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Re: [GP] sexual recombination and gender differences

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  • conor.ryan@ul.ie
    Tom, You might want to take a look at Robert Collins PhD, Studies in Artificial Evolution . I seem to remember he had a model of genders that he called the
    Message 1 of 11 , May 6, 2004
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      Tom,
      You might want to take a look at Robert Collins' PhD, "Studies in
      Artificial Evolution". I seem to remember he had a model of genders that
      he called the Peacock model. Unfortunately, I haven't seen it for a while,
      and couldn't find a link for it when I was looking for it recently.

      Conor
      >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
      Dr. Conor Ryan, Senior Lecturer >email: Conor.Ryan@...
      Dept of CSIS, >http://pyrrha.csis.ul.ie/conor
      University of Limerick >fax: +353-61-202734
      Limerick, Ireland >phone +353-61-202755
      >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

      On Mon, 3 May 2004, Tom Lenaerts wrote:

      > Hi all,
      >
      >
      > Can anyone point me in the direction of good publications discussing the
      > use of different genders in the context of evolutionary algorithms. We
      > all assume some form of sexual reproduction yet no distinction is made
      > between "male" and "female". I would like to know if any work has been
      > done on actually evolving these gender differences and the motivation
      > for it.
      >
      > kind regards
      >
      > Tom
      >
      >
      >
      >
      >
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
    • Martin Sewell
      ... Imagine a population of hermaphrodites. 1) Some will be genetically biased towards putting more time and effort into mating, their genes will thrive as
      Message 2 of 11 , May 6, 2004
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        At 20:59 05/05/2004 +0200, Tom Lenaerts wrote:
        >[...]
        >
        >Do you have any reference discussing this issue? The question we should
        >ask before is why have two sexes at all? It might be the case that this
        >asymmetric situation is correct. Yet why did it evolve in the first
        >place. It seems that this is also not clear to Biologists.
        >
        >[...]

        Imagine a population of hermaphrodites.
        1) Some will be genetically biased towards putting more time and effort
        into mating, their genes will thrive as they inseminate many others.
        2) Others will be biased towards expending energy by producing eggs and
        bearing babies, they will also be genetically successful as can do their
        best to ensure their children survive.
        Those individuals who lie in the middle , and specialise in neither
        activity, will die out.

        The first type leads to a small active gamete, the second a larger, static
        gamete. The union of two unequal gametes in reproduction is known as
        anisogamy. Inter-sex competition ensures that this dichotomy persists.

        Regards

        Martin

        Reference:
        Parker, G.A., R.R. Baker, and V.G.F. Smith. 1972. The origin and evolution
        of gamete dimorphism and the male-female phenomenon. Journal of Theoretical
        Biology 36: 529-553.
      • Lucas, Simon M
        Martin, That s the clearest description I ve seen of why we have two sexes. Are you aware of any open-ended simulations that have explored conditions under
        Message 3 of 11 , May 7, 2004
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          Martin,

          That's the clearest description I've
          seen of why we have two sexes.

          Are you aware of any open-ended simulations
          that have explored conditions under which
          this sexual dimorphism spontaneously arises?

          Best regards,

          Simon


          -----Original Message-----
          From: Martin Sewell [mailto:M.Sewell@...]
          Sent: 07 May 2004 01:22
          To: genetic_programming
          Subject: Re: [GP] sexual recombination and gender differences


          At 20:59 05/05/2004 +0200, Tom Lenaerts wrote:
          >[...]
          >
          >Do you have any reference discussing this issue? The question we
          should
          >ask before is why have two sexes at all? It might be the case that this

          >asymmetric situation is correct. Yet why did it evolve in the first
          >place. It seems that this is also not clear to Biologists.
          >
          >[...]

          Imagine a population of hermaphrodites.
          1) Some will be genetically biased towards putting more time and effort
          into mating, their genes will thrive as they inseminate many others.
          2) Others will be biased towards expending energy by producing eggs and
          bearing babies, they will also be genetically successful as can do their

          best to ensure their children survive.
          Those individuals who lie in the middle , and specialise in neither
          activity, will die out.

          The first type leads to a small active gamete, the second a larger,
          static
          gamete. The union of two unequal gametes in reproduction is known as
          anisogamy. Inter-sex competition ensures that this dichotomy persists.

          Regards

          Martin

          Reference:
          Parker, G.A., R.R. Baker, and V.G.F. Smith. 1972. The origin and
          evolution
          of gamete dimorphism and the male-female phenomenon. Journal of
          Theoretical
          Biology 36: 529-553.




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        • Tim Taylor
          Hi Simon, In my PhD thesis I describe some (admittedly fairly simple-minded) experiments with sexual reproduction in my experimental platform COSMOS, which is
          Message 4 of 11 , May 7, 2004
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            Hi Simon,

            In my PhD thesis I describe some (admittedly fairly
            simple-minded) experiments with sexual reproduction in my
            experimental platform COSMOS, which is a Tierra-like model
            of self-reproducing programs.

            However, far from seeing sexual dimorphism spontaneously
            arise, I hard-wired it into the system to start with, and
            observed that the populations quickly reverted to asexual
            reproduction in all cases.

            For details look at:
            http://homepages.inf.ed.ac.uk/timt/papers/thesis/html/node155.html

            This is an example of a more general problem with this kind
            of system, which Tom Ray and others also encountered; it is
            not only difficult to get complex adaptations to evolve, but
            it's even difficult just to have them *maintained* during
            evolution if you hard-wire them into the system to start with.
            But I think these results say more about the fragility of this
            particular kind of genetic (and phenotypic) representation than
            they do about evolutionary dynamics in general.

            Best wishes,

            Tim


            --
            Tim Taylor =======================================================
            Research Fellow, Institute of Perception, Action & Behaviour (IPAB)
            School of Informatics, University of Edinburgh

            Tel. +44 (0)131 651 3436 :: http://homepages.inf.ed.ac.uk/timt/
            Fax. +44 (0)131 651 3435 :: (full contact details on web page)
            ==================================================================


            On Fri, 7 May 2004, Lucas, Simon M wrote:

            >
            > Martin,
            >
            > That's the clearest description I've
            > seen of why we have two sexes.
            >
            > Are you aware of any open-ended simulations
            > that have explored conditions under which
            > this sexual dimorphism spontaneously arises?
            >
            > Best regards,
            >
            > Simon
            >
            >
            > -----Original Message-----
            > From: Martin Sewell [mailto:M.Sewell@...]
            > Sent: 07 May 2004 01:22
            > To: genetic_programming
            > Subject: Re: [GP] sexual recombination and gender differences
            >
            >
            > At 20:59 05/05/2004 +0200, Tom Lenaerts wrote:
            > >[...]
            > >
            > >Do you have any reference discussing this issue? The question we
            > should
            > >ask before is why have two sexes at all? It might be the case that this
            >
            > >asymmetric situation is correct. Yet why did it evolve in the first
            > >place. It seems that this is also not clear to Biologists.
            > >
            > >[...]
            >
            > Imagine a population of hermaphrodites.
            > 1) Some will be genetically biased towards putting more time and effort
            > into mating, their genes will thrive as they inseminate many others.
            > 2) Others will be biased towards expending energy by producing eggs and
            > bearing babies, they will also be genetically successful as can do their
            >
            > best to ensure their children survive.
            > Those individuals who lie in the middle , and specialise in neither
            > activity, will die out.
            >
            > The first type leads to a small active gamete, the second a larger,
            > static
            > gamete. The union of two unequal gametes in reproduction is known as
            > anisogamy. Inter-sex competition ensures that this dichotomy persists.
            >
            > Regards
            >
            > Martin
            >
            > Reference:
            > Parker, G.A., R.R. Baker, and V.G.F. Smith. 1972. The origin and
            > evolution
            > of gamete dimorphism and the male-female phenomenon. Journal of
            > Theoretical
            > Biology 36: 529-553.
            >
          • Martin Sewell
            ... Thank you. ... I m no expert on this, but the following (and the references therein) may be of interest: Bulmer, M.G. and Parker, G.A. (2002) The
            Message 5 of 11 , May 7, 2004
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              At 09:31 07/05/2004 +0100, Lucas, Simon M wrote:

              > Martin,
              >
              > That's the clearest description I've
              > seen of why we have two sexes.

              Thank you.

              > Are you aware of any open-ended simulations
              > that have explored conditions under which
              > this sexual dimorphism spontaneously arises?

              I'm no expert on this, but the following (and the references therein) may
              be of interest:

              Bulmer, M.G. and Parker, G.A. (2002) "The evolution of anisogamy: a
              game-theoretic approach." Proc. R. Soc. Lond. Ser. B 269, 2381-2388
              "A popular theory has proposed that anisogamy originated through disruptive
              selection acting on an ancestral isogamous population, though recent work
              has emphasized the importance of other factors in its evolution. We
              re-examine the disruptive selection theory, starting from an isogamous
              population with two mating types and taking into account the functional
              relationship, g(m), between the fitness of a gamete and its size, m, as
              well as the relationship, f(S), between the fitness of a zygote and its
              size, S. Evolutionary game theory is used to determine the existence and
              continuous stability of isogamous and anisogamous strategies for the two
              mating types under various models for the two functions g(m) and f(S). In
              the ancestral unicellular state, these two functions are likely to have
              been similar; this leads to isogamy whether they are sigmoidal or concave,
              though in the latter case allowance must be made for a minimal gamete size.
              The development of multicellularity may leave g(m) relatively unchanged
              while f(S) moves to the right, leading to the evolution of anisogamy. Thus,
              the disruptive selection theory provides a powerful explanation of the
              origin of anisogamy, though other selective forces may have been involved
              in the subsequent specialization of micro- and macrogametes."

              Epelman, Marina, Bobbi Low, Brian Netter, and Stephen Pollock (2004)
              "Anisogamy, Expenditure of Reproductive Effort, and the Optimality of
              Having Two Sexes"
              http://ioe.engin.umich.edu/ioe899/papers/anisogamy_rev.pdf

              Maire N., M. Ackermann & M. Doebeli. 2001. "Evolutionary branching and the
              evolution of anisogamy." Selection 2:119-132.
              http://www.math.ubc.ca/~doebeli/reprints/Doe42.pdf

              Matsuda H, Abrams PA. (1999) Why are equally-sized gametes so rare? The
              instability of isogamy and the cost of anisogamy. Evolutionary Ecology
              Research1:769-784.
              http://risk.kan.ynu.ac.jp/matsuda/publication/99EER.pdf

              Regards

              Martin
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