1. Ecosystems & Communities
Chapter 4
Ecosystems & Communities

2. Section 4-1: The Role of Climate
Key Idea:. All organisms are adapted to live in a particular climate. This is done through years of evolution.
What is the difference between weather & climate?
Weather – the day-to-day condition of the Earth’s atmosphere at a particular time & place
Climate – the average, year-after-year conditions of temperature & precipitation in a particular region
- latitude & topography play a role
Microclimate – conditions vary over small distances. South side of a rock is warmer than the north side.

3. Section 4-1: The Role of Climate
What is the Greenhouse Effect?
The atmosphere acts like a blanket because CO2 (carbon dioxide) , CH4 (methane), H2O vapor, etc. trap heat.
This is a completely natural process that helps keeps the biosphere’s temperatures suitable for life.
If it wasn’t for these gases, the Earth’s temperatures would be 30o C cooler.

4. Section 4-1: The Role of Climate
What is the effect of latitude on climate?
Latitudes farther away from the equator get less sunlight/heat.
Key Idea: This unequal heating of the Earth creates ocean currents & prevailing wind patterns, both contribute to climate.

5. Section 4-1: The Role of Climate
What are the 3 climate zones caused by latitude?
Polar:
A. Farthest from equator
B. Gets the least amount of sun/heat due to low sun angle
C o to 90o latitude

6. Section 4-1: The Role of Climate
What are the 3 climate zones caused by latitude?
Temperate:
A. Between the tropical & polar zones
B. This zone has changes of seasons
C. This is what we live in

7. Section 4-1: The Role of Climate
What are the 3 climate zones caused by latitude?
3. Tropical:
A. Nearest to & includes the equator
B. Sun is mostly directly overhead all year long & no real change of season.
C o N = Tropic of Cancer
23.5o S = Tropic of Capricorn

8. Section 4-2: Niches & Community Interactions
Key Idea: Ecosystems are shaped by biotic & abiotic factors.
Biotic Factors: all of the living things that an organism can interact with like food chains and food webs
Abiotic Factors: nonliving things that influence the interactions among organisms like climate/weather, soil type, and amount of water.
Key Idea: The biotic & abiotic factors of the area in which an organism lives is called habitat.

9. Section 4-2: Niches & Community Interactions
What is the relationship between habitat & niche?
Tolerance – the range of environmental conditions an organism can survive.
Habitat – “address” of the organism
Niche – “job” of the organism
Definition of Niche – full range of physical & biological conditions in which an organism lives & the way in which the organism uses those condition

10. Section 4-2: Niches & Community Interactions
Three things you need to know about niches:
The number of niches within an ecosystem is limited.
No two species can occupy the same niche (a.k.a. – competitive exclusion principle)
Evolution by natural selection determines which of the species get to occupy the niche.

11. Section 4-2: Niches & Community Interactions
What is the difference between a fundamental niche & a realized niche?
Fundamental niche – all of the possible niches that an organism can occupy
Realized niche – the actual niche that the organism occupies due to competition

12. Section 4-2: Niches & Community Interactions
Types of community interactions:
Competition – organisms of the same or different species attempt to use the same resource (food, shelter, nesting site, etc.)
Predation – one organism tries to capture & eat another organism
Predator: the hunter
Prey: the food organism
* Predation is a key factor in evolution; cheetahs are fast because their prey is fast

13. Section 4-2: Niches & Community Interactions
Types of community interactions:
Herbivory – coevolution occurs between plants & herbivores.
- grasses has evolved to grow from the bottom up to better survive getting eaten.
- cactus has evolved spikes to keep from getting eaten.

14. Section 4-2: Niches & Community Interactions
Types of community interactions:
Symbiosis – a close, living arrangement between two different species in which at least one of them benefits.
3 Types of Symbiosis:
1. Mutualism – both species benefit
A. Plants & their pollinators
B. Humans & intestinal bacteria
2. Commensalism – one species benefits & the other is not affected
A. Barnacles on whales
B. Remoras that attach to sharks
3. Parasitism – one species benefits & the other is harmed
A. Tapeworms, ticks, fleas, etc.

15. Section 4-3: Succession
Ecological Succession: predictable changes in a community over time
3 Types of Succession:
Primary Succession – occurs where there was no soil before (i.e. after a volcanic eruption or bare rock exposed by a melting glacier)
Pioneer Species – 1st species to populate an area; often lichens (symbiotic relationship between an alga & a fungus)
Secondary Succession – a disturbance has destroyed the existing community; occurs after a forest fire or after farmland has been abandoned. It should return to the original community known as the climax community.
Marine Succession – occurs when a dead whale sinks to the deep bottom of the ocean