Islands’ weeds don’t support evolution
Any claim that evolutionary biologists have witnessed evolution in action is of
interest to creationists. We recently talked about a claim by Dr Jared Diamond (Creation 16(3):41)
that evolution has been observed. He cited the changes in peppered moths and insecticide
resistance in mosquitos. We showed (from the work of other evolutionists around
20 years before) that these were definitely not cases in which evolution was happening.
Evolutionists of course claim large-scale evolution has occurred (non-life turned
into life, then the first ‘simple’ life evolved all the way up to people).
Yet all they point to as proof of this are minor changes — such as varying
beaks in finches, or different colours in moths. Also, evolution is supposed to
be a process generating lots of new genetic information. Yet the examples they cite
invariably turn out to show no such thing. So we were interested to read in the
scientific journal Nature, 14 March 1996, page 103, in another item by
Dr Diamond, that a case of rapid evolution had allegedly been observed off Canada’s
Pacific coast.
Researchers Martin Cody and Jacob Overton had reported ‘direct detection of
both rapid evolutionary change and the "founder effect" in populations
of wild plants. (The founder effect is the phenomenon whereby new colonies of a
species may become instantly distinct from the parent population, as a result of
their few founding individuals being an atypical sample.)’
But is this a genuine case of evolution? Was new information added to the plants’
DNA, so that something truly new could be said to have arisen? The answer again
is a resounding ‘no’.
In essence, what happened was this:
The researchers studied the ‘loss of dispersal ability’ of plants confined
to islands. Many species that are found only on remote islands seem to lack any
way of reaching those islands in the first place. So why are they different from
similar plants on the mainland?
Cody and Overton did a detailed study over 10 years of some weeds whose seeds were
dispersed by the wind (in the way we see dandelion fluff distributed by the wind).
The design features in these airborne seeds show some natural variation; some of
the plants produce airborne seeds which are able to travel further than others.
They found that in only a few generations, these plants on the island produced seeds
less able to travel far and wide (on average) than those plants on the mainland
from which they had descended. This was said to be ‘an especially clear and
simple example of evolution through natural selection, witnessed historically’.
While this may be a clear example of natural selection, it must be realized that
natural selection is not evolution (in the sense in which evolution is
normally understood) since by itself it cannot generate anything new.
Natural selection does not produce any truly novel characteristics, such as feathers
on reptiles to turn them into birds. It simply operates on characteristics that
are already present in the genetic code, like varying shapes, colours, or sizes.
This is what happened with the weedy plants on Canada’s islands. On a small
island, highly mobile seeds would be likely to travel beyond the boundaries of the
land. Or to put it another way, plants with genes for less mobile seeds are more
likely to establish their offspring on that island.
The diagram makes it clear how this effect can happen. It is an expression of the
variation which was there all along, and has nothing to do with the imagined process
of how a one-celled creature could turn into peacocks, pears, and people.
In fact, rather than proving evolution in the way Charles Darwin thought it did,
natural selection is really a wonderful example of the creationists’ principle
of conservation in operation. The genetic system maintains its identity as a specific
kind, while the distribution of characteristics within that kind is rearranged to
allow the plant or animal population to survive changes more readily in the environment.
Despite the fact that Dr Jared Diamond opens his article with a sideswipe at creationists,
the clear evidence is that the weed research on Canada’s islands points not
to evolution, but to creation.
How selection might operate on weed species ‘x’ (‘x-weeds’)
with airborne seeds
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x-weeds with genes coding for mostly far-ranging seeds
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x-weeds with genes coding for mostly short-range seeds
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x-weeds with genes coding for both, producing mostly medium-range seeds but also
occasional seeds of both short- and long-range.
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STEP 1 — before the x-weeds colonize the island
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A mixture
of gene types
in the
x-weed
population
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Empty of x-weeds
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STEP 4
The longer-range a plant’s seeds are, the more likely it is that
it will NOT contribute its genes to the next generation of plants on the island.
Plants with genes producing short-range seeds will be more likely to transmit their
genes to the next generation, and so with each generation, these become more common
on the island, even though they began in the minority.
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STEP 2
Some of the wider-ranging seeds colonize the island (short-ranging seeds can’t
easily reach it)
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STEP 5
Most of the seeds on the island are now of the short-range type, creating
the apparent (but easily resolved) conundrum of how their seeds could have arrived
here in the first place.
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STEP 3
The offspring of the original seeds to reach the island have a preponderance
of ‘long-range’ type genes. This makes the population appear a little
different from that on the mainland — an example of the so-called ‘founder
effect’.
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This is not evolution — all the genes were there in the first
place.
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