The process of an evolving population changing significantly enough so that the production of offspring with the original population becomes impossible is called speciation. (Pearson)
The theory of punctuated equilibrium was a theory that originated in the late 20th century, which stated that speciation, happens quickly, often in response to an environmental change, like a volcanic eruption, a meteorite impact, or a major climate change. In response, some species are destroyed and others adapt to their new surroundings, exploiting the niches made available by the extinction of competing species. (Pearson)
This process is also called cladogenesis. (Dictionary.com)
The frequency of cladogenesis is very low i.e. once every 500,000 years.
Examples:
The theory of punctuate equilibrium is stated as the reason for the extinction of the dinosaurs. Environmental changes such as asteroid collisions and Deccan traps are believed to have brought about the extinction of dinosaurs in a matter of hours. This demonstrates the rapid nature of cladogenesis. (University of Antwerp)
Critics of punctuated equilibrium argue that the ‘jumpy’ effect of this theory could simply be an artefact of the incompleteness of the fossil record. Discontinuities in the fossil lineages are a challenge for scientists to explain. (Pearson)
Works Cited
Dictionary.com. cladogenesis. 28 3 2015 <http://dictionary.reference.com/browse/cladogenesis>.
University of Antwerp. "Survival in the first hours of the Cenozoic." 28 3 2015 <http://uahost.uantwerpen.be/funmorph/raoul/macroevolutie/Robertson2004.pdf>.
Speciation is the formation of new and distinct species in the course of evolution. (Biology-Online)
The reason for abrupt speciation
(1) the sensitive ecological balance between an animal population and its food source;
(2) the ability for a new species to appear suddenly as a result of a gradual accumulation of advantageous recessive genes. (Stagecast.com)
Quantum speciation: This is sudden emergence of new groups by saltation. This speciation is much more rapid and sudden, and produces new species or higher groups. In small, scattered populations or populations that have migrated to new area, genetic drift, rather than natural selection plays an important role in quickly changing the species. Sometimes chance events or mega mutations aid in quick speciation. Disruptive natural selection then makes the species distinct and diverse. (iaszoology.com)
Articles showing that speciation can occur abruptly:
Works Cited
"Speciation | IASzoology.com." IASzoologycom RSS. N.p., n.d. Web. 02 Apr. 2015.
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