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This chapter explores the fundamental principles of population genetics, focusing on the concept of gene pools and genetic variation. It discusses the mechanisms of genetic variation, including random fusion of gametes, segregation during meiosis, and mutations. The chapter also highlights mass selection, hybridization, and inbreeding as methods to influence genetic traits. Furthermore, it examines the Hardy-Weinberg Principle and the conditions necessary for genetic equilibrium, addressing factors like nonrandom mating, genetic drift, migration, and mutation. Finally, it touches on the implications of these genetic changes for evolutionary theory and the ethical considerations surrounding eugenics.
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Population • A group of individuals of the same species that lives in the same area • Gene pool • All alleles that all members of a species can possess
Genetic Variation • Variations are differences in the genotypes among individuals in the same gene pool. • Variations can occur in three ways.
Genetic Variation • Random fusion of two gametes • Segregation and exchange of information during meiosis • Mutations
Mass Selection • The selection of desirable breeding stock from the entire population • Used to breed for desirable traits
Hybridization • The crossbreeding of two genetically unrelated individuals • Offspring is called a hybrid. • Heterosis or hybrid vigor • When offspring have superior characteristics to the parents
Inbreeding • The mating of an organism with itself or a close relative • Can be used to produce pure strains • Organisms that are homozygous for certain traits
Hardy-Weinberg Principle The frequency of alleles and the ratio of heterozygous to homozygous individuals remains constant unless the population is affected by outside factors.
Genetic equilibrium • Condition in which allele frequencies within a population do not change • Allele frequency • The number of times an allele occurs in a gene pool compared to the number of times other alleles occur
Hardy-Weinberg Principle Five factors must be met for genetic equilibrium to exist.
Hardy-Weinberg Principle • Random mating • Large population • No movement into or out of the population • No mutations • Equal chances of surviving and reproducing
Nonrandom Mating • Most species do not mate randomly. • Geographic barriers • Selecting of mates • Inbreeding
Small Population • When there is a change in a small population, the results are amplified. • Genetic drift
Migration • Most populations have individuals moving into or out of the population. • This means that there is genetic information coming into and going out of the population (gene flow).
Mutation • This is the only method whereby new alleles can be produced.
Selection • Not all of the members of a population will reproduce. • This may cause some of the alleles in the gene pool to be lost.
Genetic change = evolution • Population changes never create new kinds of organisms. • They only involve either the rearrangement of already existing alleles or the loss of genetic information. • Therefore, they are not valid support for evolution.
Eugenics • “Good origins” • Efforts to improve the human gene pool • Genetic screening
Eugenics • A Christian Consideration • Sanctity of human life • Dominion mandate • Salvation through Christ alone
