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Transcript of Biodiversity
What is biodiversity?
Recall that a species consists of organisms that can interbreed and produce fertile offspring.
Sometimes also referred to as BIOLOGICAL DIVERSITY
*Biodiversity is considered to be a RENEWABLE RESOURCE
*Key takeaway: General order
What does biodiversity do for us?
Think about what we have learned so far.
What do we do for biodiversity?
How did life get to be so diverse?
Through evolution via Natural Selection!
Who proposed this idea?
2. Random mutation in DNA Adaptation
1. Limited Resources Competition
3. Reproduce to spread adaptation to offspring
Scientists propose that all organisms evolved from one species.
With a partner, using what you just learned, explain how it is possible that all of the species around us today could come from one species.
Who is the most powerful species on Earth?
How did humans become so powerful?
1. Opposable thumbs
2. Upright structure
3. Complex brain
Although organisms can evolve, this process takes time.
Unfortunately, conditions on Earth are changing so rapidly, that there is not enough time for many species to evolve.
What species is responsible for the drastically changing conditions?
How are humans affecting biodiversity?
1. Increasing rate of speciation
2. Causing premature extinction of species
New species being formed
(through Natural Selection)
Most Common Method of Speciation (2 Steps)
1. Geographic isolation
2. Reproductive Isolation
Groups of the same species get physically isolated for long periods of time.
1. Physical barrier
(mountain, body of water, road)
2. Volcanic eruption or earthquake
3. Organisms being swept away by wind or water
Now groups of the same species have been physically separated.
Also, it is likely that the environments of each group is different.
So, in each environment, different traits will be beneficial.
As Natural Selection occurs in each environment, the two groups will end up evolving so differently that the groups would no longer be able to breed with each other if they were ever reconnected.
The groups that have been separated cannot mate.
An entire species dies out
A species found only in one area
*Because these species are so specialized, they are more likely to go
Costa Rica's Golden Toad
Poster species to bring awareness about how climate change is causing an increase in extinction.
2 Major Groups of Extinction
1. Background Extinction
Species disappear at a low rate (1-5 species/million yrs)
2. Mass Extinction
Huge group of species get wiped out
There have been about
3-5 mass extinctions
in Earth's history.
Although mass extinctions take away large groups of species, this process provides
room and resources for completely new species to arise.
Species are going extinct all the time.
However new species are also being created all of the time.
'BACKGROUND EXTINCTION causes limited damage to an ecosystem.'
Since Background extinction is a long process
Other organisms affected have time to adjust/evolve as a species
- number of species
- number of members of each species
Tropical regions have high species richness.
Generally, as you get further from the equator, species richness decreases while species evenness increases.
Species Richness or Species Evenness?
Scientists believe that
Higher species richness,
The more species, the more likely it is for some species to withstand natural disasters
Why are species rich ecosystems more stable and sustainable?
Species tend to be
All have different
(rely on different
If something happens to 1 resource, not every species will be harmed
As a WHOLE, species richness is more sustainable
This is the opposite of ecosystems with high species evenness.
Within a species rich ecosystem, there are species with different niches.
Two General Groups:
Generalist or Specialized?
When conditions are good/stable,
have the advantage.
When conditions are bad/unstable,
have the advantage
Over 350 million years old!
How did they survive?
Very versatile generalist species.
Can eat almost anything.
Reproduce a lot and quickly.
Evade predators with senses.
Go for long periods without food.
Areas that contain many endemic species
The organisms that will survive drastically changing environmental conditions will be those that are most...
If there is another mass extinction, which organisms would be the ones that survive?
To understand this, we need to understand a bit more about species diversity
Importance of Biodiversity
Direct economic value
Indirect economic value
Aesthetic and scientific value
We depend on plants and animals for:
We depend on plants and animals for:
waste detoxification and removal
Humans Tend to Threaten Biodiversity
Humans also do some good things for biodiversity!
National Parks and Nature Reserves
Biosphere Reserves and World Heritage
Costa Rica's megareserves
Funding conservation of
BIOLOGICAL HOT SPOTS
Corridors between habitat fragments
Legally Protecting Biodiversity
In a given ecosystem, species can be classified into
5 general groups
according to their
ONE species is not limited to ONE role
"Species that normally live and thrive in a particular ecosystem"
AKA Indigenous Species
Presence of a species in a given area is
and not due to human activity
Invasive, alien, or exotic species
Nonnative species can be good or bad...
E.g. crops, chickens, cattle, and some fish
Some domesticated species provide us with food:
Some nonnative species can push native species into extinction
E.g. killer bees
Species that provide early warning of ecosystem or community destruction
Only live in
with lots of
Trout have a very narrow range of conditions that they live in.
Although all fish benefit from clean water and lots of oxygen,
Many other fish can tolerate more variable conditions.
However, if we notice that trout are not there, scientists can monitor water quality to make sure that conditions do not get too bad.
Birds and Butterflies
by environmental changes such as
Indicator Species are
that are important so we can
limit damage to species
(frogs, toads, salamanders)
A species that has a very
other species in the ecosystem
Removal or extinction of a Keystone Species
on the community it belongs to.
Some Keystone Roles...
Maintain diversity of flowering plants
Control populations of species lower on the food chain
Because Keystone Species have such a great effect on their communities,
scientists especially focus on protecting them
In the process of using their environment to their own advantage, foundation species benefit other species
Elephants pushing over trees
Beavers building dams
Keystone Species vs. Foundation Species
have a more
effect on other species
effect on other species
Human Effect on Biodiversity
Bats and birds spreading seeds