Transcript Indicator 8-2.7

Extinctio
n
8-2.7 Summarize the factors, both natural
and man-made, that can contribute to the
extinction of a species
BrainPop Overview:
• Extinction is:
• Types of extinction:
• Examples of extinct organisms:
• Causes of extinction:
• Preventing extinctions:
Remember…
Explain It
• Why is the bird on the right more likely to pass
on its genes than the bird on the left?
When is a species
considered extinct?
• A species is extinct if no members of
that species are still alive.
Did you know that most
organisms that have ever lived
on Earth are now extinct?
Extinction is Natural
•Natural extinctions
have occurred
throughout geologic
history.
What Natural (nature-made) Factors
contribute to extinction?
•
•
•
•
•
Volcanic eruptions
Global warming
Global cooling during ice ages
Changes in oxygen levels in seawater
Massive impact from an asteroid or
comet
• Competition with new species
–Ex) tsamanian tiger vs dingo
Competition Between Species
Thylacine versus Dingo
• Tasmanian Tiger No Match For
Dingo
– ScienceDaily (Sep. 12, 2007) — The
wily dingo out-competed the much
larger marsupial thylacine by being
better built anatomically to resist
the "mechanical stresses"
associated with killing large prey,
say Australian scientists.
What Man-Made Factors contribute to
extinction?
(Have caused extinctions in more recent
times)
• Habitat Loss
– Cutting of rainforests
• Over-harvesting
–harvested for a product: food,
medicine, etc.
• Pollution and Contaminants
– Ex: DDT pesticide now outlawed
• Human Hunting
Habitat Loss
• Smoldering pastureland cleared for cattle
from the Amazon rainforest, Rondonia State,
Brazil
Why does extinction matter?
• More species will become extinct
in the future if humans continue
their behavior
• Damage to the environment is
possibly threatening some
biological resources that humans
may need
• Studying species that have recently
become extinct or that are
endangered help us know what
caused extinction and
endangerment.
• This may also help us learn what can
be done to prevent it from
happening.
Are all extinctions negative?
• NO, some species becoming
extinct provides the opportunity
for new species to emerge.
• Extinction makes way for new
kinds of life.
–Ex: smallpox virus is now extinct
b/c of a vaccine