1. May 2017
Journal:

2. Population Growth

3. Niches A. A good habitat must provide:
1) Food
2) Water
3) Shelter
4) Space
B. Within its habitat, each organism has a niche – the role that it plays
1) No two organisms can occupy the same niche

4. Examples of Niches
A. Fungus – decays dead matter and returns needed nutrients to the soil
B. Plants – begin the food chain; provide shelter for many animals; supply oxygen
C. Predators – occupy top trophic levels; eliminate weak/old prey

5. Population Characteristics
Population Density: The number of organisms in an area
Spatial Distribution: The pattern of spacing in a population within an area caused by availability of resources
Three types of dispersion
Clumped
Uniform
Random

6. Population Limiting Factors
1. Population growth rate: how fast a given population grows
Factors that influence this are:
- Birthrate
- Death rate
- Emigration - the number of individuals moving away from a population
- Immigration - the number of individuals moving into a population

7. Population Limiting Factors
2. Density-independent factors: factors that limit population size, regardless of population density
These are usually abiotic factors
They include natural phenomena
Drought, flooding, extreme heat or cold, tornadoes, hurricanes, fires, etc.

8. Population Limiting Factors
Density-dependent factors
Any factor in the environment that depends on the number of members in a population
Usually biotic factors
These include
Predation
Disease
Parasites
Competition

9. Understanding Exponentials
Put your pens down for a minute & think about this:
An employer offers you two equal jobs for one hour each day for fourteen days.
The first pays $10 an hour.
The second pays only 1 cent an hour, but the rate doubles each hour.
Which job will you accept? 9

10. Understanding Exponentials
Population Ecology: Population Growth Rate
Understanding Exponentials
Job 2 lags for a long time before exponential growth kicks in!
What would happen if this type of growth took place within a population?

11. Exponential Growth Model
Exponential growth model – Population size continuously grows
Also called J-shaped growth.

12. Limits to Exponential Growth
Population Density increases as well which leads to increased competition
When a population size reaches the maximum level that a particular environment can support it is said to have reached carrying capacity 12

13. Logistic Growth Model Often called the S-shaped growth curve
Occurs when a population’s growth slows or stops following exponential growth once the population reaches carrying capacity 13

14. So, what do you think is going to happen to the human population?

15. May 2017
Journal:

16. Communities
A community is a group of interacting populations that occupy the same area at the same time.

17. Range of Tolerance
The limits within which an organism can exist

18. Ecological Succession
The change in an ecosystem that happens when one community replaces another as a result of changing biotic and abiotic factors

19. Ecological Succession
Community Ecology: Ecological Succession
Ecological Succession
Ecological Succession
Consists of 2 types:
Primary Succession
Secondary Succession

20. Primary Succession
The establishment of a community in an area of exposed rock that does not have topsoil
It occurs very slowly at first
Lichens or mosses are first organisms to arrive
They secrete acids that can break down rock
Their dead, decaying organic materials, along with bits of sediment from the rock make up soil.
Then small plants move in, followed by larger plants and animals

21. Secondary Succession
Disturbances (fire, flood, windstorms) can disrupt a community, which allows new species to occupy the habitat afterwards.
Organisms that move in are usually those that surround the site of the disturbance
Occurs faster than primary succession

22. Biodiversity
- The variety of life in an area that is determined by the number of different species in that area - Increased biodiversity is a sign of a more stable community

23. Community Interactions

24. Competition
Organisms fight for places to live, food to eat and organisms to mate with.
Two Types:
Interspecific Competition – Occurs between species
Intraspecific Competition – Occurs between individuals of the same species

25. Keystone Predators
Species that keep the best competitor in a community in check, which helps increase species diversity

26. Predator-Prey
-Things are eating or being eaten.

27. Symbiosis A close interaction between two species Three types:
Mutualism
Commensalism
Parasitism

28. Mutualism
Both species benefit

29. Commensalism
One member benefits the other is unaffected

30. Parasitism
One member benefits and the other is harmed

31. Extinction Rates
The gradual process of becoming extinct is known as background extinction.
Mass extinctions: When a large percentage of all living species become extinct in a relatively short period of time.
250 MYA: Over 90% of species died

32. Estimated number of Extinctions since 1600
Biodiversity and Conservation: Extinctions
Estimated number of Extinctions since 1600
Group
Main-land
Island
Ocean
Total
Approximate Number of Species
Percent of Group Extinct
Mammals 30 51 4 85
4000
2.1
Birds 21 92
113
9000
1.3
Reptiles 1 20
6300
0.3
Amphibians 2
4200
0.05
Fish 22 23
19,100
0.1
Invertebrates 49 48 98
1,000,000+
0.01
Flowering Plants
245
139
384
250,000
0.2
Since the mid-1970s there has been an alarming decrease of amphibian populations, and many are on the verge of extinction.

33. Five Most Recent Mass Extinctions
Cretaceous Period (65 MYA)
Triassic Period (200 MYA)
Permian Period (250 MYA)
Devonian Period (360 MYA)
Ordovician Period (444 MYA)