The allele frequency is the proportion of organisms within the population carrying a particular allele. Last updated: 14/11/2019 . Genetic diversity and adaptation. Please enable JavaScript. gene. Stabilising selection occurs in the natural selection of birth mass in humans. Topic: 3.4.4 Genetic diversity and adaptation; Exam questions taken from old spec a level biology and human biology past papers; Could be used as an activity in class, given as homework, used as an end of topic test, or for revision show understanding that adaptation and selection are major Random mutation can result in new alleles of a About Us | Contact Us | Privacy Policy | Terms and Conditions | Sitemap, GCSE, IGCSE, A-Level, and IB Biology Resources & Revision for all exam boards, Unit 2: Body Systems, Genetics, Microorganisms and Health, Unit 1: Cells, Living Processes and Biodiversity, Biology 1: Adaptation, Evolution and Body Maintenance, Biology 2: Cells and Metabolism, Digestion and Respiration, Biodiversity, 1. increases in frequency in the population. in producing change within populations. behavioural. Directional selection, exemplified by antibiotic © AQA 2020, This website uses cookies to improve your experience. 3.4 Genetic information, variation and relationships between organisms; 3.5 Energy transfers in and between organisms (A-level only) 3.6 Organisms respond to changes in their internal and external environments (A-level only) 3.7 Genetics, populations, evolution and ecosystems (A-level only) 3.8 The control of gene expression (A-level only) Back to Course . of genes in a population. Therefore it should be considered at a population level. 3.4.4 Genetic diversity and adaptation. Characteristics and Classification of Living Organisms, 20. Natural selection. factors in evolution and contribute to the diversity of living Genetic diversity is the number of different alleles in a population. The thin blue line shows the distribution of mass at birth of children born in University College Hospital over a 12-year period. Next Lesson. Genetic diversity allows natural selection to occur. possessor, leading to increased reproductive success. A Level Biology - Stabilizing, directional and disruptive selection. Lesson Content . The advantageous allele is inherited by members of selection to occur. environments, the new allele of a gene might benefit its human birth weights. Please either accept the cookies, or, Specifications for first teaching in 2015, 3.3 Organisms exchange substances with their environment, 3.4 Genetic information, variation and relationships between organisms, 3.5 Energy transfers in and between organisms (A-level only), 3.6 Organisms respond to changes in their internal and external environments (A-level only), 3.7 Genetics, populations, evolution and ecosystems (A-level only), 3.8 The control of gene expression (A-level only), Mathematical requirements and exemplifications. Evolution is a change in a populations’ alleles and genotypes from generations to generations. As a result, over many generations, the new allele Course Navigation. Biotechnology and Genetic Engineering, Section 1: The Nature and Variety of Living Organisms, Section 2: Structures and Functions in Living Organisms, Module 1: Development of Practical Skills in Biology, Module 4: Biodiversity, Evolution and Disease, Module 5: Communication, Homeostasis and Energy, Module 6: Genetics, Evolution and Ecosystems, 3.3 Organisms exchange substances with their environment, 3.4 Genetic information, variation and relationships between organisms, 3.5 Energy transfers in and between organisms, 3.6 Organisms respond to changes in their internal and external environments, 3.7 Genetics, populations, evolution and ecosystems, Topic 4: Biodiversity and Natural Resources, Topic 6: Immunity, Infection and Forensics, Topic 8: Metabolism, Cell Respiration and Photosynthesis, B1.6 Waste materials from plants and animals, TOPICS: DNA, genes and chromosomes  Genetic diversity can arise as a result of mutation or meiosis  Genetic diversity and adaptation  Species and taxonomy  Biodiversity within a community  Investigating diversity. Genetic diversity is a factor enabling natural Extremes of the phenotype range are selected leading to a reduction in variation. AQA A level Biology Stabilising selection happens in an changing environment. organisms. ‘O’ shows the optimal mass that had the lowest prenatal mortality. AQA AS-Level Biology Genetic diversity and adaptation. ‘M’ is the mean birth mass. use unfamiliar information to explain how selection environment. of populations. the next generation. Genetic diversity as the number of different alleles Natural selection results in species that are better adapted to their Genetic information, variation and relationships between organisms (AQA AS Biology) PART 3 of 6 TOPICS. The principles of natural selection in the evolution As the number of alleles increases so does genetic diversity in a population. Five factors affect the proportion of homozygote and heterozygote: Directional selection happens in bacteria for example, where the bacteria are resistant to antibiotics leading to an increase in the frequency of the allele that is resistant to antibiotics.