{"id":9566,"date":"2026-06-01T21:33:48","date_gmt":"2026-06-01T21:33:48","guid":{"rendered":"https:\/\/kapdec.com\/help\/?p=9566"},"modified":"2026-06-01T21:33:48","modified_gmt":"2026-06-01T21:33:48","slug":"variations-in-populations","status":"publish","type":"post","link":"https:\/\/kapdec.com\/help\/variations-in-populations\/","title":{"rendered":"Variations In Populations"},"content":{"rendered":"

Unit : Natural selection<\/strong><\/h2>\n

Chapter: Variations in populations<\/strong><\/h3>\n

Reference:<\/em><\/strong> Variations, Cause of Genetic variation, Adaptations due to variations, Phenotypic variation, Cause of Phenotypic Variation, Genetic diversity, and its importance<\/em><\/p>\n

Learning objectives<\/strong><\/p>\n

    \n
  • To understand the factors responsible for variations in population<\/li>\n<\/ul>\n

    Variations<\/strong><\/p>\n

    Genotypic variations are caused by differences in number or structure of chromosomes or by differences in the genes carried by the chromosomes. Eye colour, body form, and disease resistance are genotypic variations<\/p>\n

    Genetic variation is caused by:<\/strong><\/p>\n

      \n
    • mutation<\/li>\n
    • random mating between organisms<\/li>\n
    • random fertilization<\/li>\n
    • crossing over (or recombination) between chromatids of homologous chromosomes during meiosis<\/li>\n<\/ul>\n

      Adaptations due to variations<\/strong><\/p>\n

        \n
      • Scientists describe groups of organisms adapting to their environment when a genetic variation occurs over time that increases or maintains the population’s “fit” to its environment.<\/li>\n
      •  A platypus’s webbed feet are an adaptation for swimming. A snow leopard’s thick fur is an adaptation for living in the cold.<\/li>\n
      • A cheetah’s fast speed is an adaptation for catching prey.<\/li>\n<\/ul>\n

        Phenotypic variation,<\/strong> then, is the variability in phenotypes that exists in a population. For example, people come in all shapes and sizes: height, weight, and body shape are phenotypes that vary. Hair, eye colour, and the ability to roll your tongue are variable phenotypes, too.<\/p>\n

        Cause of Phenotypic Variation<\/strong><\/p>\n

          \n
        • Phenotypes can be caused by genes, environmental factors, or both.<\/li>\n
        • When we say environmental factors, we are not necessarily talking about the trees and the climate: environmental factors are things in an organism's surroundings or lifestyle that can influence it in various ways.<\/li>\n
        • For example, body weight in humans may be influenced by genes but is also influenced by diet. In this case, diet is an example of an environmental factor.<\/li>\n
        • A lot more is known about the relationship between genes and phenotypes.<\/li>\n
        • Let us take the example of hair colour. Perhaps there is a gene in rabbits that codes for an enzyme that, in turn, makes a brown-coloured pigment in hair follicles.<\/li>\n
        • Some rabbits may have genetic differences that cause them to have more or less of this enzyme, or an enzyme that works efficiently to produce the pigment.<\/li>\n
        • We would expect these rabbits to have different phenotypes, e.g., lighter, or darker brown hair, depending on these genetic differences.<\/li>\n
        • Let us take one more example, this time in bacteria. Some bacteria may have a gene that codes for an enzyme that breaks down an antibiotic into a substance that is not harmful anymore.<\/li>\n
        • If you treat these bacteria with the antibiotic, they will survive: this phenotype is called antibiotic resistance. In contrast, bacteria without that gene will be susceptible to the antibiotic.<\/li>\n<\/ul>\n

          Genetic diversity and its importance<\/strong><\/p>\n

          All the biological data and variation that makes life on our planet work is encoded in DNA. This is known as genetic diversity.<\/p>\n

            \n
          • It strengthens the ability of species and populations to resist diseases, pests, changes in climate and other stresses.<\/li>\n<\/ul>\n

            Solved examples<\/strong><\/p>\n

            Example 1. What is the term for a feature that allows an organism to survive better in its environment?<\/p>\n

            a) variation b) adaptation c) homologous structure d) vestigial structure<\/p>\n

            Solution 1:<\/strong> b. A feature that allows an organism to survive better in its environment is called adaptation.<\/p>\n

            Example 2. Crossing similar individuals to keep certain characteristics is known as<\/p>\n

            a) hybridization b) inbreeding c) natural selection d) cloning<\/p>\n

            Solution 2:<\/strong> b. The crossing of similar individuals to keep certain characteristics is known as inbreeding.<\/p>\n

            Summary<\/strong><\/p>\n

              \n
            • Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population.<\/li>\n
            • Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism’s offspring).<\/li>\n
            • Genetic variation is advantageous to a population because it enables some individuals to adapt to the environment while maintaining the survival of the population<\/li>\n<\/ul>\n

               <\/p>\n","protected":false},"excerpt":{"rendered":"

              Unit : Natural selection Chapter: Variations in populations Reference: Variations, Cause of Genetic variation, Adaptations due to variations, Phenotypic variation, Cause of Phenotypic Variation, Genetic diversity, and its importance Learning objectives To understand the factors responsible for variations in population Variations Genotypic variations are caused by differences in number or structure of chromosomes or by […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[629],"tags":[],"class_list":["post-9566","post","type-post","status-publish","format-standard","hentry","category-ap-biology"],"_links":{"self":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/posts\/9566","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/comments?post=9566"}],"version-history":[{"count":0,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/posts\/9566\/revisions"}],"wp:attachment":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/media?parent=9566"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/categories?post=9566"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/tags?post=9566"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}