Have often wondered how plants with dark foliage, like the dark red canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in cyanobacteria and the chloroplasts of algae and plants.[1] Its name is derived from the Greek words χλω�ός, chloros ("green") and φ�λλον, phyllon ("leaf").[2] Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to absorb energy from light. Chlorophyll absorbs light most strongly in the blue portion of the electromagnetic spectrum, followed by the red portion. However, it is a poor absorber of green and near-green portions of the spectrum, hence the green color of chlorophyll-containing tissues.[3] Chlorophyll was first isolated by Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any comments...appreciated.

HB

Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words χλω�ός, chloros ("green") and φ�λλον,
phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the red
portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite interesting
to me. The explanation given, which I think is widely accepted in the
botanical community, is that some (apparently superior) structures and
functions of living organisms have not been reached by evolution because
there was no evolutionary pathway from where they came from to get there.
This accounts for the less than optimal structure of many aspects of life,
eg the human eye and the giraffe's neck. In fact it is characteristic of a
process that proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can abandon a bad
design and take a completely different approach. Evolution cannot do that.
Evolution is undirected and has no 'final' target nor does it look to the
future as an engineer does, it can only work incrementally on choosing which
variation of structure or function is better suited to the environment the
organism is in at that time.

In case anybody thinks that evolution is too academic or even off topic, I
think it is fair to say that having an understanding of evolution of plants
and organisms that relate to plants (eg predators and symbiots) will make
you a better gardener.

David

On 8/8/13 8:19 PM, David Hare-Scott wrote:
Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words χλω�ός, chloros ("green") and φ�λλον,
phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the red
portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite interesting
to me. The explanation given, which I think is widely accepted in the
botanical community, is that some (apparently superior) structures and
functions of living organisms have not been reached by evolution because
there was no evolutionary pathway from where they came from to get there.
This accounts for the less than optimal structure of many aspects of life,
eg the human eye and the giraffe's neck. In fact it is characteristic of a
process that proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can abandon a bad
design and take a completely different approach. Evolution cannot do that.
Evolution is undirected and has no 'final' target nor does it look to the
future as an engineer does, it can only work incrementally on choosing which
variation of structure or function is better suited to the environment the
organism is in at that time.

In case anybody thinks that evolution is too academic or even off topic, I
think it is fair to say that having an understanding of evolution of plants
and organisms that relate to plants (eg predators and symbiots) will make
you a better gardener.

David


In the August 2013 issue of Scientific American, the article "The
Surprising Origins of Life's Complexity" suggests that evolution
strongly depends, not so much on mutations that are advantageous, but
more on mutations that are neutral. As such mutations accumulate in the
gene pool, their combination eventually leads to changes in an organism.
See
http://www.scientificamerican.com/article.cfm?id=the-surprising-origins-of-evolutionary-complexity.


--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary

In article ,
"David Hare-Scott" wrote:

Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words É‘É…É÷Éœός, chloros ("green") and φ�λλον,
phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the red
portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite interesting
to me. The explanation given, which I think is widely accepted in the
botanical community, is that some (apparently superior) structures and
functions of living organisms have not been reached by evolution because
there was no evolutionary pathway from where they came from to get there.
This accounts for the less than optimal structure of many aspects of life,
eg the human eye and the giraffe's neck. In fact it is characteristic of a
process that proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can abandon a bad
design and take a completely different approach. Evolution cannot do that.
Evolution is undirected and has no 'final' target nor does it look to the
future as an engineer does, it can only work incrementally on choosing which
variation of structure or function is better suited to the environment the
organism is in at that time.

In case anybody thinks that evolution is too academic or even off topic, I
think it is fair to say that having an understanding of evolution of plants
and organisms that relate to plants (eg predators and symbiots) will make
you a better gardener.

David

Scientific American
April 2008

The Colors of Plants on Other Worlds

Pg. 48


The prospect of finding extraterrestrial life is no Ionger the domain of
science fiction or UFO hunters. Rather than waiting for aliens to come
to us, we are looking for them. We may not find technologically advanced
civilizations, but we can look for the physical and chemical signs of
fundamental life processes: “bio-signatures.� Beyond the solar system,
astronomers have discovered more than 200 worlds orbiting other stars,
so-called extrasolar planets. Although we have not been able to tell
whether these planets harbor life, it is only a matter of time now. Last
July astronomers confirmed the presence of water vapor on an extrasolar
planet by observing the passage of starlight through the planet’s
atmosphere. The world’s space agencies are now developing telescopes
that will search for signs of life on Earth-size planets by observing
the planets’ light spectra.

Photosynthesis, in particular, could produce very conspicuous
biosignatures. How plausible is it for photosynthesis to arise on
another planet? Very. On Earth, the process is so successful that it is
the foundation for nearly all life. Although some organisms live off the
heat and methane of oceanic hydrothermal vents, the rich ecosystems on
the planet’s surface all depend on sunlight.

Photosynthetic biosignatures could be of two kinds:
biologically generated atmospheric gases such as oxygen and its product,
ozone; and surface colors that indicate the presence of specialized
pigments such as green chlorophyll. The idea of looking for such
pigments has a long history. A century ago astronomers sought to
attribute the seasonal darkening of Mars to the growth of vegetation.
They studied the spectrum of light reflected off the surface for signs
of green plants. One difficulty with this strategy was evident to writer
H. G. Wells, who imagined a different scenario in The War of the Worlds:
“The vegetable kingdom in Mars, instead of having green for a dominant
colour, is of a vivid blood-red tint.� Although we now know that Mars
has no surface vegetation (the darkening is caused by dust storms),
Wells was prescient in speculating that photosynthetic organisms on
another planet might not be green.

Even Earth has a diversity of photosynthetic organisms besides green
plants. Some land plants have red leaves, and underwater algae and
photosynthetic bacteria come in a rainbow of colors. Purple bacteria
soak up solar infrared radiation as well as visible light. So what will
dominate on another planet? And how will we know when we see it? The
answers depend on the details of how alien photosynthesis adapts to
light from a parent of different type than our sun, filtered through an
atmosphere that may not have the same composition as Earth’s.

Harvesting Light

In trying to figure out how photosynthesis might operate other planets,
the first step is to explain it on Earth. The energy spectrum of
sunlight at Earth’s surface peaks in the blue-green, so scientists have
long scratched their heads about why plants reflect green, thereby
wasting what appears to be the best available light .The answer is that
photosynthesis doesn’t depend on the total amount of light energy but on
the energy per photon and the number of photons that make up the light.
Whereas blue photons carry more energv than red ones, the sun emits more
of the red kind. Plants use blue photons for their quality and red
photons for their quantity. Tin green photons that lie in between have
neither the energy nor the numbers, so plants have adapted to absorb
fewer of them.

The basic photosynthetic process, which fixes one carbon atom (obtained
from carbon dioxide, CO2) into a simple sugar molecule, requires a
minimum of eight photons. It takes one photon to split an
oxygen-hydrogen bond in water H2O and thereby to obtain an electron for
bio-chemical reactions. A total of four such bonds must be broken to
create an oxygen molecule (O2). Each of those photons is matched by at
least one additional photon for a second type of reaction to form the
sugar. Each photon must have a minimum amount of energy to drive the
reactions.

The way plants harvest sunlight is a marvel of nature. Photosynthetic
pigments such as chlorophyll are not isolated molecules. They operate in
a network like an array of antennas, each tuned to pick out photons of
particular wavelengths. Chlorophyll preferentially absorbs red and blue
light, and carotenoid pigments (which produce the vibrant reds and
yellows of fall foliage) pick up a slightly different shade of blue. All
this energy gets funneled to a special chlorophyll molecule at a
chemical reaction center, which splits water and releases oxygen.
The tunneling process is the key to which colors the pigments select.
The complex of molecules at the reaction center can perform chemical
reactions only if it receives a red photon or the equivalent amount of
energy in some other form. To take advantage of blue photons, the
antenna pigments work in concert to convert the high energy (from blue
photons) to a lower energy (redder), like a series of step-down
transformers that reduces the 100,000 volts of electric power lines to
the 120 or 240 volts of a wall outlet. The process begins when a blue
photon hits a blue-absorbing pigment and energizes one of the electrons
in the molecule. When that electron drops back down to its original
state, it releases this energy―but because of energy losses to heat and
vibrations, it releases less energy than it absorbed.

The pigment molecule releases its energy not in the form of another
photon but in the form of an electrical interaction with another pigment
molecule that is able to absorb energy at that lower level. This
pigment, in turn, releases an even lower amount of energy, and so the
process continues until the original blue photon energy has been
downgraded to red. The array of pigments can also convert cyan, green or
yellow to red. The reaction center, as the receiving end of the cascade,
adapts to absorb the lowest-energy available photons. On our planet’s
surface, red photons are both the most abundant and the lowest energy
within the visible spectrum.

For underwater photosynthesizers, red photons are not necessarily the
most abundant. Light niches change with depth because of filtering of
light by water, by dissolved substances and by overlying organisms
themselves. The result is a clear stratification of life-forms according
to their mix of pigments. Organisms in lower water layers have pigments
adapted to absorb the light colors left over by the layers above. For
instance, algae and cyanobacteria have pigments known as phycobilins
that harvest green and yellow photons. Nonoxygen-producing (anoxygenic)
bacteria have bacteriochlorophylls that absorb far-red and near-infrared
light, which is all that penetrates to the murky depths.

Organisms adapted to low-light conditions tend to be slower-growing,
because they have to put more effort into harvesting whatever light is
available to them. At the planet’s surface, where light is abundant, it
would be disadvantageous for plants to manufacture extra pigments, so
they are selective in their use of color. The same evolutionary
principles would operate on other worlds.

Just as aquatic creatures have adapted to light filtered by water, land
dwellers have adapted to light filtered by atmospheric gases. At the top
of Earth’s atmosphere, yellow photons (at wavelengths of 560 to 590
nanometers) are the most abundant kind. The number of photons drops off
gradually with longer wavelength and steeply with shorter wavelength. As
sunlight passes through the upper atmosphere, water vapor absorbs the
infrared light in several wavelength ands beyond 700 nm. Oxygen produces
absorption lines―narrow ranges of wavelengths that the gas blocks―at 687
and 761 nm. We all know that ozone (O3) in the stratosphere strongly
absorbs the ultraviolet (UV). Less well known is that it also absorbs
weakly across the visible range.

Putting it all together, our atmosphere demarcates windows through which
radiation can make it to the planet’s surface. The visible radiation
window is defined at its blue edge by the drop-off in the intensity of
short-wavelength photons emitted by the sun and by ozone absorption of
UV. The red edge is defined by oxygen absorption lines. The peak in
photon abundance is shifted from yellow to red (about 685 nm) by ozone’s
broad absorbance across the visible.

Plants are adapted to this spectrum, which is determined largely by
oxygen―yet plants are what put the oxygen into the atmosphere to begin
with. When early photosynthetic organisms first appeared on Earth, the
atmosphere lacked oxygen, so they must have used different pigments from
chlorophyll. Only over time as photosynthesis altered the atmospheric
composition, did chlorophyll emerge as optimal.

The firm fossil evidence for photosynthesis dates to about 3.4 billion
years ago (Ga), but earlier fossils exhibit signs of what could have
been photosynthesis. Early photosynthesizers had to start out
underwater, in part because water is a good solvent for biochemical
reactions and in part because it provides protection against solar UV
radiation―shielding that was essential in the absence of an atmospheric
ozone layer. These earliest photosynthesizers were underwater bacteria
that absorbed infrared photons. Their chemical reactions involved
hydrogen, hydrogen sulfide or iron rather than water, so they did not
produce oxygen gas. Oxygen-generating (oxygenic) photosynthesis by
cyanobacteria in the oceans started 2.7 Ga. Oxygen levels and the ozone
layer slowly built up, allowing red and brown algae to emerge. As
shallower water became safe from UV, green algae evolved. They lacked
phycobilins and were better adapted to the bright light in surface
waters. Finally, plants descended from green algae emerged onto land―
two billion years after oxygen had begun accumulating in the atmosphere.

And then the complexity of plant life exploded, from mosses and
liverworts on the ground to vascular plants with tall canopies that
capture more light and have special adaptations to particular climates.
Conifer trees have conical crowns that capture light efficiently at high
latitudes with low sun angles; shade-adapted plants have anthocyanin as
a sunscreen against too much light. Green chlorophyll not only is well
suited to the present composition of the atmosphere but also helps to
sustain that composition―a virtuous cycle that keeps our planet green.
It may be that another step of evolution will favor an organism that
takes advantage of the shade underneath tree canopies, using the
phycobilins that absorb green and yellow light. But the organisms on top
are still likely to stay green.
--
Palestinian Child Detained
http://www.youtube.com/watch?v=zzSzH38jYcg

Remember Rachel Corrie
http://www.rachelcorrie.org/

Welcome to the New America.
http://www.youtube.com/watch?v=hA736oK9FPg

David E. Ross wrote:
On 8/8/13 8:19 PM, David Hare-Scott wrote:
Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words χλω�ός, chloros ("green") and
φ�λλον, phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the
red portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite
interesting to me. The explanation given, which I think is widely
accepted in the botanical community, is that some (apparently
superior) structures and functions of living organisms have not been
reached by evolution because there was no evolutionary pathway from
where they came from to get there. This accounts for the less than
optimal structure of many aspects of life, eg the human eye and the
giraffe's neck. In fact it is characteristic of a process that
proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can
abandon a bad design and take a completely different approach.
Evolution cannot do that. Evolution is undirected and has no 'final'
target nor does it look to the future as an engineer does, it can
only work incrementally on choosing which variation of structure or
function is better suited to the environment the organism is in at
that time.

In case anybody thinks that evolution is too academic or even off
topic, I think it is fair to say that having an understanding of
evolution of plants and organisms that relate to plants (eg
predators and symbiots) will make you a better gardener.

David


In the August 2013 issue of Scientific American, the article "The
Surprising Origins of Life's Complexity" suggests that evolution
strongly depends, not so much on mutations that are advantageous, but
more on mutations that are neutral. As such mutations accumulate in
the gene pool, their combination eventually leads to changes in an
organism. See
http://www.scientificamerican.com/article.cfm?id=the-surprising-origins-of-evolutionary-complexity.

This application of complexity theory is not universally accepted. No
matter the point that I was trying to make, that the outcomes of evolution
are limited by the availablity of pathways from the previous situation to a
new one remains. Whether this postulated mechanism opens up more pathways
that permit greater leaps from one state to another remains to be seen, as
does how often it might occur.

D

D

On 09/08/2013 04:19, David Hare-Scott wrote:
Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words χλω�ός, chloros ("green") and φ�λλον,
phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the red
portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite interesting
to me. The explanation given, which I think is widely accepted in the
botanical community, is that some (apparently superior) structures and
functions of living organisms have not been reached by evolution because
there was no evolutionary pathway from where they came from to get there.
This accounts for the less than optimal structure of many aspects of life,
eg the human eye and the giraffe's neck. In fact it is characteristic of a
process that proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can abandon a bad
design and take a completely different approach. Evolution cannot do that.

It's interesting that nature didn't come up with the wheel, one of the
most energy-efficient ways of moving around (or did I read a few years
ago that there was some strange organism which could move like a wheel?
I believe that there are some desert spiders which can escape predators
by pulling themselves into a ball shape and rolling down sand dunes, but
that not really the same thing as a wheel). It's probably because the
moving parts of a wheel are completely separate from each other, and it
would not be possible to repair the revolving part of the wheel if it
was damaged, as it would have no blood supply.

Evolution is undirected and has no 'final' target nor does it look to the
future as an engineer does, it can only work incrementally on choosing which
variation of structure or function is better suited to the environment the
organism is in at that time.

That's not quite true. If it is assumed that life started in the sea,
it should have stayed in that environment, but it didn't. Some animals
changed (evolved?) to make use of land. Even more oddly, some changed
back (eg seals) to make lesser or greater use of their "old"
environment, whilst others, such as dolphins evolved (or should that be
regressed?!) to become totally dependent on their old marine environment.

In case anybody thinks that evolution is too academic or even off topic, I
think it is fair to say that having an understanding of evolution of plants
and organisms that relate to plants (eg predators and symbiots) will make
you a better gardener.

Yes, that's true. There are quite a few examples of parallel evolution
(cacti and other succulents; alpines - particularly the giant lobelias
and puyas) to support that. If you know how to grow cacti - which are
really all New World plants - you will have little trouble if you decide
to grow lithops from South Africa.

And if you find it impossible to grow giant lobelias, you will find it
just as impossible to grow puyas! :-)

--

Jeff

Jeff Layman wrote:
On 09/08/2013 04:19, David Hare-Scott wrote:
Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words χλω�ός, chloros ("green") and
φ�λλον, phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the
red portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite
interesting to me. The explanation given, which I think is widely
accepted in the botanical community, is that some (apparently
superior) structures and functions of living organisms have not been
reached by evolution because there was no evolutionary pathway from
where they came from to get there. This accounts for the less than
optimal structure of many aspects of life, eg the human eye and the
giraffe's neck. In fact it is characteristic of a process that
proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can
abandon a bad design and take a completely different approach. Evolution
cannot do that.

It's interesting that nature didn't come up with the wheel, one of the
most energy-efficient ways of moving around (or did I read a few years
ago that there was some strange organism which could move like a
wheel? I believe that there are some desert spiders which can escape
predators by pulling themselves into a ball shape and rolling down
sand dunes, but that not really the same thing as a wheel). It's
probably because the moving parts of a wheel are completely separate
from each other, and it would not be possible to repair the revolving
part of the wheel if it was damaged, as it would have no blood supply.

Evolution is undirected and has no 'final' target nor does it look
to the future as an engineer does, it can only work incrementally on
choosing which variation of structure or function is better suited
to the environment the organism is in at that time.

That's not quite true. If it is assumed that life started in the sea,
it should have stayed in that environment, but it didn't.

I see no evidence of either of those statements.

Some
animals changed (evolved?) to make use of land. Even more oddly,
some changed back (eg seals) to make lesser or greater use of their
"old" environment, whilst others, such as dolphins evolved (or should
that be regressed?!) to become totally dependent on their old marine
environment.

In saying they regressed (went backwards) you are saying there is a
particular direction that is "right". It ain't so.

In case anybody thinks that evolution is too academic or even off
topic, I think it is fair to say that having an understanding of
evolution of plants and organisms that relate to plants (eg
predators and symbiots) will make you a better gardener.

Yes, that's true. There are quite a few examples of parallel
evolution (cacti and other succulents; alpines - particularly the
giant lobelias and puyas) to support that. If you know how to grow
cacti - which are really all New World plants - you will have little
trouble if you decide to grow lithops from South Africa.

And if you find it impossible to grow giant lobelias, you will find it
just as impossible to grow puyas! :-)

OK

D

Jeff Layman wrote:

It's interesting that nature didn't come up with the wheel, one of the
most energy-efficient ways of moving around.

The wheel is the most natural phenomina in nature. The wheel has
existed since the creation of the universe... nothing is more natural
than the "orbit" (straight lines don't exist in this universe). The
wheel has always existed, man has only relatively recently
*discovered* the wheel. Anyone who thinks man invented the wheel is
the same kind of pinhead who thinks man invented fire.

On Fri, 09 Aug 2013 09:29:41 +0100, Jeff Layman
wrote:

It's interesting that nature didn't come up with the wheel, one of the
most energy-efficient ways of moving around (or did I read a few years
ago that there was some strange organism which could move like a wheel?

That's a question which comes up frequently.

There's an interesting paper on it at:
http://www.jstor.org/discover/10.230... 102539587717

The current consensus is that the main problem with biological wheels
is blood flow, but this author addresses a different argument.

In article ,
"David Hare-Scott" wrote:

Jeff Layman wrote:
On 09/08/2013 04:19, David Hare-Scott wrote:
Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words É‘É…É÷Éœός, chloros ("green") and
φ�λλον, phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the
red portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite
interesting to me. The explanation given, which I think is widely
accepted in the botanical community, is that some (apparently
superior) structures and functions of living organisms have not been
reached by evolution because there was no evolutionary pathway from
where they came from to get there. This accounts for the less than
optimal structure of many aspects of life, eg the human eye and the
giraffe's neck. In fact it is characteristic of a process that
proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can
abandon a bad design and take a completely different approach. Evolution
cannot do that.

It's interesting that nature didn't come up with the wheel, one of the
most energy-efficient ways of moving around (or did I read a few years
ago that there was some strange organism which could move like a
wheel? I believe that there are some desert spiders which can escape
predators by pulling themselves into a ball shape and rolling down
sand dunes, but that not really the same thing as a wheel). It's
probably because the moving parts of a wheel are completely separate
from each other, and it would not be possible to repair the revolving
part of the wheel if it was damaged, as it would have no blood supply.

Evolution is undirected and has no 'final' target nor does it look
to the future as an engineer does, it can only work incrementally on
choosing which variation of structure or function is better suited
to the environment the organism is in at that time.

That's not quite true. If it is assumed that life started in the sea,
it should have stayed in that environment, but it didn't.

I see no evidence of either of those statements.

That biological reactions are carried out in aqueous solutions, and that
vast amounts of water would allow divergent compounds a proximity to
each other with the chance of interacting?

Can you think of another crucible in which disparate amino acids, and
ions could interact and then multiply?

Some
animals changed (evolved?) to make use of land. Even more oddly,
some changed back (eg seals) to make lesser or greater use of their
"old" environment, whilst others, such as dolphins evolved (or should
that be regressed?!) to become totally dependent on their old marine
environment.

In saying they regressed (went backwards) you are saying there is a
particular direction that is "right". It ain't so.

Once you have reached total randomness, you need less entropy, before
you can have more again. If she no goes up, how she gonna come down?

"Natural selection" isn't the only game in evolution, the occasional
mutation can participate as well, but it is of necessity a minor player
as most mutations are not beneficial.

In case anybody thinks that evolution is too academic or even off
topic, I think it is fair to say that having an understanding of
evolution of plants and organisms that relate to plants (eg
predators and symbiots) will make you a better gardener.

Yes, that's true. There are quite a few examples of parallel
evolution (cacti and other succulents; alpines - particularly the
giant lobelias and puyas) to support that. If you know how to grow
cacti - which are really all New World plants - you will have little
trouble if you decide to grow lithops from South Africa.

And if you find it impossible to grow giant lobelias, you will find it
just as impossible to grow puyas! :-)

OK

D

For a discussion on mutations in plant breeding see:
http://en.wikipedia.org/wiki/Mutation_breeding

For a real page turner on the theory of evolution see:
http://www.amazon.com/Darwins-Ghosts...ion/dp/0812981
707/ref=sr_1_1?s=books&ie=UTF8&qid=1376073198&sr=1-1&keywords=Darwin%27s+
Ghost
Darwin's Ghosts: The Secret History of Evolution by Rebecca Stott

"Stott gives personality to her historical characters, introducing their
families, their monetary concerns, their qualms about publishing
so-called heretical theories, and the obsessions that kept them up at
night. She also brings her settings and secondary characters to life,
from the deformed sponge divers Aristotle consulted in ancient Lesbos to
the exotic animals in the caliphate’s garden that inspired Jahiz in
medieval Basra to lost seashells found by Maillet in the deserts outside
18th-century Cairo. Stott’s focus on her settings makes her narrative
compellingly readable, and it also reminds us that even as animal
species are shaped by their environment, so intellectuals are shaped by
their societies….Stott’s book is a reminder that scientific discoveries
do not happen in a vacuum, that they often stem from incorrect or
pseudo-scientific inquiries, and that they are constantly changing,
mutable concepts as they meander towards something that might eventually
be called the truth.�
― Christian Science Monitor

(Available at a library near you.)
--
Palestinian Child Detained
http://www.youtube.com/watch?v=zzSzH38jYcg

Remember Rachel Corrie
http://www.rachelcorrie.org/

Welcome to the New America.
http://www.youtube.com/watch?v=hA736oK9FPg

Jymesion wrote:
On Fri, 09 Aug 2013 09:29:41 +0100, Jeff Layman
wrote:

It's interesting that nature didn't come up with the wheel, one of
the most energy-efficient ways of moving around (or did I read a few
years ago that there was some strange organism which could move like
a wheel?

That's a question which comes up frequently.

There's an interesting paper on it at:
http://www.jstor.org/discover/10.230... 102539587717

The current consensus is that the main problem with biological wheels
is blood flow, but this author addresses a different argument.

I haven't seen this article, I will have a look time permitting. One reason
a wheel is not much use for transport biologically is that they require
roads to be efficient. Legs are much better on broken ground and can be
adapted to climbing, become wings, flippers etc.

Also have a look at the bacterial flaggelum, it isn't a wheel that supports
weight for transport but it does rotate and it is powered by biochemistry.

David

David Hare-Scott wrote:
....
This application of complexity theory is not universally accepted. No
matter the point that I was trying to make, that the outcomes of evolution
are limited by the availablity of pathways from the previous situation to a
new one remains. Whether this postulated mechanism opens up more pathways
that permit greater leaps from one state to another remains to be seen, as
does how often it might occur.

well now that there is an active designer in the house
the game will significantly change... already it has
begun and we're only in the few slivers of time in
terms of the past and how long things have gone before.

i would love to be able to sleep for five hundred or
a thousand years and be able to come back and see what
has happened.


songbird

Jeff Layman wrote:
David Hare-Scott wrote:
....
Evolution is undirected and has no 'final' target nor does it look to the
future as an engineer does, it can only work incrementally on choosing which
variation of structure or function is better suited to the environment the
organism is in at that time.

That's not quite true. If it is assumed that life started in the sea,
it should have stayed in that environment, but it didn't.

it is not an assumption, it is based upon the fossil
record found to date with the oldest specimens showing
that life did start in the seas.

the exact process and steps are not known completely
yet, but as time goes on we are getting more answers
and finer details of how it could be possible.


Some animals
changed (evolved?) to make use of land. Even more oddly, some changed
back (eg seals) to make lesser or greater use of their "old"
environment, whilst others, such as dolphins evolved (or should that be
regressed?!) to become totally dependent on their old marine environment.

the only thing required for any change in an
organism to continue is that organism procreates.
the causes/effects of selection, environment,
mutations, etc. may be completely orthogonal to
the simple fact of procreation.

how niches in the environment become occupied
is also orthogonal. the sea to land migration of
both plants and animals is pretty well understood
now. i don't think they are missing any
significant steps in those two processes.


i agree about understanding how life came about
and learning what you can about life is valuable
to a gardener. it's also just amazingly
interesting.

for one thing the possibilities are there
that life moved back and forth from the sea
to land from land to the sea several times
as different disasters happened. not every-
thing previously is wiped out, so different
creation phases coexist (and still do).

but in the past few hundred years life has
woken up and been able to start taking a
direct look at itself and the processes
invovled... all i can say now is watch out
it's gonna get very interesting.


songbird

Billy wrote:
....
That biological reactions are carried out in aqueous solutions, and that
vast amounts of water would allow divergent compounds a proximity to
each other with the chance of interacting?

Can you think of another crucible in which disparate amino acids, and
ions could interact and then multiply?

mud/clay/oils/bubbles/foams/salts

but some would say hydrothermal vents and crusts
of certain compounds may also be likely candidates.

i'm more in favor of foam/bubbles/oils/clays/muds.
i've seen them in action (building what used to be
called a skimmer in reef aquarium keeping as a
means to get organic materials out of the water,
pump a lot of bubbles through a column of water
and what comes to the top is gunk like the foam
that collects on beaches).


songbird

songbird wrote:
David Hare-Scott wrote:
...
This application of complexity theory is not universally accepted.
No matter the point that I was trying to make, that the outcomes of
evolution are limited by the availablity of pathways from the
previous situation to a new one remains. Whether this postulated
mechanism opens up more pathways that permit greater leaps from one
state to another remains to be seen, as does how often it might
occur.

well now that there is an active designer in the house
the game will significantly change... already it has
begun and we're only in the few slivers of time in
terms of the past and how long things have gone before.

i would love to be able to sleep for five hundred or
a thousand years and be able to come back and see what
has happened.


songbird

I don't understand what you are saying. Could you be more explicit?

D