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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