Anagenesis

Anagenesis is the gradual evolution of a species that continues to exist as an interbreeding population. This contrasts with cladogenesis, which occurs when there is branching or splitting, leading to two or more lineages and resulting in separate species.^[1] Anagenesis does not always lead to the formation of a new species from an ancestral species.^[2] When speciation does occur as different lineages branch off and cease to interbreed, a core group may continue to be defined as the original species. The evolution of this group, without extinction or species selection, is anagenesis.^[3]

^ Futuyma, D.J. (2009). Evolution, 2nd Ed. Sunderland, MA: Sinauer Associates
^ Archibald, J.D. (1993). "The importance of phylogenetic analysis for the assessment of species turnover: a case history of Paleocene mammals in North America". Paleobiology. 19 (1): 1–27. Bibcode:1993Pbio...19....1A. doi:10.1017/S0094837300012288. JSTOR 2400768. S2CID 86151240.
^ Futuyma, D.J. (1987). "On the role of species in anagenesis". The American Naturalist. 130 (3): 465–473. doi:10.1086/284724. JSTOR 2461899. S2CID 83546424.

[1] Futuyma, D.J. (2009). Evolution, 2nd Ed. Sunderland, MA: Sinauer Associates

[2] Archibald, J.D. (1993). "The importance of phylogenetic analysis for the assessment of species turnover: a case history of Paleocene mammals in North America". Paleobiology. 19 (1): 1–27. Bibcode:1993Pbio...19....1A. doi:10.1017/S0094837300012288. JSTOR 2400768. S2CID 86151240.

[3] Futuyma, D.J. (1987). "On the role of species in anagenesis". The American Naturalist. 130 (3): 465–473. doi:10.1086/284724. JSTOR 2461899. S2CID 83546424.

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