1. If I want to be successful by the end of the unit I will be able to:
Compare and contrast types of symbiotic relationships
Describe a population and its qualities
Describe exponential and logistic growth
Identify factors that determine carrying capacity
Compare and contrast density dependent and independent factors

2. Species Interactions

3. Types of Species interactions
Species interactions are the backbone of communities
Most important categories
Commensalism = one species benefits , one unaffected
Mutualism = both species benefit
Parasitism = one species benefits and the other is harmed
Competition = both species are harmed
Predation= one species benefits and the other is harmed S Y M B I O

4. Competition
Competition = relationship where multiple organisms seek the same limited resources they need to survive:
Food - Water
Space - Shelter
Mates - Sunlight
Intraspecific competition = between members of the same species
High population density = increased competition
Interspecific competition = among members of 2 or more species

5. Predator-Prey Relationships
Predation can drive population dynamics (cyclic)
Increased prey populations increases predators
Predators survive and reproduce
Increased predator populations decrease prey
Decreased prey population causes starvation of predators
Decreased predator populations increases prey populations

6. POPULATION ECOLOGY

7. Population Dynamics Population:
All the individuals of a species that live together in an area
Niche:
Narrow range where a species fits within a habitat.
Demography:
The statistical study of populations, allows predictions to be made about how a population will change
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

8. How are populations described?
Three Key Features of Populations
Size
Density
Dispersion
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

9. Three Key Features of Populations
Size: number of individuals in an area
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

10. Three Key Features of Populations
Growth Rate:
Birth Rate (natality) - Death Rate (mortality)
How many individuals are born vs. how many die
Birth rate (b) − death rate (d) =
rate of natural increase (r)
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

12. Three Key Features of Populations
Density: measurement of population per unit area or unit volume
Pop. Density = # of individuals ÷ unit of space
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

13. HOW DO YOU AFFECT DENSITY?
Immigration: movement of individuals into a population
Emigration: movement of individuals out of a population

14. HOW DO YOU AFFECT DENSITY?
Density-dependent factors: Biotic factors in the environment that have an increasing effect as population size increases
Examples: disease, competition, parasites

15. HOW DO YOU AFFECT DENSITY?
Density-independent factors: Abiotic factors in the environment that affect populations regardless of their density
Examples: temperature, weather

16. Factors That Affect Future Population Growth
Immigration + + -
Population
Mortality
Natality -
Emigration

17. Three Key Features of Populations
Dispersion: describes the spacing of organisms relative to each other
Clumped
Uniform
Random
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

18. Population Dispersion

19. Check Point
3- three key features of populations, describe each one 2- two types of limiting factors, examples of each 1- one buzz word to describe the spacing of organisms relative to each other

20. How Are Populations Measured?
Population density = number of individuals in a given area or volume
Count all the individuals in a population

21. How Do Populations Grow?
Idealized models describe two kinds of population growth:
Exponential Growth
When resources are unlimited, a population can experience exponential growth, where its size increases at a greater and greater rate. Does not stop
Logistic Growth
Logistic growth of a population size occurs when resources are limited, thereby setting a maximum number an environment can support. Until it reaches its carrying capacity

22. Exponential Growth Curve
Figure 35.3A

23. Logistic Growth Curve

24. “Booms” and “Busts”

25. Carrying Capacity (k):
The maximum population size that can be supported by the available resources
There can only be as many organisms as the environmental resources can support
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

26. Factors Limiting Growth Rate
Declining birth rate or increasing death rate are caused by several factors including:
Limited food supply
The buildup of toxic wastes
Increased disease
Predation

27. Reproductive Strategies
R Strategists
Short life span
Small body size
Reproduce quickly
Have many young
Little parental care
Ex: cockroaches, weeds, bacteria

28. Reproductive Strategies
K Strategists
Long life span
Large body size
Reproduce slowly
Has few young
Provides parental care
Ex: humans, elephants

29. A survivorship curve is a graph showing the number of individuals surviving to each age for a given species or group (e.g. males or females).
Curve usually based on a standardized population of individuals
Survivorship Curves

31. Survivorship curves can be classified into three general types
Type I, Type II, and Type III I II
III 50
100 1 10
1,000
Percentage of maximum life span
Number of survivors (log scale)

32. Type I curve typical of animals that produce few young but care for them well .
Death rate low until late in life where rate increases sharply as a result of old age
Humans, elephants
Type I curve

33. Type II curve has fairly steady death rate throughout life
Death is usually a result of chance processes over which the organism has little control
Rodents
Type II curve

34. Type III curve typical of species that produce large numbers of young which receive little or no care
Survival of young is dependent on luck.
Example: Larvae released into sea have only a small chance of settling on a suitable substrate. Once settled however, prospects of survival are much better and a long life is possible.
Type III curve