Partie 2
Storyboard Text
- First, mutation…mutation is like a random change in your DNA (like a bookshelf where you store every information of your body, that gives you an appearance) which can be either good or bad. For example when your parents bake a cake, they add ingredients like yeast, if they forget it that changes the physical appearance of the cake. When you put up with a germinal mutation that means a change in the reproductive cells (the little seed from the mother that comes across a little tadpole and that grows as a baby) it can be transmitted to children. In the other case you have a somatic mutation (the other cells than germinal) and you can't give it to your children.
- Following that, another kind of change and mutation can happen. Its name is natural selection, because the fact is that the change is due to the environment in which species evolve. This is the place of living that chooses some traits for the individuals, so that they can have advantages for surviving. For example the giraffe, his neck was not that big at first. But to survive she needed to eat some leaves from the trees, as a result she required to have a certain high . That’s why her neck has been stretched out. Over the time, this modification has been spread in the lineage. It is a key mechanism of evolution.
- Children, attention please! Another circumstance of evolution is genetic drift. Genetic drift is a process by which allele frequency (that is a gene developed so that we either look in a way or another, it is our characteristics) change in populations due to random and accidental events in the transmission of alleles from one generation to the next one. Sometimes, one characteristic or allele can get the upper hand on the other, as a result we can see differences in the same species over decades. However, this kind of change may provide no survival advantages. This phenomenon mostly happens in small and isolated populations. As an example we can use mice, a white and a gray one. By sheer chance, the characteristic of being gray can become more important in the DNA. Which means that if a gray and a white mouse have children the little mouse will be gray. But if two white mice have a child, it will be white. That means that after a while, only gray mice will remain.
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