extended response 1

• evolution: a process that results in cumulative, inheritable changes in a population over many generations
• theory of evolution: all organisms have developed from previous organisms and all living thing have a common ancestor in some initial form of primitive life
• all organisms are fundamentally similar because their basic chemistry was inherited from the very first primitive organism
• theory: a rational form of thinking to explain a phenomenon accepted by many people
• mechanisms that bring about evolution: mutation, natural selection, genetic drift and migration (all of which enable gene flow)
• gene flow: transfer of alleles as a result of migration of individuals between populations
• mutation: permanent change in the DNA sequence of a gene
• a mutation can change one allele into another, overall changing the frequency of an existing allele
• selection pressure = an abiotic or biotic environmental factor that limits the survival and reproduction of individuals
• a mutation can produce an allele that is selected for, selected against or selected neutral
• beneficial mutations will spread through a population over generations, through selection
• if a mutation is beneficial, and selected for by the environment, it is the ultimate source of genetic variation in populations
• new alleles enter a gene pool, changing the frequency of alleles at the time of mutations and after each generation. Therefor, mutation is a mechanism for evolution
• variations in populations are the basis of evolution
• individuals in a populations express a range of phenotypes
• members of a population have variation in their genotype that produces variation in their phenotype
• variation is based on differences in DNA sequences, which gives rise to different alleles, which results in different phenotypes
• evolution relies on genetic variation that is inheritale
• mutations introduce new alleles and thus additional variation to populations
• gene pool: sum of all alleles present in a population
• genes are the means of transmitting phenotypes from one generation to another
• Darwin & Wallace: descent with modification - all life that exists today has descended from a primitive common ancestor
• accumulation: the process of certain traits gradually becoming more common over generations
• natural selection occurs when selection pressure in the environment confer an advantage on a specific phenotype and enhance it's survival and reproduction, resulting in a change in allele frequency in the gene pool of a population
• adaptation: an inherited trait that allows an individual to survive and reproduce
• adaptive evolution: natural selection choses beneficial traits allowing the individual to survive reproduce and increase the frequency of that allele in the gene pool, while selecting against deleterious alleles, decreasing their frequency
• natural selection occurs when selection pressures in the environment confer a selective advantage on a specific phenotype to enhance it's survival and reproduction, this results in a change in allele frequency in the gene pool of a population
• embryology: the study of the anatomy of embryos and how they develop over time into the adult stage
• comparative anatomy: the study of similarities and differences in structure between different organisms
• homologous structures: show the same structural plan but perform different functions as a result of different species living in different environments with different selection pressures
• vestigial homologous structures: homologous structures that no longer serve a function to the species, however it's presence does not impede their survival
• analogous structures: features of organisms that have the same function but different structures that evolved independently
• genomics: study of the whole set of genes of a species and the interactions of genes in a genome
• conserved identical gene sequences indicate common ancestry between species that they have diverged from over time
• comparative proteomics: study of different proteins and their fundamental amino acid units
• divergent evolution: differences between groups of organisms accumulate to a critical point that leads to speciation
• speciation: the development of a new species
• divergent evolution can be the result of placing a species in different environments where they will have to adapt to selection pressures and ultimately diverge from eachother
• homologous structures are indicative of divergent evolution
• divergent evolution = adaptive radiation