Evolution Exam 2

Front 1

genetic locus

Back 1

the specific location of a gene or piece of DNA sequence on a chromosome. Mutations can modify these, creating new alleles.

Front 2

population genetics

Back 2

study of the distribution of alleles within populations and the mechanisms that can cause allele frequencies to change over time.

Front 3

fixed allele

Back 3

an allele becomes fixed in a population when all of the alternative alleles have disappeared. no genetic variation exists at a fixed locus within a population because all individuals are genetically identical at that locus. easier in smaller populations

Front 4

additive allele

Back 4

an allele that yields twice the phenotypic effect when homozygous instead of hetero. is not influenced by presence of other alleles, so no dominance. since it always has a phenotype, very prone to selection to fixation or being wiped out of population

Front 5

mutation selection balance

Back 5

maintain genetic variation through the introduction of new alleles via mutation. While selection selects against the deleterious allele, new mutations at that locus will keep emerging, increasing its frequency. This creates a "tug-o-war", balancing genetic variation.

Front 6

migration selection balance

Back 6

disadvantageous genes can often be maintained in a population by migration from populations where the gene is favored. Spatially varying selection is common, for instance in the banded vs unbanded water snake migrating through mainland islands

Front 7

negative frequency dependent selection

Back 7

rare genotypes have higher fitness than common genotypes. this process can maintain genetic variation within populations. yellow and purple Elder orchid flowers tricking bees.

Front 8

fitness

Back 8

the success of an organism at surviving and reproducing, and thus contributing offspring to future generations. The product of the entire phenotype.

Front 9

relative fitness (of a genotype)

Back 9

(w= 0-1) the success of the genotype at producing new individuals (its fitness)standardized by the success of other genotypes in the populations (ex. divided by avg fitness of population)

fitness as compared to highest fitness

Front 10

Average excess of fitness (of an allele)

Back 10

the difference between the average fitness of individuals bearing the allele and the average fitness of a population as a whole

Delta p= p x (a/w), delta p= change in allele freq due to selection, p = freq of allele, a = avg excess of fitness of that allele, w = avg fitness of pop'n

Front 11

inbreeding coefficient

Back 11

(F) the probability that the two alleles at any locus in an individual will be identical by decent. Higher F = more inbred

Front 12

Het advantage

Back 12

overdominance. NS works to increase diversity because is selecting for het. Malaria and sickle cell, Cystic Fibrosis and Typhoid Fever. Neither allele can EVER become fixed. Het relative fitness always 1.

Front 13

het disadvantage

Back 13

underdominance. relative fitness 1-x. does not maintain diversity, because NS selecting for homozygotes.

Front 14

5 assumptions of HW

Back 14

1. random mating, large pop 2. no migration 3. no genetic drift 4. no mutation 5. no natural selection

Front 15

HW equation to calc allele freq and expected genotype freq

Back 15

p + q = 1

P^2 + 2pq + q^2 = 1

Front 16

positive frequency dependent selection

Back 16

increases genetic uniformity. fitness increases a genotype becomes more common

Front 17

inbreeding

Back 17

mating with relatives or self fertilizing. increases deleterious genes, decreases fitness. More homozygotes, less HW equilibrium. Prairie chickens in Illinois

Front 18

allele freq vs. genotype freq in inbreeding

Back 18

allele freq in the next generation are the same, but it does change the genotype freq. That's the problem.

Front 19

inbreeding depression

Back 19

negative effects of inbreeding on offspring due to increasing homozygosity in individuals. reduced fertility/growth, higher mortality, diseases, etc

Front 20

2 effects of inbreeding

Back 20

1. homozygosity- loss of variation, loss of genes associated with immunity (hybrid vigor, MHC loci)

2. Inbreeding Depression- negative effects (due to het advantage)

Front 21

Identity by Descent

Back 21

matchingsegment of DNA shared by two or more people that has been inherited from arecent common ancestor without any intervening recombination.

Front 22

inbreeding coefficient

Back 22

probabilitythat 2 alleles are identical by descent; involves tracing of paths between thetwo parents via a common ancestor->

Front 23

F for half sibs, whole sibs, and self-ferts

Back 23

F = 1/8

F = 1/4

F = 1/2

Front 24

mechanisms hermaphrodites use to avoid self-ferting

Back 24

1. temporal- 1st one sex released, then the other. coral spawning events.

2. physical- male and female games in different parts of body or different genetic types. Earthworms, 2 pollen grains in plants where only one grows.

Front 25

purifying selection

Back 25

when inbreeding purges out lethal recessive alleles, like in cheetah populations

Front 26

sexual reproduction

Back 26

Process that requires a fertilization event inwhich two gametes unite. uses meiosis.

Front 27

Asexual reproduction

Back 27

1 parent, offspring nearly identical copies. uses mitosis.

Front 28

sexual reproduction pros

Back 28

sexual have more variation (mutations, recombination, random mating, random assortment), recombination reduced linkage disequilibrium

Front 29

sexual rep cons

Back 29

2 fold cost- slow and only half the offspring can directly produce offspring themselves (females)

Front 30

asexual pros

Back 30

faster, don't have to mix DNA so you get all your good DNA in offspring

Front 31

asexual cons

Back 31

no DNA mixing, so get all of your bad DNA, too. not as many chances for genetic variance.

Front 32

Muller's Ratchet

Back 32

process by which asexual genomes produce deleterious alleles irreversibly.

Front 33

the red queen hypothesis

Back 33

Sexual populations are able to keep up or adaptto new selective challenges, while the asexual populations, essentially clonal,are not. Asexual reproducers may have slight disadvantage. Trematode worm parasite in New Zealand Mud Snail

Front 34

In what scenario is sex more likely to evolve? Why?

Front 35

reproductive success

Back 35

Numberof offspring, survival, fecundity, mating success. Really proxies for alleles passed on in lifetime(fitness). Male vs. Female elephant seals

Front 36

Bateman-TriversTheory

Back 36

Asymmetry in parental investment. Typical Male cheap sperm but Maximum number of offspring is limited by Number of eggs he can fertilize Typical Femalehas expensive eggs but Output limited by Number of eggs she can produce

Front 37

fecundity in males

Back 37

(1) Small gamete size(2) Low investment(3) Produce many(4) Not limited by resources

Front 38

fecundity in females

Back 38

(1) Large gamete size(2) High investment(3) Produce a few(4) Limited by resources

Front 39

sexual dimorphism

Back 39

higher opportunity for mating success means greater selection on morphology, leading to sexual dimorphism. influences reproductive success.

Front 40

RS in Peacocks

Back 40

males have higher variance

Front 41

RS in Albatross

Back 41

little sexual dimorphism, but female eggs are still more expensive

Front 42

RS in Red-neck Phalarope

Back 42

females are more colorful, court males who do parental care. Polyandry. Still expensive eggs, so less big than in polygyny

Front 43

4 reasons for sexual selection

Back 43

1.Fundamental asymmetry in parental investment (Females invest more) 2. Difference in variance in reproductive success(Males have greater variance in fitness) 3. Selection (as we know from NS) acts on variance in fitness((Sexual) selection should be stronger on males) 4. Phenotypic consequence is sexual dimorphism(Morphology, Behavior, physiology)

Front 44

4 postulates of natural selection

Back 44

1. individuals within a population are variable 2. variations are heritable 3. individuals vary in survival and reproductive success 4. survival and reproduction are not random.

Front 45

linnaeus

Back 45

organized all known living things at the time into taxa groups. father of taxonomy.

Front 46

Lamark

Back 46

lamarkian evolution. animals could evolve quickly and pass down acquired traits.

Front 47

hutton

Back 47

world was shaped by gradual transformations of landscapes through imperceptibly long changes

Front 48

lyell

Back 48

earths landscapes created my a series of many small changes still occurring today.

Front 49

wallace

Back 49

English naturalist who wrote a theory similar to darwins and inspired him to finally publish. wrote to darwin.

Front 50

malthus

Back 50

English clergyman who wrote Principle of population, saying population growth would always outstrip the govt's efforts to help feed the poor. those who could adapt to societal needs and provide useful work would survive.