APES Review 6 Populations
Population Ecology-Populations interact with the
environment.
-Useful understanding for
Conservation efforts
-Most organisms live in groups
Adv.: protection from predators,
increased mating, division of labor
Factors that Affect Population
Viability:
- Environmental Conditions
- Birth Rate
- Presence of competitors
- Predatory defense mechanisms
- Resistance to disease
- Ability to migrate
- Ability to adapt
- Food supply
Biotic Potential
-Max. rate at which a pop. Can
grow.
-Resources are unlimited
-factors that affect biotic pot.: age
at reproduction, freq. of reprod., #
of offspring, life span, death rate
J Curves
- Happens when a pop is left
unchecked. (exponential)
(arithmetic-linear)
(geometric – exponential)
S Curves
Population growth reaches carrying
capacity and levels out.
- Density dependent
- Initial growth due to unlimited
resources, but pop stabilizes
when resources become scarce.
r-strategists – small body, grow fast,
pops. Grow exponentially, then
crash, large populations, unstable
environments, low diversity, low
resources, offspring independent
soon, type III survorship, weeds,
insects, rodents etc.
Density-Dependent Factors
- Intensifies as pop. Size
increases. Greater effect on
individuals
- Less food, fewer offspring,
limited terretories, predators
concentrate on smaller groups
r-strategists Reproductive Char.
-mature rapidly
-short life span
-tend to be prey
-many offspring (overreproduce)
-low parental care
-not endangered
-pop size limited by Dens. Dep.
factors
Historical Human Population Sizes
- pop boom due to low death
rate
- 1900 – death rate 1 .7%
2000 -= .9 %
- Increased food production,
more efficient distribution of
food, medical, sanitation,
health and hygiene
improvements, safer water
K-strategists Reproductive Char.
-mature slowly
-long lived
-both predator and prey
-high parental care
cockatoo
Carrying Capacity
- Max. # of ind. that can be
supported by the resources
available in a given population.
- CC will decrease with
environmental decline.
- Regulatory Factors- food,
space, O2, nutrients, sunlight
- If CC decreases, the pop.
Decreases
- If pop. Exceeds the CC, pop will
not be sustained.
Thomas Malthus
- 1798 mathmatician Theorized
exponential growth.
- Malthusian catastrophe – pop.
Growth outpaces agricultural
production. Back to
subsistence.
- Economics or unequal
distribution cause malnutrition
and starvation.
Density-Independent Factors
- unrelated to pop. Size and
affect all individuals.
- weather, climate, natural
disasters, seasonal changes,
hurricanes and fires
K-strategists – opposite of r
Human Population Surges
- use of tools and fire
- agricultural revolution
- industrial lrevolution with
better medical technologies
Population Change Calculation
(BR +immigration) – (DR +
emigration)
Ex. In 1950 pop was 20,000. BR = 25
per 1,000. DR = 7/1,000. IM = 600
per year, EM=200/yr
Rule of 70
Doubling time = 70 yrs/annual rate
of population change (%)
Pop Growth 8000BCE-5000BCE
Pop Growth 5000BCE-1650CE
Pop Growth 1650BCE-Present
Pop Growth Present-2050
Human Pop. Distribution
Questions:
1. Of the following terms for population growth graphs, which are synonymous? Logistical, logarithmic,
exponential, sigmoidal, J-shaped, S-shaped
2. Draw a labeled example graph of a population that is growing exponentially and one that is growing
logistically
3. Describe the differences in situations that result in the two types of graphs drawn I n the previous question.
4. Predict outcomes of exponential population growth and logistic population growth.
5. Draw a graph with the independend axis as “latitude”and the dependent axis as the “number of species”.
What would the graph look like.
6. For any (or several different) regions(s) of the earth, name a species that is non-native in each category:
river animal, terrestrial animal, terrestrial plant, terrestrial fungus. Describe how each species was introduced,
its niche, its survival strategy and the specific way(s) in which it has impacted the local flora and fauna.
7. What is the difference between a keystone and an indicatory species?
8. Using an example, explain how competition between species and within a species is dealt with over time.
9. Using an example, explain each term: symbiosis, predation, parasitism, mutualism, co-evolution, mimicry,
and commensalism.
10. Explain succession by giving an example of the progression of an ecosystem from primary succession into
late secondary succession. How long would this process take and how would the biotic and abiotic factors
change over this time.
11. Describe what is meant by carrying capacity. Explain how populations can exist far above or below the
carrying capacity.
12. Name three density-dependent and three density- independent factors that affect carrying capacity.
13. Give an aquatic and terrestrial example of a species that is an r-selected species and list 5 characterisitics
of the niche/survival strategy of each. Repeat the process for a K-selected species.
14. Graph the predicted growth patterns of an r-selected species and a K-selected species introduced to a new
environment. Describe the advantages and disadvantages of each type of species.
15. Name 3 fast-growing countries, one with a large population, one with a medium size population and one
with a relatively small population. Do the same for three slow-growing countries.
16. Define TFR and explain why it must drop below the replacement value in order to achieve ZPG.
17. Name 5 things (in order from the greatest to the least impact) that affect population growth. Support your
response with facts and examples.
18. Draw an age structure histogram for a country with rapid growth, zero growth, slow growth, and negative
growth