BIOL 1001 Reading 3.docx

O gene flow can also increase genetic diversity o

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o Gene flow can also increase genetic diversity o Important for humans as immigration occurs to Western countries, intermarrying amongst the same race is occurring, reducing genetic diversity Mutations – result due to changes in DNA codon sequencing or non-disjunction of meiosis o Increases genetic diversity o Mutations are random, they do not purposefully benefit nor inhibit fitness o Most organisms are well adapted to their environment, thus mutations likely decrease their fitness o Alleles that lower fitness are known as deleterious alleles but are usually eliminated by purifying selection o Beneficial alleles are generally rare o Mutation is not a significant evolutionary mechanism because its occurrence in humans is very low and is a slow mechanism Take away from Lenksi’s experiment o Mutations are the ultimate source of genetic variation o Evolution would eventually stop had mutations not have occurred o Mutations alone do not really have a large impact of changing allele frequencies at a particular gene Process of Evolution – How does it Work? Darwin’s Four Postualtes o Individual organisms that make up a population vary in traits they possess o Some trait differences are heritable o Many more offspring are produced than can survive o Fitness of an individual within a population is not random, rather they have heritable traits that allow them to survive Mutant TB bacteria o Rifampin was an antibiotic that binded to RNA polymerase of TB bacteria, preventing transcription and killing the bacteria o
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