A major evolutionary transition to more than two sexes?

Discussion in 'Health and medical' started by Lilith, Feb 10, 2004.

  1. Lilith

    Lilith Guest

    Quotes below abstract.

    Parker, Joel D. "A major evolutionary transition to more than two

    Abstract

    Two recently discovered cases of genetic caste determination in social insects might provide the
    first example of a major evolutionary

    system can be interpreted as comprising primarily individuals

    the perspective of demographic extinction. Additionally, I show how this mating system can be
    seen as a major evolutionary transition. For these populations, it is apparent that the mechanism
    for a three- or

    arrangements of chromosomes within individuals, but at the next level of evolutionary complexity,
    with the arrangement of chromosomes among individuals within a social system.

    >From the paper, "The Big Picture", Box 2:

    " * A mating system that evolved twice through hybridization in the seed harvester ant
    Pogonomymrmex, where queens must mate with two distinct types of male to produce a colony with both
    sterile workers and fertile females, can be considered a sytem with more than two

    * Any colony that makes a fertile queen must haev at least three parents, or be descendent from
    three distinct and seperate types of gamete.

    * Four seperate types of gamete must be maintained in the population or the population will
    become extinct.

    * The system constitutes a major evolutionary transition under the criteria of Szathmary and
    Maynard SMith.

    hybridization fo two previously autonomous social insect populations.

    order of organization of genetic information within a social population."

    Also from the paper:

    "If a queen mates by chance exclusively with males from the opposite gene pool, she can only make
    workers and parthenogenically produced haploid males. However, the colonies that produce both males
    and females, which can be considered hermaphrodites, require three gametic types (sperm from the
    yellow and blue gene pools and egg from the queen; Box 1, Figure I). The male gamete from the
    opposite gene pool is directed to the soma, or body of the colony (i.e. the workers) whereas the
    male gamete from the same gene pool as the queen contruibutes to the female reproductives. The third
    gamete type is then the egg of the queen. Only colonies that are descended from this union of the
    three gametic types can produce viable female

    hermaphroditic individuals and can only result from the contribution of three different types of
    gamete and have a minimium of three parents when selfing is excluded, thus satisfying the functional
     
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  2. On Tue, 10 Feb 2004 00:14:45 +0000 (UTC), [email protected] (Lilith)
    wrote:

    Thanks Lilith for posting this. I has been thought a sterile caste could evolve only if the genes
    for sterility are expressed conditionally, because any allele(s) that invariably caused sterility
    could not be passed on and would be quickly eliminated from the population (Seger 1981, Queller &
    Strassman 1998). In a previous thread the case for self-determination or genetic determination of
    caste was considered for the Melopine bees and it was not so certain in the Melopines since the
    genetic difference between workers and queens has not yet been measured in Melopines. In
    hybridizing Pogonomymrmex ants it is quite clear. That is interesting enough for me.

    in mating would be more interesting. Since the queen is obligated to mate with two completely
    different types of males, it does seem reasonable to agree with the authors that it can be
    thought of as

    types is from a completely different species and its genes will never enter the germline of the
    other species. These genes are only being expressed in the soma (the sterile worker caste) of the
    first species.

    partners but I don't recall any where one of the threesome was from another species. Very strange
    indeed! William L Hunt

    >Quotes below abstract.
    >
    >Parker, Joel D. "A major evolutionary transition to more than two

    >
    >Abstract
    >
    >Two recently discovered cases of genetic caste determination in social insects might provide the
    >first example of a major evolutionary

    >system can be interpreted as comprising primarily individuals

    >the perspective of demographic extinction. Additionally, I show how this mating system can be seen
    >as a major evolutionary transition. For these populations, it is apparent that the mechanism for a
    >three- or

    >arrangements of chromosomes within individuals, but at the next level of evolutionary complexity,
    >with the arrangement of chromosomes among individuals within a social system.
    >
    >
    >>From the paper, "The Big Picture", Box 2:
    >
    >" * A mating system that evolved twice through hybridization in the seed harvester ant
    >Pogonomymrmex, where queens must mate with two distinct types of male to produce a colony with both
    >sterile workers and fertile females, can be considered a sytem with more than two

    >
    >* Any colony that makes a fertile queen must haev at least three parents, or be descendent from
    > three distinct and seperate types of gamete.
    >
    >* Four seperate types of gamete must be maintained in the population or the population will become
    > extinct.
    >
    >* The system constitutes a major evolutionary transition under the criteria of Szathmary and
    > Maynard SMith.
    >

    >hybridization fo two previously autonomous social insect populations.

    >order of organization of genetic information within a social population."
    >
    >Also from the paper:
    >
    >"If a queen mates by chance exclusively with males from the opposite gene pool, she can only make
    >workers and parthenogenically produced haploid males. However, the colonies that produce both males
    >and females, which can be considered hermaphrodites, require three gametic types (sperm from the
    >yellow and blue gene pools and egg from the queen; Box 1, Figure I). The male gamete from the
    >opposite gene pool is directed to the soma, or body of the colony (i.e. the workers) whereas the
    >male gamete from the same gene pool as the queen contruibutes to the female reproductives. The
    >third gamete type is then the egg of the queen. Only colonies that are descended from this union of
    >the three gametic types can produce viable female

    >hermaphroditic individuals and can only result from the contribution of three different types of
    >gamete and have a minimium of three parents when selfing is excluded, thus satisfying the
    >functional
     
  3. [email protected] (Lilith) writes:

    > Quotes below abstract.
    >
    > Parker, Joel D. "A major evolutionary transition to more than two

    >
    ...<snip>...
    >
    > >From the paper, "The Big Picture", Box 2:
    >
    > " * A mating system that evolved twice through hybridization in the seed harvester ant
    > Pogonomymrmex, where queens must mate with two distinct types of male to produce a colony with
    > both sterile workers and fertile females, can be considered a sytem with more than two

    >
    ...<snip>...
    >
    > "If a queen mates by chance exclusively with males from the opposite gene pool, she can only make
    > workers and parthenogenically produced
    ...<snip>...

    One thing that wasn't clear to me was, where do the "males from the opposite gene pool" come from?
    Are they offspring of these queens also?

    Otherwise it seems like the queen has a way of manufacturing workers by hybridizing with another
    species, but otherwise, continues her own species by mating with other members of her own species.
     
  4. On Thu, 12 Feb 2004 00:41:43 +0000 (UTC), [email protected] (C. P.
    Weidling) wrote:

    >[email protected] (Lilith) writes:
    >
    >> Quotes below abstract.
    >>
    >> Parker, Joel D. "A major evolutionary transition to more than two

    >>
    > ...<snip>...
    >>
    >> >From the paper, "The Big Picture", Box 2:
    >>
    >> " * A mating system that evolved twice through hybridization in the seed harvester ant
    >> Pogonomymrmex, where queens must mate with two distinct types of male to produce a colony with
    >> both sterile workers and fertile females, can be considered a sytem with more than two

    >>
    > ...<snip>...
    >>
    >> "If a queen mates by chance exclusively with males from the opposite gene pool, she can only make
    >> workers and parthenogenically produced
    > ...<snip>...
    >
    >One thing that wasn't clear to me was, where do the "males from the opposite gene pool" come from?
    >Are they offspring of these queens also?
    >
    No. There are two different species both doing this hybridizing. In both species the queen is
    obligated to mate with a male from the other species to produce the hybrid workers. It is a not yet
    answered question why there are no non-hybrid species of either type in this

    seems obligatory. Are the hybrid workers so superior (hybrid vigor) to pure species workers? They
    are currently trying to determine this.

    >
    >Otherwise it seems like the queen has a way of manufacturing workers by hybridizing with another
    >species, but otherwise, continues her own species by mating with other members of her own species.
    >
    Exactly right. This had been very perplexing for some years since side by side nests would seem to
    be identical when looking at the workers only. In fact the workers were also almost identical
    genetically since they both consisted of genes that were 1/2 species A and 1/2 species B. But when
    males emerged from these nests they were clearly different. Previously it had been thought
    sufficent, for many purposes, to do genetic comparisons in ants by sampling from workers only but
    this must now change. The harvester ants are one of the most studied ants and yet only in the last
    few years has this all become clear. This hybridizing may be going on in other ant species but it
    could be almost invisible that there are really two species if the males and queens in the two
    species look similiar. William L Hunt
     
  5. Jim Menegay

    Jim Menegay Guest

    [email protected] (William L Hunt) wrote in message news:<[email protected]>...
    > On Thu, 12 Feb 2004 00:41:43 +0000 (UTC), [email protected] (C. P. Weidling) wrote:
    >
    > >[email protected] (Lilith) writes:
    > >
    > >> Quotes below abstract.
    > >>
    > >> Parker, Joel D. "A major evolutionary transition to more than two

    > >>
    > ...<snip>...
    > >>
    > >> >From the paper, "The Big Picture", Box 2:
    > >>
    > >> " * A mating system that evolved twice through hybridization in the seed harvester ant
    > >> Pogonomymrmex, where queens must mate with two distinct types of male to produce a colony with
    > >> both sterile workers and fertile females, can be considered a sytem with more than two

    > >>
    > ...<snip>...
    > >>
    > >> "If a queen mates by chance exclusively with males from the opposite gene pool, she can only
    > >> make workers and parthenogenically produced
    > > ...<snip>...
    > >
    > >One thing that wasn't clear to me was, where do the "males from the opposite gene pool" come
    > >from? Are they offspring of these queens also?
    > >
    > No. There are two different species both doing this hybridizing. In both species the queen is
    > obligated to mate with a male from the other species to produce the hybrid workers. It is a not
    > yet answered question why there are no non-hybrid species of either type in this

    > seems obligatory. Are the hybrid workers so superior (hybrid vigor) to pure species workers? They
    > are currently trying to determine this.
    >
    > >
    > >Otherwise it seems like the queen has a way of manufacturing workers by hybridizing with another
    > >species, but otherwise, continues her own species by mating with other members of her own
    > >species.
    > >
    > Exactly right. This had been very perplexing for some years since side by side nests would seem
    > to be identical when looking at the workers only. In fact the workers were also almost identical
    > genetically since they both consisted of genes that were 1/2 species A and 1/2 species B. But
    > when males emerged from these nests they were clearly different. [snip]

    Truly bizarre and fascinating. But, it appears that the interpretation

    interpretation of the terms "individual" and "species". If you postulate that colonies are
    individuals and that two biological species are united by their obligate mutualism into a single
    ecological species,

    different from a lichen, say, which may have parents for both the fungal and prokariote moieties?
    How is it different from me, who has two H. sap. parents plus a bunch of unknown parents for my
    intestinal biota?
     
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