Chapter 53

Question 1

what is density?

Answer 1

density is the number of individuals per unit area or volume

Question 2

what is dispersion?

Answer 2

dispersion is the pattern of spacing among individuals within the boundaries of the population

Question 3

immigration vs emigration

Answer 3

immigration is influx of individuals from other areas
emigration is movement of individuals out of a population

Question 4

what happens in a clumped dispersion?

Answer 4

individuals aggregate in patches, may be influenced by resource availability and behavior (starfish, wolves, fish)

Question 5

what is a uniform dispersion?

Answer 5

in a uniform dispersion, individuals are evenly distributed (usually applies to birds on land when they are spread out)

Question 6

does territoriality apply to uniform dispersion or clump dispersion?

Answer 6

both uniform and clump dispersion can be influenced by territoriality, but not in random dispersion

Question 7

what is random dispersion?

Answer 7

random dispersion is the position of each individual being independent of other individuals, so mainly in plants, sexual structures dont know where they land

Question 8

what is a survivorship curve?

Answer 8

a survivorship curve is a graphic way of representing the data in a life table,

Question 9

what three types are survivorship curves classified into?

Answer 9

• type 1: low death rate in early life, but increase among elders (humans)
• type 2: constant death rate over life span (squirrels)
• type 3: high death rate for young and low death rate for survivors (oysters)

Question 10

what is exponential population growth and the equation?

Answer 10

exponential population growth is population increase under idealized conditions, rate of increase is at its maximum
- dN/dt = r(inst)N
- J shaped curve, rate of increase is constant, more individuals when time is large

Question 11

what is carrying capacity (K)?

Answer 11

carrying capacity is the maximum population size the environment can support

Question 12

can exponential growth be sustained?

Answer 12

exponential growth cannot be sustained for long in any population

Question 13

what is the logistic population growth model? equation?

Answer 13

the logistic population growth model, the per capita rate of increase declines as carrying capacity is reached, starts with exponential but adds an expression that reduces per capita rate of increase as N approaches K
- dN/dt = r(inst)N (K-N)/K

Question 14

How do you interpret the (K-N)/K

Answer 14

• When N is small compared to K, the expression is close to 1 and the per capita rate of increase approaches the maximum
• When N is large compared to K, the expression is close to 0 and the per capita rate of increase is small
• When N is equal to K, the population stops growing (Zero population growth)

Question 15

What happens in species that exhibit semelparity?

Answer 15

they reproduce once and die

Question 16

What happens in species that exhibit iteroparity?

Answer 16

they produce offspring repeatedly

Question 17

What is K selection?

Answer 17

K selection, aka density-dependent, selects life history traits that are sensitive to population density
(produce a little offspring so they can take care of them well and make them suitable for life)

Question 18

What is R selection?

Answer 18

R selection, aka density-independent selection, selects for life history traits that maximize reproduction
(produce a lot of offspring so some survive)

Question 19

what happens with birth and death rates in density independent (R selection)?

Answer 19

birth and death rates do not change with population density

Question 20

what happens with birth and death rates in density dependent (K selection)?

Answer 20

in density dependent, birth rates fall and death rates rise with population density

Question 21

what type of feedback are density dependent birth and death rates?

Answer 21

density dependent are negative feedback, population gets smaller when it gets really big

Question 22

what do intrinsic factors play a role in?

Answer 22

in density-dependent birth and death rates, along with many other factors such as resources, disease, predation

Question 23

what are intrinsic factors?

Answer 23

intrinsic factors are physiological factors that can regulate population size

Question 24

examples of intrinsic factors?

Answer 24

in mice, overcrowded environment can cause hormonal changes and aggressiveness that increases mortality
in elephants, stress messes with hormones and slows reproduction

Question 25

what is the trade off between survival and parental care?

Answer 25

normal amount of offspring are likely to get good care and survive (but may die of infection or predation), too many offspring can cause parents to get worn out and offspring may die

Question 26

what are two ways to maintain population stability in humans?

Answer 26

zero population growth = high birth rate & high death rate or low birth rate & low death rate

Question 27

what is the demographical transition?

Answer 27

going from high birth rate high death rate to low birth rate low death rate

Question 28

what is demographic transition associated with in terms of women?

Answer 28

increasing health care and education may lower birth rates for women

Question 29

what is age structure?

Answer 29

the relative number of individuals at each age