Evolution by Natural Selection

Anatomical Adaptations We ObserveAnatomical AdaptationsLarge eyes of nocturnal animalsCamouflageMimicryClaws for diggingThe anatomical adaptations allow these animals to find food and shelter or protects them from predators

Chemical adaptations such as DNA that can change in a short period of timePhysiological adaptations

We observe changes of physiological adaptations in Antibiotic resistant bacteria and new strains of the cold and flu viruses every yearMechanisms for SpeciationHow do anatomical and physiological adaptation change?Mechanisms for speciationMutationsNatural SelectionReproductive isolationGenetic driftImmigration or emigrationMechanisms for speciationWhat are mutations?

How do mutations affect populations?

How can mutations cause the creation of new species?Changes in the DNA sequence of individualsSome mutations have no affect on the genotype and phenotype of an individual while others change a single amino acid or many amino acids affecting protein production and genotypes and phenotypes. When individuals of a population mate together these mutations are inherited and passed along from parent to offspring.Favorable mutations will be inherited and can cause changes in the gene pool of a population eventually creating a new species.Mechanisms for speciationWhat is natural selection?

How does natural selection affect populations?

How can natural selection cause the creation of new species?When organisms with favorable variations in an area survive and produce offspring with the favorable traitsNatural selection can lead to a change in the number of times a particular trait is seen in the gene pool.Over time, the genes that are inherited and passed from generation to generation change and begin to separate a population. Natural Selections affect on single gene traits and polygenic traitsNatural Selection acts on single gene traits byProviding two distinct phenotypes in a population

Providing many phenotypes in a populationFavoring individuals in a population in three different waysNatural Selection acts on polygenic traits byNatural Selection and Single gene traits

2 phenotypesNatural Selection favoring average individuals in a populationCalled Stabilizing selectionReduces variation in a population

Small beakLarge beakNumber of birds in populationNatural Selection favoring one extreme variation in a populationCalled Directional selectionCan lead to the rapid evolution of a population

Small beakLarge beakNumber of birds in populationNatural Selection favoring both extreme variations in a populationCalled Disruptive selectionleads to the evolution of two new species

Small beak Large beakNumber of birds in populationMechanisms for speciationWhat is genetic drift?

How does genetic drift affect populations?

How can genetic drift cause the creation of new species?The random changes in allelic frequency within small populationsWhen mutations in a small population change the genotypes in that population the number of times an allele is seen may be different than those within a large population.If the variations after mutations are more favorable than the ones before the mutations then those organisms will mate and pass along the new traits in increasing numbers.Mechanisms for speciationWhat is reproductive isolation?

How does reproductive isolation affect populations?

How can reproductive isolation cause the creation of new species?When two populations no longer interbreed and produce fertile offspringThe population no longer breeds together, therefore creating a new gene pool. This may happen when members of a population no longer recognize mating behaviors, are separated by a physical barrier, or mate at different times of the year than normal.When gene pools split and genes are no longer shared by a population over time a new species developsMechanisms for speciationWhat is immigration?

What is emigration?

How does immigration or emigration affect populations?

How can immigration or emigration cause the creation of new species?The movement of individuals into a populationThe movement of individuals out of a populationMigration changes the gene poolMigration will change the variations within a population in turn changing the species over a long period of time.Evidence for EvolutionAnatomical adaptationsPhysiological adaptationsFossil recordsEmbryo developmentBiochemistryFossil Records

Trace fossilCastPetrified fossilImprintsAmber preservedMoldTypes of Fossils

Relative dating technique

Radioactive datingEvolutionary relationships are displayed through

Homologous structures

Analogous structures

Vestigial structures

Embryo development

BiochemistryCan be similar in arrangement, function or bothbut similar functionHave common evolutionary originHave NO common evolutionary originHas no present day function, but probably useful in ancestorsEarly stage of growth and development are similarSimilarities in DNA and RNA sequences