Evolutionary Genetics

Question 1

evolution

Answer 1

changes in the genetic makeup of populations over time, sometimes resulting in adaptation to the environment and the origin of new species

Question 2

natural selection

Answer 2

where there is variation in a population of organisms, the variants best suited to the environment have a greater chance of being passed down which leads to adaptations

Question 3

types of variation

Answer 3

environmental variation - some apples develop in the sun, others in the shade

genetic variation - differences in genotype among individuals in a population. arises from mutations

Question 4

tree of life

Answer 4

evolutionary theory predicts that new species arise by divergence of populations from a common ancestor.

• closely related species are more likely to look alike
• all of these relationships produce a tree
• branches are bacteria, archaea, eukaryotes

Question 5

population genetics

Answer 5

patterns of genetic variation

Question 6

gene pool

Answer 6

all the alleles present in all individuals in a population or species

Question 7

population

Answer 7

all the individuals of a given species that live and reproduce in a particular place; one of the several interbreeding groups of organisms of the same species living in the same place

Question 8

mutation

Answer 8

generates new variation

Question 9

recombination

Answer 9

shuffles mutations

Question 10

somatic mutations

Answer 10

affects individuals

Question 11

germline mutations

Answer 11

passed down

Question 12

mutations can be

Answer 12

neutral, deleterious (harmful) or advantageous (increase in frequency)

Question 13

evolution in terms of genes

Answer 13

is the change in allele or genotype frequency overtime

- change in genetic makeup overtime

Question 14

hardy Weinberg

Answer 14

when allele and genome frequencies do not change - absence of evolutionary forces

1. no difference in survival and reproduction success between individuals
2. populations must not be added to or subtracted by migration
3. no mutation
4. populations must be sufficiently large to prevent sampling error (no genetic drift)
5. individuals must rate at random

Question 15

hardy Weinberg equation

Answer 15

AA is p^2, Aa and pq and aa is q^2

p + q = 1

Question 16

fitness

Answer 16

a measure of the extent to which an individual’s genotype is represented in the next generation

Question 17

modern synthesis

Answer 17

the current theory of evolution, which combines Darwin’s theory of natural selection and Mendalien genetics

Question 18

how does natural selection work?

Answer 18

increases frequency of favourable alleles

can cause allele fixation (frequency of 1)

Question 19

postive selection

Answer 19

natural selection increase the frequency of a favourable allele

Question 20

negative selection

Answer 20

reduces the frequency of a deleterious allele

Question 21

balancing selection

Answer 21

natural selection that acts to maintain two or more allies or a given gene population

• populations in dry might favour one allele, populations in wet, another
• heterozygote advantage: heterozygous fitness is greater than either homozygote

Question 22

stabilising selection

Answer 22

maintains the status quo and selects against extremes

- human birth weight

Question 23

directional selection

Answer 23

select against one of two extremes and leads to a change in a trait overtime - finches

Question 24

artificial selection

Answer 24

form of directional selection, similar to natural selection but without the competition. successful genotypes are selected by a breeder

Question 25

disruptive selection

Answer 25

operates in favour of extremes and against intermediates. flies have evolved to eat apples or hawthorns but not both (might lead to speciation)

Question 26

sexual selection

Answer 26

promotes traits that increase an individuals access to reproductive opportunities
- peacock tail

intrasexual selection: members of one sex compete for access to another sex

intersexual: interaction between males and females, as when females choose from males (bird dancing)