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In many small populations completely random fluctuations in the frequencies of certain alleles or gene combinations may occur, even under constant environmental conditions. These fluctuations constitute genetic drift or Sewall Wright effect. The potential role of drift in microevolution is considerable. Dunker religious community in Pennsylvania (U.S.A.) comprises a small population. The gene frequencies at [...]

1. What are the propositions of Darwin’s theory? Ans. According to the book “Origin of Species by means of Natural Selection” (1859) the Propositions of Darwin concept may be summarized as follows: a) Hypothesis: i) Prodigality of Production. ii) Resources are constant. Deductions: Struggle for existence. b) Hypothesis: i) Struggle for existence. ii) Universal occurrence [...]