Science Notes For Revision EVOLUTION.docx

Science Notes For Revision "EVOLUTION" - Biodiversity (biological diversity) is defined as the number and variety of genes, species, or ecosystems. - Species diversity is the number of different species within an ecosystem. - Genetic diversity is the range of variation in the genes...

Science Notes For Revision "EVOLUTION" - Biodiversity (biological diversity) is defined as the number and variety of genes, species, or ecosystems. - Species diversity is the number of different species within an ecosystem. - Genetic diversity is the range of variation in the genes within a species. - Evolution is the change in the characteristics (physical traits and appearances) of a species over long periods of time and over several generations. THEORY OF EVOLUTION: - The idea behind evolution is that every living thing on the planet originated from a common ancestor. Causes of Genetic Variation - Genetic variation: mutations within genes that are passed on through generations - Environmental variation: acquired characteristics which are selected for in response to the environment **[MUTATIONS-]** random alterations in genes produce new gene options and new phenotype outcomes - Mutation can occur in all organisms and is the source of new genetic variation. - A change in the genetic code in DNA can lead to a change in the production of the protein that is coded for and produced by that section of DNA. - This can drastically change an organism's characteristics. Gene pool of a population consists of all the copies of all the genes in that population. Allele frequency refers to how common an allele is in a population BOTTLENECK EFFECT FOUNDER EFFECT  Genetic variation is important as it can code for an individuals phenotype, some of which may better suit that organism to a particular environment than others, giving it an increased chance of survival. If it survives it has an increased chance of reproducing and passing that advantageous gene onto its offspring -- which increases overall species survival. NATURAL SELECTION AND SPECIATION - - According to Darwin, the driving force behind evolution is NATURAL SELECTION -