Adaptations

This led him to the idea of natural selection. Natural selection is “the survival of the fittest.” Organisms that are better suited to their environment will survive and reproduce.

Natural selection rests on three indisputable facts: Organisms produce more offspring than can survive.

2. Individuals vary in their characteristics. Which mice would be better suited to a dark environment?

Many characteristics are inherited by offspring from their parents. If a black mouse and a white mouse breed…

It follows logically that … • Some individuals will be better suited to their environment - they will survive and reproduce more successfully than individuals without those characteristics. • Future generations will thus contain more genes from better-suited individuals. • As a result, characteristics will evolve over time to resemble those of the better-suited ancestors.

What gets natural selection started? Occasionally, members of a population acquire a genetic mutation that changes the organism’s phenotype. Sometimes the mutation is bad…

But sometimes the mutation is advantageous…. Some bacteria acquire a genetic mutation that makes them resistant to antibiotics. Some antibiotics cannot kill these bacteria, so they live and reproduce.

If the mutation is advantageous then the organisms with the mutation will survive and reproduce more. The organisms without the mutation will die faster, and eventually more of the organisms with the mutation will be left.

These mutations are not a choice of the organism, but rather a random genetic event.

Darwin knew about artificial selection, which is the intentional selection of certain traits (i.e. purebred dogs). He figured that the same types of processes must happen in nature. Wild mustard & domestic cruciform vegetables Domestic dogs Wild canids