Chapter 4
Ecosystems and Communities
Ch 4.1
Objectives
• Differentiate between weather and climate
• Identify the factors that influence climate
Weather vs. Climate
• Weather is the day to day conditions of Earth’s atmosphere
• Climate refers to average conditions over long periods
• Defined by year after year patterns of temperature and
precipitation
Microclimates
• Areas within a region can vary in their climate
• Ex: southern exposure, changes in elevation, land bordering large
bodies of water
Factors that Affect Climate
• Solar energy trapped in the biosphere
• Latitude
• Transport of heat by winds and ocean currents
Temperature
• Earth’s average temperature is
determined by the balance of
heat that stays in the biosphere
and that which is reflected back
to space
• Greenhouse gases, like CO2,
cause more heat to be trapped
near Earth’s surface
The Greenhouse Effect
Latitude and Solar Energy
The angle at which the sun’s rays
reach the Earth creates 3 distinct
regions of climate: tropical,
temperate and polar
• Seasons are created by the tilt
of the Earth
Effect of Climate on Biomes
Ch 4.2 Niches and Community
Interactions
• Define niche
• Describe the role competition plays in shaping communities
• Describe the role predation and herbivory play in shaping
communities
• Identify the three types of symbiotic relationships in nature
Niche
• Organisms occupy different environments because each has a range
of conditions under which it can grow and reproduce
• Every organism has a unique range of tolerance
stress
stress
• Tolerance for environmental conditions helps determine an organism’s
habitat- general place where an organism lives
Niche
• An organism’s niche describes not only what it
does, but how it interacts with the biotic and
abiotic parts of its environment
• This includes:
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Place in food web
Environmental conditions it needs to survive
Type of food it eats
How it obtains food
Other species that use it as food
When and how it reproduces
What is the niche of a bullfrog?
Niche
• Competitive Exclusion Principle - no two species can occupy the same
niche in the same habitat at the same time
• Sharing a niche results in competition in nature often results in winner
and loser – losing organism fails to survive
• Different species can occupy similar niches.
• Resource partitioning helps organisms with similar niches avoid
competition
Warbler Niches
Cape May Warbler
Feeds at the tips of branches
near the top of the tree
Bay-Breasted Warbler
Feeds in the middle
part of the tree
Spruce tree
Yellow-Rumped Warbler
Feeds at the lower parts of
the tree and bases of middle
branches
Community Interactions
• Competition- same or different species attempt
to use an ecological resource in the same place
at the same time
Community Interactions
• Predation - one organism captures and
feeds on another organism
• Predator – the one killing and eating
• Prey – the food
Community InteractionsSymbiosis
• Symbiosis- an interaction between two species living close together
• Three types:
• Parasitism – one is harmed (host), one benefits (parasite)
• Mutualism – both benefit
• Commensalism – one is neutral, one benefits
Mutualism
Parasitism
Commensalism