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Final

Bio A02 Final Study Notes

20 Pages
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Department
Biological Sciences
Course Code
BIOA02H3
Professor
Dr.Persaud

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Biology FINALS Study Notes
CHAPTER 22: THE MECHANISM OF EVOLUTION
CHARLES DARWIN
oSpecies change over time
oProcess that produce these changes is natural selection
oOffspring not identical
oINDIVIDUALS DO NOT EVOLVE. POPNS DO !!
oNo actual experiments just observations
oPopn genetics help support arguments
ALFRED RUSSEL WALLACE also proposed natural selection hypothesis
MALTHUS argues: since popn growth > food production famine; thus,
unchecked pop. Growth = famine
oDarwin: death rates must be high
NATURAL SELECTION: differential contribution of offspring to the next gen. by
various genetic types belonging to same popn.
POPULATION: group of individuals of a single species that live and interbreed in a
particular geographic area at the same time
For popn to evolve must have heritable genetic variation
popn evolves when individual w/ diff phenotypes survive/reproduce at diff.
rates
ADAPTATION: both processes by which characteristics appear to be useful to the
owner that evolves AND the characteristics themselves
GENE POOL: sum of all alleles found in a popn
CHARACTERS: feats. Of a phenotype ie. eye colour
TRAIT: specific form of a character ie. brown eyes
HERITABLE TRAIT: characteristic of an organism that is partly determined by its genes
www.notesolution.com
POPN GENETICS 3 MAIN GOALS:
1.explain origin & maintenance of genetic variation
2.explain patters & organization of genetic variation
3.understand mechanisms that cause changes in allele freqs in popns
rediscovered from Mendels work
MENDELIAN POP’N: local popn of individuals belonging to same species and
exchanging genes with one another; describes genetic structure
FREQUENCY: proportion of allele/genotype in gene pool
HARDY-WEINBERG EQUILIBRIUM: eqn describes a model where allele freqs dont
change across gens. And genotype freqs can be predicted p2+ 2pq + q2=1 ;
FACTORS THAT MUST BE PRESENT :
mating is random
population size is infinite
no gene flow
no mutation
natural selection
MECHANISMS OF EVOLUTIONARY CHANGE:
1.mutations create genetic variation
2.gene flow change allele freqs
3.genetic drift causes BIG changes in SMALL popns
popn bottlenecks: only few survive a random event
founder effect: establishing a new popn in new region
4.non-random mating
FITNESS: reproductive contribution of a phenotype to new gens relative to
contribution of other phenotypes; determined by average rates of survival and
reproduction of one with that phenotype
www.notesolution.com
NATURAL SELECTIONS 3 DIFF RESULTS:
1.stabilizing selection preserves average characteristic of a popn by favouring
AVERAGE individs.
2.Directional selection characteristics of popn favouring one that vary in 1
direction from mean
3.Disruptive selection favour individs that vary in opposite directions from mean
of popn
SEXUAL SELECTION
Acts on characteristics that determine reproductive success
Darwins descent of man, and selection in relation to sex based on this
oEither; compete for access
oOr; attract opposite sex
MALTE ANDERSONS : African long-tailed widowbird study cut&glued tails 
found that females preferred long tail
TIM BIRKHEAD: studied zebra finches colour and relation to carotenoids as
health symbol
GENETIC VARIATION MAINTAINED BY:
1.Neutral mutations
2.Sexual recombination (increases # of possible genotypes)
3.Frequency-dependant selection (fitness of genotype depends on freq in a
popn)
4.Environmental variation
5.Geographically distinct SUBpopulations
CONSTRAINTS OF EVOLUTION:
1.Developmental processes
Like the fishes; still have the same body shape
2.Trade-offs constrain
www.notesolution.com

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Description
Biology FINALS Study Notes CHAPTER 22: THE MECHANISM OF EVOLUTION CHARLES DARWIN o Species change over time o Process that produce these changes is natural selection o Offspring not identical o INDIVIDUALS DO NOT EVOLVE. POPNS DO !! o No actual experiments just observations o Popn genetics help support arguments ALFRED RUSSEL WALLACE also proposed natural selection hypothesis MALTHUS argues: since popn growth > food production famine; thus, unchecked pop. Growth = famine o Darwin: death rates must be high NATURAL SELECTION: differential contribution of offspring to the next gen. by various genetic types belonging to same popn. POPULATION: group of individuals of a single species that live and interbreed in a particular geographic area at the same time For popn to evolve must have heritable genetic variation popn evolves when individual w diff phenotypes survivereproduce at diff. rates ADAPTATION: both processes by which characteristics appear to be useful to the owner that evolves AND the characteristics themselves GENE POOL: sum of all alleles found in a popn CHARACTERS: feats. Of a phenotype ie. eye colour TRAIT: specific form of a character iebrown eyes HERITABLE TRAIT: characteristic of an organism that is partly determined by its genes www.notesolution.comPOPN GENETICS 3 MAIN GOALS: 1. explain origin & maintenance of genetic variation 2. explain patters & organization of genetic variation 3. understand mechanisms that cause changes in allele freqs in popns rediscovered from Mendels work MENDELIAN POPN: local popn of individuals belonging to same species and exchanging genes with one another; describes genetic structure FREQUENCY: proportion of allelegenotype in gene pool HARDY-WEINBERG EQUILIBRIUM: eqn describes a model where allele freqs dont 2 2 change across gens. And genotype freqs can be predicted p + 2pq + q =1 ; FACTORS THAT MUST BE PRESENT : mating is random population size is infinite no gene flow no mutation natural selection MECHANISMS OF EVOLUTIONARY CHANGE: 1. mutations create genetic variation 2. gene flow change allele freqs 3. genetic drift causes BIG changes in SMALL popns popn bottlenecks: only few survive a random event founder effect: establishing a new popn in new region 4. non-random mating FITNESS: reproductive contribution of a phenotype to new gens relative to contribution of other phenotypes; determined by average rates of survival and reproduction of one with that phenotype www.notesolution.com
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