Download Unit 3: Evolution, Biodiversity, Climate, Weather, and Biomes

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Biodiversity Video (6 min)
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BIODIVERSITY is the range and number of organisms found
in a single place
 A forest has 15 different species with 100 individuals of 1 species
and 1 individual of each of the other 14 species.
 Another forest also has 15 species, but this one has 7 individuals of
each of the 15 species.
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Which is more diverse?
 The spread of individuals between species is more important than
the total number of individuals in a habitat.
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Biodiversity can be explored at three different levels:
 Genetic diversity, Species diversity and Habitat diversity
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What causes isolation?
 Physical - Earthquakes, volcanoes, flooding, other
catastrophes
 Social – emigration (ex: movement from a
continent to a island)
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Example – Svladbard Reindeer
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Svalbard is an ancient
island within the Arctic
circle (1100 km from
the North Pole)
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During the last Ice Age
it was connected to
the mainland
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Island Conditions
 Permanent ice covers much of
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Svalbard
Only coastal lowlands see
melt in summer
Snow melt causes erosion of
limited soil cover
Short growing period
No trees
Wind and frost make it
difficult for plants
Few animals other than
Svalbard reindeer have
colonized the island
No large predators
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Mainland Reindeer (Rangifer
tarandus)
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Live in herds
Thick fur insulates against winter
Lack of social interaction within herds
Dig through snow with large feet during
winter
In winter survive eating lichen
In summer eat a wide variety of plants
Long heads with eyes set back to spot
predators when grazing
Living in herds give protection but
increases competition for food
Starve in summer
Affected by parasitic warble fly
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Svalbard Reindeer (Rangifer
tarandus platyrhynchus)
 Live singularly or in small groups
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due to lack of predators
Smaller and more squat (galloping
inefficient)
Less competition for food
Smaller antlers lost in winter
Feed on tough vascular plants year
round
Large adapted stomachs with
unique microorganisms to help
digest poor diet
Put on fat stores during summer to
survive harsh winter
Few parasites because of living in
small numbers
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28% of world’s oxygen turnover (CO2 →O2)
Huge amount of biodiversity
 40-75% of all species
 Large numbers of species endemic to area
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Most species have evolved to inhabit very specialized
niches in their environment
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When humans disrupt that environment, many species
cannot survive
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Humans have destroyed/disturbed about half of these
forests
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Because species depend on each other in a
complicated web of relationships, changing just one
part of the web harms the entire ecosystem
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This breakdown of rainforest ecosystems will likely
lead to the disappearance of up to 10% of the world’s
species within the next 25 years
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Humans depend on the rainforest’s millions of
life forms for its own existence
 The genetic diversity provides invaluable additions
to the gene pool which help maintain and improve
domestic crops
 Without a diversity of strains, crops become overly
homogenous and vulnerable
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The projected major harmful effects:
 Reduce Earth’s vital biodiversity
▪ Destroying/degrading the habitats of unique organisms
 Accelerate climate change due to global warming
▪ Reduction of CO2 consumption
 Alter regional climate patterns to prevent return of
diverse forests in cleared lands