The steps of natural selection
|Automatic translation||Updated June 01, 2013|
Natural selection is the process that leads to the appearance of species.
In 1798, Thomas Malthus note that living species tend to have exponential growth, so that resources can grow together. It concludes that a demographic catastrophe is inevitable.
Image: living species tend to have an exponential growth when resources can not grow at the same rate.
A drawback becomes an advantage
The peppered moth is a moth that occurs in two forms, a light colored morph said typica and the other dark or melanic carbonaria said.
Regarding the black butterflies, the disadvantage of color had become a major advantage in this new environment.
Image: the peppered moth (Biston betularia L.) is an insect of the order Lepidoptera, family Geometridae. Here, two butterflies and dark colored. Butterflies are clear easy prey for birds. Credit: David Fox / Oxford Scientific Films and The work of the group of B. Kettlewell.
Between Lamarck and Darwin
The concept of evolution of species was proposed by Jean-Baptiste Lamarck in 1809.
These theories were taken independently, some fifty years later by the British Charles Darwin and Alfred Russel Wallace. Darwin, during a scientific expedition to South America and the Galapagos Islands, had noticed that some species of the mainland and islands were very similar between them. By comparing species that sketched for the book that made him famous, "On the origin of species through natural selection." He put that in a group of animals belonging to the same species, individuals vary in their anatomical and physiological characteristics. Thus, young people are never completely identical to the parents, nor identical. This "variability native" is different from "acquired variability," in which the medium is gradually transforming the animal until such time that the species is adapted to their new living conditions.
|NB: Jean Baptiste Lamarck 1809, publishing philosophy zoologist, he proposed transmutation. He defends the idea of inheritance of acquired characteristics from one generation to another. This is the first evolutionary theory to be formulated.|
NB: Charles Darwin's 1859 publication of "On the Origin of Species." Darwin proposed a scientific theory of evolution based on the principle of natural selection. It is the first to state the fact that the human race is also the result of a change due to natural selection. He did not believe in saltation. In biology, saltation is a sudden change from one generation to the next, that is large, or very large, in comparison with the usual variation of an organism.