Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in heritable traits of a population over time. The term "natural selection" was popularised by Charles Darwin who compared it with artificial selection, now more commonly referred to as selective breeding.
The endothermic process is any process which requires or absorbs energy from its surroundings, usually in the form of heat. It may be a chemical process, such as dissolving ammonium nitrate in water, or simply the melting of ice cubes.