SBI4U
Independent Study - Population Dynamics – PART II
Read pages 509 in your textbook and then answer the following questions.
Changes in Populations
1) What are the four factors that influence a species change in population?
Which of these factors are often ignored and why?
Births, Deaths, Immigration and Emigration
Immigration and emigration b/c they are roughly equal
2) In what types of scenarios I is important to measure a species population
growth rate?
Expanding quickly and endangered populations
3) Answer Learning Check question #10 and #11.
10) 700 geese per year (3600-1500)/3
11) Population A shows a greater increase because its population started
out with a higher initial population. To make for a more meaningful
comparision of the change in population size, one would want to compare
the rate of change per individual (otherwise known as per capita)
4) Explain the meaning of the term “biotic potential”. What factors influence
the biotic potential of a species?
Biotic Potential – highest possible per capita growth rate for a population
Based on: number of offspring/reproductive cycle, number of offspring that
survive long enough to reproduce, age of reproductive maturity, number of
individuals that reach reproductive maturity, lifespan
5) Draw well-labelled graphs showing exponential and logistic growth.
Indicate what type of environment would precipitate each type of growth
model.
See diagrams on p. 514 and 515
Exponential seen when resources are unlimited such as in a lab setting
Logistic is seen when resources are limited
6) Define “carrying capacity”. What factors influence what this carrying
capacity will be? (ie. “limiting factors”)
Carrying capacity is the max population size that a habitat can sustain
over an extended period of time (with available resources)
7) Compare organisms that have r- and K life strategies. Do this in the form
of a table. Provide an example species for each life strategy.
See p. 517-518
8) Answer Question #12 on p. 519.
See graph on p. 516 which really shows the influence of limiting factors
and how population will fluctuate around carrying capacity
9) Answer Questions #41 and #42 on p. 543 and Questions #62 and #64 on
p. 545.
Q41
Foxes will bring down hare population, allowing their population to
increase dramatically. Over time, hares will reach a new carrying
capacity, as the environment can only hold so many foxes. Foxes will
reach a carrying capacity. Their populations will likely be correlated to
each other. In other words, when hares rise, foxes will have a latent
rise… when hares decline, foxes will have a latent decline
Q42
Pick an abiotic (non-living) factor (eg. sunlight) and draw connections to
how the factor could limit population growth
Q62
Strategies include but are not limited to.
Using a range of different pesticides to deal with the insects
Introducing a predator that would consume the insects
Finding an alternative insect that does not
Q64
The first graph shows logistic growth. Slow growth at the beginning as
there are few organisms to reproduce. Then, because resources are
plentiful, population growth can take off as plenty of reproduction can take
place. Eventually, the paramecium reaches carrying capacity as
resources in the environment become limited
The second graph shows linear growth at the start but then as time goes
around, the population density reaches its carrying capacity. (similar
reasoning to graph 1)
The third graph shows that the populations are competing together for
resources. It would appear that P. caudatum has a tougher time
competing and therefore its population begins to decline. P. Aurelia starts
off slower than before likely because of the competition with the P.
caudatum. P Aurelia may be more efficient overall with its competition for
food and resources