Lecture 20 Flashcards

1
Q

what is the eq for pop growth?

A

delta N / delta t = births - deaths + immigrants - emigrants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the eq for the rate of change in pop size

A

delta N / delta t = rN

r = b-d
r = rate of increase per individual

b= birth rate
d= death rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When does exponential growth happen in pops

A
  • only occurs in pops with unlimited resources that are able to reproduce at a max rate, after:
    a) introduction to a new environment
    b) recovery from a disaster (few competitors)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the eq for exponential growth

A

dN/dt = rN

differential rate eq in calc, where growth rate is independent of density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

explain what happened during the mouse plague in australia 2021

A
  • wet year with high grain harvest
  • lots of stored wheat that was invaded by mice that can produce new offspring every 3-4 weeks
  • invading houses in search of more food as competition for food increases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does the carrying capacity (k) mean?

A
  • max number of individuals that a particular environment can support
  • k is affected by the availability of resources (ex. light, nutrients, water, territory, nesting sites, etc) and provides a limit to continued pop growth

ex. damaged coral reef = very low k for fish
productive reef = high k for fish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

explain logistic growth

A
  • as a pop approaches k, density dependent factors will affect b and/or d, and N and other parameters.

Either:
- intraspecific (within species)
- interspecific (between species)

ex.
- competition for resources
- behavioural changes like conflicts, reproduction declines, infanticide, cannibalism
- disease or predation

  • creates logistic curves!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  • gwhat is the eq of a logistic growth curve?
A

dN/delta t = rmaxN * (k-N)/k

when N is small, expression is close to 1 bc (1000-10)/1000 = 0.99 and exponential growth continues

when N is large, (1000-900)/1000 = 0.1, the expression gets smaller and slows the rate of growth (by 90%)

when N is at carrying capacity (k=N), the expression is 0, and growth stops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What affects the carry capacity of humans? how can we increase k?

A
  • food production capability (increase k!)
  • increase agricultural areas? fish farms? greenhouse areas in non-arable land? etc.
    BUT
    all solutions have consequences, especially for non-humans
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the current global average fertility rate?

A
  • 2.5 children per woman
  • above the replacement rate of 2.1 children per woman, which replaces her and one male
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

explain Anthropocene!!!

A
  • an Earth whose future is controlled by activities of the human pop
  • maximizing k for humans will have negative effects on most other species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly