Recombination, Mutation, Genetic Drift, Gene Flow Also evolution Also evolution

Recombination  Remember Meiosis? This is when recombination occurs This is when recombination occurs Shuffling of chromosomes/genes/alleles Shuffling of chromosomes/genes/alleles Also crossing over Also crossing over  Remember fertilization? Coming together of shuffled genes Coming together of shuffled genes  New alleles not created, just rearranged for more genetic variability rearranged for more genetic variability

Mutations  Creates new alleles  Beneficial, neutral, or lethal  Passed on to new generations if they arise in gametes  Can reduce chances of survival and reproduction

 If it causes severe reductions, usually ends with death  Neutral mutation changes base sequence but has no effect on survival or reproduction  Beneficial mutation ex. – corn plant has a mutation that makes it grow faster or larger giving it best access to sunlight and nutrients  Neutral mutation might prove helpful if the environment changes

Genetic Drift  Random changes in allele frequencies over time  Effect is greatest in small populations – leads to loss of genetic diversity Allele will become more or less prevalent in small pops Allele will become more or less prevalent in small pops  Bottleneck  and Founder Effect

Bottleneck  Drastic reduction in population size because of severe pressure

Founder Effect  A few individuals establish a new population  Unpredictable genetic shifts occur

Gene Flow  Physical movement of alleles into and out of a population  Opposes the effects of mutation, natural selection, and genetic drift  Keeps populations similar to one another  Increases genetic variability in that new population

Cladograms  Aka. Phylogenetic tree, branching tree, evolutionary tree  Lines not still apparent at present are extinct  Do not have to all face the same way