BISC 300 Lecture Notes - Lecture 4: Effective Population Size, Genetic Drift, Four Causes
24 Jun 2020
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The four causes of organic evolution: mutation: fuel of evolution, random, migration: quick way to get fuel, drift: powerful retarding force, random, selection: only known cause of design. Mutation is random in terms of need (doesn"t care if mutated genes help population or not) Random process that results in a change in allele frequency. Not adaptive, and not the result of selection. Violates hwe, because populations are finite (and drift is much stronger in small populations) Sampling error: random discrepancy between theoretical and actual results. Drift = random sampling error in the production of zygotes from a gene pool: each new generation may inherit more of the same genes than another (random) or certain species survive longer. Causes of drift: continuous (background) drift, occurs naturally in genotypes, founder effect, population bottle necks. Continuous population fluctuations: historical lynx population cycles in canada. Drift in alleles: increase population = increase alleles, decrease population = decrease alleles.
