Evolution of metamorphosis

Discussion in 'Biology & Genetics' started by arauca, Oct 13, 2011.

  1. Hercules Rockefeller Beatings will continue until morale improves. Moderator

    Messages:
    2,720
    Mod note: Wellwisher’s post (and associated replies) have been moved to a dedicated thread for collecting the numerous posts (spam) by wellwisher on his 'alternative hypothesis' that entropy explains anything and everything in biology.

    http://www.sciforums.com/showthread.php?p=2853509

    Edit: Eight more 'wellwisher entropy' posts (and associated replies, 18 posts total) have been moved to the dedicated wellwisher/entropy thread.
     
    Last edited: Nov 12, 2011
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. arauca Banned Banned

    Messages:
    4,564
    Migratory monarchs are at least two generations removed from those that made the journey the previous fall," said Steven M. Reppert, MD, professor and chair of neurobiology and senior author of the study. "They have never been to the overwintering sites before, and have no relatives to follow on their way. There must be a genetic program underlying the butterflies' migratory behavior. We want to know what that program is, and how it works."

    In a paper published in the journal Cell, Reppert and UMMS colleagues Shuai Zhan, PhD, and Christine Merlin, PhD, along with collaborator Jeffrey L. Boore, PhD, CEO of Genome Project Solutions, describe how next-generation sequencing technology was used to generate a draft 273 Mb genome of the migratory monarch. Analysis of the combined genetic assembly revealed an estimated set of 16,866 protein-coding genes, comprising several gene families likely involved in major aspects of the monarch's seasonal migration. The novel insights observed by Reppert and colleagues in the newly sequenced monarch genome include:

    identifying genes involved in visual input and central processing by the sun compass
    a full repertoire of molecular components for the monarch circadian clock
    all members of the juvenile hormone biosynthetic pathway whose regulation is critical for a successful migration and which shows an unexpected regulation pattern
    additional molecular signatures of oriented flight behavior
    monarch-specific expansions of odorant receptors potentially important for long-distance migration
    a variant of the sodium/potassium pump that underlies a valuable chemical defense mechanism to fend off predators during the migration

    "Why sequence another species?" said Laurie Tompkins, Ph.D., who oversees grants focused on the genetics of behavior at the National Institutes of Health's National Institute of General Medical Sciences, which supported the work. "In this case, it's because monarch butterflies are exceptional in that they migrate thousands of miles, seasonally. Genomic sequence provides the raw material for understanding the remarkable behavioral and physiological adaptations that enable the butterflies' long-distance migration."

    http://www.physorg.com/news/2011-11-sequence-monarch-butterfly-genome.html
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152
    why did the larva need wings?
    why did it need to go anywhere?
    how far did they go when the landmasses were closer together?
    did these long migratory routes increment gradually from short ones?
    how does any creature navigate?
    what is the oldest known migratory animal?


    evolution addressed all of this and more.....much more!
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. kwhilborn Banned Banned

    Messages:
    2,088
    Maggots resemble little caterpillars, and flies a smaller version of butterflies. Evolution of flying species like this is unique, and basically the "baby" developed legs or ability to move somewhat for self defence.
    There are probably other versions of the species where the baby could not move, and either could not provide enough sustenance to survive, or was killed too often for the species to propagate.
    Insect wings are probably very delicate, and all flying insects develop wings after birth. The butterfly wing is quite extreme and requires the caterpillar to hide away for at least a week.
     
  8. arauca Banned Banned

    Messages:
    4,564
    I am sure it does address , but some time is it sensible,
    The butterfly is born , die , rises from the ashes and back .
    I am curious for an explanation. Not just , " it is evolution" or, " shit happens "
     
  9. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152
    Earlier you mentioned that the caterpillar dies. No, it morphs. It does go dormant, but it is not dead. It is reconstructing itself, using the tools of nature, which include tools exploited during the evolution of a species. And of course this is the general trend among vast numbers of insects, whose adult form needs wings.

    I asked you why they need wings. It would seem that this is the best way to spread sexual variation, by covering vast regions where regional variations can help species survive.

    In this regard, metamorphosis would appear to have evolved, or at least to reflect the evolved aspects of increasing the range to increase the variation, i.e., to strengthen the contribution of variation by sexual reproduction.

    Your say you are searching for an understanding of metamorphosis. Have you considered a course in entomology?
     
  10. Crunchy Cat F-in' *meow* baby!!! Valued Senior Member

    Messages:
    8,423
    Considering all the correct responses you have been given, I can only presume that you do not understand them. Perhaps taking some college classes on evolutionary biology in your area of the world will help as it can be communicated in whatever your native language is.
     
  11. arauca Banned Banned

    Messages:
    4,564
    Well as you pointed out , the larva did not die ok so it evolves into a butterfly, U accept that.
    But In the case of Monarch butterfly what is the explanation , without me taking an entomology course
     
  12. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152
    No actually it does not evolve. We use the term metamorphosis here to distinguish from the evolution over generations.

    I guess I didn't understand what you are asking about the butterfly. Could you state more fully what you are saying about this critter in regard to evolution?
     
  13. Hercules Rockefeller Beatings will continue until morale improves. Moderator

    Messages:
    2,720
    Mod note: 22 off-topic posts moved to here.
     
  14. ULTRA Realistically Surreal Registered Senior Member

    Messages:
    1,555
    I've not read the whole thread yet, (its pretty late) but i'm not sure that darwinian evolution does express the metamorphasis process. Its a process that is still not well understood, and I would say would be best described by the differentiation of cells. It is only in this metamorphasis process I can think of where any complex life (barring nematodes) seems to be able to rebuild itself in this way.
     
  15. Hercules Rockefeller Beatings will continue until morale improves. Moderator

    Messages:
    2,720
    Whilst I’m not claiming that humans metamorphosize in the same way insects do, I’ve always thought that the changes humans, particularly males, undergo during puberty might be considered to be a mini-metamorphosis. Growth spurts, breaking voices, hair growth, muscle growth, sexual maturity etc etc. There are some pretty dramatic changes and they are all hormone-, cell proliferation- and cell differentiation-driven physiological events, just as the metamorphosis of an insect is a hormone-, cell proliferation- and cell differentiation-driven event.
     
  16. Fraggle Rocker Staff Member

    Messages:
    24,690
    The word "metamorphosis" is applied very specifically in science. It has to be an abrupt and conspicous change in body structure, such as a frog growing legs, lungs and tongue in one day. Growth spurts, increase in the size of limbs or organs, and glands ramping up their production of hormones are just maturation, not metamorphosis.

    Many of the changes which begin (or at least become noticeable) in human adolescence are not completed at the end of that period. In particular, the synapses which manage what we think of as adult reasoning or "wisdom" (deferred gratification, caring for others, long-term thinking, risk analysis and management, etc.) are not fully formed until the 30's.

    This is why armies are primarily comprised of very young people--not just because they're stronger and heal faster.
     
  17. Sock puppet path GRRRRRRRRRRRR Valued Senior Member

    Messages:
    3,112
  18. Hercules Rockefeller Beatings will continue until morale improves. Moderator

    Messages:
    2,720
    Yeah, dude, my doctorate and first postdoctoral position was in the area of developmental biology (neurodevelopmental biology to be precise). I have four first-author and two additional co-author publications in various developmental biology journals. I have a better than average understanding of animal body plan development. Even a cursory glance at what I wrote indicates that I was not saying humans undergo a genuine metamorphosis.
     
  19. Fraggle Rocker Staff Member

    Messages:
    24,690
    Sure, but the rest of the members might not understand that. No offense intended, sorry.
     
  20. Hercules Rockefeller Beatings will continue until morale improves. Moderator

    Messages:
    2,720
    Mod note: 12 off-topic posts moved here.

    Mod note: Thread title changed from ‘Darwinian evolution’ to ‘Evolution of metamorphosis’. The new title is more reflective of the intended discussion; the old title was attracting irritating uneducated general evolution denialism posts.
     
    Last edited: Nov 30, 2011
  21. arauca Banned Banned

    Messages:
    4,564

    "... But to build a butterfly you have to break down a caterpillar.
    The thing that drives caterpillars (and other flying insect larvae) to stop feeding their faces, settle down somewhere safe, and pupate, is the hormone ecdysone. It's the same hormone that causes the larvae to moult each time they outgrow their current skin. The reason this final moult into a butterfly is so different from the earlier ones is because the level of another hormone — juvenile hormone — is suddenly lower.

    Juvenile hormone is the great controller of metamorphosis, by delaying it until the caterpillar has moulted and grown enough to produce a decent-sized butterfly. It works by blocking the genes in the imaginal discs, keeping those wannabe butterfly cells in a holding pattern. So while juvenile hormone is being pumped out of tiny glands behind the brain, all the caterpillar can do is feed, grow and — when instructed by ecdysone — moult. (It's so good at preventing larvae from maturing that a lot of insecticides have been based on artificial juvenile hormone).

    But juvenile hormone isn't just a suppressor of butterfly development, it's essential for the caterpillar's own cells to stay alive.

    The cells that make up the caterpillar's muscles, gut and salivary glands are destined to end up as spare parts for the greater-butterfly-good. Each cell is poised to self-destruct during metamorphosis by activating some of its own enzymes, called caspases.

    Like digestive enzymes, caspases tear through the cell's proteins, releasing prime butterfly-making material. (This process is called apoptosis, or programmed cell death, and it's the same thing that happens to about 50 million cells in your body every day to make sure you don't double in size every time your cells multiply). At any given time juvenile hormone is the only thing stopping all those caterpillar cells from ending it all.

    Like other flying insects that undergo complete metamorphosis, caterpillars go through five regular moults during their mindless hungry lives, upsizing their outer skin each time.

    When the caterpillar is big enough, usually after the fifth moult, the level of juvenile hormone drops off. With less juvenile hormone around, instead of inducing a regular moult the ecdysone now drives the caterpillar to pupate. Once the caterpillar is safely ensconced in some kind of silky hideaway, juvenile hormone stops being made altogether.

    Without juvenile hormone to suppress the imaginal discs, or to keep the regular cells from topping themselves, the two trademarks of metamorphosis kick into full swing. And in the kind of beautifully orchestrated way that only nature or really top-shelf creators can manage, the demise of caterpillar and creation of butterfly happen side-by-side


    Were you familiar with this process ?
     
  22. arauca Banned Banned

    Messages:
    4,564
    the very hungry caterpillar hits puberty

    The cells in the imaginal discs are like stem cells without commitment issues. From early on in the caterpillar's life, each one of them is locked into becoming a particular bit of butterfly anatomy. And they're all just sitting there, waiting to get the go ahead to start making butterfly parts.

    But to build a butterfly you have to break down a caterpillar.

    During the week or two spent in its chrysalis (pupation) the caterpillar gradually digests all of its own tissue, releasing the nutrients that all those imaginal discs then use to grow into butterfly wings, legs, feelers and the rest. It's the ultimate in recycling makeovers, and it's due to some interdependent hormonal changes that make puberty look like a doddle.

    The hormonal tango

    From little grubs butterflies grow

    The thing that drives caterpillars (and other flying insect larvae) to stop feeding their faces, settle down somewhere safe, and pupate, is the hormone ecdysone. It's the same hormone that causes the larvae to moult each time they outgrow their current skin. The reason this final moult into a butterfly is so different from the earlier ones is because the level of another hormone — juvenile hormone — is suddenly lower.

    Juvenile hormone is the great controller of metamorphosis, by delaying it until the caterpillar has moulted and grown enough to produce a decent-sized butterfly. It works by blocking the genes in the imaginal discs, keeping those wannabe butterfly cells in a holding pattern. So while juvenile hormone is being pumped out of tiny glands behind the brain, all the caterpillar can do is feed, grow and — when instructed by ecdysone — moult. (It's so good at preventing larvae from maturing that a lot of insecticides have been based on artificial juvenile hormone).

    But juvenile hormone isn't just a suppressor of butterfly development, it's essential for the caterpillar's own cells to stay alive.

    The cells that make up the caterpillar's muscles, gut and salivary glands are destined to end up as spare parts for the greater-butterfly-good. Each cell is poised to self-destruct during metamorphosis by activating some of its own enzymes, called caspases.

    Like digestive enzymes, caspases tear through the cell's proteins, releasing prime butterfly-making material. (This process is called apoptosis, or programmed cell death, and it's the same thing that happens to about 50 million cells in your body every day to make sure you don't double in size every time your cells multiply). At any given time juvenile hormone is the only thing stopping all those caterpillar cells from ending it all.

    Like other flying insects that undergo complete metamorphosis, caterpillars go through five regular moults during their mindless hungry lives, upsizing their outer skin each time.

    When the caterpillar is big enough, usually after the fifth moult, the level of juvenile hormone drops off. With less juvenile hormone around, instead of inducing a regular moult the ecdysone now drives the caterpillar to pupate. Once the caterpillar is safely ensconced in some kind of silky hideaway, juvenile hormone stops being made altogether.

    Without juvenile hormone to suppress the imaginal discs, or to keep the regular cells from topping themselves, the two trademarks of metamorphosis kick into full swing. And in the kind of beautifully orchestrated way that only nature or really top-shelf creators can manage, the demise of caterpillar and creation of butterfly happen side-by-side.

    http://www.abc.net.au/science/articles/2011/12/07/3384014.htm?site=science/basics
     
  23. scheherazade Northern Horse Whisperer Valued Senior Member

    Messages:
    3,788
    Interesting information on butterflies, arauca. Thanks for the link.

    Delightful creatures, are butterflies, and so much diversity in their size and color.

    Please Register or Log in to view the hidden image!



    We even have a number of them in the Yukon, as in the following photo.

    Please Register or Log in to view the hidden image!

     

Share This Page