Download Chapter 18

Biological
Communities
Chapter 18
18-1 How Organisms
Interact in Communities
Objectives
 Identify the distinguishing features of
symbiotic relationships
SCS: B-6.1
Species Evolve in
Response to each other
 Interactions among species
 Insects/flowers
 Coevolution
 Predator/Prey relationships
 Predation is when one organism feeds on
another
 Symbiosis
 When two or more species live together in a
close, long-term association.
Parasitism – when one organism feeds on
and usually live on or in another
Example: Ticks and dogs
Ticks benefit, but dogs do not
 Mutualism – a symbiotic relationship in
which both benefit from the relationship
Example: flowers and bees
Flowers are pollinated and bees have food
 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
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
 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
 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
 Predation can lesson competition
 Eliminates those species less adaptive
 Promotes biodiversity
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
 Climate determines where species lives
 Climate is the prevailing weather conditions
of an area
 Temperature and moisture
 Temperature and moisture determine biological
communities
Types of Terrestrial
Biomes
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Tundra
Taiga
Desert
Grassland
Temperate Forests
Tropical Rain Forests
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)
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…..
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
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
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
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Animals: Deer, raccoons, and salamanders are
characteristic inhabitants.
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