Topic 16

Question 1

What factors influence population growth (b, d, r) in crowded populations (at high N) ?

Answer 1

• intraspecific competition increases
• predator density increases
• parasite density
• disease

Question 2

Density dependence may reduce growth, survival and reproduction of individuals in a population thereby affecting….

Answer 2

population growth through b and d (r) with increased crowding

Question 3

Logistic model of population growth primary underlying assumption

Answer 3

factors limiting population growth exert stronger effects on b and d as a population grows

Question 4

Under the logistic model of population growth K represents a..

Answer 4

stable equilibrium around which the population size fluctuates

Question 5

Degree of fluctuation often due to..

Answer 5

time delay in feeling the effects of increased population density

Question 6

Density independent factors

Answer 6

environmental (temp, precipitation). influence b and d and reproduction rates

Question 7

If changing environmental conditions exceed an organisms range of tolerance then..

Answer 7

growth, reproduction, maturation, survival and dispersal can all be altered

Question 8

Spruce bud work outbreaks are connected to

Answer 8

long periods of drought, outbreaks end when moist conditions return and are beyond their tolerances

Question 9

Density dependent factors tend to bring populations under..

Answer 9

control and maintain their size close to K (cause of biotic factors, competition)

Question 10

Density independent factors tend to reduce populations far below..

Answer 10

K and initiate periods of population recovery (abiotic factors, temp, environment)

Question 11

The relative importance of DD and DI factors will depend on

Answer 11

• intensity and frequency of environmental fluctuations

- life history characteristics of population in question

Question 12

DD factors likely interact with DI factors in a

Answer 12

complex way to cause variable patterns in population size

Question 13

Sustainability

Answer 13

matching quantities of harvest rate to rate of population growth (supply rate = demand rate)

Question 14

We want to harvest the max number of individuals from a population without …

Answer 14

diminishing ability of the population to regenerate over the long term

Question 15

Yield

Answer 15

number of individuals of a species harvested per unit time

Question 16

Sustainable yield objective

Answer 16

ensure a similar yield at each harvest

Question 17

Assumptions of sustainability

Answer 17

species or resources are renewable (resupplied)

Question 18

If non renewable

Answer 18

harvest if never sustainable. ex: mineral resources (copper) can be recycled efficiency reduces harvest rate (demand)

Question 19

If renewable at slow rate

Answer 19

harvest is non sustainable. ex: fossil fuels, supply rate is around 0 at the rate of human consumption

Question 20

If renewable at fast rate

Answer 20

to be sustainable the demand rate should not exceed the supply rate, otherwise the population will decline

Question 21

Maximum sustainable yield (MSY)

Answer 21

largest average harvest/yield that can be continuously taken from a population without causing a population decline (supply > or = harvest/yield)

Question 22

MSY goal

Answer 22

maximize economic gains. harvest rate = replacement rate

Question 23

We can to keep N where..

Answer 23

r is the highest

Question 24

The rate of change of a population is max at

Answer 24

K/2

Question 25

Intermediate population sizes have the..

Answer 25

greatest growth rate (or ability to produce the max number of harvestable individuals)

Question 26

Opitimist harvest (economic gains) by ...

Answer 26

harvesting enough individuals to keep the population at intermediate sizes (K/2)

Question 27

Problems w MSY

Answer 27

- hard to quantify N at given time - environmental conditions constantly change K, so difficult to quantify K/2 - density independent factors can be unpredictable causing high mortality and reducing N - age structure of pop. chance. r depend on age specific b and d rates - failure to incorporate economics

Question 28

Examples of problems a MSY

Answer 28

fisheries. if reduce harvest fishers cannot maintain payments, wages of crew = unemployment. politicians will lose votes as fishers lose livelihood.