Life Science
Notes Chapter 29-1
Identifying Problems
Extinction is the process
in which a species passes
out of existence, or no
longer is found on earth.
 90-99% of all living
things that have been
on earth are extinct.
 For 600 million
years things have
became extinct at a
rate of 1 per year.
 In recent times
extinction rates have
risen sharply to 40100 species per day.
Most organisms become
extinct because they can’t
adapt as fast as humans
are changing their habitat.
When an organism’s
environment changes for
the worse they become
more and more rare.
When an organism is in
danger of becoming
extinct it is classified as
endangered.
2 categories for
endangering an organism:
1) Intentional killingthis is when humans
directly cause a
decrease in the
population of an
organism.
a. Over huntingrhinos and elephants
have been over
hunted for their tusks
i. Passenger (carrier)
pigeons and snowy
egrets have been
over hunted to
extinction.
b. Destruction of
habitat- ruining the
places where
organisms live.
i. Deforestationremoval of forests
to make room for
cities and farms
1. Rainforests are
decreasing
quickly
2. 50% of the
earth’s rainforests
are already gone.
3. Farms made on
land that used to
be rainforest are
only productive
for 3 or so years.
4. Acid rain can
also kill forests.
5. Deforestation
increases
pollution and
runoff into
streams.
ii. Desertification- is
the changes in the
conditions of an
area to cause an
desert to form
where there wasn’t
one.
1. Over grazing of
livestock can kill
grasslands.
iii. Wetland
Destructiondraining and filling
of wetlands for
human use.
1. for farmlands,
roads, and new
buildings
iv. Pollution- is
anything foreign
added to an
environment that
harms it.
1. Farming
pesticides kill
insects
2. DDT was the
cause of many
birds of prey to
become
endangered.
3. Biomagnificat
ion is the buildup
of toxins as one
moves up the
food chain.
c. Changing
Communitiesintroduction of exotic
species.
i. Species introduced
to an area they had
not previously been
in are called exotic
species.
1. These species
often out
compete other
native species.
2. Kudzu vine out
competes many
plants.
3. Dogs, rats,
pigs, cats, and
mongoose can be
exotic predators
4. Exotic goats
and cattle have
killed native
plantlife by over
grazing.
5. Current
problem exotics
are the zebra
muscle, Eurasian
milfoil, and
snakefish.
2) Accidental Killing- is
unintended killing of
species.
a. Manatee collisions
with motorboats
b. Overcollection of
organisms such as
parrots, orchids,
cactuses, and tulips.
Reasons to protect wildlife:
1) Aesthetics- beauty
of the living
organisms
2) Economic and
Scientific Valuemany things are made
from the plants of the
rainforest.
a. Rubber and
medicines (rosy
periwinkle)
b. Evolutionary
discoveries
3) Genetic Diversityhaving a vast variety
of genes to select
from or study
a. Organisms may
have genes that can
help other species
such as for disease
resistance.
4) Preserving the web
of life- If enough
strands of the food
web are removed the
human food web may
collapse.
Life Science
Notes 29-2
Seeking Solutions
Wildlife ConservationThe methods used to
preserve and protect
endangered species,
manage populations of
wild organisms, and
ensure wise use of living
resources.
 Wise handling of
resources so they
provide the greatest
amount of benefit.
Ways of Conservation:
1. Setting limits- not
allowing for
unregulated killing of
organisms.
 Limits on the
numbers of
organisms
hunters and
fishermen can
take
 Regulations on
size, sex, and
species of
organisms
taken
2. Preserving Habitatsprotecting organisms’
places to live
 Setting up
protected habitats
such as parks or
wildlife refuges or
preserves
3. Raising reproductive
rates- this may include
captive breeding.
 This may include
controlled
breeding in zoos
and possibly
reintroduction into
the wild.
 Test tube babies
or clones of
endangered or
extinct species.
 People- everyday
activities of people
can help
conserve.
o People have
organizations to
raise $
o Habitat
restoration
o Conserve
electricity to cut
down on
pollution
o Recycle
o Write to
congress asking
for legislation to
protect wildlife
o Stop buying
exotic pets