The concept of natural selection
was first proposed by Charles Darwin after he observed the finches population
in the Galapagos Islands. From this
observation, Darwin said that there is first overpopulation in the
species. In the overpopulated population,
there are different genetic differences or individuals with different
characteristics controlled by the genes.
Some have greater fitness because the genetic variation is helpful for
its survival in a certain environment.
The less fit individuals have characteristic that are not beneficial for
the survival in the certain environment.
Once there is overpopulation, there are competitions among the
individuals in the population for food, mating partners, habitat etc. When there are competitions, there are
winners and losers and it is these winners that have a greater fitness. Because the fitter individuals survive more,
they have better chance of reproducing and pass on the fitter genes to the
offspring. As many generations pass, the
fitter genes are spread more and more and now, most of the individuals in the
population have the fitter genes.
In the article, the snail
population has undergone natural selection.
In the north of England where the climate is cooler, there are more
snails with brown and pink color because these two colors are better at
absorbing the little heat. If they are
to live in the south, more heat absorption will kill them. However, snails with yellow shell that don’t
absorb as much heat survive better in the south because it can withstand the
heat. They have a better chance of
survival and so they will have more chance of reproducing and pass on their
genes. As generations pass, the brown
and pink pass on their genes in the north and the yellow pass on their genes in
the south and these colors become more dominant.
According to Discovery.com,
another example of natural selection is the peacock. They are birds with large colorful
tails. Females choose the mating partner
based on the tails. However, in the
past, not all males have large colorful tails because of genetic
variation. The ones with the bigger
tails are fitter for reproduction and as time pass, the ones with the bigger
tails will be able to pass on their genes.
Now in the present, males with small tails are very rare because they
did not have as much chance of reproducing and therefore cannot pass on their
genes for small tails.
Evolution has been a topic of
study for centuries. In the past many
people have been coming up with theories to explain how species come
about. Charles Darwin has been the most
successful in explaining this change in species with his species of natural
selection. A lot of times, natural
selection not only change one species, but all of the species in the
ecosystem. When the food source changed,
the predators also change along with them.
Also, change in the ecosystem cause the species to change. For example, in the snail example, there have
been a decline in the birds preying on the snails and this will cause the
population of the snail to increase.
This can be the result of the snails hiding better from the birds. Natural has selected the snail to survive
because of the fit characteristic. The
birds with the better variation that can find more food source will be selected
by nature to survive and pass on the genes.
