Study Guide – Chapter 3 - Ecosystems: What Are They and How do They Work?
The case study on tropical rainforests is a central problem for conservation if the world’s
Look at the pictures in Figure 3-1; this is not an uncommon sight in tropical
regions around the globe.
We will discuss many important organisms this semester, both
plants and animals), and
(e.g., bacteria), the latter of which are
extremely important in the nutrient cycling processes that fuel ecosystems.
Individuals within a
can mate and produce fertile offspring.
We know about 1.8 million
of them, but there may be 10 times that number yet to be described - can we afford to
destroy habitats before we discover these species, what they do, why they are important in
nature, and how they might be important to us?
is a group of individuals within a species that live together and exchange genetic
material; it is different from a species.
For example, cottontail rabbits in Australia may be the
same species as cottontail rabbits in the U.S., but they are very different populations.
Individuals within populations vary because of
and the constant
recombination of genes as each successive generation mates.
All populations live in a
t, which provides resources such as food, water, proper
environmental conditions, and cover from predators.
is a group of populations living in a particular habitat.
They may be similar
populations (e.g., birds in a forest), but the community will also include very dissimilar
organisms (insects, fungi, mammals that also live in the forest).
is a community and its environment (biotic and abiotic); they can be small or
large, and many are not distinct, they grade into each other to produce habitats known as
Note the Science Focus on page 54.
We often ignore insects, even more often try and destroy
them as pests, yet they are an incredibly important part of ecosystem function.
Earth’s life-support systems consist of the
(where life is found), the
most important to us), the
(water as ice, liquid, or vapor), and the
the Earth’s core, mantle, and crust.
Terrestrial ecosystems are divided into
, large land areas with distinctive climate and
resident biotic communities.
These can be visualized in Figure 3-7, which shows several
biomes that differ primarily in temperature and rainfall.
Aquatic ecosystems are divided into
aquatic life zones
, which are analogous to biomes, and differ in characteristics such as
depth, salinity, and water velocity.
Besides gravity, life on earth depends on the