What is survival of the fittest, and how are we led to compete for survival? In this IBDP Biology post, we will see how evolution stems from selective natural behaviour, a natural phenomenon that occurs throughout generations and generations.
How natural selection leads to evolution
- Natural Selection increases frequencies of characteristics that make individual better adapted
- Natural Selection decreases the frequencies of other characteristics
- This leads to change within a species
Natural Selection and Galapagos Finches
- Variation in the shape and size of the finch beaks is mostly due to genes with only some effect coming from the environment
- Beak size and diet are closely related
- The small finches are only small in body and beak size on Daphne Major (island)
- When there is no competition for small seeds the small finches are also able to feed on large seeds
Medium sized finches fed more as better adapted beaks for larger seeds
- When a population produces more offspring than the carrying capacity, individuals compete for resources such as food and shelter.
- The variation between the individuals (from independent assortment and crossing over) makes some more successful in this struggle for survival.
- The more successful ones are more likely to reproduce, passing on these genes.
- After one generation, there will be slightly more advantageous genetic traits than the others.
- This situation repeats and after many generations these traits become common.
- As this process continues, other traits might dissapear from the gene pool of the population, and all individuals might be the kind that is more successful.
- This is the "cumulative change in the heritable characteristics of a population" or evolution.
Drafted by Venetia (Biology)