ch 15

Question 1

A population consists of

Answer 1

all the individuals of a species that live together in one place at one time. A population can be widely distributed or confined to a small area.

Question 2

In the exponential model of population growth, the growth rate remains

Answer 2

constant. Rapid, continuous growth is the result.

Question 3

In the logistic model of population growth, the growth rate ___ as population size rises. The population stabilizes at the carrying capacity, the maximal population size the environment can sustain.

Answer 3

declines

The population stabilizes at the carrying capacity, the maximal population size the environment can sustain.

Question 4

Populations of species that are r-strategists are characterized by

Answer 4

exponential growth.
reproduce early in life
have many offspring that are small, mature rapidly, and receive little parental care.

Question 5

Populations of species that are K-strategists are characterized by

Answer 5

slow population growth.
reproduce late in life
have few offspring that are large, mature slowly, and often receive extensive parental care.

Question 6

Human populations have evolved with many of the characteristics of ___, however, the human population is now growing ___.

Answer 6

K-strategists

explosively.

Question 7

The Hardy-Weinberg principle states that

Answer 7

the frequencies of alleles and genotypes in a population remain constant unless evolutionary forces act on them.
This principle holds true only for large populations in which individuals mate randomly and in which forces that change the proportions of alleles are not acting.

Question 8

The five forces that can cause allele frequencies to change are

Answer 8

mutation,
migration,
nonrandom mating,
genetic drift,
and natural selection.

Question 9

Natural selection reduces the frequency of a harmful recessive allele slowly because

Answer 9

very few individuals are homozygous recessive and express the allele.

Question 10

Population

Answer 10

all the individuals of a species that live in one place at one time.

Question 11

Demography

Answer 11

statistical study of populations

Question 12

Population features:

Answer 12

Size
density
dispersion

Question 13

Size

Answer 13

number of population

Question 14

Large populations may be doing well, but

Answer 14

if in small area (high density) may run low on resources and more vulnerable to spread of contagious illnesses and excess waste.

Question 15

Small Populations - may be in danger of going extinct due to:

Answer 15

Inbreeding (mating with relatives) which increase number of homozygous genotypes. If more homozygous recessives, more change of recessive genetic disorder.
Less genetic diversity therefore less able to survive a new pressure
Difficulty in finding mates if in a large area

Question 16

Density

Answer 16

number per square unit

Question 17

Dispersion

Answer 17

pattern of positioning

Question 18

Types of dispersion

Answer 18

Random
Even
Clumped - most common… can indicate where resources are.

Question 19

Model

Answer 19

hypothetical population that has key characteristics of a real population uses previous data to predict future trends.

Question 20

Stage 1 Model:

Answer 20

r (rate of growth) = birth rate – death rate (all per 1000 per year)

Question 21

Stage 2 Model:

Answer 21

N=current pop.

ΔN (number added) = r x N

Question 22

Stage 3 (logistic)Model:

Answer 22

K = Carrying Capacity, population size the environment can sustain

ΔN = r x N x (k-n /k)

Question 23

Logistic model

Answer 23

accounts for decreasing resources available to a population as well as more waste and/or spread of contagious diseases… as population reaches K level.

Question 24

r-strategists characteristics

Answer 24

large populations due to large # of offspring and/or reach maturity fast,
little care of offspring,
exponential pop. growth,
good in unstable environment BECAUSE of the large population size and/or there quick reproduction cycle they have more genetic variation that enables them to respond to changes - they evolve/adapt quicker.

Question 25

K-strategists characteristics

Answer 25

small population sizes due to small # of offspring and/or long time to reach maturity,
much care of offspring,
slow pop. growth,
good in stable environments, highly specialized adaptation.

Question 26

Hardy-Weinberg principle

Answer 26

(in large populations with random mating) the populations do not change unless evolutionary forces act upon them.

Question 27

Hardy-Weinberg equation:

Answer 27

Allele frequency formula: p + q = 1

p = frequency of dominant allele (# of dominant allele/total pop.)
q = frequency of recessive allele (# of recessive allele/total pop.)

Question 28

Genotype frequency formula:

Answer 28

p2 + 2pq + q2 = 1

Question 29

Evolutionary forces that can quickly change allele and genotype frequencies:

Answer 29

For SMALL populations:
Migration – individuals (and alleles) moving out or into a population
Genetic Drift – frequency of allele changed by effects of chance event in small populations
Non-random Mating (Inbreeding) is a type of non-random mating that often happens in small populations where organisms have to mate with close relatives.
Disadvantages:
increased homozygous genotypes, less heterozygous…increased homozygous recessive genotypes=more genetic disorders
decreased gene pool=less variation to respond to change

For ALL populations:
Non-random Mating – species members selectively choose mates with specific traits.
Natural Selection – environmental forces select for or against traits. Only works on phenotypes.

Question 30

Mutation (in gametes)

Answer 30

little or no effect except when combined with natural selection but it IS the ultimate source of variation which enables evolution

Question 31

· Natural selection operates on

Answer 31

phenotype, not genotype.

Question 32

· Mutations of alleles mostly

Answer 32

recessive and destructive.

Question 33

Recessive alleles only expressed if

Answer 33

individual has two recessive alleles(both parents carry at least 1).

Question 34

Genetic polymorphism

Answer 34

significant frequency two or more types of phenotypes present in a pop.

Question 35

Polygenic trait

Answer 35

controlled by interaction of several genes. Results in Normal Distribution - “Bell” shaped curve for trait expression.

Question 36

Normal Distribution

Answer 36

“Bell” shaped curve for trait expression.

Question 37

growth of human population

Answer 37

10000 years ago - the development of agriculture increases K values
Black Death - increased death rates
1700s - better sanitation decreased death rate
1940s - vaccines & antibiotics decreased death rate
1960s - modern agro-chemical agriculture increases K values

Question 38

Directional selection

Answer 38

selection against (or for) one end of curve towards other

Question 39

Stabilizing selection

Answer 39

selection against ends favoring middle of curve.

Question 40

Disruptive selection

Answer 40

selection against middle favoring ends