Transcript Kelp forests - University of Arizona

Biodiversity – diversity of life
•Variety of ecosystems
–coral reefs, rainforests
•Variety of species
•Variety of genes among individuals of
a species
–color, height
• Kingdoms:
– Monera – bacteria (no cell nucleus)
– Protists – single-celled organisms
– Fungi
– Plants
multi-celled organisms
– Animals
Hierarchical nomenclature
• Table/ classification of organisms
What is a species?
• Common definition: A species is
reproductively isolated from every other
species in nature.
• 1.6 million species have been described
and recorded.
• Total number of species?
30 – 100 million
Species estimates
• High estimates came about in the 19601970s when new communities were
discovered.
• Rain forest canopy
• Deep ocean hydrothermal vents
How many species are there?
Speciation – creation of new species
• Populations evolve by becoming
genetically different.
– Genetic drift
– Natural selection
Genetic diversity
• Caused by mutations – errors in duplication
of the genetic code.
• Mutations are often bad, in which case they
are not passed on to the next generation.
• But mutations can also be helpful, in which
case they are passed on to offspring and
genetic diversity of the population increases.
Example: sickle cell anemia
• Substitution in the gene
sequence for hemoglobin in
humans
• Valine instead of glutamic acid in
2 places
• Red blood cells are different
• Homozygous – sickle cell anemia
• Heterozygous – protection
against malaria.
• This genetic “defect” persists
because there are advantages.
Natural selection
“Survival of the fittest!”
More “fit” organisms tend to be more
successful and their genes are more
likely to be passed on.
Fit = best adapted
Success = have more offspring
Example: Peppered moth
Pre-industrial England, moths
were predominantly white,
with black moths (mutation)
rare.
Moths rest on tree trunks
during the day, and are
eaten by birds.
In industrial areas, pollution
turned tree trunks black. In
these areas black moths
eventually became
dominant.
Geographic isolation
• Reproductive isolation is induced by a
barrier such as a river, glacier, rising
ocean.
• Population is split into two groups, each
of which undergo genetic drift and
natural selection.
• May eventually become separate
species.
Species adaptation
• Organisms become adapted to a certain
“lifestyle.”
• Ecological niche – functional role in an
ecosystem
– Range of environmental conditions.
– Types of resources used.
– Interactions with living and non-living
matter.
– Role in flow of energy and cycling of
matter.
Species tolerances
Ecosystems
• an assemblage of different species and
their physical environment, all organized
in a way that each population of
organisms obtains energy and nutrients
through specific pathways within the
ecosystem. Each species has a distinct
ecological niche.
Example ecosystem: Rocky intertidal
Ecosystem components
1. Functional groups of organisms
a. Producers (autotrophs)fix energy and
inorganic nutrients into organic forms that
are accessible to other organisms.
b. Consumers (heterotrophs) get energy and
nutrients by consuming the producers.
c. Decomposers (heterotrophs) get energy
and nutrients by decomposing all other
organisms that have died.
Energy transfer
2. Unidirectional transfer of energy from one
functional group to another until it is
dissipated from the ecosystem as heat
Energy is transferred in one direction, from
producers to consumers to decomposers.
After decomposers have extracted energy
from dead organic matter, the energy is no
longer available within the ecosystem.
Nutrient cycling
3. Cycling of nutrients among the various
groups of organisms through trophic (feeding)
interactions
Unlike energy, nutrients do not move
unidirectionally through the ecosystem. They
are recycled through the activity of
decomposers, which return the organic
nutrients to their inorganic forms.
This process is called mineralization. The
mineral nutrients are then available again to
producers and microbes that can use them.
Fig: ecosystem
Example ecosystem: Rocky intertidal
Complex species interactions within an
ecosystem – food webs
Simple food web
• Energy flow diagrams
represent energy
movement between
trophic levels.
• Changes in species
population sizes can
affect species in other
trophic levels in the
food web.
top predators
2° consumers
1° consumers
autotrophs
Increase in autotrophs. . .
Decrease in autotrophs. . .
Primary productivity is an important control
on ecosystem productivity
Change in top consumer. . .
• overfishing
Keystone species
• If that species is removed there are
dramatic changes in and population
densities of all the other species in the
community.
• Keystone species are usually predators
• No comparable changes appear when
other species are removed from the
ecosystem.
The kelp forest ecosystem
• Kelp forests along the Pacific coast.
• 30 – 40 m water depth
– Determined by light availability
• Found almost exclusively at areas of
upwelling
– Require high nutrient concentrations
• Water temperatures cooler than 20oc
fig/ distribution of kelp and mangroves
slide/ kelp forest
• Gas – containing
sacs to keep them
buoyant
• Grow as much as
50 cm a day
• Continue to grow
once they reach
the surface
• Supports diverse community
• Provide
– Food
– Protection/ hiding place from predators
– Substrate/ habitat
slide/ sea urchin
slide/ otter in kelp bed
otters eat
sea urchins
fig/
otter,urchi
n, kelp
circle
sea urchins
eat kelp
kelp
provides
habitat
for otter
fig/ graphs of urchin vs. kelp
With otters
Without otters
The role of sea otters in kelp communities
• A ‘keystone’ predator
• Sea urchins graze kelp beds
• Otters keep sea urchin populations under
pressure
– Keep the sea urchin populations from growing
too large and destroying the kelp.
• What happens if you remove the otters?
– Intensive hunting of otters in 1800s led
decline of kelp forests.
(Altered) Yellowstone ecosystem
• Missing the natural top predator (wolf)
• High population levels of bison and elk
grazers.
– Destroy habitat, diminish food resources.
– Increased disease.
– Unstable population sizes.
Increased grazing pressure in Yellowstone
Wolves
• Top predator
• Typical feast and famine diet
• Pack of 6 will consume about 2 elk and one
deer a month.
– Select ill and weaker animals, which controls
disease and strengthens the population
– Control population density of prey.
– Provide food for other animals – ravens, eagles,
grizzlies.
Reintroduction program
• Reintroduction program began in 1995.
• Yellowstone had 22% more visitors in
June 1995.
• Wolves now have viable populations
(producing offspring).
• Beginning to prey on bison as well as
elk.
Activity: Should we drill in the Artic National
Wildlife Refuge?
pretty picture
Comparison of ANWR to Continental
US
Map
Predators
Pictures
Snow geese
Porcupine caribou
Vegetation
Muskoxen
Oil