The Nature of Mutations

Does the above post actually mean something and it is just too abstruse for me to grasp, or is it just gibberish?

What about larger scale mutations such as gene duplications or even whole genome duplications?

When you say genetic *or* developmental what are you thinking of? Epigenetic factors such as histone remodelling and DNA methylation?
I dont think the science paper is available on line. Is this the paper you were thinking of about the 20,000 generations?Lenski RE, Winkworth CL, Riley MA.
Rates of DNA Sequence Evolution in Experimental Populations of Escherichia coli During 20,000 Generations.
J Mol Evol. 2003 Apr;56(4):498-508.
Available online (not sure of subscription status) at
http://link.springer.de/.../02/2423/s00239-002-2423-0ch.html

What sort of changes would these be Brad?

Dear Brad,Do you intentionally make your posts almost incomprehensible? I'm sorry if it is just that English is not your first language but even so I'm sure you could easily express your thoughts with less pointless jargon i.e. correlationally contiguous.I can't make head nor tail of your sentence on Newton's third law and whatever 'non-function known' changes are.

Thanks for clearing that up Brad.

Dear Mammuthus,AS far as I was aware the most widely accepted theory behind the evolution of imprinting was the parental conflict hypothesis. Do you have any references for this differential NS driven theory or is it just the parental conflict hypothesis by another name, your description certainly doesnt make it seem so.cheers,wounded

There is as Mammuthus says a large amount of work on some of the evolutionarily conserved genes regulating eye development, particularly Pax6. In terms of the origin of these developmental pathways the research on the pax genes found in cnidaria and other such invertebrates is perhaps more informative.

Here are three referencesEvolution of paired domains: isolation and sequencing of jellyfish and
hydra Pax genes related to Pax-5 and Pax-6.Sun H, Rodin A, Zhou Y, Dickinson DP, Harper DE, Hewett-Emmett D, Li WH.Proc Natl Acad Sci USA 1997 May 13;94(10):5156-61.Pax proteins are a family of transcription factors with a highly conserved paired domain; many members also contain a paired-type homeodomain and/or an octapeptide. Nine mammalian Pax genes are known and classified into four subgroups: Pax-1/9, Pax-2/5/8, Pax-3/7, and Pax-4/6. Most of these genes are involved in nervous system development. In particular, Pax-6 is a key regulator that controls eye development in vertebrates and Drosophila. Although the Pax-4/6 subgroup seems to be more closely related to Pax-2/5/8 than to Pax-3/7 or Pax-1/9, its evolutionary origin is unknown. We therefore searched for a Pax-6 homolog and related genes in Cnidaria, which is the lowest phylum of animals that possess a nervous system and eyes. A sea nettle (a jellyfish) genomic library was constructed and two pax genes (Pax-A and -B) were isolated and partially sequenced. Surprisingly, unlike most known Pax genes, the paired box in these two genes contains no intron. In addition, the complete cDNA sequences of hydra Pax-A and -B were obtained. Hydra Pax-B contains both the homeodomain and the octapeptide, whereas hydra Pax-A contains neither. DNA binding assays showed that sea nettle Pax-A and -B and hydra Pax-A paired domains bound to a Pax-5/6 site and a Pax-5 site, although hydra Pax-B paired domain bound neither. An alignment of all available paired domain sequences revealed two highly conserved regions, which cover the DNA binding contact positions. Phylogenetic analysis showed that Pax-A and especially Pax-B were more closely related to Pax-2/5/8 and Pax-4/6 than to Pax-1/9 or Pax-3/7 and that the Pax genes can be classified into two supergroups: Pax-A/Pax-B/Pax-2/5/8/4/6 and Pax-1/9/3/7. From this analysis and the gene structure, we propose that modern Pax-4/6 and Pax-2/5/8 genes evolved from an ancestral gene similar to cnidarian Pax-B, having both the homeodomain and the octapeptide.Pax-6 origins--implications from the structure of two coral pax genes.Catmull J, Hayward DC, McIntyre NE, Reece-Hoyes JS, Mastro R, Callaerts P, Ball EE, Miller DJ.Dev Genes Evol 1998 Aug;208(6):352-6Vertebrate Pax-6 and its Drosophila homolog eyeless play central roles in eye specification, although it is not clear if this represents the ancestral role ofmthis gene class. As the most "primitive" animals with true nervous systems, the,Cnidaria may be informative in terms of the evolution of the Pax gene family. For this reason we surveyed the Pax gene complement of a representative of the basal cnidarian class (the Anthozoa), the coral Acropora millepora. cDNAs encoding two coral Pax proteins were isolated. Pax-Aam encoded a protein containing only a paired domain, whereas Pax-Cam also contained a homeodomain clearly related to those in the Pax-6 family. The paired domains in both proteins most resembled the vertebrate Pax-2/5/8 class, but shared several distinctive substitutions. As in most Pax-6 homologs and orthologs, an intron was present in the Pax-Cam locus at a position corresponding to residues 46/47 in the homeodomain. We propose a model for evolution of the Pax family, in which the ancestor of all of the vertebrate Pax genes most resembled Pax-6, and arose via fusion of a Pax-Aam-like gene (encoding only a paired domain) with an anteriorly-expressed homeobox gene resembling the paired-like class.Pax gene diversity in the basal cnidarian Acropora millepora (Cnidaria,
Anthozoa): implications for the evolution of the Pax gene family.Miller DJ, Hayward DC, Reece-Hoyes JS, Scholten I, Catmull J, Gehring WJ, Callaerts P, Larsen JE, Ball EE.Proc Natl Acad Sci U S A 2000 Apr 25;97(9):4475-80Pax genes encode a family of transcription factors, many of which play key roles in animal embryonic development but whose evolutionary relationships and ancestral functions are unclear. To address these issues, we are characterizing
the Pax gene complement of the coral Acropora millepora, an anthozoan cnidarian. As the simplest animals at the tissue level of organization, cnidarians occupy a key position in animal evolution, and the Anthozoa are the basal class within this diverse phylum. We have identified four Pax genes in Acropora: two (Pax-Aam and Pax-Bam) are orthologs of genes identified in other cnidarians; the others (Pax-Cam and Pax-Dam) are unique to Acropora. Pax-Aam may be orthologous with
Drosophila Pox neuro, and Pax-Bam clearly belongs to the Pax-2/5/8 class. The Pax-Bam Paired domain binds specifically and preferentially to Pax-2/5/8 binding sites. The recently identified Acropora gene Pax-Dam belongs to the Pax-3/7 class. Clearly, substantial diversification of the Pax family occurred before the Cnidaria/higher Metazoa split. The fourth Acropora Pax gene, Pax-Cam, may correspond to the ancestral vertebrate Pax gene and most closely resembles Pax-6. The expression pattern of Pax-Cam, in putative neurons, is consistent with an ancestral role of the Pax family in neural differentiation and
patterning. We have determined the genomic structure of each Acropora Pax gene and show that some splice sites are shared both between the coral genes and between these and Pax genes in triploblastic metazoans. Together, these data support the monophyly of the Pax family and indicate ancient origins of several introns.The PNAS references should be available free online.

So its being proposed that only point mutations be considered 'mutations' and that we call everything else 'heritable changes'? But many mutations, sorry 'heritable changes', other than point mutations are, well lets say stochastic since random is such a controverial concept for some people. I could see a point in distinguishing between sequence rearrangements, chromosome rearrangements and heritable epigenetic changes, but this current idea seems to be based on nothing except trying to make point mutations somehow unique.

I think your phrasing here makes it sound like the mutations are transmissable between cells. The maintenance of a mutation in the daughter cells of a somatic cell is still an example of a heritable change, simply one within the cell population rather than that of the organismal population.

The Greenish Warbler is another example of a ring species. Ned's example with the 2 end sub-species being reproductively isolated is certainly the classical one.see

Irwin DE, Bensch S, Price TD.
Speciation in a ring.
Nature. 2001 Jan 18;409(6818):333-7.

Dear Percy,

Perhaps you would care to contribute further to the thread you started on speciation which has recently been revived.[This message has been edited by Wounded King, 05-31-2003]

Salty's thread is at this location .

Dear Salty,A recent paper in 'Development' has shown a number of developmental defects in C. elegans associated with defects in meiosis. These defects are caused by RNAi knockout of the Anaphase promoting complex (APC) and include cases where only meiosis 1 occurs and meiosis 2 is skipped entirely. I was wondering if you were aware of this work and if you felt it was in line with, or in deed at all relevant to, your own theories.Cheers,Wounded