Biodiversity Unit Review

Biodiversity Unit Review
Opening Video clip
• Mau forest and why it’s important
• What are some other Ecosystem Services
that we would have a hard time living
Threats to Biodiversity
The HIPPO Dilemma
• H—Habitat destruction/fragmentation
• I—Invasive species
• P—Population growth of HUMANS
• P—Pollution
• O--Overconsumption
Case Study—Genetic
The Corn Crisis of 1970
What led to the problem?
• In 1970, most corn crops were genetically
• In 1970, the Southern Corn Leaf Blight
(caused by a fungus) hit U.S. corn crops.
Effects of uniform crops?
• A trait bred into the corn to
increase seed production
actually increased the
corn’s susceptibility to the
• 15% of U.S. corn crops
were destroyed the first
year – costing about $1
Trying to solve the problem …
• The process took many
years and lots of corn (and
money) was lost during that
• Breeders used seeds from
older corn varieties (saved
in gene banks) to produce
new disease-resistant
variety of corn.
What we should have learned
from this …
• Low crop diversity increases the chance of
devastating diseases.
• To deal with diseases, we often look for a
different genetic variety resistant to that
disease that could help current crops
adapt to changing conditions.
Have we actually learned this
• There are some limited systems in place
to increase crop diversity.
• However, crops in the U.S. have actually
become more uniform over the past 40
years rather than more diverse.
Ways to preserve Biodiversity
1. Gene Banks
• Place where seeds are
saved in cold storage.
– A small amount of as
many varieties as possible
are saved.
– Not all seeds “survive” in
gene banks – some will
not germinate (grow) later.
– Not all seeds can even be
saved in this manner.
2. Cultivation of Rare Plant Varieties
• There are groups, such as Seed Savers, that
share seeds and plants (and even animals)
among individuals and organizations.
• Buying heirloom varieties of seeds/plants
(usually through groups or catalogues because
not often in stores).
• Encourages widespread dispersal of these rarer
plants – hopefully having them available in the
3. Habitat Preservation
• Oftentimes we return to areas where a
plant originally evolved and look for
varieties not currently being cultivated, but
containing beneficial characteristics.
• Sometimes useful plants exist where we
never looked before.
• Maintaining wild habitats and sustainable
agriculture is vital.
• In 1977, a new variety of
wild corn was discovered by
Rafael Guzman in a remote
mountain area of Mexico.
• Called teosinte:
– Can withstand hot, dry
– Reproduces easily
– Resistant to the Southern
Corn Leaf Blight
For Example:
4. Sustainable Agriculture
• Farming that requires few to no chemical
pesticides & fertilizers.
• Growing crops appropriate to the climate found
in that region.
– Reduces the need for irrigation and other resourceheavy practices.
• Growing crops originally found in that region.
– Encourages diversity of genetic types worldwide.
• Planting a variety of crops and maintaining
reasonable number of animals.
– Animal waste can be dealt with on the farm rather
than polluting larger environment.
– Farmers investment is protected by diversity of plants
if weather conditions or disease affect one type of