In the context of evolution In biology, evolution is change in the genetic material of a population of organisms through successive generations. Although the changes produced in a single generation are normally small, the accumulation of these differences over time can cause substantial changes in a population, a process that can result in the emergence of new species, certain traits or alleles An allele (pronounced /ˈæliːl/ , /əˈliːl/ (US); from the Greek αλληλος allelos, meaning each other) is one of a series of different forms of a gene. The word is a short form of allelomorph ('other form'), which was used in the early days of genetics to describe variant forms of a gene detected as different phenotypes. Alleles are now of a species There are many definitions of what kind of unit a species is . A common definition is that of a group of organisms capable of interbreeding and producing fertile offspring of both genders, and separated from other such groups with which interbreeding does not (normally) happen. Other definitions may focus on similarity of DNA or morphology. Some may be subject to selection. Under selection, individuals with advantageous or "adaptive" Adaptation is the process whereby a population becomes better suited to its habitat. This process takes place over many generations, and is one of the basic phenomena of biology traits tend to be more successful than their peers reproductively—meaning they contribute more offspring to the succeeding generation than others do. When these traits have a genetic basis, selection can increase the prevalence of those traits, because offspring will inherit Genetics , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the process of those traits from their parents. When selection is intense and persistent, adaptive traits become universal to the population or species, which may then be said to have evolved.
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