Speciation is the method of formation of new species. A species can be defined as one or more populations of interbreeding organisms that are reproductively isolated in nature from all other organisms. As natural selection adapts populations occupying different environments, they will diverge into races, subspecies, and finally separate species. When populations no longer interbreed, they are thought to be [...]
Organisms are equipped in a number of ways to cope with their environment. The adjustments made by the individuals in response to the specific environmental conditions are known as adaptations. Adaptations are structural or physiological characteristics that allow an organism to exist under the conditions imposed by its habitat. All organisms have adaptations that help them survive and thrive. Some [...]
The theory of organic evolution seems to be the most acceptable explanation of the occurrence of varied forms of plants and animals on Earth. Evolution, which started out as a hypothesis, is now supported by evidence from many fields of science. The various convincing evidences for the occurrence of descent with modification is summarised in the Fig. 15. 1. Evidence [...]