Download Population Sampling Methods Sample Problems

IB Senior Review
Chapter 52: Population Ecology
Population Ecology
Population—
A group of individuals of the same species
living in a particular geographic area
Population Ecology—
Concentrates mainly on the factors that
affect how many individuals of a particular
species live in an area
Exponential Growth
Species
Immigration
Density
Sigmoid/Logistic Growth
Mortality
K-Strategy Growth
r-Strategy Growth
Demographic
Emigration
Carrying Capacity Exponential Growth
Natality
Life History
Species
1. ____________
A group of organisms that can interbreed and produce fertile
offspring.
Density
2. ____________
Number of individuals per unit area or volume. Ex. White Oak
trees per square kilometer in Potter County Pennsylvania
3. Demographic
____________ The study of the rise and fall of population sizes over time
Natality
4. ____________
Rate of Birth (# of individuals in a given period of time)
Mortality Rate of Death (# of individuals in a given period of time)
5. ____________
Immigration The movement of individuals into a population
6. ____________
Emigration The movement of individuals out of a population
7. ____________
Cap. The maximum population size that can be supported by the
8. Carrying
____________
available resources, symbolized by K.
9. Exponential.
___________ The geometric (larger the quantity gets, the faster it grows)
increase of a population as it grows in an ideal, unlimited environment
Sigmoid A model describing population growth that levels off as
10. __________
population size approaches carrying capacity
HistoryThe series of events from birth through reproduction and death
11. Life
__________
r-Strategy The concept that in certain populations, a high reproductive rate
12. __________
is the chief determinant of life history and survival
13. K-Strategy
__________The concept that in certain populations, life history is centered
around producing relatively few offspring that have a good chance of survival
Think back to the Wissahickon Trip.
How did we measure avian biodiversity?
Simpson’s Biodiversity Index
D = Σ(n(n -1) / N(N-1)) … 1-D
Where:
D = Bias corrected form for Simpson Index
n = Number of individuals of one species
N = Total number of individuals in community
1-D = Relative biodiversity (the closer to 1, the more
diverse the community)
Simpson’s Index Sample Problem:
Which community is more diverse?
Community #1
3 Chickadees
6 Robins
9 Carolina Wrens
2 Blue Jays
Total: 20
(3 (3-1) + 6 (6-1) + 9 (9-1) + 2(2-1))
(20 (20-1))
Community #2
3 Downy Woodpeckers
2 Robins
6 Crows
2 Carolina Wrens
Total: 13
(3 (3-1) + 2 (2-1) + 6 (6-1) + 2(2-1))
(13 (13-1))
D = 110 / 380 = .29
D = 40 / 156 = .26
1-D = .71
1-D = .74
Define the term random sample.
A sample where every member of a population
(plant or animal) has an equal chance of being
selected
Sample selected without bias
Why is it important to take random samples?
To ensure the data taken for the biodiversity or
population size/distribution indices represents
the whole population
What is one method for estimating
animal population sizes?
Lincoln Index/Mark-Recapture Method
(“hunting forks” activity)
Population size = ((n1 x n2) / n3)
Where
n1 = number of individuals initially caught,
marked, and released
n2 = total number of individuals caught in the
second sample
n3 = number of marked individuals in the
second sample
What is one method for
estimating plant distribution?
Quadrat Transect Method
Transects are distributed evenly across the entire site so all
plants may be sampled
Each quadrat is spaced evenly along the transects, again so
all plants have the chance of being sampled
The percent of area covered by each plant species is
estimated within each quadrat which 1 meter squared in
size
Each of these total species percentages is divided by the
total quadrat percentages (100% for one quadrat, 200% for
two quadrats etc.) to get the relative percentage of each
plant species
Calculating the yearly change in population
Change in population size per year =
births – deaths + immigration - emigration
Often, immigration and emigration are said to
cancel out, so unless otherwise stated, assume
immigration – emigration = 0
MC- 1. A population of ground squirrels has an
annual per capita birth rate of 0.06 and an
annual per capita death rate of 0.02. Estimate the
number of individuals add to or lost from a
population of 1,000 individuals after one year.
a. 120 individuals added
b. 40 individuals added
c. 20 individuals added
d. 400 individuals added
e. 20 individuals lost
(1000 x 1.06) – (1000 x 1.02) = + 40 individuals
Population Growth Curves
Exponential Growth
K–––––––––––––
Unrestricted growth
Sigmoid/Logistic Growth
Exponential phase
natality much higher
than mortality
Transitional phase
natality higher than
mortality
Plateau phase
natality = mortality
Plateau
Transitional
Exponential
What is the general ecological feature
that limits population growth?
Carrying Capacity –
The maximum number of individuals of one
species the environment can support based on
available resources
These resources are known as densitydependent factors
Means the size of the population is dependent on
these factors.
MC-2. Which of the following
statements correctly describes the
carrying capacity of an environment?
a. The maximum rate of population
growth for a species.
b. The area of land that can support a
denned population of species.
c. The minimum population of a species
that can be sustainably supported by
a given environment.
d. The maximum population of a species
that can be sustainably supported by
a given environment.
MC-3. As N approaches K for a certain
population, which of the following is
predicted by the logistic equation?
a. The growth rate will not change.
b. The growth rate will approach zero.
c. The population will show an Allee
effect.
d. The population will increase
exponentially.
e. The carrying capacity of the
environment will increase.
Name some density-dependent factors.
Food supply
Water supply
Breeding/nesting sites
Habitat/shelter
Predator-prey relationship
Disease
Territory
MC-4. Which of the following can
contribute to density-dependent
regulation of populations?
a. the accumulation of toxic waste
b. intraspecific competition for nutrients
c. predation
d. all of the above
e. none of the above
r- and K-Strategy Growth
Only HL kids need to know this in depth
r-Strategy Growth
high reproductive rate
little or no investment in offspring
short lives
small size
can adapt to variable environments
K-Strategy Growth
low reproductive rate
large investment in offspring
long lives
large size
prefer stable environments
MC-5. All the following characteristics are
typical of an r-selected population except
a. occurrence in variable environments
b. high intrinsic rate of growth
c. onset of reproduction at an early age
d. extensive parental care of offspring
e. occurrence in open habitats
IB Exam Question
1. Describe a method, used by ecologists, for
estimating accurately the size of a plant
population.
(Total 4 marks)
divide sample area using transects;
use quadrats;
position them randomly;
count the percentage of coverage of the plant
species in each quadrat;
count as many quadrats as possible;
total (density) = total percentage of one
species / total percentage (per meter squared)
IB Exam Question
2. The data shows the number of flowers per flower head
of a random sample from a white clover (Trifolium repens)
population. 36
51
56
62
62
63
65
69
73
83
Mean = 62
Standard deviation = 12.5
What statistical percentage of the population has between
49 and 75 flowers per flower head?
A. 5 %
B. 32 %
C. 68 %
D. 95 %
IB Exam Question
3. Describe the use of one technique that ecologists use
to estimate accurately the size of a population of
animals, including details of any calculations that need
to be done.
(6 marks)
capture-mark-release method;
capture a sample of population;
example of method of capture (cages…);
mark each captured individual and release;
allow to settle back into the environment/ wait at
least 24 hours/ until randomly dispersed;
recapture as many individuals as possible;
count the marked and unmarked individuals;
Lincoln Index calculation:
number marked originally x recaptured
number marked and recaptured
IB Exam Question
4. Discuss why an index of diversity could be
useful in monitoring environmental change.
(3 marks)
an index of diversity is a measure of species
diversity;
can be used with plant or animal species;
index diversity of species is a measure of health /
stability / degree of stress of an environment;
comparison of two values is a measure of change for
better or worse;
data can be used for policy decisions regarding the
environment;
measure of species richness / diversity;
low diversity indicates environmental stress;
IB Exam Question
5. State three factors that can affect the
distribution of animal species. (1 mark)
temperature,
water,
breeding sites,
food supply,
territory,
predation,
competition
IB Exam Question
6. Explain the reasons for the sizes of animal
populations within communities changing and
the reasons for them staying the same. (8 marks)
Natality/ birth / reproduction increases populations;
As long as natality is higher than mortality;
Abundant food allows increase / food shortage causes
decrease;
Low levels of predation allows increase / high level
causes decrease;
Low level of disease allows increase / high level causes
decrease;
Immigration increases populations;
As long as immigration is higher than emigration;
Population rise until a plateau is reached;
This is the carrying capacity of the environment when
the resources of the environment cannot support any
more individuals
IB Exam Question
7. Describe with the aid of a diagram the phases
of a sigmoid population growth curve. (4 marks)
K–––––––––––––––––
2
1. (exponential) – rapid increase in population;
2. (transitional) – slowing of growth;
3. (plateau) – leveling off, birth rate = death rate;
carrying capacity labeled;
Next Week
There will be a short quiz on this chapter,
including some IB data-based questions.
Please study these notes. If you want me to
email them to you, please drop me a note at
[email protected]
I will try to get the notes on Mr.Herb’s
website.
Remember, we are not covering everything,
just the major topics. You also need to study
on your own.