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Chapter 9 review
Lucas Collins
Section 1
Species are becoming extinct 1,000 times faster than
when modern humans first arrived. But by the end of
the twenty-first century, its expected to be around
10,000 times faster
There are 2 types of extinction: Biological, which
occurs when a species can not be found anywhere on
the planet. Mass extinction, is the extinction of many
species within a short period of time
Section 1 (cont.)
There are two classifications for species that are on the
way to becoming biologically extinct. Endangered,
which has few individual survivors and could soon
become extinct. Threatened, which still has enough to
survive a short-term period, but eventually could
become extinct
Section 1 (cont.)
Some species have behavioral characteristics that make
them more likely to become extinct. For example, the
passenger pigeon traveled in large numbers, making
them easier to be killed.
Some species are more threatened to extinction
because of human activities and actions
Human activities were the result of the Passenger
Pigeons’ extinction in 1900
Section 2
There are four major reasons why we should work to
prevent the extinction of other species:
Species are a vital part of the life support system
Most species contribute to our economic services
It will take 5-10 million years for natural speciation to
rebuild biodiversity
Many people believe that all species have the right to
exist, even if they are not significant
Section 2 (cont.)
We cannot protect all species from extinction so we
must distinguish which are more worth saving. Most
species that become extinct, we know little about and
therefore are not fully able to protect them.
Section 3
HIPPCO: Summarization of the most important direct
causes of extinction due to human actions
H: Habitat destruction, degradation, and fragmentation
I: Invasive species
P: Population growth and increasing use of resources
P: Pollution
C: Climate change
O: Overexploitation
Section 3 (cont.)
The greatest threat to wild species is habitat loss.
Invasive species, which are deliberately introduced into
some ecosystems, can be very harmful and can majorly
disrupt them
Section 3 (cont.)
There are ways to reduce threats from invasive species:
Fund a massive research program
Increase ground surveys and satellite observation
Identify harmful invader species and establish treaties
banning transfers
Require cargo ships to discharge their ballast water and
replace it
Educate the public about the effects of releasing exotic
plants and pets into the environment
Section 4
The Endangered Species Act of 1973 was designed to
identify and protect endangered species in the US and
other countries
It was the most far-reaching environmental act ever
In 1903, President T. Roosevelt established the first US
federal wildlife refuge at Pelican Island, to protect birds
from extinction
Section 4 (cont.)
The precautionary principle: to take precautionary
action to avoid causing more extinctions and more loss
of biodiversity
Scientist use it to argue for preservation and protecting
of entire ecosystems
Also used as a strategy for preventing exposure to
harmful chemicals in the air, water, and food
Three Big Ideas
1. We as humans increase the extinction of species by
degrading their habitats, introducing invasive species,
population growth, pollution, climate change, and
overexploitation of species.
We should avoid causing the extinction of species
because of their ecological and economic services they
We can try to prevent the extinction of any species by
using laws, protecting wildlife refuges, and increasing
use of the precautionary principle