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Article #4733Re: parthanogenesis
From: Doug Eernisse
Date: Mon, 11 Oct 1993 03:08
Date: Mon, 11 Oct 1993 03:08
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In article <293nbg$3il@zikzak.apana.org.au> Lynne Shandley, bunny@zikzak.apana.org.au writes: >Well, I'd say one of the reasons why males of any species are not capable of >parthenogenesis (as far as I know) is because of the different forms of >gametogenesis that occur in male and female. The gametes produced by >males tend to be little sacs of DNA with not much in the way of cell >cytoplasm, whilst females tend to produce what could be considered a whole >cell that is lacking half its chromosome complement - probably an easier start >point for parthenogenesis to occur. Anyway, aren't the products of >parthenogenesis clones of the parent? That is one kind of parthenogenesis, termed apomixis. That is when unreduced eggs complete development without fertilization, sometimes involving pseudogamy. Examples include digenean trematodes, bdelloid rotifers, some nematodes, tardigrades, coccids, cladocerans, aphids, cynipid wasps, telid lizards, the clam Lasaea (all but the last example from Bell, G. 1982: The Masterpiece of Nature..., p. 36). Another kind of parthenogenesis is automictic thelytoky, in which syngamy occurs between nuclei of the same (female) gender, sometimes involving pseudogamy. An example is when a polar body fuses with the oocyte haploid nucleus. This is very much like self-fertilization in its genetic consequences. It is a form of severe inbreeding, which will lead to very low (if any) heterozygosity, in contrast to apomixis which preserves heterozygosity. I recommend Bell's book for a review of parthenogenesis, although you will have to catch up on examples published in the last decade. I would assume that you won't find examples of parthenogenetic "males," for reasons others have mentioned. Doug
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 107c0a,74a4e12886d65a60 X-Google-Attributes: gid107c0a,public X-Google-Thread: 10a7a9,74a4e12886d65a60 X-Google-Attributes: gid10a7a9,public X-Google-Thread: feea0,74a4e12886d65a60 X-Google-Attributes: gidfeea0,public X-Google-ArrivalTime: 1993-10-10 21:02:33 PST Path: arc1-ca.pugleaf.net!gmd.de!newsserver.jvnc.net!howland.reston.ans.net!math.ohio-state.edu!caen!lsa.umich.edu!usenet From: Doug Eernisse <Doug_Ee@um.cc.umich.edu> Newsgroups: sci.bio,bionet.molbio.evolution,sci.bio.ecology Subject: Re: parthanogenesis Date: 11 Oct 1993 03:08:35 GMT Organization: University of Michigan - College of Literature, Science, and TheArts Lines: 31 Distribution: world Message-ID: <29ainj$8o3@controversy.math.lsa.umich.edu> References: <28v7ou$f8d@news.u.washington.edu> <293ejt$s0t@nuscc.nus.sg> <293nbg$3il@zikzak.apana.org.au> <1993Oct10.232145.7859@usl.edu> NNTP-Posting-Host: 141.211.110.79 X-UserAgent: Nuntius v1.1.1d24 X-XXDate: Sun, 10 Oct 93 04:15:51 GMT