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Genetic Convergent Evolution: Stunning Gene Similarities Among Diverse Animals

Posted by Soulskill on from the science-is-beautiful dept.

Toe, The writes "It has long been understood that completely different animals can end up with very similar traits (convergent evolution), and even that genes can converge. But a new study shows an unbelievable level of convergence among entire groups of genes. The study shows that animals as diverse as bats and dolphins, which independently developed echolocation, converge in nearly 200 different genomic regions concentrated in several 'hearing genes.' The implications are rather deep, if you think about it, delving into interesting limitations on diversity or insights into the potential of DNA. And perhaps more importantly, this finding goes a long way toward explaining why almost aliens in the universe look surprisingly identical to humans (though still doesn't explain why they all speak English)."

24 of 164 comments (clear)

  1. Dolphins and Bats are Mammals by MightyYar · · Score: 2, Insightful

    Not to pooh-pooh this study, but dolphins and bats aren't as far apart as say, bats and moths. If a fish or reptile converged with a mammal that would be more "unbelievable". I think we're in "Oh, cool," territory more than "WHAT????"

    --
    W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
    1. Re:Dolphins and Bats are Mammals by goombah99 · · Score: 4, Interesting

      Not to pooh-pooh this study, but dolphins and bats aren't as far apart as say, bats and moths. If a fish or reptile converged with a mammal that would be more "unbelievable". I think we're in "Oh, cool," territory more than "WHAT????"

      Well that's the point. they all start with some common underlying mamallian hearing genes and then they tweak them to develop echolocation.

      My guess is that in addition to certain mutations being easy to evolve (for example a particular mutation might set a rate constant on a binding protein to a be in some useful range for a typical return signal time, to create a clock), that viruses could carry genetic material between species that would bind the dna in common regions and transfer the point mutations between species.

      --
      Some drink at the fountain of knowledge. Others just gargle.
    2. Re:Dolphins and Bats are Mammals by MightyYar · · Score: 2

      they all start with some common underlying mamallian hearing genes and then they tweak them to develop echolocation.

      I guess that's less surprising a result to me than when things like koala thumbs happen. The front paws are kind of like our hands, except that the opposable split happened at the index finger so that they have two "thumbs". In the rear, the split happened at the same place, but then the two "thumbs" fused together, creating a new single "thumb" that is completely different from ours. If they had developed thumbs in the same way that we did, it would have surprised me less.

      --
      W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
    3. Re:Dolphins and Bats are Mammals by Impy+the+Impiuos+Imp · · Score: 2

      Well, that's true except they independently developed this feature, meaning the common split point didn't have it at the genetic level.

      Did these common genes develop from the same common genes, or completely different ones? As things break and re-arrange, some paths would be more common than others by the very mechanisms of reproduction.

      It may be more like fin vs. arm, the "same stuff", where that is defined as the same genes with alteration, except in this case, the common ancestor genes had nothing to do with echolocation.

      --
      (-1: Post disagrees with my already-settled worldview) is not a valid mod option.
    4. Re:Dolphins and Bats are Mammals by Ungrounded+Lightning · · Score: 2

      they all start with some common underlying mamallian hearing genes and then they tweak them to develop echolocation.

      Actually, a lot of animals that aren't credited with using echolocation actually use a variation of it: Sounds from their own motion (such as footsteps) create echoes, which their hearing system processes into a map of nearby objects.

      People, for instance, do this. That's why you can "feel" the nearness of walls and objects in the room (especially those near or immediately behind you) without looking, when you're moving.

      There's at least one recorded instance of a totally blind child who learned to ride a bicycle and avoid objects, by making clicking sounds with his mouth to provide excitation for this system.

      (The hearing system of things like mammals is evolved from the lateral line of fish - which both detects other nearby fish by direction-finding on the sound from their muscle twitches and other sound-reflecting objects by detecting the echoes of muscle twitches of the fish doing the listening. (A flat surface, for instance, would produce an acoustic mirror image of the fish every time it twitched, identifying the return as an echo of the fish itself.) It would not surprise me if the processing for echolocation in other animals is just a revival or slight remapping of this same mechanism.)

      --
      Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
    5. Re:Dolphins and Bats are Mammals by nashv · · Score: 2

      Actually it is. The gene responsible is PAX-6 which is responsible for eye development in nearly ALL creatures. However, the convergence is functional, not based entirely on sequence similarity. This is no surprise because while gene sequence similarity indicates common protein structure, different sequences can have similar structures and similar functions. Moreover, it is often particular regions of genes that are important for function , not the entire thing. Mutations outside these functional hotspots can have effects that only subtly affect prominent functions.

      Funny part is, you can take squid PAX-6 and stick it in a fruit fly...and it makes fruit fly eyes. Which tells you that the mechanistic aspects of this convergence is not simply by sequence similarity in one gene...it is the entire system - the genetic network/cellular context that is converging. And that explains why sequence similarity is not that important...when you thousands of parameters, there are multiple routes to the global minimum.

      --
      Entia non sunt multiplicanda praeter necessitatem.
  2. What I've said all along by dorpus · · Score: 5, Insightful

    I got my PhD in statistical genetics. Why should we equate genetic homology to evolutionary homology? All these studies that speak of a hypothetical Adam or Eve assume that the same mutations could not have arisen independently in different parts of the world.

    1. Re:What I've said all along by Charliemopps · · Score: 2

      Not at all. We interbred with Neanderthals and still retain many of their genes. I suspect that as species diverge this sort of thing happens a lot. The chicken or the egg analogy is flawed, as there were likely hundreds of eggs all over the world that hatched into what we would now consider a chicken at around the same time. They inter-bred with non-chickens and passed on their genes that eventually became dominant due to evolutionary pressures.

      There was no genetic Adam and Eve. "Humans" slowly came to be human over thousands of years, and we're still evolving. Scientists have found differences in our genes over periods as short as a few decades (usually due to disease)

    2. Re:What I've said all along by Guppy06 · · Score: 4, Informative

      /sigh

    3. Re:What I've said all along by tburkhol · · Score: 2, Informative

      Underlying genetic evolution is the notion that genes pick up random mutations over time. Most of these have no effect on function, so you can estimate how long ago two species diverged by counting how many differences are in the genome. These guys had the clever idea of taking species that we think diverged a long time ago, but that have a similar trait (ie, echolocation), with the hypothesis that the genes controlling that might be more similar, even in these very different animals, than the genes for dissimilar traits.

      Imagine a software project that forks and is maintained by separate groups. Over time, the two projects look more and more different. Now imagine that both of these forks end up with a new feature in common that didn't exist in the pre-fork code. The study hypothesis is essentially that code related to the new feature will be similar between the two projects, where code associated with other features that aren't the same between projects, will be more different

      Genetically, this might happen either because the random mutations in hearing genes that facilitate echolocation facilitate echolocation in any environment, provide a survival advantage, and become conserved in multiple environments. As dolphins and echolocating bats diverged, acute hearing was favored in both species, so their hearing genes are more similar than those of echolocating and non-echolocating bats, even though the genes for "wings" are more similar between bats than dolphins. Because it seems unlikely that the large number of differences that separate bats as a group from dolphins might have come up separately, the study proposes that the first bat-ears were as different from dolphin-ears as bat wings are different from dolphin flippers, and that the specialization into echolocating bats brought those hearing genes closer together, following a convergent path.

      This is a much more subtle form of convergent evolution that, say, wings. "Wings" as a feature provide a definite advantage, and wing structures have evolved multiple times in multiple forms. The genes that define insect wings are completely different from those that define bat wings. It's a dramatic demonstration of nature using multiple solutions to the same problem. The current study suggests that nature is also capable of finding the same solution from multiple starting points.

    4. Re:What I've said all along by wonkey_monkey · · Score: 2

      Does any of that mean we don't all share a common female ancestor?

      --
      systemd is Roko's Basilisk.
  3. English by bob_jordan · · Score: 2

    It simply proves that through a process of survival of the fittest, English is evolving at the expense of weaker languages into the perfect language. :-)

    Eventually all you will have is English, and all the programming languages derived from it.

    Bob.

    1. Re:English by psyque · · Score: 2

      Maybe one day we'll all be named Bob.

    2. Re:English by Rob+Riggs · · Score: 2

      Maybe one day we'll all be named Bob.

      I'm one step ahead of you.

      --
      the growth in cynicism and rebellion has not been without cause
    3. Re:English by Anonymous Coward · · Score: 2, Insightful

      Now some would try and argue that that ability made humans the fittest, and in a way it is true, but it is not what is meant by the phrase survival of the fittest.

      You're wrong. This is, in fact, exactly what is meant by "survival of the fittest," and exactly what Darwin meant by it. He said that organisms that were selected by evolution were those best suited for surviving in their immediate environment. And in this case, cooperative humans were the best suited for survival - ergo, they survived and flourished.

  4. Explains SciFi Shows?? by l0ungeb0y · · Score: 2

    And perhaps more importantly, this finding goes a long way toward explaining why almost aliens in the universe look surprisingly identical to humans

    I know this is tongue in cheek humor, but -- NO, IT DOES NOT DO ANYTHING OF THE SORT! DNA is chemical in origin and so goes, different chemical compositions of different planets would give rise to vastly different DNA compositions resulting in life nothing like our own.

  5. They all speak English by WarJolt · · Score: 2

    They all speak English because they've been watching all our old shows that have been beamed into space for decades.

  6. Re:almost aliens by Anonymous Coward · · Score: 2, Funny

    We come from.... France.

  7. Re:Random (letter) selection by reve_etrange · · Score: 3, Insightful

    Only it's entirely credible. That is entire premise of a peer-reviewed publication.

    You know your argument is worthless when it hinges entirely on nitpicking common expressions.

    --
    .: Semper Absurda :.
  8. No by roguegramma · · Score: 2

    Epigenetics does in general not change or mutate genes(*).
    At least the most common examples for epigenetics are cases where a gene's activity has been increased or decreased, which can be explained by molecules attaching to the DNA. The study is talking about evolution, hence mutation, and not about epigenetics.

    (*)Of course, someday someone will find a rare example where epigenetics actually changes the mutation rates of genes.

    --
    Hey don't blame me, IANAB
  9. Re:Isn't this what you would expect from a Creator by oodaloop · · Score: 4, Interesting

    Then the evidence is overwhelmingly pointing to no creator. The genes that code for intelligence in corvid birds and chimpanzees are different. The genes that code for wings in birds, bats, insects, and pterasaurs are completely different. The genes that code for white fur and similar looking white filaments in plants are way off. Wouldn't a creator just reuse white fur on cotton plants? The genetic diversity across the seven kingdoms and the millions of species is vast, with genetic convergence the extremely rare exception, not the rule (hence why this is newsworthy). Sorry, your own argument points to there being no creator.

    --
    Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
  10. Re:Stunning atom similarities as well by xevioso · · Score: 2

    I don't know if this is true. Some life contains compounds made up of elements that don't exist in other forms of life. Tungsten, for example. Quoth wikipedia: "Tungsten, at atomic number 74, is the heaviest element known to be biologically functional, with the next heaviest being iodine (Z = 53). It is used by some bacteria, but not in eukaryotes. For example, enzymes called oxidoreductases use tungsten similarly to molybdenum by using it in a tungsten-pterin complex with molybdopterin (molybdopterin, despite its name, does not contain molybdenum, but may complex with either molybdenum or tungsten in use by living organisms). "

  11. Comes down to the programing. by Trax3001BBS · · Score: 2

    To perform the analysis, the team had to sift through millions of letters of genetic code using a computer program developed
    to calculate the probability of convergent changes occurring by chance, so they could reliably identify ‘odd-man-out’ genes.

    I was following a different train of thought; trying to support it came across this:

    "In the traditional approach, the dynamic programming based pair-wise alignment is used for measuring the similarity between two sequences.
    This method does not work well in a large data set."
    http://link.springer.com/static-content/lookinside/465/chp%253A10.1007%252F3-540-45554-X_47/000.png

    Paywall, the above is all there is. Text mining techniques were used in the research.

    http://link.springer.com/chapter/10.1007%2F3-540-45554-X_47
    Hoang Kiem and Do Phuc (snicker, he said...).

  12. Proof of Creation!! by haruchai · · Score: 3, Interesting

    They were all very intelligently designed by the Great Programmer. There's even code reuse.

    --
    Pain is merely failure leaving the body