A Müllerian mimicry ring

Professor Ceiling Cat continues to be distressed at the lack of interest (reflected in comments, at least) on the science posts: those posts that are the hardest to write. Nevertheless, he persists.

Here is a likely example of aposematic (warningly colored) mimics in different orders of insects having evolved to resemble each other (tweet courtesy of Matthew Cobb).  This phenomenon is well known in biology, and is known as Müllerian mimicry after the German zoologist Fritz Müller.

If distasteful, noxious, or dangerous species share a common predator, they may evolve a convergent pattern or color that the predator recognizes and avoids. The presumed advantage is that if these species have a common pattern, the predator has to undergo less “learning” to recognize and avoid the shared pattern. What that means to one of these insects like those below is that if an individual of species 2 gets a mutation that somehow resembles a pattern that predators have already learned to avoid in species 1, it has a reproductive advantage over individuals of species 2 with some other aposematic mutation. Do you see why that is? It’s because the first few individuals of species 2 with a different aposematic pattern stick out in the environment, and the predator hasn’t yet learned to avoid them. Learning means that it has to sample the insect (likely killing it) before it learns to avoid the new pattern. You have a survival advantage if you fit in to an already-evolved/learned system rather that starting another one with a mutation that hasn’t been “learned.”

This, biologists presume, is the reason why members of different species evolve to resemble each other when they’re all noxious to predators.

Here we have species from three different insect orders—Coleoptera, Diptera, and Lepidoptera—which have evolve a common orange and black striped pattern.

While we can’t observe the evolution of this convergent pattern, we can make predictions from our evolutionary scenario.

First, these insects have to share a common predator: that is, there should be one or more species of predator that lives in the area that all these species inhabit, and has learned to recognize and avoid the pattern. That, of course, can be tested. (There are some twists here, but not important enough to mention.)

Second, that common predator has learned or can be taught to learn to avoid the pattern.

Third, if you have trained a predator (say, a naive, hand-reared bird) to avoid the pattern, introducing the predator to a different species with the same pattern should show that it’s avoided more often than a brightly colored species with a different pattern.

I know that the second prediction has been tested and confirmed for some aposematic insects, but I’ve no idea whether the first and third have been for members of Müllerian mimicry rings. (Hypothesis three has been tested and confirmed for members of singe aposematic species.)

The important thing is that the evolutionary hypothesis is testable. Creationists, of course, could just say “God made a group of insects this way so they’d survive”, but that assertion can lead to different predictions. I won’t go into those, but perhaps you can think of some.

113 Comments

  1. Weary
    Posted January 8, 2018 at 2:48 pm | Permalink

    I do read these posts. Please keep doing them. I just get them in my daily email so have little need to come to the blog to read them

    • Flaffer
      Posted January 8, 2018 at 3:31 pm | Permalink

      I agree! I read almost all posts and relish the science ones in particular. yet, I hardly comment because I have little to add or do not have the time.

      • Posted January 9, 2018 at 7:17 am | Permalink

        And I’m in the same boat – consider it work invested in the interested but learning masses. Not qualified to comment but fascinated.

  2. ploubere
    Posted January 8, 2018 at 2:51 pm | Permalink

    I too read them, but am not knowledgeable enough to comment on them. Nevertheless, I find them interesting and informative.

    • Glenda Palmer
      Posted January 8, 2018 at 3:14 pm | Permalink

      +1

    • Richard Bond
      Posted January 8, 2018 at 4:22 pm | Permalink

      Exactly my position.

      • Malcolm
        Posted January 8, 2018 at 5:05 pm | Permalink

        I feel I am in the same position – I love these posts and would definitely like to see more of them

    • Heather Hastie
      Posted January 8, 2018 at 5:23 pm | Permalink

      Mine too. I read these posts to try and reduce my ignorance, not expose it! Therefore, commenting wouldn’t be a good idea.

      I do have a question in this case though, and I don’t care if it’s a stupid one because I want to know: Do critters that are not unpalatable to the predator evolve the same patterns to trick the predator and make themselves safe?

      • Posted January 8, 2018 at 5:33 pm | Permalink

        That’s not a stupid question at all. This is a common phenomenon called Batesian mimicry (see Wikipedia). One example are those moths and flies that mimic bees and wasps. This isn’t unpalatability, but it’s danger: pain from a sting. There are plenty of cases involving edible species mimicking toxic ones, though.

        • Heather Hastie
          Posted January 8, 2018 at 5:48 pm | Permalink

          Thanks mate. 🙂

        • Posted January 9, 2018 at 2:13 am | Permalink

          So what you’re saying is Batesian mimicry is when non-poisonous species evolve to mimic poisonous species, and Müllerian mimicry is when poisonous species evolve similar patterns to prior poisonous species?

          I love the science posts, by the way. It’s my favorite part of this website.

        • Brian Davis
          Posted January 13, 2018 at 2:02 am | Permalink

          Can this dilute the effectiveness of the noxious species’ markings? If enough non noxious species pretend to be noxious does it eventually become worthwhile for predators to target them?

      • Diana MacPherson
        Posted January 8, 2018 at 7:17 pm | Permalink

        I’d comment but I’m so ignorant, the keyboard would just make farting noises.

    • danstarfish
      Posted January 8, 2018 at 8:09 pm | Permalink

      +1

    • joanfaiola
      Posted January 9, 2018 at 4:28 am | Permalink

      I too would be sorry if you stopped the science posts. I also lack the knowledge to comment on them, and I have to say I sometimes struggle to understand, but there is a good chance that something sticks and my knowledge is improved.

    • Terry Sheldon
      Posted January 9, 2018 at 7:38 am | Permalink

      Same here. Love the posts but there are so many qualified and knowledgeable readers of this site who make relevant and insightful comments, I don’t feel that I have anything to add.

  3. Serendipitydawg
    Posted January 8, 2018 at 2:54 pm | Permalink

    Ditto – they are always the most illuminating.

    • Posted January 8, 2018 at 3:00 pm | Permalink

      Ditto. Somehow comments of “Gee! I didn’t know that!” or “Wow!” seem inappropriate.

    • Paul S
      Posted January 8, 2018 at 3:08 pm | Permalink

      IEBGENER – Always fascinating and educational. As Ploubere, I’m not knowledgeable enough to comment and any questions would amplify that fact.

      • Dragon
        Posted January 8, 2018 at 11:35 pm | Permalink

        +1
        RE: IEBGENER – I didn’t know other MVS (OS/390, z/OS) nerds frequented this blog.

    • Posted January 8, 2018 at 3:10 pm | Permalink

      +1 to both of these. Enjoy the posts, almost never knowledgeable enough to add anything of value except “Very nice”. If that helps keeping them coming, I’ll comment accordingly or similarly.

  4. alexandra Moffat
    Posted January 8, 2018 at 2:58 pm | Permalink

    The Science articles are fascinating, wonderful, appreciated. I am, compared to you, Cobb and others so ignorant, I wouldn’t dream of commenting. That doesn’t stop me from being eternally curious as I try to comprehend and absorb all that you write about.

    • Posted January 8, 2018 at 5:35 pm | Permalink

      I wasn’t trying to elicit reassurance here; just expressing frustration. But I’d be delighted for readers to ask questions, even if I don’t see them sometimes. As I tell my students, “There’s no such thing as a dumb question if you are curious about the answer.”

      • ThyroidPlanet
        Posted January 8, 2018 at 6:37 pm | Permalink

        “There’s no such thing as a dumb question if you are curious about the answer.”

        Excellent – never heard this one!

        Wow, I’m going to remember that one…

      • David Coxill
        Posted January 9, 2018 at 5:25 am | Permalink

        All right ,chew on this .Those species of Spiders that have evolved to mimic Ants .Seeing as Ants use Pheromones to identify fellow Ants ,have Spiders evolved to smell like ants .

        • Jonathan Wallace
          Posted January 10, 2018 at 6:32 am | Permalink

          I don’t know about the spiders you refer to but olefactory mimicry certainly exists. An example is the larvae of the Large Blue Butterfly Maculinea arion which are carried by ants of a particular species (Myrmica sabuleti)into their nest where the larva then feeds on ant grubs until it pupates and eventually emerges from the nest as an adult butterfly. It appears that the larva gives off chemical signals that dupe the ants into treating the it as one of their own. I believe a number of other lycaenid butterflies exhibit similar strategies.

  5. ThyroidPlanet
    Posted January 8, 2018 at 3:01 pm | Permalink

    Sub

  6. Posted January 8, 2018 at 3:05 pm | Permalink

    Commenting on science issues is much more daunting for non-scientists than, say, commenting on Oprah running for president. I’m a biologist and commenting on some science posts far outside my field of expertise is daunting to me, so I grok the reluctance. Often, unlike politics or posts on social issues, there is very little room in science posts for either conjecture or opinion. So that shuts of some of the stream as well.

    To be honest, if it wasn’t for the science posts I’d probably not visit WEIT much. Come for the science, stay for the social commentary.

    • Posted January 8, 2018 at 3:26 pm | Permalink

      Oh. You DID ask for conjecture in this one;

      “Creationists, of course, could just say; ‘God made a group of insects this way so they’d survive’, but that assertion can lead to different predictions. I won’t go into those, but perhaps you can think of some.”

      Hmmm. I’ll venture a guess….perhaps one would expect there would be no differential survival among variants, unless they are ol’ Yahweh’s chosen ones.

      • Posted January 8, 2018 at 5:36 pm | Permalink

        Yes, that’s one of many answers; if God did it for his pleasure, there’s no reason the creationists’ predictions (if there are any) should match those from the evolutionary explanation.

        • Posted January 10, 2018 at 11:41 am | Permalink

          The creationist is using an example of what Bunge calls a “male fide” ad hoc hypothesis, for sure. (I.e., one not testable independent of what it is “protecting”.)

    • colnago80
      Posted January 8, 2018 at 7:03 pm | Permalink

      Well, I have a science degree (PhD in physics) but I would be reluctant to comment on a post on biology unless I had a good reason for doing so.

  7. Peter Nonacs
    Posted January 8, 2018 at 3:07 pm | Permalink

    Fair enough. A comment or clarification – they do not ALL have to share a common predator. Imagine a predator that eats only A to D. Another that eats only C to F. Another only E to H. As long as you get some overlap of the prey species, you can get a Mullerian ring without any single common predator living with and eating all the species. However, a common predator that might eat all the species would be strong evidence for convergence.

    • Posted January 8, 2018 at 5:37 pm | Permalink

      Yes, that’s true (good point) but there must still be predators in common between at least two of the species in a ring.

  8. Johan Richter
    Posted January 8, 2018 at 3:09 pm | Permalink

    It is easy to see that you might want to look like a poisonous species, whether you are poisonous yourself or not. It is not so easy to understand how the first individuals can benefit and spread their genes from looking distinctive since by assumption predators won’t be familiar with the fact that they are poisonous.

    • nicky
      Posted January 8, 2018 at 3:45 pm | Permalink

      Yes, that is something I’ve been pondering about and did not find a satisfactory answer. We have to assume that 1- victims of predators survive (spat out?) often enough to reproduce, or 2- it is pure kin-selection. Is there a ‘3-‘?
      I have even more problems with venomous animals. How can the predator learn if it is killed off? Or do they just don’t learn? I note that aposematic colouring is more common among poisonous or unpalatable animals than venomous ones.

      Science posts are the best, please keep them coming. As mikeyc pointed out, we are often bit weary to comment on them out of fear to appear completely asinine.

      • Posted January 8, 2018 at 5:41 pm | Permalink

        There are several answers suggested, including kin selection. But #! won’t work if the first brightly colored insects experience a net decrease in fitness if they’re attacked too often. The issue is that, except for broods that express a new mutation, it always seems that a single more visible mutant would be attacked more often, and if it’s just one, the chances that a predator would learn and then avoid that individual, presuming it survives, seems low.

        Kin selection has been suggested for aposematic caterpillars because they tend to be gregarious species more often than non-aposematic but still distasteful caterpillars.

        • nicky
          Posted January 9, 2018 at 10:38 am | Permalink

          Yes, I think kin selection is one of the more plausible mechanisms at first sight. But then, science teaches us that ‘at first sight’ can sometimes be spectacularly wrong.
          Must be possible, difficult but possible, to test these things.

      • Jonathan Wallace
        Posted January 10, 2018 at 6:58 am | Permalink

        Where the aposematic critter is not distasteful but gives a nasty sting or bite we do not have the same theoretical difficulty and one can see how how such a signal could get going along the lines of #1: the predator gets a sharp and very memorable message that this is not an insect to be messed with and the insect itself survives to spread its genes. This might be why the familiar yellow and black striped abdomen of bees, wasps and their many mullerian and batesian mimics is so widespread and succesful?

    • Posted January 8, 2018 at 3:52 pm | Permalink

      Yes, I thought Muller showed convergence was mutually beneficial, not that one species could free ride on the aposematic pattern of the other.

      • Posted January 8, 2018 at 3:58 pm | Permalink

        PS The science posts are the main reason I come to this site.

      • nicky
        Posted January 9, 2018 at 10:35 am | Permalink

        How so? How would a genuine unpalatable (or poisonous) individual benefit from Batesan free riders?

        • nicky
          Posted January 9, 2018 at 10:44 am | Permalink

          Sorry, interpreted you the wrong way.

    • jaxkayaker
      Posted January 8, 2018 at 4:31 pm | Permalink

      Looking like an unpalatable species without being unpalatable is known as Batesian mimicry, after the renowned 19th century naturalist Henry Bates, a collaborator of Alfred Russel Wallace.

      Examples are the scarlet snake (Cemophora coccinea) and the scarlet kingsnake (Lampropeltis elapsoides) resemble the venomous coral snake (Micrurus fulvius) of the southeastern United States.

      To partially address nicky’s valid concern about venomous animals, not all venomous species are equally lethal to all potential victims/would-be predators.

      Jerry – re: the science post: read it, liked it, appreciated it, learned something, and thank you for posting it.

      Although I wrote a term paper back in the day on mimicry in herps, I don’t remember ever learning about Mullerian mimicry rings.

      I wonder if the Monarch/queen/viceroy butterfly mimicry can be considered another example of a Mullerian mimicry ring, or are they too closely related. I know they’re considered an example of Mullerian mimicry, although it could potentially also be explained by close common ancestry/parallel evolution.

    • Posted January 8, 2018 at 6:31 pm | Permalink

      Re: “It is not so easy to understand how the first individuals can benefit and spread their genes from looking distinctive since by assumption predators won’t be familiar with the fact that they are poisonous.” I haven’t studied this area, but pondering a bit, here’s a mechanism I find plausible. (1) A species exists, is poisonous, and looks like *something* – even if that something is cryptic or whatever. (2) A predator evolves or learns to recognize that species, by recognizing some kind of pattern, in order to avoid it because it’s poisonous. This would happen even if the species is cryptic; when a predator *does* happen to spot a cryptic individual, it is useful for the predator to be able to recognize that that particular type of cryptic individual is not palatable. (3) The prey species evolves to look “more like itself”, in a specific sense: it evolves to more effectively trigger whatever pattern-recognition algorithm the predator is using to differentiate it from other more edible prey. The key point here is that this step 3 might involve changes in appearance that would make the species less cryptic and more visible, as long as they happen to more effectively trigger whatever pattern-recognition algorithm the predator is using. (4) The predator’s pattern further evolves to better recognize the new prey appearance. (5) go back to 3 and 4, lather rinse repeat. This leads to a runaway process that might very well lead to flashy aposematic patterns like bright orange stripes, etc.; each step along the way, the prey species is getting better at telling the predator that it is not edible, and the predator is getting better at distinguishing it from edible species. The increase in visibility of the prey species, at each step, would need to be more than compensated for by the increase in the effectiveness of the aposematic message; but that seems quite plausible. I have no idea if this has been proposed by others already or not; probably it has, it’s very hard to come up with a really new hypothesis in evolutionary biology. :->

      Incidentally, this is a bit like how Google’s “dreaming” visual-effects tool works. It starts with a neural network that recognizes some particular type of visual feature (this is the predator’s pattern-recognition algorithm), and then it modifies an image to more effectively excite that neural network (this is the prey’s evolution). Applied iteratively, in a similar sort of “runaway process”, it tends to make stronger and stronger patterns, in more and more garish colors. Of course in that scenario there is no disadvantage to evolving in that direction, whereas in nature, the benefit in increased aposematic recognition has to outweigh the cost in increased visibility, as I said.

    • Posted January 8, 2018 at 10:00 pm | Permalink

      This brings up the point that not all members of the ring need to be unpalatable. Some can sneak into the ring as Batesian mimics. I see a fly in the above group, and possibly a treehopper.

      • Diane G.
        Posted January 11, 2018 at 11:26 am | Permalink

        Dipterans are mentioned in both the caption and Jerry’s commentary…

        Got me to wondering–are there ever unpalatable flies? Are some taxa less likely to develop unpalatability due to diet (or some other factor)? Does it mostly/solely occur in herbivorous species which have already been co-evolving with plants and all their chemical defenses?

  9. Posted January 8, 2018 at 3:13 pm | Permalink

    Iy’s a bit surprising if your third prediction has not been tested. Of course, I wouldn’t know about it if it had been tested. Anyway, keep the science coming.

  10. Jacques Hausser
    Posted January 8, 2018 at 3:22 pm | Permalink

    It would be interesting to measure a difference in avoidance of “perfect” mimics and imperfect mimics. Imperfect mimics should be submitted to a stronger pressure and – if they show some polymorphism – a stronger selective pressure.

  11. Mark Perew
    Posted January 8, 2018 at 3:22 pm | Permalink

    As others have noted here and in other posts, many of us eagerly read your missives in our email. Having nothing to add or ask, we smile and shift attention to the next email. (The moving eye reads; and having read moves on.)

  12. Warren Bailey
    Posted January 8, 2018 at 3:39 pm | Permalink

    When I found out that you were considering stopping the science posts I began to make it a point to always come to the post itself rather than just reading the email. Most of the time I don’t feel qualified to comment on the post though I always learn something. Maybe I should say something regularly so you’ll know that it’s appreciated

  13. BJ
    Posted January 8, 2018 at 3:41 pm | Permalink

    Like many others, I read every science post, but I’m just not knowledgeable enough to add anything. I do occasionally post questions, though (especially when it comes to physics). Please keep them coming.

  14. Posted January 8, 2018 at 3:46 pm | Permalink

    PCC should probably not be overly concerned about “lack of interest.” As others have noted, we read them but often do not have much to add content-wise. I think that it has also been noted that visits to the post is not the full picture of readership or interest since many of us read the post via email rather than linking to WEIT.

  15. Posted January 8, 2018 at 3:46 pm | Permalink

    I too read your science posts and find them fascinating but also feel unqualified to comment.

  16. Posted January 8, 2018 at 3:52 pm | Permalink

    Keep the science posts rolling. Thank you for giving us so much of your valuable time.

  17. eliz20108
    Posted January 8, 2018 at 3:57 pm | Permalink

    I think you dont get comments on scientific writing bc I cant think of a comment.

    I read your scientific writings with great excitement.

    Liz

  18. Randall Schenck
    Posted January 8, 2018 at 4:02 pm | Permalink

    The non biology experts among us want to know but often do not want to tip off the stupidity in comment. It is another form of mimicry, yes?

  19. Susan D.
    Posted January 8, 2018 at 4:02 pm | Permalink

    If a creationist was to say to me “God made a group of insects this way so they’d survive” I would ask why she favoured one group of insects over another? Or why she didn’t just let all groups survive? Sure I wouldn’t get a coherent answer.
    Keep the science posts coming, love them, but don’t have expertise to comment much.

    • nicky
      Posted January 9, 2018 at 10:46 am | Permalink

      Sounds like the old: “Whose side is God on, the Gazelle’s or the Cheetah’s?”

  20. Taz
    Posted January 8, 2018 at 4:11 pm | Permalink

    1. As others have noted, laymen such as myself rarely comment on science posts because we have nothing to add.
    2. Your site almost always puts an entire post on the front page – nothing “below the fold”, so to speak. (A feature I love, by the way.)

    Combine 1 and 2, and it means a lot of people read the science posts without ever clicking on them.

    I wonder if it would be worth adding a check box to the bottom of every post – “I read this”.

  21. Steve Pollard
    Posted January 8, 2018 at 4:13 pm | Permalink

    Like most of the commenters above, I find all the science posts fascinating, and I usually re-read them to be sure I’ve taken everything in. I don’t often comment because, like others, I don’t feel qualified to do so, and I don’t want to make a pillock of myself by saying something naive or ignorant. My New Year’s resolution is therefore to remember to say “thank you” more often!

    • Posted January 8, 2018 at 4:33 pm | Permalink

      Yes, thanks to Dr. Coyne for the science articles, and thanks to Steve Pollard for saying pretty-much what I had in mind.

      In short, when it’s about biology I read, I learn, and I try not to embarrass myself by posting something.

  22. John Dentinger
    Posted January 8, 2018 at 4:21 pm | Permalink

    PCC: Thanks for all your posts, science & otherwise.

  23. Paul Doerder
    Posted January 8, 2018 at 4:30 pm | Permalink

    I too enjoy and learn from the science posts. Most are out of my immediate area, so I rarely comment. Also, sometimes its just a matter of being busy.

    Humans see the yellow/brown stripes. What does the predator see, given that many animals see different wavelengths or perhaps no color at all?

    • nicky
      Posted January 9, 2018 at 10:51 am | Permalink

      Well, as far as insects go, birds and reptiles are -I guess- their main predators, at least for many species.
      Birds are tetrachromatic, and (IIRC) some reptiles are even pentachromatic. No real problem there, it seems.

  24. KD33
    Posted January 8, 2018 at 4:44 pm | Permalink

    I’m going to try to comment when I find a science post interesting so as to add to the chorus of support to encourage PFC to keep such postings!

    And this one is interesting!

    It’s always intrigued me that there would be enough species, of similar size and pattern to an existing predator-repelling species, that would, by accidental mutation, assume a pattern similar enough to also repel the predator. Here, by “enough species,” I mean to jibe with the observed occurences of such mimicry, some of which are even shared by multiple species, as in this example.

  25. Debra Coplan
    Posted January 8, 2018 at 5:03 pm | Permalink

    I read and relish them coming. Please keep sending them out.
    I spend a lot of time on them but don’t comment-

  26. Max Blancke
    Posted January 8, 2018 at 5:17 pm | Permalink

    Lack of comments does not equate lack of interest. I find these articles interesting, I just don’t have additional knowledge of the subject to contribute in the comments.

  27. Gregory Kusnick
    Posted January 8, 2018 at 5:18 pm | Permalink

    The presumed advantage is that if these species have a common pattern, the predator has to undergo less “learning” to recognize and avoid the shared pattern.

    This seems to imply that the predator learns the single pattern faster if there are multiple prey species exemplifying it. But of course what you mean (and later say) is that individual prey animals gain an advantage from mimicking a pattern that the predator population has already learned (however difficult that learning may have been).

    A case could perhaps be made that some patterns are easier to learn than others due to quirks of the predator’s visual system. In that case we’d expect selection pressure on prey species causing them to converge on those attractor patterns, but the strength of that pressure should be independent of the number of prey species it affects.

    To add to what others have said, one of the things I value about this site is the high signal-to-noise ratio in most comment threads. My policy is to refrain from commenting unless I have something substantive to add that hasn’t already been said, and I appreciate it when other readers do likewise.

    • Posted January 8, 2018 at 6:33 pm | Permalink

      Free-riding on a pattern the predators have already learned is what PCC described but, at least according to the Wikipedia article, that is not what Muller’s model described. As described there, the advantage is that the prey species share the burden of teaching the predators (i.e., by being eaten) so the advantage to a prey species depends on its relative size in the total prey population. If the prey species populations are of equal size, the patterns converge and the species benefit equally.

      • Gregory Kusnick
        Posted January 8, 2018 at 8:28 pm | Permalink

        I’m not sure I follow the distinction between “free riding” and “sharing the burden”. Either way some individuals benefit from the sacrifice of other individuals.

        • Posted January 8, 2018 at 10:56 pm | Permalink

          Well, with free-riding the mimic bears none of the costs of detering the predator species(in terms of deaths to “teach” the predator to avoid the pattern), but gets the benefit for free so to speak. With Mullerian mimicry, as I understand it, all species in the ring bear the costs of teaching the common predator in proportion to their relative population size. Also, I interpret the Mullerian model as mutual mimicry converging on a common pattern rather than there being a clear model-mimic distinction. Of course, I have a layman’s understanding, or misunderstanding.

          • Gregory Kusnick
            Posted January 9, 2018 at 12:51 am | Permalink

            Seems to me the “free rider” is just as likely (per capita) to be eaten by a naïve predator. So in that sense it shares the cost of training up new generations of predators, even if it didn’t participate in training prior generations.

            • Posted January 9, 2018 at 9:32 am | Permalink

              I agree. I am objecting to the narrative of how the species in the ring get the same aposematic pattern. You (and PCC) describe a prior state in which a bad-tasting prey species without a pattern copies the existing pattern of another bad-tasting species which has the same predator. But that is just Batesian mimicry by a bad-tasting species.

              But why should such a prior state exist? Why doesn’t the first bad-tasting species have its own warning pattern? Muller explains that it is more efficient for bad-tasting prey species to evolve the same warning pattern against a common predator. More efficient because that way the species in the ring share the cost of training the predator rather than bearing it all by itself. It is mutual mimicry rather than one species copying the evolved pattern of another (which is what I meant by free-riding.)

              • Posted January 9, 2018 at 10:11 am | Permalink

                What makes Muller’s theory interesting to me is that it describes the evolution of a public good (the common warning pattern) rather than a species simply exploiting an opportunity (which is common enough.)

              • Gregory Kusnick
                Posted January 9, 2018 at 12:27 pm | Permalink

                “But that is just Batesian mimicry by a bad-tasting species.”

                Not as I understand it. Mimicry of a bad-tasting species by a bad-tasting species is by definition Müllerian, and Batesian mimicry is by definition a palatable species free-riding on the pattern established by an unpalatable one.

                By your logic, any living member (palatable or unpalatable) of an existing Müllerian ring would count as a free rider, since none of those living individuals can be credited with establishing the ring; they’re all benefiting from the fact that it already exists. Moreover, those living “free riders” aren’t actually doing anything different than the founders did; they’re displaying a pattern that causes predators to learn to avoid them, just as the founders did. I don’t see why descendants of the first individuals to display that pattern deserve more credit for being good citizens than members of a species that joined the ring later by convergence. Again, they all run the same risk of being eaten by naïve predators.

              • Posted January 9, 2018 at 2:21 pm | Permalink

                The prey species in a Mullerian ring are not free riding. Individuals of all prey species die in order to train new generations of the common predator species to avoid the pattern. It is a learned avoidance behavior so every generation of predators must be taught anew. The advantage is in the cost sharing.

                Distinguishing Batesian and Mullerian mimicry according to whether the prey is good or bad-tasting seems pointless to me. Why not just define all mimicry as a prey species, good or bad-tasting, copying an existing avoidance pattern of another prey species and be done with it?

              • Gregory Kusnick
                Posted January 9, 2018 at 2:49 pm | Permalink

                The salient difference between Müllerian and Batesian mimicry is that in Müllerian mimicry, all individuals pay the metabolic cost of producing the bad-tasting toxin, whereas in Batesian mimicry, some individuals avoid that cost while still enjoying protection from predation. That’s the sense in which Batesian mimics are free riders.

              • Posted January 9, 2018 at 3:32 pm | Permalink

                Good point. Thanks.

  28. rickflick
    Posted January 8, 2018 at 5:31 pm | Permalink

    If God did it, and not Müller, I would think we would predict the pray species would all have the same pattern, not just approximate mimicry. The variety seen in the image above suggests each species created a pattern from whatever genetic material was at hand, which means that some will show only color, some one stripe and some two stripes, etc. God, as we all know, has no constraints and would be embarrassed at the disarray of natural selection.

    • Posted January 8, 2018 at 5:43 pm | Permalink

      Yes, another good point, which goes along with the point that if God designed all creatures, we wouldn’t see imperfections like the position of the prostate gland–imperfections that can be explained by evolution.

      • Jake Sevins
        Posted January 8, 2018 at 6:56 pm | Permalink

        Or the left recurrent laryngeal nerve in giraffes. What was God thinking??

  29. Loic
    Posted January 8, 2018 at 5:32 pm | Permalink

    Hello,

    I guess most of your audience is educated but not expert in your field. We will comment only if we feel we have something to contribute. « Wow » does not make a productive comment.

    However, it would be really nice if you could tag your posts in mails so your audience can sort or filter post as they come in. [cat] [science]… any short list of category you find relevant.

    Thanks.

  30. Jake Sevins
    Posted January 8, 2018 at 6:53 pm | Permalink

    I think you get more comments on news than on science because news tends to be more polarizing than science.

    But news is not more captivating, more inspiring or more fascinating than science. Keep it up Professor! 🙂

  31. Dee
    Posted January 8, 2018 at 7:11 pm | Permalink

    I’m another who really likes the science posts but lacks the background to add to the discussion. The science posts are my favorites.

  32. J Cook
    Posted January 8, 2018 at 7:20 pm | Permalink

    Ditto to the reply 31 above

  33. µ
    Posted January 8, 2018 at 7:29 pm | Permalink

    What makes you think this is Müllerian mimicry, rather than Batesian mimicry. Or why not a mix of Müllerian and Baterian mimicry?

    The lycid beetles are toxic (pyrazines), but where is the evidence that all (or any) of the mimicking flies and moths are also toxic?

    I am obviously missing something here, and there was no additional info in the original post from Virginia Tech Insect Collection: http://collection.ento.vt.edu/?p=401

    • Posted January 8, 2018 at 10:13 pm | Permalink

      The moths and the beetles can be toxic. But I also think that among the species are unpalatable, there are some species there that look like that would be palatable Batesian mimics. The fly, for example.

  34. Alpha Neil
    Posted January 8, 2018 at 7:41 pm | Permalink

    I started writing a question about the visual system of predators but then realized that it was covered by Gregory Kusnick in #27 so I’ll just quickly add my voice to the chorus of those asking the good PCC to please keep up the science posts! Before I comment on a science post I’m always reminded of the words of the great educator Mr. Garrison: “…there are no stupid questions, just stupid people”.

  35. Ken Kukec
    Posted January 8, 2018 at 7:58 pm | Permalink

    Keep the science post comin’, boss; it’s a chance for us laymen to learn something. If we kids keep eating our vegetables, eventually we’ll come to like ’em.

  36. Posted January 8, 2018 at 8:27 pm | Permalink

    “If distasteful, noxious, or dangerous species share a common predator, they may evolve a convergent pattern or color that the predator recognizes and avoids.”

    “If distasteful, noxious”… I understand this part of the statement but this part i found curious “or dangerous species”
    If a predator ‘learns’, would not a dangerous prey to a predator also be ‘learned ‘ to be avoided regardless of markings?
    Would it push the pray species down the pecking order of a meal worth time and effort, risk? or is that the point?
    I can think of a couple of reason why a healthy dangerous prey would mimic to warn off a predator or predators.
    Some predator(s) don’t regard it as dangerous enough and/or have adapted to handle it.
    Two, it won’t be bothered by predators in going about it’s business saving energy costs, injury and ultimately in both, to live another day.
    Following on, it mimics for taste and/or being noxious, as being dangerous means diddly squat and on the negative side of an arms race (in it’s ability to strike back) when it comes to being on the menu. Nutritional gains for a predator being a consideration here… is the opportunity worth it.

    Taste! what a weapon… or is it colour markings?
    Look at that! nope, yuk!

  37. Jeff Chamberlain
    Posted January 8, 2018 at 9:35 pm | Permalink

    I’m not a scientist and I come here for the science posts. I seldom think I have anything to comment about in response to a science post, although more frequent thank-yous would perhaps not be amiss. (Thank you….) I don’t doubt they are the hardest to write. I very much appreciate your science posts and I hope you will keep doing them.

  38. Posted January 9, 2018 at 2:24 am | Permalink

    If I were omnipotent and wanted to save a bunch of insects from predation, I’d eliminate the predators. Or give the insects a more deadly toxin. Or program their predators to avoid those insects. There are probably a lot more solutions but that’s what I came up with while I was typing.

  39. MKray
    Posted January 9, 2018 at 3:55 am | Permalink

    Your scientific posts are valued by this physicist who rarely feels competent to comment.

  40. Brian salkas
    Posted January 9, 2018 at 4:01 am | Permalink

    Im sure this is an obvious question but I’ll ask it anyway. When it comes to Bastsian mimicry, as opposed to mullerian mimicry, will it just reach a point where there are too many harmless imitators and the common predator will have less and less chance of actually eating the toxic species? Do you guys find that Mullerian rings like the one you wrote about here can grow larger than Batsian rings? I would bet that there is a certain threshold where a type of dilution takes place and the aposemtic pattern loses its effect all together. A good way to test that would be to compare the sizes and variability of mullarian vs. batseian mimicry rings and if the mullarian rings are consistently much larger, that could imply that significant dilution does take place when not all of the species are toxic and there are too many free-loaders.

  41. John Power
    Posted January 9, 2018 at 5:21 am | Permalink

    This is my first comment on your website, though I have been reading for several years. Please don’t stop mistake my lack of comments as a lack if interest, and please don’t stop posting science posts, as i find the majority informative and fascinating.

  42. Bob
    Posted January 9, 2018 at 5:24 am | Permalink

    I have to agree with others that I do read them but am not competent to comment. Perhaps if someone who is could comment additional information or, even better, reference other articles or books for laypeople.
    A question does come to mind and I do hope it was not addressed and I missed it.
    If eating a mimic causes death in the predator, how does that protect others in the mimic group? A dead predator cannot pass on information very well. If eating a mimic causes illness or even tastes terrible, how does that protect others in the mimic group? Most lower forms, especially insects, do not raise their young and send them to school.
    This may seem a “stupid” question, but is one that tickles the back of my mind.

    • Gregory Kusnick
      Posted January 9, 2018 at 11:36 am | Permalink

      “If eating a mimic causes illness or even tastes terrible, how does that protect others in the mimic group?”

      A predator that has a bad experience won’t eat any more of that kind of prey. Even if each individual predator has to learn that lesson the hard way, that still adds up to a lot of potential prey not eaten.

  43. Nick260682
    Posted January 9, 2018 at 7:36 am | Permalink

    I echo what pretty much everyone has said here – they are enjoyable and illuminating, but not personally having any level of expertise in the field, I have nothing to add.

    Don’t stop them!

  44. Russel Jacobe
    Posted January 9, 2018 at 8:58 am | Permalink

    Please continue your science related posts. They are interesting; don’t let the lack of comments discourage you!

    Thank you,

    Russel Jacobe

  45. Reggie Cormack
    Posted January 9, 2018 at 9:24 am | Permalink

    Do keep the science post coming Prof Ceiling Cat. Like so many others above it’s all well above my pay grade and wouldn’t want to look too much of a twat for making a daft comment. Keep on keeping on with the posts. They really are appreciated as every one reduces my ignorance just a little.

  46. ThyroidPlanet
    Posted January 9, 2018 at 10:56 am | Permalink

    The best way to get PCC(E) to keep writing science posts is to ask good questions and contribute to discussion.

    I’m not saying I am an example to go by. Mostly I just sub – for whatever reason.

  47. nicky
    Posted January 9, 2018 at 10:59 am | Permalink

    Another question, why are aposematic colour patterns so often black and yellow or black and red? And so often a striped kind of pattern? From wasps to the fire salamander (Salamandra salamandra)
    Again, I can think of several explanations, but non of them really satisfactory. Are there some solid theories there?

  48. rebscar
    Posted January 9, 2018 at 11:26 am | Permalink

    You shouldn’t interpret lack of comments as lack of interest. I’m not a scientist, so I read your posts with interest, but without enough knowledge to comment.

  49. W.Benson
    Posted January 9, 2018 at 1:05 pm | Permalink

    When 30 years old, Fritz Müller fled Germany to escape persecution (he was an atheist and a 48er). He did all of his scientific work in Brazil, was naturalized Brazilian, and after immigrating never returned to Europe. He became an evolutionist when in Brazil. Johann Friedrich Theodor Müller was a Brazilian biologist.

    • W.Benson
      Posted January 9, 2018 at 2:13 pm | Permalink

      Müller was a damn good botanist too. He was the first to work out, in the 1860s, how vines and lianas organized their vascular and support tissues to permit flexibility and how woody plants of all types converge to the same general morphology when they evolve the vine life-form. When Darwin wanted observations on tropical flowers, it was the biologist Müller he called on. On the other hand, I am hard put to call Har Gobind Khorana a biologist, although he was certainly a top-notch biochemist.

  50. Don Mackay
    Posted January 9, 2018 at 1:24 pm | Permalink

    Are there any examples of mimicry (either Batesian or Mullerian) among homeotherms?

  51. Andrea Kenner
    Posted January 9, 2018 at 6:34 pm | Permalink

    I read your post and enjoyed it, but I don’t feel I have enough of a background in science to contribute anything worthwhile to the conversation. That’s the case with a lot of your science posts. Keep ’em coming, though, if you can. They’re interesting, and I have learned a lot from reading them!

    Too bad I couldn’t have been in one of your classes!

  52. Posted January 9, 2018 at 10:51 pm | Permalink

    A biology prof here… Just commenting in appreciation of the science posts. They often provide examples and clear explanations that enrich my teaching. And, even after more than 30 years teaching, I’m delighted by the opportunity to learn (and/or to see verification of the approach I take to help my students understand).

  53. Posted January 30, 2018 at 5:05 pm | Permalink

    I am so bad at remembering names that I’d be happier if they didn’t name mimicries after people! I have enough trouble with Malpighi, Golgi and the other dead white males whose names span morphology.


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