Natural Selection

Join now

If you're ready to pass your A-Level Biology exams, become a member now to get complete access to our entire library of revision materials.

Join over 22,000 learners who have passed their exams thanks to us!

Sign up below to get instant access!

Join now →

Or try a sample...

Not ready to purchase the revision kit yet? No problem. If you want to see what we offer before purchasing, we have a free membership with sample revision materials.

Signup as a free member below and you'll be brought back to this page to try the sample materials before you buy.

Download the samples →
  • The theory of natural selection by Charles Darwin is a vital milestone in the origin of species and the evolutionary process. Many scientists before Darwin stated that a species evolves from an ancestor or from a different species. However, no scientific evidence was present at that time to prove the idea of evolution. During 19th century, Charles Darwin presented his theory of natural selection which was widely accepted by the scientists as well as the general public.
  • In order to study the evolutionary process, Charles Darwin engaged himself in extensive research on animals and plants. He understood the basic idea of evolution through his bird study in the Galapagos islands located at the eastern Pacific Ocean. He noted that the features of birds living in different islands had minor differences.
  • The study made him identify the different species of Finches with varying sizes and beak shapes. The type of food available in a particular region caused the difference in beaks. As opposed to this, he examined only a single species of Finches living in South America. He thought that the species in Galapagos could have been a result of the evolvement of species found in South America.
  • As per his knowledge, the original Finch species were dispersed into environments with varying conditions upon their arrival at the islands. As time passed, the birds’ anatomy underwent natural modifications to adapt to its current conditions. Simply put, their modifications aided them in obtaining better food access thus increasing their rate of survival for reproduction. For instance, a beaked species was better-suited for feeding on thorny plants and displayed better chances of survival within the arid areas compared to other regions. Although this particular bird lived on and reproduced, others who could not adjust to the environment perished. This adaptive feature or modification may have developed several generations later. Since the birds were physically different from one another, they remained reproductively isolated and gave birth to separate species. This explains the evolvement of a new species of Finches from the original one.
  • Darwin, while applying the evolutionary concept to all living things, stated that the individuals of the same species exhibited some kind of variation among them. Organisms that have favourable features for survival and reproduction pass their genetic material from generation to generation. In the end, after several generations, the genetic features or traits become increasingly common. Hence a population containing only the favourable traits evolve.
  • Human breeders practice breeding procedures on domestic animals much like the same way as natural selection. In the case of poultry breeding, the best and the productive chickens are selected for breeding. This helps to eliminate the undesirable traits on a gradual basis. Similar to this, natural selection favours adaptable superior species while discarding the inferior species with time.
  • Darwin’s evolutionary concept differs very much from the theory of organic evolution (1801) by Lamarck. Darwin’s theory states that the nature chooses only the organisms best-suited to a specific environment whereas Lamarck’ theory argues that the changes in organisms are brought about by the environment itself.
  • Natural selection plays a critical role in the evolutionary process. It aids in the accumulation and preservation of useful mutations which elevate an organism’s chances in the battle for survival.
  • The story of peppered moth which took place during the Industrial revolution in the 19th century is a classic example of evolution by natural selection. During this period, trees in forests were coated in soot due to the pollution from factories turning white trees into black. This colour change in the trees caused rapid changes in that region’s peppered moth population. It took only a few years for the not-so common dark moths to dominate while the more common white moths started to experience near-extinction.