Transcript Chapter 4: ECOSYSTEMS AND COMMUNITIES

Ecology
Lesson 9.1
Lesson Objectives
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Distinguish between abiotic and biotic factors.
Describe ecological levels of organization in the biosphere.
Define organism, population, community, ecosystem, biome,
and biosphere as the term are used in ecology and other
ecological concepts.
Compare and contrast exponential and logistic growth.
Compare and contrast niches and habitats.
Introduction
Levels of Organization
• Ecologists study organisms and their
environments at different levels of
organization:
– Organisms: are individual living things.
This is the lowest level of organization that
ecologists study. Biologists study organisms,
organ systems, organs, tissues, cells,
organelles, and molecules. Chemists study
atoms and subatomic particles.
Organisms and the Environment
• Organisms: life form consisting of one or
more cells; has characteristics of life.
• Environment includes both living (biotic)
and nonliving things (abiotic).
Biotic and Abiotic Factors
• Biotic living organisms
• Abiotic nonliving or physical factors
• Together determine productivity of the
ecosystem in which organisms’ live
What Is a Population?
In biology, a population is a group of organisms of the
same species that live in the same area, interact with
one another, and produce fertile offspring.
.How large a population is and how fast it is growing
are often used as measures of its health.
What Is a Community?
Communities are made up of populations
of different species that live in the same
area and interact together.
What Is an Ecosystem?
An ecosystem is a unit of nature and the focus
of study in ecology. It consists of all the biotic
and abiotic factors in an area and their
interactions. Ecosystems can vary in size.
A lake could be considered an ecosystem. So
could a dead log on a forest floor. Both the lake
and log contain a variety of species that interact
with each other and with abiotic factors.
Ecosystem Components
• Niches
• Habitats
• Competitive Exclusion Principle
The Niche
Niche organism’s occupation (role), where it
lives, and way in which organism’s use
conditions they exist in
– Food it eats
– Place in food web
– How it gets food
– Range of temperatures
needed for survival
– When and how it
reproduces
The Habitat
• Physical environment to which an
organisms has become adapted and
survives in.
Competitive Exclusion Principle
• Two different species
cannot occupy the
same niche in the
same geographic area.
If they do they will compete
with one another for the
same food and other resources.
Eventually, one species will
out compete the other.
What Are Biomes?
A biome is a group of similar ecosystems with the
same general abiotic factors and primary
producers.
Biomes may be terrestrial or aquatic.
What Is the Biosphere?
The biosphere is the global sum of all ecosystems; integrating
all living beings and their relationships, including their
interactions with the elements of the lithosphere, hydrosphere,
and atmosphere.
Lesson Summary
• Ecology is the study of how living things interact with each other and with their environment. The
environment includes abiotic (nonliving) and biotic (living) factors.
• Organisms are dependent upon their environments for energy and matter.
• Population growth rate is how fast a population changes in size over time. It is determined by
rates of birth, death, immigration, and emigration.
• Under ideal conditions, populations can grow exponentially. The growth rate increases as the
population gets larger. Most populations do not live under ideal conditions and grow logistically
instead. Density-dependent factors slow population growth as population size nears the carrying
capacity.
• A community is the biotic part of an ecosystem. It consists of all the populations of all the species
that live in the same area. It also includes their interactions.
• An ecosystem consists of all the biotic and abiotic factors in an area and their interactions. A niche
refers to the role of a species in its ecosystem. A habitat is the physical environment in which a
species lives and to which it is adapted. Two different species cannot occupy the same niche in the
same place for very long.
• The biosphere is composed of all the ecosystems on Earth.