Networked evolution

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Networked evolution or “reticulate evolution” is a special pattern in the evolution of many biological taxa and groups. An evolutionary line (e.g. a species (biology) ) can arise in the case of networked evolution through hybridization and introgression, horizontal gene transfer and viral transduction or endosymbiosis (see endosymbiont theory ). The relationships between the species or higher taxa thus created cannot therefore be represented as a simple cladogram that always bifurcates . Rather, the relationships correspond to a network of evolutionary lines. An evolutionary line often has several parent species to which it goes back. Species groups with reticulate evolution are taxonomically difficult to grasp, since transitional forms and pronounced geographic variation often occur.

One example is the speciation processes in stony corals . According to JEN Veron , different geographical variations, species and also genera mix again and again in the course of evolution over centuries and millennia. Since the coral larvae live planktonically, they can be displaced to other areas by changing ocean currents and the coral stocks growing from them will then mix with the corals endemic there. There is no genetic cohesion of the species, branches of the family tree can not only branch, but also grow together again. The species currently described by science can mix or branch into a new species in the future. An individual species can only be precisely determined taxonomically at a specific location . Geographical local forms lose their identity with increasing distance.

literature

  • JEN Veron: Corals in Space and Time - The biogeography and evolution of the Scleractinia . UNSW Press, Sydney, ISBN 0-80148-263-1
  • KORALLE 33 , Networked Evolution, marine aquarium specialist magazine, June / July 2005, Natur und Tier Verlag Münster, ISSN  1439-779X