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However, the punctuational equilibrium model may still be inferred from both the observation of stasis and examples of rapid and episodic speciation events documented in the fossil record. [70] Dawkins also emphasizes that punctuated equilibrium has been "oversold by some journalists", [71] but partly due to Eldredge and Gould's "later writings ...
Parapatric speciation is modelled on continuous variation within a "single", connected habitat acting as a source of natural selection rather than the effects of isolation of habitats produced in peripatric and allopatric speciation. [33] Parapatric speciation may be associated with differential landscape-dependent selection.
The Bak–Sneppen model is a simple model of co-evolution between interacting species. It was developed to show how self-organized criticality may explain key features of the fossil record, such as the distribution of sizes of extinction events and the phenomenon of punctuated equilibrium .
Gould's most significant contribution to evolutionary biology was the theory of punctuated equilibrium [2] developed with Niles Eldredge in 1972. [3] The theory proposes that most evolution is characterized by long periods of evolutionary stability, infrequently punctuated by swift periods of branching speciation.
Additionally, scientists research the 'tempo' of speciation, i.e. the rate at which species change genetically and/or morphologically. Classically, competing hypothesis for the tempo of specieation include phyletic gradualism and punctuated equilibrium). Lastly, what are the causes of speciation is also extensively researched. [1]
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]
The first is that cells of opposite mating type are present together in the same ascus, the sac that contains the cells directly produced by a single meiosis, and these cells can mate with each other. The second reason is that haploid cells of one mating type, upon cell division, often produce cells of the opposite mating type with which they ...
Two useful introductions to the fundamental theory underlying the unit of selection issue and debate, which also present examples of multi-level selection from the entire range of the biological hierarchy (typically with entities at level N-1 competing for increased representation, i.e., higher frequency, at the immediately higher level N, e.g., organisms in populations or cell lineages in ...