carrying capacity and population growth with claims, evidence and reasoning

1. Do Now
• Define the different types of symbiosis and give an
example
– Commensalism –
• Example:
– Mutualism –
• Example:
– Parasitism –
• Example:

2. Do Now
• Define the different types of symbiosis and give an example
– Commensalism – a relationship in which one organism benefits and
the other is not affected
• Example: Barnacles on a whale
– Mutualism – a relationship in which both organisms benefit from
each other
• Example: Birds eating pest off a rhino’s back
– Parasitism – A relationship in which one organism benefits and the
other is harmed
• Example: Ticks on a dog

4. Population Growth and
Carrying Capacity

5. Principles of Population Growth
• Population is a group of organisms, all of
the samespecies, that live in a specificarea
at the same time.
• Population growth is defined as an
increase in size of a population over time…
• However, populations grow
at different rates.

6. Linear Growth
• If a population grew at a set amount each
year, say by 10 organisms per year, then the
population has LINEAR GROWTH
• However, populations normally do not have
linear growth. Linear growth looks like this
(Please draw in your notes)

7. Question
• Your parents give you two options for allowance
1. 1,000 a month
2. A penny on the first day of the month that
doubles to two pennies on the second day
and so on until the last day
of the month
• Which option do you choose?

9. .01 .02 .04 .08 .16 .32
.64 1.28 2.56 5.12 10.24 20.48 40.96
81.92 163.84 327.68 655.36 1310.72 2621.44 5242.88
10,485.76 209711.52 41943.04 83886.08 167772.16 335544.32 671088.64
1342177.28
2684354.56
5368709.12
10,737,418.24
Over 10 million!!
On 31 day months

10. Exponential Growth
• If you graph the allowance we just saw on the
graph it will look like this: (Please draw in your
notes)
0
2000
4000
6000
8000
10000
12000
14000
16000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

11. Exponential Growth
• A population that is growing without any limits,
would have exponential growth.
• Meaning that as the population gets bigger, it also
will grow faster
• But, populations cannot keep exponential growth
for very long, because the environment would
not be able to support it.

12. Exponential Growth

13. Carrying Capacity
• The environment has a CARRYING
CAPACITY for each population…
• Maximum # of organisms in a population
supported by an ecosystem’s
resources/limiting factors
– Effected by factors such as the amount of:
• Food, water, space, etc…
– Can change when these factors change
• EX: more food = higher carrying capacity!

14. Limiting Factors
• Definition?
Any biotic or abiotic factor that
causes population size to
decrease and influences what
can live where

15. Question
• What are some examples of things that can
limit growth?

16. Question
• What are some examples of things that can
limit growth?
– Food, space, ability to reporduce

17. What can limit growth?
• Limiting factors limit growth
• Different sizes of populations will also
have different factors affecting them.
• When growth has been limited its
graph will look like this:
(please draw in your notes)
0
200
400
600
800
1000
1200
1400
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

18. Claim
• Human beings have exceeded their carry
capacity on Earth

21. Reasoning
• What will cause the human population to go
down?

22. Reasoning
• What will cause the human population to go
down?
– Disease
– Starvation
– Weather events (hurricanes, tornados, global
warming)
– War/Crime
– Lack of fresh water
– Pollution

23. QUESTION: Interpreting Graphs and
Data
What happens
during the
“transitional
stage”?
a. Birth rates rise; death rates drop; population increases
b. Birth rates drop; death rates drop; population decreases
c. Death rates drop; birth rates are stable; population
increases
Figure 7.18

24. QUESTION: Viewpoints
Do you believe that national governments should
implement policies, subsidies, or other programs to
reduce birth rates?
a. No, not at all
b. Yes, but only positive incentives for fewer children
c. Yes—penalties for too many children
d. Yes, both incentives and penalties

25. Exit Ticket
• What is population growth?
• Describe the the difference between linear
and exponential growth?
• What is a carrying capacity?
• Name 3 reasons that the human population
may decline?

26. Centers
• Bill Nye Center
• Population Growth Center
• Otter Game – Counts as 2 centers