1. Biological Communities
Chapter 18

2. 18-1 How Organisms Interact in Communities
Objectives
Identify the distinguishing features of symbiotic relationships
SCS: B-6.1

3. Species Evolve in Response to each other
Interactions among species
Insects/flowers
Coevolution
Predator/Prey relationships
Predation is when one organism feeds on another

4. Symbiosis
When two or more species live together in a close, long-term association.

5. Parasitism – when one organism feeds on and usually live on or in another
Example: Ticks and dogs
Ticks benefit, but dogs do not

6. Mutualism – a symbiotic relationship in which both benefit from the relationship
Example: flowers and bees
Flowers are pollinated and bees have food

7. Commensalism – a relationship in which one organism benefits and the other neither is benefits or is harmed
Example: Spanish moss and trees
Trees are not hurt nor benefit, but the moss benefits from additional sunlight

8. 18-2 How Competition Shapes Communities
Objectives
Describe the role of competition in shaping the nature of communities
Distinguish between fundamental and realized niches
Describe how competition affects an ecosystem
Summarize the importance of biodiversity
SCS: B-6.1, 6.2

9. Common Use of Scarce Resources leads to competition
Organisms compete for food, space, light, minerals, and water
Resources must be in short supply if competition occurs
Competition can limit how species use resources
Competition can lead to extinction or elimination of a species

10. Niche – the role of a species in a ecosystem
How does the organism affect the environment
If niches overlap it may cause competition
Niches can vary in size

11. Predation can lesson competition
Eliminates those species less adaptive
Promotes biodiversity

12. 18-3 Major Biological Communities
Objectives
Recognize the role of climate in determining the nature of biological communities
Describe how elevation and latitude affect the distribution of biomes
Summarize the key features of the Earth’s major biomes
SCS: B-6.1, 6.2

13. Climate determines where species lives
Climate is the prevailing weather conditions of an area
Temperature and moisture
Temperature and moisture determine biological communities

14. Types of Terrestrial Biomes
Tundra
Taiga
Desert
Grassland
Temperate Forests
Tropical Rain Forests

16. Tundra extremely short growing season (6 to 10 weeks)
long, cold, dark winters (6 to 10 months with mean monthly temperatures below 32° F or 0° C.)
low precipitation (less than five inches/year)
Animals and animals: Musk ox, artic hare and fox, permafrost (permanently frozen ground)

18. Taiga
Long, severe winters and short summers (50 to 100 frost-free days) are characteristic, as is a wide range of temperatures between the lows of winter and highs of summer.
Mean annual precipitation is 15 to 20 inches, but low evaporation rates make this a humid climate.
Vegetation and Animals: Conifers, beaver, lynx, deer, sparrows…..

20. Deserts Temperature: Average of 38°C (day), average of -3.9°C (night)
 Precipitation: About 250 mm of rain per year
 Vegetation: Cacti, small bushes, short grasses
 Animals in the desert: coyotes, lizards and snakes, insects, and even some birds) are adapted for burrowing to escape the scorching heat of the desert sun

22. Grasslands
Temperature: Dependent on latitude, yearly range can be between -20°C to 30°C  
Precipitation: About 500 to 900 mm of rain per year  
Vegetation: Grasses (prairie clover, salvia, oats, wheat, barley, coneflowers)
Animals: bison and antelope

24. Temperate Forests
Temperature: -30°C to 30°C, yearly average is 10°C, hot summers, cold winters  
Precipitation: 750 to 1,500 mm of rain per year  
Vegetation: Broadleaf trees (oaks, maples, beeches), shrubs, perennial herbs, and mosses
Animals: Deer, raccoons, and salamanders are characteristic inhabitants.

26. Tropical Rain Forest
Temperature: 20°C to 25°C, must remain warm and frost-free
 Precipitation: 2,000 to 10,000 millimeters of rain per year
 Vegetation: Vines, palm trees, orchids, ferns
Animals and plants: monkeys, cat like mammals, reptiles, insects, diverse flowers, hard wood trees, and medicinal plants