Question

Briefly describe Sewall-Wright effect.

Answer 1

The theory concerned with the gene frequency of a reproducing small population called genetic drift or Sewall Wright effect was developed by Sewall Wright in 1930. All representative alleles may not be formed in a small population. Violation of Hardy-Weinberg's law has great influence on heredity. The frequency of character increases found in a small population has little adaptive value. So genetic drift may remain a significant factor to create the origin of new species on islands and other isolated populations.The reduction of low frequency on losing alleles, quantity of genetic variations occurs in small populations. Continual mating within such populations may cause a decrease in the proportions of heterozygotes and increase in the number of homozygotes. The small population develops characters different from that formed in the main population. Such deviations may lead to speciation or formation of a new species. When a small grouped individuals due to genetic drift become founders of a new population it is called as founder principle. The new population often has genotype frequencies different from the parent population. Due to the occurrence of genotypic frequencies of changes interbreeding in a small and large population may not be possible.