News speciation

Arguing for separate but same eel species

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American Eel
American eel/Fisheries and Oceans Canada

Because Darwin.

From Science Nordic:

Both groups breed in the same area in the Caribbean, the Sargasso Sea, but typically you would expect a long-term physical separation of the two, to allow them to develop in different directions. This makes them a great mystery of evolution.

Now scientists have solved this puzzle. It turns out that the eels became two species 3.5 million years ago, when Panama arose from the sea, separating the Atlantic and Pacific Oceans. One group of eels were led to Europe by the Gulf Stream, where a new species emerged

The eel’s life story is difficult to understand from an evolutionary perspective.

When they say “an evolutionary perspective,” they mean a Darwinian perspective, of course.

Take an eel in a Danish stream — when it is time to mate, they do not choose the easy option and find an eel in the same river to breed with.

Instead, they embark on a perilous 5,000 kilometre journey to spawn in the Sargasso Sea.

The same goes for eels from all across Europe, and in this way they comprise a single population of European eels that all go to breed on the other side of the Atlantic.

After the breeding season is over, the new eel larvae float all the way back to Europe, following the Gulf Stream and other ocean currents. A few years later, they settle in coastal waters, rivers, and lakes. They can be found in Iceland and Norway in the north, all the way down to Morocco in the south, and this epic life cycle begins all over again.

But the Sargasso Sea is not the reserve of European eels — American eels also breed there, and the two breeding areas overlap. Sometimes the two species also breed with each other, which has been difficult to explain.

Unless they aren’t really two separate species, just two populations.

The genomes were virtually the same, except for a couple of differences in a few very specific parts — those affecting growth and metabolism. More.

But remember, Darwin’s followers need separate species the way a crack addict needs his fix.

Having listened to this kind of thing for many years now, I suggest ignoring it all unless you have an exam to write. And then just front the house line for a pass.

Alchemy was probably a lot like this. One of these days, we’ll have real information.

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Hey, eels climb rock wall to get back home:

9 Replies to “Arguing for separate but same eel species

  1. 1
    ppolish says:

    Both eels live & breed on the same side of Panama. Share breeding grounds. Mate with each other sometimes.

    But the Gulf Stream carries only European eels to Europe?

  2. 2
    News says:

    Is it possible that that is why they call them European eels?

  3. 3
    wd400 says:

    If they aren’t different species, why do they differ at those genomic positions (and have different life histories)? If they just mated randomly in their breeding ground then such difference would be wiped out by interbreeding?

    If you don’t like using the name “species” for such differences that’s fine, but this is an example of populations being able to maintain genetic differences in spite of the possibility of such differences being destroyed by interbreeding. That’s a key problem in the genetics of speciation, so this system is pretty interesting, no?

  4. 4
    ppolish says:

    “why do they differ at those genomic positions.., If they just mated randomly in their breeding ground then such difference would be wiped out by interbreeding?”

    Yes WD400, that is the longstanding “mystery”. And I assume you agree that the Panama Theory solves the mystery. But seems like Cargo Cult Just So Science a bit. Just s bit.

  5. 5
    wd400 says:

    I would have to read the papers to decide on the “Panama” theory. But how does that relate to News’ “But remember, Darwin’s followers need separate species the way a crack addict needs his fix” melodrama?

  6. 6
    ppolish says:

    And why go back to the Sargasso Sea. A strange Sea if you ask me. Unguided, without purpose – back to the Sargasso? Long strange trip for both types of eels. Inefficient trip one would think.

    I’m guessing Pacific eels are not so weird.

    Edit…addiction to crack and addiction to Darwinism are related I’m guessing again. Dopamine receptor?

  7. 7
    Mapou says:

    wd400, still reeling from the fact that Darwinism is killed dead by the curse of dimensionality:

    If you don’t like using the name “species” for such differences that’s fine, but this is an example of populations being able to maintain genetic differences in spite of the possibility of such differences being destroyed by interbreeding. That’s a key problem in the genetics of speciation, so this system is pretty interesting, no?

    I’m sure there are genetic differences between an Eskimo and an African Pygmy. Why do they belong to the same species but not the eels in the story?

  8. 8
    wd400 says:

    “the possibility of such differences being destroyed by interbreeding”. Genetic differences between Eskimo and African populations accrued during the ~200 000 years that those populations had no chance to interbreed.

  9. 9
    drc466 says:

    Why do scientists always leave out the interesting stuff? In this case – what happens when American eels and European eels interbreed? Why aren’t the genetic differences bred out, as wd400 says? Is it because the Amer-European eel offspring are such a minority, like ligers and tions? Or are they sterile, like mules? Do they live with American eels, or European eels? Which parent do they take after, genetically? Is it actually a case like dog breeding, where the “pure” strains are simply genetically deficient versions of the “mutts” produced by interbreeding? Will Amer-European Eels inherit the earth?

    So many interesting possibilities having nothing to do with Darwinism (in the sense that ligers, zorses, mules, mutts, and human races don’t), so little information.

    As for the main point of the story – big deal. Humans used to do the same thing – how many stories are there that talk about how racial groups would send their children back to the “home country” to find partners? It goes back to at least the time of Abraham… 😉

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