Re: Why Haven't Cyanobacteria Changed?
- From: "Entertained by my own EIMC Internetional Ptd. Lty." <fell_spamtrap_in@xxxxxxxxxxxx>
- Date: Thu, 2 Oct 2008 00:59:00 -0400 (EDT)
"Tom Hendricks" <tom-hendricks@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 than
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 being
thrown in to a bio-friendly locality where there were already vast numbers
of competing species". :-\
and the big seasonal temperature fluctuations have high selection pressure
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".~= different locality-dependent sets of environmental factors
affecting the fitness of "reproductive units".]
You are again trying to 'nail-down' how species arouse with 'a candle'. ;)
.
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