International Journal of Botany Studies


International Journal of Botany Studies


International Journal of Botany Studies
International Journal of Botany Studies
Vol. 4, Issue 2 (2019)

Punctuated equilibrium theory, shifting balance theory, allopatric speciation theory and species selection theory for macroevolution valid or not


Md. Abdul Ahad

Genetic drift represents the punctuated equilibrium theory, the shifting balance theory, the allopatric speciation theory, the species selection theory and work in small isolated populations. Those theories advocated that all plants and animals man arose through macroevolution. However, genetic drift and small isolated populations are the key factors of those theories. But genetic drift loses/changes the gene frequency randomly, which are very harmful to any organism and thus could not produce any new species. Again, drift unfits to create any variation (raw material of evolution). Again, small isolated populations and produce homozygous organisms. Those organisms have low fecundity, suffer from various disease, least fitted to survive and may extinct suddenly, e.g. American heath hen. Thus, any kind of evolution is quite impossible through those theories. Therefore, biologists rejected the genetic drift, shifting balance theory (a condition to declare invalid of those theories) and also the punctuated equilibrium theory as the theory of evolution. Again, the fossil is the only evidence of those theories but fossil opposes macroevolution (another condition to declare invalid of those theories) but support the gradual evolution. Moreover, evolution is reasonably absurd by the extinction of living organism. Consequently, those theories are invalid and no one plant and animal including human arose through those theories. Hence, Darwinists, Neo-Darwinists and Sociobiology’s oppose those theories.
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