Recombination, Recombination, Mutation, Genetic Drift, Mutation, Genetic Drift,

Gene FlowGene FlowAlso evolution Also evolution

RecombinationRecombination

Remember Meiosis?Remember Meiosis? This is when recombination occursThis is when recombination occurs Shuffling of chromosomes/genes/allelesShuffling of chromosomes/genes/alleles Also crossing overAlso crossing over

Remember fertilization?Remember fertilization? Coming together of shuffled genesComing together of shuffled genes

New alleles not created, just New alleles not created, just

rearranged for more genetic variabilityrearranged for more genetic variability

MutationsMutations

Creates new allelesCreates new alleles Beneficial, neutral, or lethalBeneficial, neutral, or lethal Passed on to new generations if they arise Passed on to new generations if they arise

in gametesin gametes Can reduce chances of survival and Can reduce chances of survival and

reproductionreproduction

If it causes severe reductions, usually ends with If it causes severe reductions, usually ends with deathdeath

Neutral mutation changes base sequence but Neutral mutation changes base sequence but has no effect on survival or reproductionhas no effect on survival or reproduction

Beneficial mutation ex. – corn plant has a Beneficial mutation ex. – corn plant has a mutation that makes it grow faster or larger mutation that makes it grow faster or larger giving it best access to sunlight and nutrientsgiving it best access to sunlight and nutrients

Neutral mutation might prove helpful if the Neutral mutation might prove helpful if the environment changesenvironment changes

Genetic DriftGenetic Drift

Random changes in allele frequencies over Random changes in allele frequencies over timetime

Effect is greatest in small populations – Effect is greatest in small populations – leads to loss of genetic diversityleads to loss of genetic diversity Allele will become more or less prevalent in Allele will become more or less prevalent in

small popssmall pops

Bottleneck Bottleneck and Founder Effectand Founder Effect

BottleneckBottleneck

Drastic reduction in population size Drastic reduction in population size because of severe pressurebecause of severe pressure

Founder EffectFounder Effect A few individuals establish a new A few individuals establish a new

populationpopulation Unpredictable genetic shifts occurUnpredictable genetic shifts occur

Gene FlowGene Flow

Physical movement of alleles into and out of a Physical movement of alleles into and out of a populationpopulation

Opposes the effects of mutation, natural Opposes the effects of mutation, natural selection, and genetic driftselection, and genetic drift

Keeps populations similar to one anotherKeeps populations similar to one another

Increases genetic variability in that new Increases genetic variability in that new populationpopulation

CladogramsCladograms

Aka. Phylogenetic tree, branching tree, Aka. Phylogenetic tree, branching tree, evolutionary treeevolutionary tree

Lines not still apparent at present are Lines not still apparent at present are extinctextinct

Do not have to all face the same wayDo not have to all face the same way