Evolution through natural selection
Evolution is a change in the inherited characteristics of a population over time through the process of natural selection, which may result in the formation of new species.
Natural selection
The natural process whereby the best-adapted individuals survive longer, have more offspring and thereby spread their characteristics. Sometimes referred to as 'survival of the fittest'. is a process where organisms that are better adapted to an environment will survive and reproduce. This means that the advantageous Different forms of the same gene. of this variant organism are passed on to offspring. Over many generations, the process of natural selection leads to The process of change in the inherited traits of a population of organisms from one generation to the next. occurring.
Charles Darwin was a famous English naturalist. During his life he came up with the theory of natural selection and how this drives The process of change in the inherited traits of a population of organisms from one generation to the next. of new species.
Darwin is associated with the term 'survival of the fittest', which describes how natural selection works. Individual organisms in an environment are 鈥榮elected for鈥. This means that only the organisms that have the best characteristics for that particular environment will survive. If they survive then they are the 鈥榝ittest鈥 for this environment, they reproduce and pass on the advantageous characteristics to their offspring.
Natural selection: peppered moths example
Before the industrial revolution in Britain, in the early 1800s, most peppered moths were of the pale variety. This meant that they were An ability to blend in with a background. against the pale birch trees that they rest on. Moths with a mutant black colouring were easily spotted and eaten by birds. This gave the white variety an advantage, and they were more likely to survive to reproduce.
During the last half of the 1800s, airborne pollution in industrial areas blackened the birch tree bark with soot. This meant that the mutant black moths were now camouflaged, while the white variety became more vulnerable to predators. This gave the black variety an advantage, and they were more likely to survive and reproduce. The dark moths passed on the Different forms of the same gene. for black wing colour leading to offspring with the black wing colour The visible characteristics of an organism which occur as a result of its genes.. Over time, the black peppered moths became far more common in urban areas than the pale variety.
Note that this change in phenotype was not due to pollution making the moths darker. The dark variety had always existed, but was the best suited variant when the environment changed. It took many generations before the population of moths was mainly black in colour.