ch 28 complex and quantitative traits

Question 1

complex traits

Answer 1

characteristics that are determined by several gene are significantly influenced by environmental factors

Question 2

quantitative traits

Answer 2

traits, usually polygenic in nature, that can be described using numbers

Question 3

quantitative genetics

Answer 3

the field of genetics that studies complex and quantitative traits

Question 4

continuous traits

Answer 4

quantitative traits that fall along a continuum rather than occurring in discrete categories

Question 5

meristic traits

Answer 5

traits that can be counted and expressed in whole numbers

Question 6

threshold traits

Answer 6

traits that are inherited through the contribution of many genes

Question 7

frequency distribution

Answer 7

a graph that displays the numbers of individuals that are found in each of several phenotypic categories

Question 8

normal distribution

Answer 8

a distribution for a large sample in which the trait of interest varies in a symmetrical way around an average value

Question 9

biometric field

Answer 9

a field of genetics that involves the statistical study of biological traits

Question 10

mean

Answer 10

the sum of all the values in a group divided by the number of individuals in the group

Question 11

variance

Answer 11

a measure of the variation around the mean within a population

Question 12

standard deviation (SD)

Answer 12

a statistic that is computed by taking the square root of the variance

Question 13

covariance

Answer 13

a statistic that describes the degree of variation between two variables within a group of individuals

Question 14

correlation coefficient (r)

Answer 14

a statistic with a value that ranges between -1 and +1; it indicates how two factors vary in relation to each other

Question 15

polygenic

Answer 15

refers to a trait that is controlled by multiple genes

Question 16

polygenic inheritance

Answer 16

the transmission of any trait that is governed by two or more different genes

Question 17

quantitative trait locus (QTL)

Answer 17

the location on a chromosome of one or more genes that affect the outcome of a quantitative trait

Question 18

QTL mapping

Answer 18

the determination of the locations of qtls using mapping methods, such as genetic crosses coupled with analysis of molecular markers

Question 19

inbreeding

Answer 19

sexual reproduction between two genetically related individuals

Question 20

monomorphic

Answer 20

a term used to describe a trait that is found in only one form in a population or a gene that is found as only one allele in a population

Question 21

genotype-environment interaction

Answer 21

the phenomenon that occurs when the environment effects on phenotype differ according to genotype

Question 22

genotype-environment association

Answer 22

the phenomenon that occurs when certain phenotypes are preferentially found in particular environments

Question 23

heritability

Answer 23

the amount of phenotypic variation due to genetic variance within a specific group of individuals raised in a particular environment

Question 24

broad-sense heritability

Answer 24

heritability that takes into account different types of genetic variation that may affect phenotype

Question 25

narrow-sense heritability

Answer 25

heritability that takes into account only the additive effects of alleles

Question 26

selective breeding

Answer 26

(also called artificial selection) programs and procedures designed to modify phenotypes in economically important species of plants and animals

Question 27

selection limit

Answer 27

the phenomenon in which several generations of artificial selection results in a plateau where artificial selection is no longer effective

Question 28

realized heritability

Answer 28

a form of narrow-sense heritability that is observed when selective breeding is practiced

Question 29

inbreeding depression

Answer 29

the phenomeon in which inbreeding produces homozygotes that are less fit, thereby decreasing the reproductive success of a population

Question 30

heterosis

Answer 30

(also called hybrid vigor) the phenomenon in which hybrids display traits superior to those of either parental strain; usually different from overdominance because the hybrid may be heterozygous for many genes, not just a single gene, and because the superior phenotype may be due to the masking of deleterious recessive alleles