Common descent

Common descent is the principle that different organisms trace their lineages to shared ancestral populations. It explains the nested similarities among species through branching inheritance over generations.

Phylogenetics: The study of evolutionary relationships among organisms using branching models of lineage history. Phylogenetic trees represent the branching relationships implied by common descent.
Genetic inheritance: The transmission of genetic information from organisms to their offspring. Inheritance carries ancestral DNA into descendant generations.
Tiktaalik: An extinct lobe-finned fish from the Devonian period with features associated with early tetrapods. Its anatomy documents a transitional stage within the ancestry of limbed vertebrates.
Independent origin of life: The hypothesis that life began separately in more than one lineage or location. Multiple origins differ from the single shared ancestry inferred for known living organisms.
Evolutionary taxonomy: The classification of organisms using their evolutionary relationships and patterns of descent. Classification groups species in ways that reflect inferred shared ancestors.
Homology (biology): Similarity between biological features due to inheritance from a shared ancestor. Homologous traits provide evidence that species inherited features from common ancestors.
Mutation: A heritable change in the nucleotide sequence of genetic material. Mutations create differences that accumulate among descendant lineages.
Archaeopteryx: A Jurassic fossil animal combining feathers and wings with skeletal features of non-avian dinosaurs. Its mix of traits fits the shared ancestry of birds and other theropod dinosaurs.
Special creation: The belief that distinct forms of life were created separately by supernatural agency. Separate creation rejects descent from shared ancestral populations as the source of species.
Tree of life: A model of the evolutionary relationships connecting Earth's organisms across deep time. It extends common descent into a comprehensive picture of life's history.

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