* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Genetic Variation
Genetic code wikipedia , lookup
Genome evolution wikipedia , lookup
Biology and consumer behaviour wikipedia , lookup
Dual inheritance theory wikipedia , lookup
Group selection wikipedia , lookup
Medical genetics wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Gene expression programming wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Genetic testing wikipedia , lookup
Dominance (genetics) wikipedia , lookup
Behavioural genetics wikipedia , lookup
Public health genomics wikipedia , lookup
Designer baby wikipedia , lookup
Koinophilia wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genetic engineering wikipedia , lookup
Genome (book) wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Heritability of IQ wikipedia , lookup
Genetic drift wikipedia , lookup
Human genetic variation wikipedia , lookup
Genetic Variation KEY CONCEPT A population shares a common gene pool. Genetic variation in a population increases the chance that some individuals will survive. • Genetic variation leads to phenotypic variation. • Phenotypic variation is necessary for natural selection. • Genetic variation is stored in a population’s gene pool. – made up of all alleles in a population – allele combinations form when organisms have offspring • Allele frequencies measure genetic variation. – measures how common allele is in population – can be calculated for each allele in gene pool Genetic variation comes from several sources. • Mutation is a random change in the DNA of a gene. – can form new allele – can be passed on to offspring if in reproductive cells • Recombination forms new combinations of alleles. – usually occurs during meiosis – parents’ alleles arranged in new ways in gametes Genetic variation comes from several sources. • Hybridization is the crossing of two different species. – occurs when individuals can’t find mate of own species – topic of current scientific research Genetic Variation • Provide material for natural selection • Brought about by mutation • Provides genetic diversity – Allows a species to adapt a new niche in its environment • Leads to natural selection Phenotype Phenotype • The observable characteristic of an organism such as coat color, eye color or size. • Can be caused by genes, environmental factors, or a combination of both. Phenotype Variation • Is a fundamental prerequisite for evolution by natural selection. It is the living organism as a whole that contributes (or not) to the next generation, so natural selection affects the genetic structure of a population indirectly via the contribution of phenotypes. Without phenotypic variation, there would be no evolution by natural selection. Phenotype and Natural Selection • Phenotypes provide an outward appearance for natural selections – Example: The peppered moth color variation was naturally selected according to the color of the forest that it lives within. – If the phenotype white is preferred in a light forest then the black moths find it hard to survive to reproduce thus leaving the white moths to reproduce. Phenotype Variation • Environmental factors are things in an organism's surroundings or lifestyle that can influence it in various ways. 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 Phenotype Variation • A lot more is known about the relationship between genes and phenotypes. Let's take the example of hair color. Perhaps there is a gene in rabbits that codes for an enzyme that, in turn, makes a brown-colored pigment in hair follicles. Some rabbits may have genetic differences that cause them to have more or less of this enzyme, or enzyme that works more or less efficiently to produce the pigment. We would expect these rabbits to have different phenotypes, e.g. lighter or darker brown hair, depending on these genetic differences.