Chapter 4
Self-Quiz
Unit 1: Diversity of Life
Biodiversity
Review
An
is all of the species that live in a given area and the areas or
they inhabit.
refers to the number of species in the entire world or more locally, a particular ecosystem. There are about 3 million to 30 million
species
on Earth; of these only
million have been discovered and
named.
Loss of
biodiversity
is reflected in the loss of species, or
.
The most diverse ecosystem is the
. These
rainforests
are losing about 27,000 species per year. Why is preserving biodiversity important?
At least
5
episodes have been documented in the past, the most severe was 250 million years ago in the
late
Period. Previous extinctions were the result of
climate
, increased
,
changing
,
impact,
or
moving
continents.
Humans may have been responsible for species extinctions in the past. The disappearance of
large animals
from continents and islands such as
,
,
, and
coincided with the arrival of humans. Humans may be the main agent for a
mass extinction.
The biggest threat to biodiversity is
loss
and deterioration. Habitat
can reduce breeding territories for area-sensitive species such as the
Greater Sage-Grouse
and
songbirds
due to the
effect. Human population
growth
is a main factor in habitat loss.
The introduction of
species can
displace
native species which are not
to the alien species. Sometimes an
exotic
species is introduced as a
of other
invasives,
but this has its own pitfalls!
Other threats to biodiversity include
change,
pollution,
over-
and
over-
. Human activity is a major component in these
factors
as well.
The more species that are present in an ecosystem, the more
that
ecosystem
is, because more
can be used. The
hypothesis
predicts a sudden collapse of an ecosystem when species loss reaches a threshold due to the
among species. The more diverse an ecosystem, the more resilient it is to environmental challenges. What is the
value
of
biodiversity
?
bio1100 Home
Feb 23, 2006
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Chapter 4
Self-Quiz