Get folders AND bindersAlso have out your natural selection

reading assignment from the weekend

Gene flowGene poolGenetic drift

Species a group of individual organisms that

are capable of interbreeding to produce fertile offspring in nature.

PopulationA group of organisms of one species

that interbreed and live in the same place at the same time

Common AncestorAn organism which is the shared ancestor

of two (or more) different descendant groups of organisms.

Evolution: Darwin’s Theory of Natural Selection•You will be able to describe Darwin’s theory of natural selection as well as give examples that support the theory.•You will be able to describe the conditions required for natural selection.

MisconceptionsHumans did not evolve from apes, gorillas

or chimps. We are all modern species that have followed different evolutionary paths, though humans share a common ancestor with some primates, such as the African ape

•Evolution: changes that transform life over an immense time.•Darwin published , The Origins of Species making two main points for the mechanisms of evolution…1.Descent with

modification2.Natural

selection

Descent with ModificationSpecies living today descended from ancestral

speciesSpecies spread into various habitats over

millions of yearsSpecies accumulated different modifications, or

adaptations, to diverse ways of life as genes are passed on

Results in diversity of species

Natural SelectionProcess by which

individuals with inherited characteristics well-suited for their environment leave more offspring on average than do other individuals

Survival and reproduction of the fittest

Theory of Natural Selection Flow ChartPopulation of Organisms

Overproduction

Variation

Struggle for existence

Differences in reproductive success

Evolution of adaptations

What have you learned?What are the two main points that Darwin made

in is book to ague the mechanisms of evolution?Descent with modification and natural selection

What is natural selection?Process by which individuals with inherited

characteristics well-suited for their environment leave more offspring on average than do other individuals

Describe some conditions that could lead to a struggle for existence among individuals in a population.Over population, limited resources, changes

occurring in the environment

Evidence of EvolutionThe fossil record= shows patterns of

evolution over millions of yearsComparative AnatomyComparative Embryology (Not on foldable)Comparative Biochemistry: amino acid tablesGeographic Distribution: similar organisms

separated by land

Comparative AnatomyHomologous structures= anatomically

similar structures inherited from a common ancestor

Comparative AnatomyAnalogous

structures= Structures of different species having similar or corresponding function but not from the same evolutionary origin

Comparative anatomyVestigial structures= Vestigial structures

are body parts that seemingly have no purpose or function. Perhaps they once did, but somewhere along the way they lost their functions and are now basically useless

Comparative EmbryologySimilar phases of development

Geographic distribution

Theory of Natural Selection Flow ChartPopulation of Organisms

Overproduction Variation

Struggle for existence

Differences in reproductive

success

Evolution of adaptations

Changes in the gene poolYou will be able to discuss mechanisms of evolution other than natural selection such as genetic drift and gene flow.

Gene PoolConsists of all the alleles in all the individuals that make up a population.

The process of meiosis (specifically crossing over) and fertilization shuffle alleles in the gene pool giving us genetic diversity

Genetic DriftA change in the population due to chanceAll populations are subject to some genetic

drift; however, the smaller the population the greater the impact.Bottleneck effect- disasters can reduce

the size of a population. By chance some alleles are represented more than others while others are completely eliminated

Founder effect- when a few individuals colonize an isolated habitat. There is low genetic make-up

Bottleneck effect

Founder Effect

Demonstration for Genetic DriftHypothesis:

What would the populations look like generations from now if there were no environmental changes and the gene pool remained the same?

Analysis:What are some deadly “chance” events?How did the removal of some of the marbles

(change in the gene pool) affect each population?

How did the impact of genetic drift contrast between the small population and the larger population?

Gene FlowThe exchange of genes with another

population Occurs when fertile individuals or their

gametes migrate between populationsTends to reduce genetic differences between

populations

What have you learned?What is a gene pool?

All of the alleles in all of the organisms that make up a population

What are the two main forces of evolutionary change in gene pools other than natural selection?Genetic drift and gene flow

How can genetic drift cause a substantial change in allele frequencies in small populations?It can reduce genetic variations