Re: Why Haven't Cyanobacteria Changed?

On Oct 1, 11:59=A0pm, "Entertained by my own EIMC Internetional Ptd.
Lty." <fell_spamtrap...@xxxxxxxxxxxx> wrote:
"Tom Hendricks" <tom-hendri...@xxxxxxx> wrote in message

news:gb78m6$27uf$1@xxxxxxxxxxxxxxxxxxxxxx



Blue green bacteria, cyanobacteria of today are almost identical to
billion year old fossils. "Approximately 90 species of fossilized
blue-green bacteria have contemporary look-alikes."
So why haven't they changed.

"Tropical forests produce the largest number of species and rank first
worldwide in species diversity..." But what's second? "... more plant
species are found in areas with big seasonal temperature fluctuations t=
han
in areas with more even climates... The plant survey suggests that the
tropics are biologically rich despite their even climates, not because =
of
them." So why have they diversified?*...... (Quotes from S. B. McGrayne=
)

I suggest my model of selection pressure explains both cases.

The greater the selection presssure , directional or diversifying
selection, the greater the speed of evolution.
AND
The lower the selection pressure, stabilizing selection, the lower the
speed of evolution.

In the case of bacteria the author says, "With this much success why
bother evolving". Thus low selection pressure leads to lower speed of
evolution.

In the case of the tropics and the areas with big seasonal temperatures=
,
both have high selection pressure on the species that live there -
tropics have high selection pressure from the vast numbers of competing
species,

You seem to be saying that: "As if life started to become diverse by bein=
g
thrown in to a bio-friendly locality where there were already vast number=
s
of competing species". :-\

Nope didn't mean to. There would not be the pressure that causes the
change.
I think it is the stress of competing species that speeds up the
evolution,
not the bio-friendly locality. That's what the initial study said.

and the big seasonal temperature fluctuations have high selection press=
ure
because of the demands of the temperature fluctuations.

Different temperature ranges offer different degrees of intrinsic and
extrinsic opportunities for life to form and flourish. ["Extrinsic
opportunites".~=3D different locality-dependent sets of environmental fac=
tors
affecting the fitness of "reproductive units".]

You are again trying to 'nail-down' how species arouse with 'a candle'. ;=
)


.

Relevant Pages

  • Re: The pooh-poohing of... Re: Haldanes Dilemma
    ... and the species has _not_ become extinct. ... was that 1024::1 selection pressure would extinguish ... moths dropped due to selection pressure, ... No "excess deaths" would occur, ...
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    ... enough selection pressure on a species, so that they overpopulate an area, ... painful death to members of that species. ...
    (rec.pets.cats.anecdotes)
  • Re: Why Havent Cyanobacteria Changed?
    ... "Tropical forests produce the largest number of species and rank first ... species are found in areas with big seasonal temperature fluctuations than ... I suggest my model of selection pressure explains both cases. ... In the case of the tropics and the areas with big seasonal temperatures, ...
    (sci.bio.evolution)
  • Re: Why Havent Cyanobacteria Changed?
    ... billion year old fossils. ... "Approximately 90 species of fossilized ... the greater the speed of evolution. ... The lower the selection pressure, stabilizing selection, the lower the ...
    (sci.bio.evolution)
  • Re: Darwin, Evolution, the Animal Kingdom, and Man
    ... >> more with the speed of propagation and dissemination of the species. ... >suggestion is that humans have passed ... >through a number of extreme selection pressure episodes relatively recently. ... >If it's true that genomic variation bodes well for a species when severe ...
    (sci.cognitive)
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