Topic 16 Flashcards Preview

Biol 2390 > Topic 16 > Flashcards

Flashcards in Topic 16 Deck (28)
Loading flashcards...
1
Q

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

A
  • intraspecific competition increases
  • predator density increases
  • parasite density
  • disease
2
Q

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

A

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

3
Q

Logistic model of population growth primary underlying assumption

A

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

4
Q

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

A

stable equilibrium around which the population size fluctuates

5
Q

Degree of fluctuation often due to..

A

time delay in feeling the effects of increased population density

6
Q

Density independent factors

A

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

7
Q

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

A

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

8
Q

Spruce bud work outbreaks are connected to

A

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

9
Q

Density dependent factors tend to bring populations under..

A

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

10
Q

Density independent factors tend to reduce populations far below..

A

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

11
Q

The relative importance of DD and DI factors will depend on

A
  • intensity and frequency of environmental fluctuations

- life history characteristics of population in question

12
Q

DD factors likely interact with DI factors in a

A

complex way to cause variable patterns in population size

13
Q

Sustainability

A

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

14
Q

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

A

diminishing ability of the population to regenerate over the long term

15
Q

Yield

A

number of individuals of a species harvested per unit time

16
Q

Sustainable yield objective

A

ensure a similar yield at each harvest

17
Q

Assumptions of sustainability

A

species or resources are renewable (resupplied)

18
Q

If non renewable

A

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

19
Q

If renewable at slow rate

A

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

20
Q

If renewable at fast rate

A

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

21
Q

Maximum sustainable yield (MSY)

A

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

22
Q

MSY goal

A

maximize economic gains. harvest rate = replacement rate

23
Q

We can to keep N where..

A

r is the highest

24
Q

The rate of change of a population is max at

A

K/2

25
Q

Intermediate population sizes have the..

A

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

26
Q

Opitimist harvest (economic gains) by …

A

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

27
Q

Problems w MSY

A
  • 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
28
Q

Examples of problems a MSY

A

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