[Taxacom] Taxacom Digest, Vol 150, Issue 18

Andrea Silverthorne hfhxk at stu.ca
Sun Oct 28 12:47:49 CDT 2018


There is a link between Cyanobacteria and Dinoflagellates.
Andrea

On Sun, Oct 28, 2018, 1:00 PM <taxacom-request at mailman.nhm.ku.edu> wrote:

> Daily News from the Taxacom Mailing List
>
> When responding to a message, please do not copy the entire digest into
> your reply.
> ____________________________________
>
>
> Today's Topics:
>
>    1. Cyanobacteria and the Origin of Life (Kenneth Kinman)
>    2. Re: Cyanobacteria and the Origin of Life (Mary Barkworth)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 28 Oct 2018 01:56:07 +0000
> From: Kenneth Kinman <kinman at hotmail.com>
> To: taxacom <taxacom at mailman.nhm.ku.edu>
> Subject: [Taxacom] Cyanobacteria and the Origin of Life
> Message-ID:
>         <
> CY4PR11MB1480C102A290559BC3F578BDC1F20 at CY4PR11MB1480.namprd11.prod.outlook.com
> >
>
> Content-Type: text/plain; charset="Windows-1252"
>
> Hi All,
>          I have long believed that Cyanobacteria are the most primitive
> forms of cellular life to have survived to the present day.  And that the
> earliest cyanobacteria might not have been capable of oxygenic
> photosynthesis (at least one that required both Photosystems I and II).
>  The question is whether a recent October 2018 research paper might help
> support such an hypothesis.  Opinions (pro or con) are welcome.  Here is a
> weblink to the paper:
> http://www.pnas.org/content/early/2018/09/26/1808176115
>
>                                ----------------Ken Kinman
>
> ________________________________
> From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of John
> Grehan <calabar.john at gmail.com>
> Sent: Wednesday, October 24, 2018 5:55 AM
> To: taxacom
> Subject: [Taxacom] Orthogeneisis
>
> For anyone interested in such esoterica, below is the text of an article
> published in The International Encyclopedia of Biological Anthropology
> (2018). If anyone wants a pdf please contact me.
>
> John Grehan
>
> Like many controversial concepts, orthogenesis
> will mean different things to different people.
> For most evolutionary biologists the term is
> likely to embody an obsolete view of evolution as
> teleological or predetermined, or that it involves
> some kind of “straight line” or linear evolution
> that is incompatible with the reality of evolutionary
> divergence. As emphasized by Darwin (see
> Darwin, Charles R), evolution was (and still
> is) largely seen as the result of random variation
> subject to natural selection. But even Darwin
> referred to “laws of growth” and other early
> evolutionists saw that evolution was not entirely
> “random” as novel variations failed to obfuscate
> the existence of preexisting ancestral architecture
> (To put this issue in simplistic terms: A penguin
> in the water remains a bird and does not become
> a fish.) There was also widespread acceptance that
> evolution was generally irreversible—that while
> individual characters may sometimes revert,
> overall structural organization did not. Darwin
> later expressed regret over his initial emphasis on
> natural selection (see evolution).
>
> The idea of orthogenesis was proposed in 1893
> by the German evolutionist William Haacke, who
> argued that if any kind of variation was possible,
> one would expect reversals to be as frequent as
> novelties. The rarity of such reversals was seen as
> evidence that the evolutionary origin of variation
> was not only limited, but constrained or biased by
> preexisting biological organization. Orthogenesis
> was subsequently adopted by a minority of evolutionists,
> including some who applied it to theories
> of vital forces or goal-driven evolution.The fossil
> record was sometimes regarded as demonstrating
> a linear direction to evolution, such as the classic
> reduction of horse digits from five to one.This linear
> concept is widely seen as having been refuted
> by evidence that evolution was not linear, but
> involved a process of diversification or branching
> (e.g., Ernst Mayr (see Mayr, Ernst), George
> Gaylord Simpson (see Simpson, George Gaylord),
> Stephen Jay Gould (see Gould, Stephen
> J.)—see Grehan and Ainsworth 1985). This
> critique mistakenly conflated linear evolution
> with orthogenesis. Haacke cited the reduction of
> horse toes from five to one as an illustration of a
> biologically driven trend, not a linear or purposeful
> evolution. Whether or not horse evolution
> was “linear” or a radiating “bush,” there was a
> reduction of toes that took place over space and
> time resulting in the single-toed horse of today.
> This reduction may be attributed to “random”
> variations that imparted increased fitness (see
> fitness), or it may be attributed to a biological
> process where new variants resulted in reduction
> of toes. Horses survived because these reductions
> were compatible with the requirements of
> ecological survival. The apparent contradiction
> between an orthogenetic trend and evolutionary
> divergence was addressed by Leon Croizat (1958,
> 1964) in the panbiogeographic evolutionary synthesis.
> He regarded differentiation as the result
> of allopatric divergence across a widespread
> ancestral range. The heterogeneous distribution
> of genetic characters across this range provides
> spatially different starting points that biased
> subsequent differentiation and speciation.
>
> In natural selection theory, a random variation
> is spread through a population by differential
> reproductive success (fitness). In orthogenetic
> models, a new variant does not require differential
> reproduction to become established. While
> observations of biological organization and biogeographic
> distribution led some evolutionists
> to adopt orthogenetic models of evolution, there
> remained the widespread objection that the
> concept was “mysterious” because there was
> no mechanism to explain the spread of novel
> variants without requiring natural selection.
> But in recent decades evolutionary biologists
> have widely recognized that aspects of genomic
> architecture, gene structure, and developmental
> pathways are difficult to explain without
> involving nonadaptive processes of genetic drift
> and mutation. Gene expression is controlled by
> complex pathways and networks of interacting
> regulatory genes, and there has been no formal
> demonstration of an adaptive origin for any
> genetic network.Many features of transcriptional
> networks can readily arise through nonadaptive
> drift, mutation, and recombination. This raises
> the question as to whether natural selection is
> sufficient or even necessary for the origin of
> gene-network topologies. Recombination events
> are accompanied by unidirectional exchanges
> known as gene conversion. There is evidence,
> for example, that many eukaryotes, including
> humans, are GC-biased—that is, their total DNA
> complement contains a higher-than-expected
> proportion of guanine–cytosine base pairs. In
> humans, there is a genome-wide positive correlation
> between crossover rate and GC content.
> Other biological processes capable of producing
> evolutionary trends without environmental selection
> include the emergence of error minimization
> in the genetic code, expansion of genome size
> by mobile element proliferation, and widespread
> reductions in genome size in multiple lineages of
> mammals. Complementary to genetic and developmental
> studies is the widespread existence
> of trends in morphology involving reduction,
> suppression, and fusion in complex multipartite
> structures such as the angiosperm flower and
> vertebrate skull.
>
> The recognition of orthogenesis does not
> imply a rejection of natural selection. Orthogenesis
> implies only that biological mechanisms can
> result in mutations and the spread of mutations
> without requiring increased fitness. As natural
> selection can also result in the spread of mutations
> (variants), there are two kinds of dynamic
> processes involved with evolution: one internal
> and biological and the other external and environmental.
> These are not two separable entities.
> Earlier formulations of orthogenesis emphasized
> a contrast between the roles of “internal” and
> “external” forces in evolution, but no biological
> process exists without an environment; and
> conversely, the effects produced by environmental
> forces are contingent upon the organisms
> involved. How these biological and environmental
> processes interact to “co-construct” organisms
> and their ecological relationships through development
> represents a new and largely unexplored
> aspect of evolutionary biology—one that involves
> intrinsic biological mechanisms, regardless
> of whether they are labeled orthogenesis or
> something else (Heads 2016).
> _______________________________________________
> Taxacom Mailing List
> Send Taxacom mailing list submissions to: Taxacom at mailman.nhm.ku.edu
>
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> The Taxacom Archive back to 1992 may be searched at:
> http://taxacom.markmail.org
> To subscribe or unsubscribe via the Web, visit:
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> You can reach the person managing the list at:
> taxacom-owner at mailman.nhm.ku.edu
>
> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 28 Oct 2018 11:35:20 +0000
> From: Mary Barkworth <Mary.Barkworth at usu.edu>
> To: Kenneth Kinman <kinman at hotmail.com>, taxacom
>         <taxacom at mailman.nhm.ku.edu>
> Subject: Re: [Taxacom] Cyanobacteria and the Origin of Life
> Message-ID:
>         <
> BL0PR07MB57450746C250F21AD03279EA96F20 at BL0PR07MB5745.namprd07.prod.outlook.com
> >
>
> Content-Type: text/plain; charset="utf-8"
>
> Thank you for sharing that link
> -----Original Message-----
> From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> On Behalf Of Kenneth
> Kinman
> Sent: Saturday, October 27, 2018 7:56 PM
> To: taxacom <taxacom at mailman.nhm.ku.edu>
> Subject: [Taxacom] Cyanobacteria and the Origin of Life
>
> Hi All,
>          I have long believed that Cyanobacteria are the most primitive
> forms of cellular life to have survived to the present day.  And that the
> earliest cyanobacteria might not have been capable of oxygenic
> photosynthesis (at least one that required both Photosystems I and II).
>  The question is whether a recent October 2018 research paper might help
> support such an hypothesis.  Opinions (pro or con) are welcome.  Here is a
> weblink to the paper:
> http://www.pnas.org/content/early/2018/09/26/1808176115
>
>                                ----------------Ken Kinman
>
> ________________________________
> From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of John
> Grehan <calabar.john at gmail.com>
> Sent: Wednesday, October 24, 2018 5:55 AM
> To: taxacom
> Subject: [Taxacom] Orthogeneisis
>
> For anyone interested in such esoterica, below is the text of an article
> published in The International Encyclopedia of Biological Anthropology
> (2018). If anyone wants a pdf please contact me.
>
> John Grehan
>
> Like many controversial concepts, orthogenesis will mean different things
> to different people.
> For most evolutionary biologists the term is likely to embody an obsolete
> view of evolution as teleological or predetermined, or that it involves
> some kind of “straight line” or linear evolution that is incompatible with
> the reality of evolutionary divergence. As emphasized by Darwin (see
> Darwin, Charles R), evolution was (and still
> is) largely seen as the result of random variation subject to natural
> selection. But even Darwin referred to “laws of growth” and other early
> evolutionists saw that evolution was not entirely “random” as novel
> variations failed to obfuscate the existence of preexisting ancestral
> architecture (To put this issue in simplistic terms: A penguin in the water
> remains a bird and does not become a fish.) There was also widespread
> acceptance that evolution was generally irreversible—that while individual
> characters may sometimes revert, overall structural organization did not.
> Darwin later expressed regret over his initial emphasis on natural
> selection (see evolution).
>
> The idea of orthogenesis was proposed in 1893 by the German evolutionist
> William Haacke, who argued that if any kind of variation was possible, one
> would expect reversals to be as frequent as novelties. The rarity of such
> reversals was seen as evidence that the evolutionary origin of variation
> was not only limited, but constrained or biased by preexisting biological
> organization. Orthogenesis was subsequently adopted by a minority of
> evolutionists, including some who applied it to theories of vital forces or
> goal-driven evolution.The fossil record was sometimes regarded as
> demonstrating a linear direction to evolution, such as the classic
> reduction of horse digits from five to one.This linear concept is widely
> seen as having been refuted by evidence that evolution was not linear, but
> involved a process of diversification or branching (e.g., Ernst Mayr (see
> Mayr, Ernst), George Gaylord Simpson (see Simpson, George Gaylord), Stephen
> Jay Gould (see Gould, Stephen J.)—see Grehan and Ainsworth 1985). This
> critique mistakenly conflated linear evolution with orthogenesis. Haacke
> cited the reduction of horse toes from five to one as an illustration of a
> biologically driven trend, not a linear or purposeful evolution. Whether or
> not horse evolution was “linear” or a radiating “bush,” there was a
> reduction of toes that took place over space and time resulting in the
> single-toed horse of today.
> This reduction may be attributed to “random”
> variations that imparted increased fitness (see fitness), or it may be
> attributed to a biological process where new variants resulted in reduction
> of toes. Horses survived because these reductions were compatible with the
> requirements of ecological survival. The apparent contradiction between an
> orthogenetic trend and evolutionary divergence was addressed by Leon
> Croizat (1958,
> 1964) in the panbiogeographic evolutionary synthesis.
> He regarded differentiation as the result of allopatric divergence across
> a widespread ancestral range. The heterogeneous distribution of genetic
> characters across this range provides spatially different starting points
> that biased subsequent differentiation and speciation.
>
> In natural selection theory, a random variation is spread through a
> population by differential reproductive success (fitness). In orthogenetic
> models, a new variant does not require differential reproduction to become
> established. While observations of biological organization and
> biogeographic distribution led some evolutionists to adopt orthogenetic
> models of evolution, there remained the widespread objection that the
> concept was “mysterious” because there was no mechanism to explain the
> spread of novel variants without requiring natural selection.
> But in recent decades evolutionary biologists have widely recognized that
> aspects of genomic architecture, gene structure, and developmental pathways
> are difficult to explain without involving nonadaptive processes of genetic
> drift and mutation. Gene expression is controlled by complex pathways and
> networks of interacting regulatory genes, and there has been no formal
> demonstration of an adaptive origin for any genetic network.Many features
> of transcriptional networks can readily arise through nonadaptive drift,
> mutation, and recombination. This raises the question as to whether natural
> selection is sufficient or even necessary for the origin of gene-network
> topologies. Recombination events are accompanied by unidirectional
> exchanges known as gene conversion. There is evidence, for example, that
> many eukaryotes, including humans, are GC-biased—that is, their total DNA
> complement contains a higher-than-expected proportion of guanine–cytosine
> base pairs. In humans, there is a genome-wide positive correlation between
> crossover rate and GC content.
> Other biological processes capable of producing evolutionary trends
> without environmental selection include the emergence of error minimization
> in the genetic code, expansion of genome size by mobile element
> proliferation, and widespread reductions in genome size in multiple
> lineages of mammals. Complementary to genetic and developmental studies is
> the widespread existence of trends in morphology involving reduction,
> suppression, and fusion in complex multipartite structures such as the
> angiosperm flower and vertebrate skull.
>
> The recognition of orthogenesis does not imply a rejection of natural
> selection. Orthogenesis implies only that biological mechanisms can result
> in mutations and the spread of mutations without requiring increased
> fitness. As natural selection can also result in the spread of mutations
> (variants), there are two kinds of dynamic processes involved with
> evolution: one internal and biological and the other external and
> environmental.
> These are not two separable entities.
> Earlier formulations of orthogenesis emphasized a contrast between the
> roles of “internal” and “external” forces in evolution, but no biological
> process exists without an environment; and conversely, the effects produced
> by environmental forces are contingent upon the organisms involved. How
> these biological and environmental processes interact to “co-construct”
> organisms and their ecological relationships through development represents
> a new and largely unexplored aspect of evolutionary biology—one that
> involves intrinsic biological mechanisms, regardless of whether they are
> labeled orthogenesis or something else (Heads 2016).
> _______________________________________________
> Taxacom Mailing List
> Send Taxacom mailing list submissions to: Taxacom at mailman.nhm.ku.edu
>
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> The Taxacom Archive back to 1992 may be searched at:
> http://taxacom.markmail.org To subscribe or unsubscribe via the Web,
> visit: http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> You can reach the person managing the list at:
> taxacom-owner at mailman.nhm.ku.edu
>
> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
> _______________________________________________
> Taxacom Mailing List
> Send Taxacom mailing list submissions to: Taxacom at mailman.nhm.ku.edu
>
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> The Taxacom Archive back to 1992 may be searched at:
> http://taxacom.markmail.org To subscribe or unsubscribe via the Web,
> visit: http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> You can reach the person managing the list at:
> taxacom-owner at mailman.nhm.ku.edu
>
> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
>
> ------------------------------
>
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> To subscribe or unsubscribe via the Web, visit:
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> You can reach the person managing the list at:
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>
> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
>
>
> ------------------------------
>
> End of Taxacom Digest, Vol 150, Issue 18
> ****************************************
>


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