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Thread: Yet another puzzle

  1. #71
    Banned Stromnessbees's Avatar
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    Quote Originally Posted by gavin View Post
    Modelling three colonies in one isolated apiary, each with queens of different genotype and a pool of randomly chosen drones, 10 types per queen and 15 types in the population, over a period of years and assuming annual requeening, also assuming random mating within the apiary and no incursions from outside .... now *that* would be a nice model.
    According to the back of my envelope (a big brown one with lots of scribbles on it) you lose 6 alleles in your first season already, as with 3 queens you can only keep a maximum of 9 alleles going.

    After that you are bound to lose more soon, as some of the alleles will turn up in more than one queen and therefore not leave room for all of the other variants.

    Doris
    Last edited by Stromnessbees; 14-09-2010 at 11:01 AM.

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    I'm game if you want to try it but I need a fair but of input to define the "rules" and it would come with the caveat that it'd be for illustration purposes only.

    The magic bowl of fruit would be a lot easier though

  3. #73

    Default just one fruit left

    Quote Originally Posted by gavin View Post
    Once upon a time there was a magic bowl of fruit. It had 6 plums, 6 apples, 6 pears and 6 oranges. A hungry family ate half of the fruit each day - totally at random. This being a magic bowl of fruit, every remaining item duplicated itself overnight.

    After the first night, how many types of fruit had you lost - any?! Half of them? I can't be bothered working out the probabilities, but in many cases all would survive into the subsequent year (no, day) despite the high overall attrition rate.

    The system is self-balancing. If a fruit gets slightly more abundant than is its due, it is more likely to be picked and its frequency will fall back again. Although random events will eliminate single types of fruit from time to time, in general an equilibrium is reached.
    Strangely chosen analogy if you wanted to demonstrate the robustness of an isolated population/ closed system, under threat, and its ability to maintain diversity. In this fruit bowl story, the inevitable outcome is a bowl containing 24 of the same fruit. This could happen after two days, or two years; but it would happen, unless a pear spontaneously mutated into an apple overnight.
    How else do apples reappear once they are eliminated ' from time to time'?
    What we're discussing is surely the nub of decreasing biodiversity in a time of increasing environmental threats and only snailpaced species adaptation/mutation. To minimise current risks to so many species in fragmented, depleted environments is a suprising move for a beekeeping genetisist, so I will assume the' fruit bowl' is a devil's advocacy ploy, and it's working.
    Last edited by Johnthefarmer; 16-09-2010 at 06:20 PM.

  4. #74
    Administrator gavin's Avatar
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    Hi John

    Welcome to the forum.

    I thought that I was trying to get Eric to see that his 50% reduction in diversity every generation wasn't right, that's all.

    It isn't about trying to advocate that certain systems are robust or fragile, but to inject some realism into the arguments that have been made in the beekeeping press.

    Yes, the fruit bowl *could* turn rather boringly uniform quickly, but usually it will take many generations to do so. The diversity of the bowl is at risk, but just don't expect it to half every day.

    In terms of real populations of bees or wild animals or plants, fragmentation of habitat is a massive issue. The linkage (in terms of cross-breeding) between isolated populations is crucial to maintain the genetic integrity of the overall population ... which is why gene flow between fragmented populations is a big issue.

    Interesting to have a perspective on bee gene flow between isolated populations which comes from watching the movement of an invading pathogen like Varroa. Varroa has had some big hiccoughs in its march westwards and northwards due to restricted opportunities to leap between widely separated apiaries. The same must apply to small vulnerable bee populations - little chance to mate with the neighbouring apiary if it is over the mountain range and in the next valley.

    best wishes

    Gavin

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    Senior Member Adam's Avatar
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    Keep going guys. I don't know if I'm any the wiser but it's interesting to wade through the thread from time to time. This post has now had 900 views so others must be looking at it too!

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    Administrator gavin's Avatar
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    Many of these views will be by the crawl-bots used by the main search engines ... and also the spam-bots looking for sites with poor security. But a fair number will also be by interested beekeepers ...

    As a special reward for all the intelligent comments here, some words from a great Scottish philosopher. Thanks to David Ollason and my lovely sister-in-law for the prompt, unconscious though it was.


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    Senior Member Adam's Avatar
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    Blimey, I haven't heard Ivor Cutler since I listened to John Peel who played his stuff when I was at school!

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    Administrator gavin's Avatar
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    Ah ... another person of culture!

    At the risk of disrupting an excellent thread further, another small gift for the beekeepers amongst you who believe that you should always strive hard to understand the map, and never assume that you always have it right!


  9. #79
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    Quote Originally Posted by Stromnessbees View Post
    According to the back of my envelope (a big brown one with lots of scribbles on it) you lose 6 alleles in your first season already, as with 3 queens you can only keep a maximum of 9 alleles going.

    After that you are bound to lose more soon, as some of the alleles will turn up in more than one queen and therefore not leave room for all of the other variants.

    Doris
    Doris, you are a genius! I have to say that when you posted that I thought .... hmmmnn .... I'll bet that there's more than that, I'll work it out later. You are in fact spot-on! Here is my offering for the most diverse combinations from three colonies in a fully-isolated apiary. I see that I allowed myself 15 sperm alleles per queen, but it doesn't affect the outcome. Double digits indicate a subsequent generation. q above the queen genotype, s above the types of sperm she carries (but the software isn't allowing me the extra spaces so its a bit bunched up):

    q1 s1
    a b c d e f g h i j k l m n o p q

    q2 s2
    c d a b e f g h i j k l m n o p q

    q3 s3
    e f a b c d g h i j k l m n o p q

    q11 s11
    a g a b c d e f

    q22 s22
    d h a b c d e f

    q33 s33
    e i a b c d e f

    Beyond that second generation you're just into a fruit bowl situation. Expect to see something of this turn up in the genetics talk at the Fife meeting, for those who are going.

    Now then, should I find another Ivor Cutler video as a reward?! It is said that he kept some Ivory Cutlery in his kitchen drawer simply to entertain guests.

    G.

  10. #80

    Default yet another puzzle (Part 1)

    Hi Guys
    Honey, I'm home!! Guernsey was stunning!

    Dear All
    I have surfed the current thread and I note the chickens are still running around as if they were headless.
    At least they have a choice for comfort. As well as the bowls of hypothetial fruit to dine on they also have nesting material from the skiers.
    I suppose the thread is now virtually dead apart from some really interesting input from Doris and John the Farmer. Just as well I am not superstitious or a Carib Juju worshipper!
    I have lifted some comments, which I found interesting, listed not necessarily in chronological order.
    I do not expect any responses!


    Gavin
    If you have three colonies fully isolated from all other apiaries then it will be hard to maintain 6 alleles in the long term. Easier with 4 colonies, not so hard at all with 5. The bottleneck is the queen. Each queen can only make drones of two types as the drones arise only from the genes carried in her own cells. The workers and queens each queen makes can be more diverse as they are fertilised with stored sperm, but over time this strong filtering when queens make drones will reduce the diversity in such small isolated populations. Of course few apiaries are really isolated. I would doubt, for example, that Mull is fully isolated from the mainland.


    (Hi Gavin
    I seem to remember that the original postulation was about annual loss of 50% of coloniies, you are cheating. You do not have the luxury of "in the long term" if you remain true to the original post!)
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    (JON)
    I think you are misunderstanding how this works.
    You can start with ten colonies, lose 5, increase to ten the following year and still maintain every one of the CSD alleles.
    Unless you are in a completely isolated situation, there will be incoming genetic material from neighbouring colonies via their drones.
    Even in an isolated situation, bees can maintain genetic diversity as the queen mates with multiple drones.

    (Hi Jon
    Watch my lips! The original post referred to a totally isolated apiary. Your statement - viz - "Unless you are in a completely isolated situation, there will be incoming genetic material from neighbouring colonies via their drones". misses the point When I was a student the most important factor when answering a question was to understand the question!

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    Jon
    Breeding from your best colony is not a problem when the drones in the general population local to it carry all or most of the csd alleles. (adopting italic convention)
    You would need to demonstrate that the local drone population carries less than 6 csd alleles before suggesting that this strategy would lead to an inbreeding problem.

    (Hi Joh
    Blundered again! There is no local population - the apiary in question is totally isolated!)


    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    Jimbo
    Going back to Gavin's point. Three isolated colonies have been found in an isolated part of Scotland that were surveyed for black bees in 1993-94. by the Stoakleys The colonies were checked again this year and still found to contain pure black bees. How have three colonies managed to survive for about 16 years in isolation?

    (Hi Jimbo
    From the two statements by Jon above - your school don't believe in "isolated". Gavin rfused to divulge the location of these colonies or if they had varroa when i asked for that info. An honest reply would have clearedup any dubiety re isolation!)

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    Jimbo
    Who mentioned Imidacloprid?

    (Hi Jimbo
    In the classic West of Scotland school pupil reply - "It wisnae me"! I'm not a clype but it was Jon)


    Jimbo
    Back to inbreeding I went for a second opinion today and asked one of our top genetic professors who's speciality is human population genetics. He did not use a bowl of fruit example but said if you have a large bag of hundreds and thousands of all diffrent colours (he admits to having a sweet tooth) and you take out a handful you will still have at least one of every colour. The probability of picking out all the red ones in the first handful is very remote therefore you will still maintain your genetic diversity. If you relate this to the bee with so many CSD alleles the probability of you getting inbreeding is remote. You could still get inbreeding if you were very unlucky and managed to picked out all the same allele but the probability of this was extremely remote


    (Jimbo
    In my postulation we are not dealing with hundreds of thousands of genes - we are dealing with - how many? You tell me! As I stated in my response to Gavin - I have witnessed massive inbreeding and colony collapse due to loss of genetic diversity caused by reducing colony numbers over time in a totally isolated apiary situation, (and not cosmic time!).

    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

    Doris
    There's me, promoting this forum (including screenshot) in my talk at the Irish conferece and recruiting new members, and then I come back to this!
    ( Hi Doris
    Was meinst du damit? Unsinniges Thema oder nicht das Redenswert? Meines Errachtens ein solches Thema, für dich sei äusserst relevant!)

    In defence of Roger, I have to point out that his remark of genetics having been dreamt up on an April 1st was obviously a joke, which earned him a number of laughs and a friendly response from Dorian.

    (I corresponded with Mr Paterson about his queen problems a number of years ago- he was in denial of inbreeding then! As now? What do you know of Harry Wickens?

    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;

    We have about 80 colonies, of which +/- 25 are in or around Kirkwall. The rest is scattered around the mainland and several islands. We don't want to import bees/queens to avoid getting varroa and other nasties.

    (Your scattered colonies are in imminent danger of inbreeding problems! You have an intelligent breeding program pending I hope.)

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    I have bred queens this summer, but not for requeening, only for increasing the number of colonies. I don't want to produce too many daughters from one queen alone, as otherwise her genes would be overrepresented in the local genepool.

    (Good thinking! But I think even Gavin would agree that breeding multiples of queens from all of your Orkney colonies and then distributing them "with malice aforethought" would be a good ploy. Considering the foregoing arguments regarding csd.)

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    I had come across Eric's calculations previously and found them too simplistic.
    Gavin, your example with the fruitbowl needs a lot of refinemet, too, for a start: I imagine that the fruitbowl represents an isolated apiary, but there is no pairing of traits.
    I thought of my own analogy, which involved a chairlift carrying skiers in different coloured skisuits, who randomly have to share seats but get eliminated if they share with a matching suit...

    ( Why does no-one do the Math here - I penned the original piece which appeared in both the bq and the SB try to stimulate awareness ininbreeding. This thread has hopefully focused some beekeeper minds on the need for good stock management!)

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    See Part 2 for continued reading!

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