Hardy-weinberg Equilibrium

Question 1

Allele frequency

Answer 1

Frequency of a particular allele in population.

-population fundamental unit of evolution

Question 2

Genetic basis

Answer 2

For evolution to occur, genetic differences must account for phenotypic differences

Question 3

Natural selection

Answer 3

Favors traits most adaptive under present environment (better foragers or better camoflouged or avoid predation)

Question 4

Ever-changing environment

Answer 4

• individuals must MIGRATE, ADAPT, DIE
• natural selection acts on existing variations
• environment never creates favorable alleles

Question 5

New alleles arisen by

Answer 5

Mutation and genetic drift , gene flow, nonrandom mating

Gene flow( when individuals disperse) alters allele frequency

Question 6

Mutation

Answer 6

Changes in DNA base sequence

Question 7

Genetic drift

Answer 7

Random changes in allele frequencies without regard to adaptation
Ex: elephant seals
Large population becomes small and increased to large
GENETIC BOTTLENECK: large-reduced-large)
-allele frequency is altered due to population crash
-small populations have big effect
-genetic drift inversely related to population size

Question 8

Change in heritable characteristics

Answer 8

Consequence of change allele frequencies
-all evolutionary change is described as sequential origin of new alleles, their replacement of old ones and occasionally the origin of New through duplication or lateral transmission from another lineage leading to insertion. (By virus)

Question 9

Hardy-Weinberg equilibrium

Answer 9

-situation where no evolution is occurring
-genetic equilibrium
-allele frequency will not change:
No natural selection
No mutation
No genetic drift (no infinte population size)
No allele flow
Random mating
-how a particular genotype will become more or less common over time

Question 10

Phenotype frequency

Answer 10

Proportion of individual exhibiting observable traits

-#indiv with phenotype/ total

Question 11

Genotype frequency

Answer 11

Proportion of genotypes at a given locus

-Indiv with genotype/ total

Question 12

Allele frequency

Answer 12

Proportion of alleles at a given locus
-p= freq. dominant allele

-q= freq. recessive allele

Question 13

Allele frequencies from number of individuals

Answer 13

• p= ((#AA + 1.5(#Aa))/ N
• q= ((#aa) + 1.5(#Aa))/N

N=total

Question 14

Genotype freq. to allele freq.

Answer 14

P= f(AA) + 1.5(f(Aa))

q= f(aa) + 1.5 (f(Aa))

TO GO FROM ALLELE TO GENOTYPE MUST ASSUME HW EQUIL

Question 15

Genotype to allele

Answer 15

AA= p^2
Aa=2pq
aa=q^2

P^2+2pq+q^2=1.0

Question 16

In order to be in hardy Weinberg

Answer 16

Allele frequency must predict genotype frequency

Question 17

Two processes that generate variation

Answer 17

1. Mutation: ultimate source of new genes
   Create different versions of alleles
2. Genetic recombination: this results in new recombinations of genes

Question 18

Genetic drift

Answer 18

Occurs when founders start a new population or after a genetic bottleneck with interbreeding

• endangered species go thru genetic bottleneck so suffer from reduced genetic variation
• small populations

Question 19

Founder effect

Answer 19

When founders contain a fraction of total genetic diversity of original population
Ex: grey seals in Britain,
-metapopulation to increase genetic variation
Ex: island of Tristan da cunha
-founded by britons. One had allele for blindness, among their defenders 4 are blind and 9 carriers
Ex: Amish population pen
-closed community
-genetic disease higher than in German population
-sheer chance

Question 20

Neutral theory of molecular evolution

Answer 20

Mooto Kimura
2 observations:
-Excessive amounts of protein polymorphism
-Molecular clock
Refers to apparent constant rate of protein evolution over large periods of time
Kimura: clock reflects action of random drift not selection

Question 21

New alleles

Answer 21

• origin through spontaneous mutation of a single nucleotide within sequence
• single cell: immediately new allele and subject to drift
• multi cell: nucleotide substitution must arise within germ line that gives rise to gametes
• most alleles lost to genetic drift but occasionally become more common and random accident replaces.

Question 22

Natural selection…

Answer 22

Is not same as evolution

Different from evolution by natural selection

No efect unless diff phenotypes also differ in genotype

Variation in average reporoductive success (including survival) among phenotypes.

Question 23

three principles of Darwin evolution

Answer 23

Competition, sturggle for exisistence
Heritable variation
Heritability, variation matters in struggle

Survival and reproduction are not random. Must be correlation between fitness and phenotype

Question 24

People wanted life itself to be purposeful and creative

Neo-Lamarckism

Orthogenesis

Mutationism

Answer 24

Inheritance of acquired characteristics

Variation that arises is directed toward a goal

Discrete variations are all that matter

Question 25

Gene flow

Continent-island model of migration

Answer 25

• Movement of individuals from one sub population to another
• Movement of gametes from one subpopulation to another followed by fertilization
• Results in movement of alleles between populations
• Can be a very local or long- distance phenomenon

Continent (large pop) to island (small pop)

• alleles from continent represent a large fraction of island gene pool
• alleles from island have negligible effect on gene frequencies in continent
• even small amounts of gene flow can negate genetic drift
• if natural selection favors certain in some and different in others, gene flow oppose local natural selection

Question 26

When will negate the effects of genetic drift

Answer 26

-m=proportion of migrants exchanged per generation-
-N= number of indiv in each population
Negate if m> (1/(2N))
-one migrate every other generation is sufficient to prevent genetic drift
-gene flow from a large, central adapted to a diff environment might swamp the effects of NS. by causing influx less fit alleles
Ex: grey squirrels and fox
-competitive vs anti-predator
-smaller v larger
-conspicuous color v deep woods cmaoflaugh
-tenacious v sophisticated

Question 27

Non random mating

Three patterns

Answer 27

• 1. Mating strategies
     
     2. inbreeding (mating between relatives)
     3. Assortment mating

Question 28

Inbreeding

Answer 28

-high levels of inbreeding causes loss of heterozygous genotype
-exposes recessive alleles to selection since they are most likely to be present in homo state.
Ex; island of Tristan da cunha
-can cause dramatic decline in fitness of a pop possibly extinction. Another others ineffective by inbreeding.

Question 29

Assertive mating and sexual selection

Answer 29

Occurs when individuals choose their mates based on their resmeblence to each other at a certain locus or a certain phenotype