a question seems, at times, like academic esoterica—little different than discussing how many angels can dance on the head of a pin. But accurate species definitions lie at the heart of biological investigations and management of natural resources (e.g., the US Endangered Species Act). It is troublesome, therefore, that new information on the genetic structure of long-recognized species of birds could jeopardize their status as full species.

The problem, in a nutshell, is that the DNA of many familiar species of birds holds signatures of substantial exchange of nuclear genes with other bird species. Such gene exchange matters because, by decades-old definitions, it is the isolation of gene pools that defines species. Substantial genetic exchange raises questions about whether these populations truly constitute species.

A case-in-point concerns the blue- and golden-winged warblers, two beautiful and very distinctive little songbirds that have long been regarded as separate species. A recent study, however, showed that these two “species” share more than 99 percent of their nuclear genes—much more gene sharing that we would expect between full species. More.

However, their mitochondrial genes are characteristic of separate species.

Idea! Use the money currently allotted to “Selling Darwinism to a Wary Public” to fund a re-examination of how we determine the boundaries of life forms instead.

See also: Big squawks over bird speciation?

and

Nothing says “Darwin snob” like indifference to the mess that the entire concept of speciation is in

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5 Replies to “Redefining species: Nuclear vs. mitochondrial genes in birds

  1. 1
    Dionisio says:

    “Idea! Use the money currently allotted to “Selling Darwinism to a Wary Public” to fund a re-examination of how we determine the boundaries of life forms instead.”

    Yes, and also to fund more top-down research on how exactly the biological systems function and also to promote open-mindedness among scientists so that they think out of wrongly preconceived boxes and stop being ‘unexpectedly surprised’ by their own discoveries.

    Here’s a starter:
    Does anyone understand exactly the whole enchilada of the formation and interpretation of morphogen gradients?

  2. 2
    Armand Jacks says:

    The fuzziness around species distinction is exactly what we would predict from evolution. Reproductive isolation is a requirement of speciation, but reproductive isolation is seldom absolute. For example, polar bears and grizzly bears are considered different species but where their ranges overlap, they will interbreed.

    Of greater interest, however, is how ID explains this.

  3. 3
    News says:

    Armand Jacks at 2, anyone familiar with the pop science media knows that speciation is the Holy Grail of Darwinism – otherwise, why the iconic status of Darwin’s finches? Speciation is a central problem for Darwinism, which began with a mechanism to explain the “Origin of Species” (now called, for convenience, natural selection acting on random mutation of individual parent genomes). It’s a mechanism that isn’t really very importoant because natural selection is a tautology and genomes turn out to be rather plastic from the outside too.

    Speciation is not an issue for ID because ID would expect plasticity. Who knows, maybe permanent, irreversible speciation is just a step on the road to extinction?

  4. 4
    Armand Jacks says:

    News:

    Armand Jacks at 2, anyone familiar with the pop science media knows that speciation is the Holy Grail of Darwinism – otherwise, why the iconic status of Darwin’s finches?

    In that we will never observe it in real time, yes, it is like the holy grail. But that is where the similarity ends. But we never see mountain or valley formation occur in real time either.

    Speciation is a central problem for Darwinism, which began with a mechanism to explain the “Origin of Species”…

    That would make a great title for a book.

    …now called, for convenience, natural selection acting on random mutation of individual parent genomes.

    Except that nobody considers this to be the complete story of evolutionary theory, except maybe ID proponents because they feel they can poke holes in that limited theory. It also involves HGT, drift, epigenetics, inversions, translocation, transformation, etc., etc. That is one of the requirements and strengths of science. You modify the theory to explain new data and, if necessary, discard it. Maybe you can explain to me the modifications that have been made to ID theory to accommodate new data.

    It’s a mechanism that isn’t really very importoant because natural selection is a tautology and genomes turn out to be rather plastic from the outside too.

    Old news. Plasticity has been known about for a long time and the theory accounts for it. Nobody is saying that DNA is a blueprint. We have known that the phenotype is affected by both the genome and the environment.

    Speciation is not an issue for ID because ID would expect plasticity.

    Maybe you could expand on this. What mechanisms in ID would explain this plasticity? We understand what many of them are in the evolutionary theory, but I have not read anything here about the mechanisms used by the designer, or even about the nature of the designer.

  5. 5
    Eric Anderson says:

    Armand Jacks @4:

    . . . but I have not read anything here about the mechanisms used by the designer, or even about the nature of the designer.

    I’m glad to hear that, given that intelligent design is not a mechanistic theory, unlike traditional evolutionary theory. And given that the nature of the designer is largely irrelevant to whether something was designed.

    Please review my comments #11, 24, and 40 from the following thread, as it should help you understand the issues:

    http://www.uncommondescent.com.....ent-505272

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