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Flashcards in BIO220 Lecture 19 Deck (64)
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1

Humans are a very unique species that need an ___ perspective, and have ___, ___, ___ issues.

ecosystem;
political;
sociological;
ethical

2

The carrying capacity of the Earth is limited by...

- food supply
- land (space)

3

What impact do humans have on natural systems?

- population size
- consumption
- technology
- affluence (have a lot of money)

4

Growth trajectory: shape & assumptions

shape: density-dependent, exponential
assumptions: rates are constant, [births + immigration] > [death + emigration]

5

immigration vs. emigration

immigration: move into population
emigration: move out of population

6

problem with growth trajectory model

too simple, populations cannot continue to grow unchecked

7

model/formula for exponential growth trajectory

dN/dt = rN
N_t = (N_0)(e^rt)

8

with is the simplest model of density-dependent regulation of growth?

logistic growth model
- dN/dt = rN[(K-N)/K)
- sigmoidal curve
- carrying capacity K

9

what was the first really successful ecology textbook?

The Great APPES
by Allee et. al

10

in the mid-20th century, ___ was viewed as an ecological law

logistic growth model

11

What was was predicted by Allee et. al in 1940's regarding human growth?

Human population should level off at 2.6 billion (predicted until 2010)
Current population: 2.4 billion

12

What is the current population (2011)?

7 billion +

13

Human population growth curve looks...

exponential rather than logistic

14

Why did extrapolating from logistic growth model give poor prediction for human growth?

Statistical error:
- extrapolating is dangerous
- logistic curve is too simple
Biological:
- logistic allows no overshoots
- logistic assumes r and K are constant

15

If we allow populations to overshoot K, what will the population model look like?

- dramatic overshoot (exponential growth)
- dramatic crash (exponential decrease)
= sinusoidal wave (mean of wave is K)

16

Why is current human population growing so fast?

- birth rate has always been high, but now, death rate is very low (technology, medicine, sanitation, nutritious foods)
- slightly increase in fertility
- increased K due to changes in agriculture (genetics, machine, fertilizers, biocides)

17

Growth (r) depends on...

fertility rates (bx) & mortality (inverse Lx)

18

What is the UN's guess about human growth trajectory?

level off at about 9 billion (maybe)

19

current observations on human growth trajectory

still growing exponentially, but much slower
- 2% growth/year (x^2) -> 1.2% (x^1.2)
- 74 million increase/year

20

leveling off the growth trajectory requires...

- less birth
- more deaths

21

___ structure affects trajectory

age

22

Shape of age pyramid: fast-growing populations

high momentum;
broad base, small tip: even if r = 0, populations keep growing as children reach reproductive age

23

shape of age pyramid: slow-growing populations

low momentum;
broad middle

24

Who made the first estimate of human capacity of earth? What was his estimate?

Antoni van Leewenhoek;
13.4 billion
- estimated land area of globe & applied density of Holland

25

Leewenhoek invented...

the microscope

26

What was seen in Cohen's history of K estimate?

the carrying capacity prediction varies more as times are more modern

27

The real answer to human K depends on...

how people are living

28

Who said that human K depends on how people are living?

Lester Brown

29

Current food production can support ___ people if we consume like India

10 billion

30

Current food production can support ___ people if we consume like Canada/US

2.5 billion