population genetics detail

Question 1

4 main factors which influence allele frequency distribution

Answer 1

natural selection, genetic drift, mutation and gene flow

Question 2

wha ar eeasurbale traits

Answer 2

quantitative traits

Question 3

quantitative traits

Answer 3

is a measurable phenotype that depends on the cumulative actions of many genes and the environment

Question 4

discontinuous traits

Answer 4

most traits are discontinuous e.. tongue roll/no tongue role

Question 5

traits that vary continuously are called

Answer 5

quantitative traits - height and wait

Question 6

continous variation

Answer 6

-no distinct categories -quantitative -controlled by lots of genes -strongly influenced by environment

Question 7

continuous traits are

Answer 7

controlled by lots of genes and the environment

Question 8

discontinuous variation

Answer 8

-distinct categories -controlled by a few genes -unaffected by the environment

Question 9

three reasons quantitative genetics is important

Answer 9

medicine agriculture conservation

Question 10

medicine and quantitative genetics

Answer 10

susceptibility to disease;; complex genetic and environmental interactions and understanding gents vs environmental causes 1) prevention 2) genetic counselling 3)genetically tailored treatment

Question 11

agriculture

Answer 11

economically important traits= quantitative traits. -basis for selective breeding programs -enviromental variation reduces efficiency of selection

Question 12

conservation

Answer 12

1)endangered species 2) captive breeding programs

Question 13

poly genic traits

Answer 13

Polygenic traits are those traits that are controlled by more than one gene. Such traits may even be controlled by genes located on entirely different chromosomes. Human height, eye and hair color are examples of polygenic traits. Skin color is another polygenic trait for humans and a variety of other animals.

Question 14

3 polygenic traits

Answer 14

metric- continous scale (height)

meristic- discrete scale (countable traits)

threshold- present or absent -all based on the assumption of normal distribution (affected/not effected)

Question 15

the there polygenic traits (metric, meristic and threshold) are based on

Answer 15

the assumption of normal distribution

Question 16

metric traits

Answer 16

e.g. height mean-centre of the phenotypic distribution

Question 17

Meristic traits

Answer 17

countable traits- can be sued to describe a particular species of fish or to identify an unknown species e.g. contain the bristol number on drosophila

Question 18

threshold traits

Answer 18

discrete phenotypes e.g. affected and unaffected -multifactoral e.g. alcoholic, alzheimers, cancer, diabetes, heart disease

Question 19

phenotype=

Answer 19

genotype and environment

Question 20

phenotypic variance equation

Answer 20

Vp=Vg +Ve +Vge

Question 21

Vp

Answer 21

phenotypic variance -total phenotypic variation of the segregating population

Question 22

Vg

Answer 22

genetic variation -genetic variation that contributes to the total phenotypic variation

Question 23

Ve

Answer 23

environmental variance -environmental contribution to the total phenotypic variation

Question 24

Vge

Answer 24

g x e interaction variance how far the environment and genes interact -variation associated with the genetic and environmental factor interactions

Question 25

therefore genetic variance =

Answer 25

Vg=Va + Vd +Vi

Question 26

Va

Answer 26

additive genetic variance - when a number of genes influence a genetic trait e.g. hair colour

Question 27

Vd

Answer 27

dominance genetic variance - phenotypic deviation caused by interactions b/w alternative alleles which control one trait

Question 28

Vi

Answer 28

interaction genetic variation -epistasis

Question 29

environmental variation is

Answer 29

stabilising

Question 30

mendelian inheritance patterns allow us to.

Answer 30

predict expected frequencies of alleles

Question 31

positive assortative mating

Answer 31

where organisms mate with others with similar character trait

Question 32

positive assortative mating causes

Answer 32

an increase in homozygous individuals a decrease in heterozygous individuals

Question 33

heritability of trait describes

Answer 33

how much variation is genetic

Question 34

two types of heritability

Answer 34

broad sense narrow sense

Question 35

heritability

Answer 35

measures the total genetic influence on phenotype –> considers additive genetics, dominance and epistatic

Question 36

broad sense heritability

Answer 36

it tells you how much is related to the environment and how much is related to genetics

Question 37

narrow sense heritability

Answer 37

Narrow sense heritability is the proportion of total phenotypic variation that is due to the additive effects of genes. This component of variation is important because it is the only variation that natural selection can act on.

Question 38

H^2

Answer 38

H^2 should be between 0 and 1 -can vary widely across traits, environment and diff pop. -can be used to predict change in population mean under selection

Question 39

when H^2 increases..

Answer 39

the response to selection increases

Question 40

examples of heritability narrow sense

Answer 40

Question 41

measuring heritability

Answer 41

similarity between relative, compared to random individuals in population is one measure of H^2 pic

Question 42

measuring additive genetic effects:infinitesimal model

Answer 42

a simple model of inheritance of quantitative traits, which assumes an infinite number of unlinked loci, each with an infinitesimal (so large) effect. Infinite number of genes controlling phenotypic traits each with a very small effect