1. Chapter 43 & 44 Review
AP Biology!

2. Definitions
Population – individuals of a species that interact with one another within a given area at a particular time
Population Density – the number of individuals per unit of area or volume
Population Size – total number of individuals in the population
Habitats – particular kinds of environments

3. 2. Population densities are “dynamic”. What does that mean?
They change over time

4. 43.2 BD Model Equation and Components
Nt+1 – is the number of individuals in a population at some time in the future (new population number)
Nt – the current population number
B = number born
D – number that die
Nt+1 = Nt + B - D

5. 4. What is growth rate of a population. 5. What if it’s negative. 6
4. What is growth rate of a population? 5. What if it’s negative? 6. What is per capita growth rate and what is the symbol?
Growth rate is how much the population is changing over time
If growth rate is negative, that means the population is shrinking
Per capita growth rate is the average individual’s contribution to total population growth rate. Symbol is r.

6. 7,8,9 If B> D, then R>0 and the population grows.
If B <D, then R<0 and the population shrinks
If B=D, then R=0 and the population size does not change.

7. 43.3 – Why is it important to understand the life history of an organism?
Because then we can understand
Their growth
Their development
Their reproduction
Their death

8. What 2 pieces of info do life tables provide?
Survivorship
fecundity

9. Definitions and 13-14
Survivorship – fraction of individuals that survive from birth to different life stages or ages
Fecundity – the average number of offspring each individual produces at those life stages or ages
The higher the fecundity and the higher of survivorship, the higher r will be.
If reproduction shifts to earlier ages, r will increase as well.

10. Fact to know
Individual organisms must acquire materials and energy to maintain homeostasis and to fuel metabolism, growth, activity, defense, and reproduction.

11. Principle of allocation
Once an organism has acquired a unit of some resource, it can be used for only 1 function at a time.
It means that organisms have to divide the resources they get among competing functions – like maintenance, foraging, growth, defense, and reproduction.

12. R vs. K strategists Small body size Early maturity Short life span
R strategists
Small body size
Early maturity
Short life span
Large broods
Little or no parental care
Live in unpredictable environments
Examples: mosquitoes, weeds
Large body size
Slow development
Long life spans
Low reproductive rate
Invest in parent care
Live in stable environments
Examples; elephants, humans

13. 43.4 18&19 & 20 & 21 Exponential population growth Optimal conditions
S shaped growth curve
J shaped growth curve
Logistic population growth
Population reaches limit to how much environment can hold; called carrying capacity (K)
When approaching K, populations will crash initially depending on how exhausted the resources are
Populations are dynamic and therefore fluctuate at K
More common in nature because a population can’t grow forever, eventually there will be limiting factors due to competition.
Exponential population growth
Optimal conditions
Constant per capita growth rate
No limitations

15. 22. Density dependent factors
Predation
Disease
competition

16. 23.
Populations fluctuate at K because resources and the limitations are changing and the environment is changing.
K may change due to food availability, water supply, environmental conditions and living space etc.

17. 24 & 25. Human population Human growth is still in exponential form
However, the per capita growth rate has declined so we will reach our capacity by the end of the 21st century (predicted)
Significant factors are
Technology

18. 43.5 BIDE MODEL
Number of individuals in a population at some time in the future = the number now + Births + number of Immigrants – Deaths - Emigrants

19. Chapter 44 – Species interactions
Characteristics
Example
Competition
-/-
Microbes attacking same host
Consumer Resource (Predation)
+/- Prey is killed
Fox preys on rabbit
Consumer-Resource (Parasitism)
+/- Host is not killed
Tapeworms living off pig intestines
Mutualism
+/+
Humans and gut bacteria
Commensalism
+/0
Buffalo birds feeding on insects disturbed by bison’s movements
Amensalism
-/0 mostly accidental
Herd of buffalo kill insects with each step

20. 44.2 Intra vs. inter Competition Within same species
Intraspecific
interspecific
Competition Within same species
Examples: competing for food, water, shelter etc.
Most significant because it could be detrimental to everyone
Between different species
Can lead to extinction of ONE species.
Can affect the distributions of species

21. 44.3 figure explanation
When both species are grown together, they grow slower (growth rate decreases) and they reach lower equilibrium densities

22. #4. Curves and species Identification
Curve A is the large herbivore; population not affected by predators; food sources are constantly available
Curve B is small herbivore; large population size; it’s population decreases as predator increases
Curve C is the predator; small population size; increase of predators follows increase of herbivores.

23. The stellate barnacles are out-competed by the rock barnacles, so they have restrictions in their habitat distributions
44.4 Figure

24. 6. Resource partitioning
It occurs when 2 or more species coexist in spite of competing for same resources.
The resources are divided up and the species occupy slightly different niches
These warblers coexist all feeding off the same tree, but at different heights

25. 44.3 defense mechanisms Speed Size Weapons Hide
Camouflage to avoid being detected
Mimic unpalatable species
Thick armor
poisonous

26. Animal defenses - Aposematic
Using warning colors to advertise that they are unpalatable to potential predators

27. Animal defenses - BATESIAN
When a defenseless species is protected because it resembles a dangerous species in some way

28. Animal defenses - MULLERIAN
Different species, all of which are poisonous/harmful resemble one another
Because they all look the same, higher numbers of them give them an advantage.

29. Animal defenses - Cryptic
Color or markings that help them hide from predators by blending into their physical surroundings

30. 44.4 Invasive
Introduced species have no enemies present, so they can reach high population densities
That’s what invasive means – reproduce rapidly and spread widely