Evolutionary theory

Evolutionary theory explains how inherited variation, differential reproduction, and other processes change populations over generations and produce biological diversity.

Natural selection: The process by which heritable traits that improve reproductive success become more common in a population. It explains adaptation when inherited differences affect survival or reproduction.
Allele: One of two or more alternative forms of a genetic sequence at a particular locus. Changes in allele frequencies are a standard measure of evolution within populations.
Jean-Baptiste Lamarck: A French naturalist who proposed an early systematic theory of species transformation in the early nineteenth century. His account of acquired characteristics contrasts with later explanations based on inherited variation.
Creationism: The belief that the universe or living things originated through divine creation, often rejecting evolutionary explanations. It offers a non-evolutionary account of life's origins and diversity.
Common descent: The proposition that organisms share ancestors through branching lines of descent. It explains why similarities among organisms often reflect shared ancestry.
Genetic drift: Random changes in allele frequencies, especially influential in small populations. It changes populations without favoring traits for their effects on fitness.
Heritability: The proportion of variation in a trait, within a population and environment, associated with genetic variation. Evolution by selection requires trait differences to be transmitted across generations.
Charles Darwin: An English naturalist who developed the theory of evolution by natural selection. His work supplied a powerful mechanism for explaining adaptation and common descent.
Intelligent design: The claim that certain features of life are best explained by an intelligent cause rather than unguided natural processes. It disputes whether evolutionary mechanisms can explain biological complexity without design.
Speciation: The formation of new species through the evolution of reproductive isolation between populations. It explains how evolutionary change can produce distinct, diverging lineages.

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