Sponge: Set up Cornell Notes on pg. 19
Topic: G5 Population Ecology
Essential Question: Describe the major
differences between r-strategists and Kstrategists. Include examples.
BIOZONE: 232-236 due Thurs
G5 Population Ecology
Describe the major differences between r-strategists
and K-strategists. Include examples.
Key Vocabulary:
r-strategy
K-strategy
BIOZONE: 232-236
Which of these two organisms is most likely to
survive an ecological disaster which caused
extreme changes in both terrestrial (land) and
aquatic ecosystems?
Zebra Mussel
Zebra
Which of these two organisms is most likely to survive an ecological disaster which caused
extreme changes in both terrestrial (land) and aquatic ecosystems?
• In order to answer this question properly, we need to understand some background
information about the animals in question:
• With your table, make a list (whiteboards- 2 per table) of everything you know about the
habitat (environment), reproduction (offspring #/parenting styles/reproduction rate),
growth rate, food habits, life span, size…. of the zebra mussel or zebra (feel free to use
internet on phone)
Zebra Mussel
P. 18
Zebra
Zebra Mussel
• Live 4-5 years
• Unstable environment
• Lays thousands of eggs which
hatch into free swimming larvae
• Most of the eggs will die (eaten)
• Hundreds will survive
• No parental care
• In the event of an ecological
disaster: A few would be likely to
survive
• Known as r-strategy
Zebra
• Live up to 40 years
• Requires a stable environment
• Long gestation period (pregnancy)
during which the mother needs good
nutrition
• Baby zebra need maternal care
• Savannah must have enough food
• In the event of an ecological disaster:
The few offspring produced would
NOT survive
• Known as K-strategy
Assessment Statement
• G.5.1 Distinguish between r-strategies and K-strategies
P. 19
r-strategist
(rate)
K-strategist
(K=carrying capacity)
K-strategists
• Organisms that live in stable environments tend to make few,
"expensive" offspring.
• K-selected species— species whose population sizes fluctuate at or
near their carrying capacity (K)
r-strategists
• Organisms that live in unstable environments tend to make many,
"cheap" offspring
• r-selected species, also called r-strategist, species whose
populations are governed by their biotic potential (maximum
reproductive capacity, r, or rate)
Assessment Statement
• G.5.2 Discuss environmental conditions that favor either rstrategies or K-strategies
• Use whiteboards to brainstorm:
• Life span:
• Size:
• Reproduction rate:
• Offspring #s:
• Parental care:
• Growth rate:
• Type of environment they live in:
• Includes examples of animals
r- Strategy
K- Strategy
•
•
•
•
• Nurturing
• Larger animals- almost all
mammals
• Long life span
• Few offspring
• Later maturity-grow slowly
• Large body size
• Produce offspring more than
once during life span
• Parental care likely
• Stable environment
•
•
•
•
•
“disposable offspring”
Mostly insects
Life span short
Many offspring- most are
lost
Early maturity-grow quickly
Small body size
Usually only reproduce once
during lifetime
No parental care
Unstable environments
Ecological Disruption:
• Favors r-Strategists!!!!!
• If you call something a “pest”, its likely an r-strategist
• It is adapted to become established quickly before its competitors get
a foothold
• In a balance ecosystem, the r-strategists have interactions with other
species that control their numbers (they get eaten)
Sponge: Set up Cornell Notes on pg. 21
The Population Explosion
Topic: The Population Explosion
Essential Question: None.
BIOZONE: 232-236 due Thurs
BIOZONE: 232-236
The Population Explosion
Overpopulation
• It took the ENTIRE history of humankind for the population to reach 1
billion in 1810
• Just 120 years later, it was 2 billion (1930)
• 4 billion (1975)
• 7.2 billion (2014)
• 9.7 billion (2050)?
Current and Projected World Population by 2050
North America- United States
The World
Africa- Congo
The Causes….
• Until recently, birth and death rates were equal
• People had a lot of children, but many of them died before the age of 5-6
• During the Industrial Revolution:
• Increases in food production/distribution
• Improvement in public health (water/sanitation)
• Medical technology (vaccines/antibiotics)
The Consequences…
• Population grows fastest in the world’s poorest countries
• High poverty usually equals high fertility and high infant mortality
• But infant mortality rates are dropping due to improved standards of living
• That leaves a huge % of the world’s population as young people in child bearing
years
• Which means we need to…
• Meet food/water needs
• Health care/education
• Try and control poverty levels
Any real advances in well being are negated
by further population growth!
Population Reference Bureau (3m35s)
• https://www.youtube.com/watch?v=d1dIAtvSFLM
Solutions….
Table Discussion: 2014 Population Reference Bureau
1. Current country with top population?
2. Projected 2050 country with top population?
3. What is the average children, per female, in a Nigerian family?
4. What country is having the least amount of children per family?
5. Why might less developed countries have a higher birth rate than more developed
countries?
6. What is the World percentage of infant deaths per year vs. births per year?
(death#/birth# x 100)
7. What is the difference in percentage of infant deaths in less developed countries to
more developed countries? (find % for more and less developed then subtract)
8. Worldwide how many infants die per minute?
9. How many people worldwide live on less that $1.25 a day? Where?
10. Take a look at the world population pyramids. What might explain Africa’s almost
perfect pyramid shape vs. Europe’s “bush” shaped pyramid?
11. What might explain the drastic difference in maternal mortality in undeveloped
countries vs. developed countries?
Homework/Classwork
• Please read “The Population Explosion: Causes and Consequences”
• Highlight important details
Sponge: Set up Cornell Notes on pg. 23
Population Decline Case Study:
Why Have all the Sea Lions Gone?
• Topic: Population Decline Case Study: Why Have
all the Sea Lions Gone?
Essential Question: None.
BIOZONE: 232-236 due Today!!!
BIOZONE: 232-236
Please open them to
pg. 226 and turn in
to Mrs. McC
“Mystery in Alaska: Why Have All The Sea
Lions Gone?”
Background Information: Steller Sea Lions
• Please read/highlight the Steller Sea Lion information sheet
• Note key details on their diet (food habits), population size, and
predators/hunting
“A Mystery in Alaska”- Clip
• https://www.youtube.com/watch?v=_fBneJlJwZU
• Please take 5-10
bullets on the video
on pg. 22
Mystery in Alaska
With a Partner please read and answer the questions in the case study
• Part I
• Part II
• Part III
• Make sure you do the calculations properly!
Discussion to Follow
Discussion Questions
• What were several possible reasons for the decline of the Steller Sea Lion
population?
• How would the shift in fish populations affect the diets of the Western and Eastern
stocks of sea lions? (decrease Herring, increase Pollock)
• Describe an experiment that could be used to test your hypothesis for why the
Western stock #s were decreasing, but the Eastern stock #s were slowing increasing.
Make sure to include your hypothesis.
• What experiment was conducted at the Vancouver Aquarium to compare the effects
of eating Pollock and herring?
• Based on your calculations, which fish better meets the energy needs of the Steller
sea lions?
• Why do you think the sea lions lost weight when they were aloud to eat unlimited
amounts of Pollock in the experiment?
• What is the significance that sea lion pups were affected more than adults? Why
were they especially impacted?
Steller Sea Lion Population Decline and
Increase
The Good News…