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  • Snail That Gives Birth To Live Young Reveals Evolutionary Leaps Happen

    From Pro Plyd@21:1/5 to All on Fri Jan 5 20:15:47 2024
    https://www.iflscience.com/snail-that-gives-birth-to-live-young-reveals-evolutionary-leaps-happen-gradually-72291

    Egg laying was the go-to for snails for millions
    of years – but at some point in the last 100,000,
    a group of marine snails ditched eggs in favor of
    live birth. The switch happened in the blink of an
    eye in evolutionary terms, and scientists have now
    discovered that it was driven by around 50 genetic
    changes. The rare opportunity to study the genetic
    architecture of an evolutionary change has revealed
    that the secret isn’t making one huge leap, it's
    about the accumulation of many gradual changes.
    ...
    Tracing back through the wealth of genetic
    information revealed that live-bearing young in
    marine snails emerged gradually over the last
    100,000 years as a series of mutations accumulated.
    However, we don't yet know which of those
    incremental changes were pivotal in the striking
    change in reproductive strategy.

    "Exactly which one was needed specifically for the
    live-bearing trait, I think we can’t say at the
    moment,” continued Butlin. “All of the 50 occur
    together in all the live-bearing snails, so it looks
    like many of them are necessary – together – for
    live-bearing. But some of them, we think, are
    probably responsible for other things that go with
    live-bearing, like the change to breeding
    all-year-round instead of breeding only in one
    season.”
    ...


    https://www.science.org/doi/10.1126/science.adm9239
    Evolutionary paths to new phenotypes
    Ecological model systems inform on innovative traits
    in plants and animals


    Abstract
    Adaptation by natural selection cannot take any
    evolutionary path; it operates within the
    constraints of genetic variation and environmental
    context, with futures contingent on the past.
    Therefore, how new suites of traits arise is an
    enduring issue and is key to understanding the
    diversity of life (1). On pages 108 and 114 of
    this issue, Chomicki et al. (2) and Stankowski
    et al. (3), respectively, investigate two
    different cases of fascinating biological
    complexity that arose through convergent and
    convoluted evolutionary paths—one in carnivorous
    pitcher plants (Nepenthes gracilis and Nepenthes
    pervillei) and another in marine periwinkle snails
    (Littorina saxatilis). The studies use different
    approaches to reconstruct evolution to reveal how
    complex phenotypic traits arise in unexpected ways.
    The results advance understanding not only of the
    specific traits that are studied—feeding structures
    in plants and live-bearing (as opposed to
    egg-laying) in snails—but also how evolution in
    general might arrive at apparently unlikely
    combinations.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Robert Carnegie@21:1/5 to All on Sun Jan 14 03:30:18 2024
    To complicate this, do we say that a fertilised
    egg is a living thing? I'm not making a point
    about evolution exactly, just looking for an
    argument. :-) Or perhaps to say that a critter
    that leaves its parent* inside an eggshell
    and one that comes out naked aren't so much
    different. *Sea horses. And "George Francisco"
    in _Alien Nation_ (TV).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From RonO@21:1/5 to Pro Plyd on Mon Jan 15 20:10:43 2024
    On 1/5/2024 9:15 PM, Pro Plyd wrote:


    https://www.iflscience.com/snail-that-gives-birth-to-live-young-reveals-evolutionary-leaps-happen-gradually-72291

    Egg laying was the go-to for snails for millions
    of years – but at some point in the last 100,000,
    a group of marine snails ditched eggs in favor of
    live birth. The switch happened in the blink of an
    eye in evolutionary terms, and scientists have now
    discovered that it was driven by around 50 genetic
    changes. The rare opportunity to study the genetic
    architecture of an evolutionary change has revealed
    that the secret isn’t making one huge leap, it's
    about the accumulation of many gradual changes.
    ...
    Tracing back through the wealth of genetic
    information revealed that live-bearing young in
    marine snails emerged gradually over the last
    100,000 years as a series of mutations accumulated.
    However, we don't yet know which of those
    incremental changes were pivotal in the striking
    change in reproductive strategy.

    "Exactly which one was needed specifically for the
    live-bearing trait, I think we can’t say at the
    moment,” continued Butlin. “All of the 50 occur
    together in all the live-bearing snails, so it looks
    like many of them are necessary – together – for
    live-bearing. But some of them, we think, are
    probably responsible for other things that go with
    live-bearing, like the change to breeding
    all-year-round instead of breeding only in one
    season.”
    ...


    https://www.science.org/doi/10.1126/science.adm9239
    Evolutionary paths to new phenotypes
    Ecological model systems inform on innovative traits
    in plants and animals


    Abstract
    Adaptation by natural selection cannot take any
    evolutionary path; it operates within the
    constraints of genetic variation and environmental
    context, with futures contingent on the past.
    Therefore, how new suites of traits arise is an
    enduring issue and is key to understanding the
    diversity of life (1). On pages 108 and 114 of
    this issue, Chomicki et al. (2) and Stankowski
    et al. (3), respectively, investigate two
    different cases of fascinating biological
    complexity that arose through convergent and
    convoluted evolutionary paths—one in carnivorous
    pitcher plants (Nepenthes gracilis and Nepenthes
    pervillei) and another in marine periwinkle snails
    (Littorina saxatilis). The studies use different
    approaches to reconstruct evolution to reveal how
    complex phenotypic traits arise in unexpected ways.
    The results advance understanding not only of the
    specific traits that are studied—feeding structures
    in plants and live-bearing (as opposed to
    egg-laying) in snails—but also how evolution in
    general might arrive at apparently unlikely
    combinations.




    The article is paywalled, but I subscribe. https://pubmed.ncbi.nlm.nih.gov/38175895/

    It isn't a normal example of evolution. Populations that were thought
    to be the same species turned out to not be monophyletic. It looks like
    after live bearing reproduction evolved in one lineage, two species
    interbred and the live bearing genes were transferred to a different
    lineage. Whole genome phylogenetic analysis places the two live bearing species as different lineages, but one of the lineages has most of the
    genome of one species, but has the reproductive genes from the other
    live bearing species.

    This is an example that Behe should be looking into. It looks like the
    live bearing phenotype is associated with 50 recent variants that the
    authors claim were "recruited" to evolve the live bearing phenotype.
    They claim that it was likely that many variants had to come together to
    create the live bearing form of reproduction. They haven't worked out
    the order of when the mutations needed to occur, but they claim in the
    paper that it is likely that several of the mutations likely had to
    exist before the phenotype could evolve.

    Behe wants his 3 neutral mutations within a given period of time to
    evolve new function and make a system his type of IC. These researchers
    claim that around 50 variants were "recruited" within the last 200,000 generations to produce the live-bearing phenotype. My guess is that
    they use recruited instead of mutation because the variants could have
    come from other species. They already have evidence that the whole
    system could be transferred, so parts of it could have come from other
    species.

    Ron Okimoto

    --- SoupGate-Win32 v1.05
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