Evolution Genetics Intelligent Design

Trout adapted from salt to fresh water in only 120 years?

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steelhead trout/John McMillan

Well, not exactly. From ScienceDaily:

Steelhead trout, a member of the salmon family that live and grow in the Pacific Ocean, genetically adapted to the freshwater environment of Lake Michigan in less than 120 years.

Steelhead were intentionally introduced into Lake Michigan in the late 1800s in order to bolster recreational and commercial fisheries. In their native range, which extends from California to Russia, steelhead hatch in freshwater rivers, migrate to the ocean, and return to freshwater to spawn. This migration allows steelhead to feed in the ocean, where they can grow larger and produce more eggs than if they remained in freshwater streams for their entire lives.

The steelhead introduced into Lake Michigan continue to spawn in small freshwater tributaries and streams, but now treat the entirely freshwater habitat of the Great Lakes as a surrogate ocean. After their introduction into Lake Michigan, steelhead began to naturally reproduce and established self-sustaining populations throughout the Great Lakes. To examine how these fish adapted to this novel environment, a team led by Mark Christie, an assistant professor of biological sciences at Purdue University, sequenced the complete genomes of 264 fish. The team then compared steelhead from Lake Michigan to those from their ancestral range, searching for outlier regions associated with genetic adaptation.

The research, which was published in in the journal Molecular Ecology, found that regions of three chromosomes in steelhead evolved after they were introduced in Lake Michigan, offering insight into how this ocean-migrating fish adapted to an entirely freshwater environment. Paper. (paywall) – Janna R Willoughby, Avril M Harder, Jacob A Tennessen, Kim T Scribner, Mark R Christie. Rapid genetic adaptation to a novel environment despite a genome-wide reduction in genetic diversity. Molecular Ecology, 2018; DOI: 10.1111/mec.14726 More.

In short, in their original habitat, the trout were spawned in fresh water, lived in salt water, and – as adults – returned to fresh water to spawn. But having no salt water available in the new habitat, they have adapted to lifelong freshwater living. It’s a good find but these fish were already capable of living in both environments. It’s not as if they moved from lifelong salt water to lifelong fresh water.

From Elizabeth Pennisi at Science:

Although we tend to think of evolution as happening over thousands, if not millions, of years, critical changes can take little more than a century. That’s what happened with a group of steelhead trout transplanted from the salty seas of California to the fresh waters of Lake Michigan for game fishermen in the 1890s. A new study shows that the fish, which typically live part of their lives in the ocean like salmon, developed key genetic differences that allowed it to live wholly in freshwater—in little more than 100 years.

The discovery shows how quickly organisms can adapt to a new lifestyle—if they have some of the right genes to start with, says Michael Blouin, a geneticist at Oregon State University in Corvallis. “The work is a nice example” of how evolution can happen “over very short time periods.”More.

A friend writes to point out, “Here is the key phrase in the article, ‘The discovery shows how quickly organisms can adapt to a new lifestyle—if they have some of the right genes to start with,’ with emphasis on ‘right genes to start with.’ That’s important when considering claims about evolution.”

If some of the fish were returned to the Pacific coast, would they then go back to their original lifestyle within a century or so? Too bad no one person will live to find that out but it might be worth testing. For one thing, how do we know that the genetic change took over a century? Genome mapping wasn’t available thirty years ago. Maybe this is something they can do in a few generations. After all, blind cave fish were bred to see again.

See also: A Tunable Mechanism Determines the Duration of the Transgenerational Adaptations
Cornelius Hunter

and

Devolution: Getting back to the simple life

26 Replies to “Trout adapted from salt to fresh water in only 120 years?

  1. 1
    Trumper says:

    It only took me 8 years to adapt to city life. I grew up on a farm in Oregon but after graduating I migrated to the city…only finding my way back to the farm occasionally but dang..isn’t evolution amazing…
    I had to chuckle at that article when it came through last week on my Science Daily feed. Every steelhead that my dad or I ever caught were in fresh water. Had there been some serious scientific research on how long it really takes a fish to evolve into a fish might want to take a look at how long it took salmon that spend a great deal of their lives in the salty ocean to ‘evolve’ into ‘kokanee’. Basically just one year. For example Wallowa Lake Oregon- when their dam was built in the early 1900’s …the salmon that hatched in the lakes headwaters were trapped… and survived their whole life-cycle in those cold fresh waters all the while producing. Sure they lost size but who wouldn’t when they no longer can feast on the bounty of the ocean.

  2. 2
    Belfast says:

    “Although we tend to think of evolution as happening over thousands, if not millions, of years, critical changes can take little more than a century. ”
    The Foxtrot/Gould Theory of evolution, slow, slow, quick, quick, slow.

  3. 3
    Jon Garvey says:

    If they’ve been present for 120 years, presumably they’ve been successfully breeding in fresh water for 120 years. So the changes were either rapid, or optional to breeding success.

  4. 4
    News says:

    Yes all, and as noted above, how do we know it took over a century? If there is a sort of on/off switch for salt/fresh water, it might not take long at all, just long enough to trigger the switch. That would make more sense in a life form that must adapt to different ambient conditions during an individual life cycle.

    One suspects that the science media are looking for Swift Darwin. But they better keep looking.

  5. 5
    PaV says:

    From the abstract:

    This study illustrates that species can rapidly adapt to novel environments despite genome?wide reductions in genetic diversity.

    Darwin said evolution MUST be gradual. And Fisher said that fitness increases with increased genetic diversity.

    Both of these theses are contradicted by this study.

    And evolutionists say: “Ho-hum. Keep moving. Nothing to see here.”

  6. 6
    Amblyrhynchus says:

    News,

    There is no “switch” here, the paper is looking for genetic variants that changed in frequency. So it’s certainly selection. It’s not possible to know if the strongest effect of selection occurred early, though I don’t think any of the selected alleles are fixed so it’s likely selection is still operating.

    PaV,

    Darwin got a lot wrong, not sure why modern evoluionary biologists should care about that (though I’m not sure this results is a case in pont). Fisher only said that all else being equal, adaptation faster when genetic diversity is high. Nothing in this result is at odds with that.

  7. 7
    aarceng says:

    @6 “There is no “switch” here, the paper is looking for genetic variants that changed in frequency.”

    How much of that was due to founder effect and nothing to do with selection? (Sorry I don’t have the time or inclination to read the paper myself.) However even if it is all due to selection that is only evolution in the Population Genetics sense; not in the universal common ancestry sense.

  8. 8
    Amblyrhynchus says:

    These are all changes associated with particular parts of the genome (i.e. much greater than the genome-wide background rate associated with founder effects). It’s true that this is only evoltution in the sense of that word used by biologists, I guess.

  9. 9
    aarceng says:

    Amb @8 “evoltution in the sense of that word used by biologists, I guess.”
    No, biologists use a different definition. Population Geneticists define evolution as “a change in allele frequency in a population over time”.

    See for instance the definition Jerry Coyne gives in “Why Evolution is True”; “Life on earth evolved gradually beginning with one primitive life form – perhaps a self-replicating molecule – that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection. ”

    That’s a big difference.

  10. 10
    PaV says:

    Ambly:

    Darwin got a lot wrong, not sure why modern evoluionary biologists should care about that (though I’m not sure this results is a case in pont).

    So, “nothing to see here,” eh?

    As I said, evolutionists were going to say:
    “Ho-hum. Keep moving. Nothing to see here.”

    BTW, modern evolutionary biologists “should care” an awful lot about Darwin being wrong.

    Here’ what I mean: the only “Theory” of evolution that I know of are Lamark’s and Darwin’s (and I suppose Erasmus Darwin’s, too).

    If Darwin is ‘wrong,’ then there is NO ‘theory of evolution.’ Doesn’t this bother you? It seems to me it ought to. I know it would bother me to find myself in that kind of situation.

    Fisher only said that all else being equal, adaptation faster when genetic diversity is high. Nothing in this result is at odds with that.

    Here’s what Wikipedia has to say about Fisher’s theory as they quote Fisher:

    “The rate of increase in fitness of any organism at any time is equal to its genetic variance in fitness at that time.

    In more modern parlance:

    “The rate of increase in the mean fitness of any organism at any time ascribable to natural selection acting through changes in gene frequencies is exactly equal to its genetic variance in fitness at that time”

    All these ingredients are there; but, not in the way that Fisher’s theorem predict.

    So, what do we have?

    We have Darwin’s prediction of ‘gradualism’ overturned, thus undermining confidence in his theory; we have Fisher’s prediction concerning ‘genetic variation’ being overturned, thus undermining confidence in “neo-Darwinism”, which leaves us, I guess, with the theory of neutral of “molecular evolution” (not ‘biological’) which sees NS only playing a minor role; and the response is————yes:

    “Ho-hum. Keep moving. Nothing to see here.”

    How do you put a stake into the heart of such a theory? Only God knows.

  11. 11
    Amblyrhynchus says:

    aarceng,

    The biological definition of evolution is change in heritable traits over generations. Coyne’s paragraph is a description of what has happened, not a definition of evolution.

    PaV,

    What are you on about? I’m not sure if you understand what the words “rate” or “variance” mean. Nothing in this result in counter to Fishers theorem.

  12. 12
    Silver Asiatic says:

    The biological definition of evolution is change in heritable traits over generations.

    That’s the theory of evolution?

  13. 13
    Amblyrhynchus says:

    That’s the definition. People around here seem to be hard of reading.

  14. 14
    aarceng says:

    No it’s not THE definition. Actually there is no one universally agreed definition of biological evolution. You can go to https://www.thefreedictionary.com/Biological+evolution and pick the one you want.

    To avoid equivocation use an appropriate definition. If you intend ONLY a change in heritable traits over generations then your definition is ok. If you mean it to include the origin of existing species from ancestors unlike them. then say so. If you mean it to include universal common ancestry then say that. Anything less is equivocation.

    So Amblyrhynchus I will accept your definition specifically excluding anything not included in the definition. As a YEC I have no objection to evolution=adaptation.

  15. 15
    Silver Asiatic says:

    When challenged, evolution is defined in the most minimalist terms. Because otherwise it is too easy to expose a more wide-reaching definition as false.

    At dispute is not a minimalist definition of a term, but rather whether or not there is a coherent, valid theory of evolution. Darwin’s theory has been falsified.

  16. 16
    Amblyrhynchus says:

    I can assure you this is always the definition of evolution. Amazingly, a 120 yr natural experiment in one lineage doesn’t recapitulate billions of years of evolution in millions of lineages. But then, who would imagine that it should?

  17. 17
    aarceng says:

    Perhaps I’m also at fault since I didn’t distinguish between “evolution” and the “theory of evolution”. Unfortunately the word evolution is often used as shorthand for the theory of evolution.

    In that case this example would show evolution while providing scant support for the theory of evolution.

  18. 18
    kairosfocus says:

    On micro- vs macro- [= body plan] evolution and information/complexity thresholds, informed by the island of function issue from molecules to coherent interaction of organ-based body systems. KF

    PS: Recall, Steelhead are a strain of Rainbow trout (a variety of the Pacific Salmon family that does not mate once and die) that is sea-going.

  19. 19
    PaV says:

    Ambly:

    I’m not sure if you understand what the words “rate” or “variance” mean. Nothing in this result in counter to Fishers theorem.

    There you have it: “Ho-hum. Keep moving. Nothing to see here.” It’s all about what words mean. As Bill Clinton helped us to understand: “It’s all about what the meaning of is is.” (Or, in this case, what the definition of ‘adaptation’ is.)

    The study shows that the variance in the population decreased as it adapted. Adaptation MUST be defined as an ‘increase in fitness.’ So, fitness increases while variation decreases.

    But, no problem: we’ll just say that in ‘certain circumstances’ it could happen that “adaptation” might not actually result in in an increase in “fitness”; and then everything is OK.

    “Ho-hum. Keep moving. Nothing to see here.”

    Or, do you have something more to say than simply implying that I don’t know what rate or variation means? Please tell me in what ways I’m deficient.

  20. 20
    aarceng says:

    “The study shows that the variance in the population decreased as it adapted.”

    This is to be expected. Selection can’t create new alleles so it works by eliminating undesirable ones. This is adaptation by devolution.

    If selection produces a new species that species will have less variation than the ancestor population. If it speciates again variability will be further reduced. Eventually the line runs out of sufficient variation to adapt to new conditions and it goes extinct. Speciation is a negation of Darwinian evolution rather than a confirmation.

  21. 21
    Amblyrhynchus says:

    PaV,

    You are really confused here. I’m not sure how you yourself into this mess (other than choosing to bloviate away on a topic you know nothing about).

    Fisher’s theorem says the rate of adaptation is determined by the genetic variance in fitness. That doesn’t mean the rate of adaptation is zero in populations that are less diverse than they used to be (in fact, if a bottleneck is associated with a new habit genetic variance in fitness might increase).it certainly doesn’t mean selection should increase variance (that’s literally backwards).

    So I’m not trying to play games with the definitions of words, I’m trying to understand how you are getting this so wrong.

  22. 22
    Amblyrhynchus says:

    If selection produces a new species that species will have less variation than the ancestor population. If it speciates again variability will be further reduced. Eventually the line runs out of sufficient variation to adapt to new conditions and it goes extinct.

    This might be true if mutation didn’t exist. But it does, so lineages created by speciation events accumulate genetic diversity and adapt via new mutations.

  23. 23
    Allan Keith says:

    Aarcenq,

    If selection produces a new species that species will have less variation than the ancestor population. If it speciates again variability will be further reduced. Eventually the line runs out of sufficient variation to adapt to new conditions and it goes extinct. Speciation is a negation of Darwinian evolution rather than a confirmation.

    You have completely ignored sources of increased variation (meiosis, mutation, inversions, etc). But you have presented a great argument against the idea of ID by front end loading.

  24. 24
    aarceng says:

    Allan Keith,

    Meosis is the formation of sex cells. Barring mutations it does not add any variation. Inversions are a type of mutation. All you’ve said is that you are relying on mutations to increase variation.

    Q. What can you gain when you lose something?
    A. You gain variety when you lose genetic information (a mutation)

    Observation is that the overwhelming proportion of mutations are information losing, even where they increase variety; e.g. sickle cell trait, adult lactose tolerance, black/tan desert mice, etc.

    As has been shown in other posts in UD even Nylonaze is a poor example of an information gaining mutation.

  25. 25
    Allan Keith says:

    aarceng,

    Meosis is the formation of sex cells. Barring mutations it does not add any variation.

    Of course meiosis increases variation. If it didn’t all of your siblings would be identical to you.

  26. 26
    Amblyrhynchus says:

    aacrenng,

    You have about 100 mutations in your genome. How much genetic information have you lost as a result?

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