Mechanisms of Evolution

• Evolution is also about the change in genetic frequency in a population.
• Allele frequency represents the incidence of a gene variant in a population.
• Population is defined as a group of individuals of the same species living and interbreeding within the given area.
• Genotype pertains to the genetic make up of an organisms.
• Phenotype is the observable characteristics or traits of an organisms.
• Mechanisms of change is any heritable trait that is influenced by the genes.
• Mechanisms of change should possess variations.
• 1st mechanism (mutation)
• Mutation is defined as any change or alteration occurs during the process of dna replication.
• Beneficial mutation increase the survivability and genetic variation.
• Harmful mutation decrease the survivability and genetic variation.
• 2nd mechanism (gene flow)
• Gene flow is the result of migrating individuals that breed in a new location.
• Immigration is the movement of individuals into a population.
• Emigration is the movement of individuals out of the population.
• 3rc mechanism (genetic drift)
• Genetic drift is any change in the allele frequencies in a population.
• Genetic drift may happen to all populations.
• Founder event occurs when a small group of individuals is separated from the rest of the populations.
• Bottleneck effect occurs when most of the population is destroyed.
• 4th mechanism (natural selection)
• Natural selection is when the environment changes natural selection favors different traits in a species.
• The peppered moth is a case forwarded by the biologist J.B.S. Haldane in 1924.
• Pale moths were dominant in the Manchester (early 18th century).
• Melanic moths were better in avoiding predation.
• Variation is genetic variation within a population which can be inherited.
• Overproducing of offspring that leads to competition for survival.
• Individuals with beneficials adaptations are most likely to survive to pass on their genes.
• Selection is when over many generations there is a change in the allele frequency.
• Stabilizing selection is wherein the intermediate character will favor to the selective pressure from the environment.
• Directional selection is wherein the species on one extreme end will survive.
• Disruptive selection is wherein the selective pressure favors two both extreme ends.
• Artificial selection sort of controlled by human purpose rather than natural forces.
• Animal breeding is shifting the frequency of alleles in various breeds.
• Microevolution is the frequency of alleles in the population has changed but not great enough to produce an actual species.
• Hardy - Weinberg Equilibrium states that a certain population has a constant genetic stability.
• Homozygous dominant (GG) = p^2
• Heterozygous (Gg) = 2pq
• Homozygous Recessive (gg) = q^2
• Hardy - Weinberg Principle = p^2 + 2pq + q^2 = 1