Transcript File

Ecology
Dr. Jared Heidinger M.D. Ph.D.
Masters of Ecology, Doctorate of
ecology, undergraduate of
ecology, know it all of ecology, full
of it ecology…
• Ecology – study of
interrelationships b/w living
organisms and b/w organisms and
their abiotic environment
Levels of Organization in Biology
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Ecosphere – global ecosystem
Biosphere – global community
Ecosystem – community and environ.
Community – group of populations
(same place, same time)
• Population – same species of organism
(same area, same time)
• Organism – individual living thing
Continued…
• Organ system – groups of organs that
carry out a function (eg. digestive
system)
• Organ – two or more tissues that work
together at a function (eg. Kidney)
• Tissue – groups of cells with similar
structure and function (eg. Muscle)
• Cell – basic unit of life
Continued…
• Organelle – structures within cells
• Molecule – group of atoms bonded
together
• Atom – basic unit of all matter
Other important definitions…
• Species – organism which can
interbreed and produce fertile
offspring
• Habitat – environment in which a
species normally lives or the
location of a living organism.
Ecosystems (community and
environment)
• Consists of:
– biota (living things (eg. organisms
from the five kingdoms))
– Abiota (non-living things (eg. Soil,
water, air, weather))
Interrelationships within
ecosystem
• Biota affects biota: man eats fish
• Biota affects abiota: animals
release gas to atmosphere
• Abiota affects abiota: fire destroys
nesting sites
• Abiota affects abiota: water erodes
rock
Pork CHNOPS – Pork what???
Within Ecosystem
• Matter is cycled
• C, H, N, O, P, S
• Molecules cycle between biota and
abiota (biogeochemical cycles)
• Energy does NOT cycle
• Enters by sun, travels through food
chain, leaves as heat
Biogeochemical Cycles
• All chemical elements in living
organisms (mainly CHNOPS) are:
– Part of biogeochemical cycles
– Move through land, water and air
Continued
• Biogeo. Cycles summarize
movements of elements
– Through the biota (via food chains)
forming complex organic molecules
– Through the abiota forming simpler
reusable organic forms.
Continued
• Affected by human activity resulting in:
– Ozone depletion
– Green house effect and global warming
– Acid rain
– Algal blooms
– Biomagnification of pesticides
Nitrogen Cycle
HUMAN IMPACT SHEET
Continued
N2 cycle has 3 phases
Phase 1
• Nitrogen fixation – conversion of
atmospheric nitrogen (N2) to nitrates
(NO3-)
• Often NH3 is formed first
• Mostly done by aerobic bacteria:
– Some free-living in soil
– Some symbiotic live in plant roots
• Some industrial fixation for fertilizer
Phase 1 cont…
• Legumes (beans, peas, alfalfa,
clover) – have root nodules that
containing N2 fixing bacteria
• Mutualistic relationship – both
organisms benefit (+/+)
• Increase soil nitrates – farmers
rotate their crops with these plants
Phase 2
• Nitrification
– Process of changing NH3 to NO2- to
NO3– Done by bacteria in soil
Phase 3
• Denitrification – conversion of nitrates
(NO3-) to 2N
• Anaerobic bacteria do this
• Lowers available nitrates for plants
• Plants don’t grow as well
• Aerate, plow, dig, anything to get some
O2 back in soil helps to counteract the
plot of the evil, evil denitrifying bacteria
(not really evil, unless you are a
gardener)
Final Thoughts
• Animals get all nitrogen (eg. found in protein, DNA) from plants
– Need nitrogen fixation to survive
Farming
• Breaks the natural nitrogen cycle
by removing all of the plant matter
at harvest
• Less matter to decompose and
replenish nitrogen
• Results in the need to fertilize
Carbon Cycle
• Often called carbon oxygen cycle
• Interrelated
• Major processes
– Photosynthesis
– Decomposition: breakdown of organic
matter, mostly done by fungi and
saprophytic bacteria
– Combustion: mostly done by automobiles
Problems
• Global Warming
• Deforestation – causes decline in
photosynthesis
Not the same
• Greenhouse effect is a natural process.
Without it we could not survive on
earth.
• Greenhouse gases (CO2, H2O vapour,
CH4 (methane), nitrous oxide, CFC’s)
help to keep heat (infrared radiation)
close to the earth’s surface
• Global warming an increase in the
earth’s average temperature due to the
burning of fossil fuels releasing excess
amounts of CO2
• Worst case scenario – warming is
greatest at poles causing melting of ice
caps
• Ocean could rise by 100m resulting in
flooding of coastal regions up to 150km
inland
• Change in climate could mess with
agriculture as well.
Water Cycle
Steps:
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Evaporation – l to g
Transpiration – l to g from plants
Condensation – g to l form clouds
Transport – movement of clouds
Precipitation – rain, sleet, snow, etc.
Runoff – streams, lakes, rivers
Groundwater – aquifers, underground
streams
Problems
• Acid rain
• Toxic waste dumping
• Leaching (chemical compounds seep
into underground water)
• Deforestation
– runoff increases, minerals run into
streams, disrupting balance in ion
concentrations in water
– Transpiration rates are changed.
Phosphorous Cycle
Phosphorous uses in Biota
• Cell membranes (phospholipids)
• Energy storage (ATP)
• Genetic information (DNA, RNA)
in Abiota…
• Phosphate ions (PO43-) combined
with other elements in rock
• Ions dissolved in water move with
water cycle
Problems
• Eutrophication
Human Impact Worksheet
Energy Flow in the Biosphere
• E flows through an ecosystem:
– Enters as light, leaves as heat
– Is transferred through the food chain.
Food Chain
• Shows flow of energy thorough
ecosystem
• DIAGRAM
Producer
Consumer
• Eats something
• Primary – eats producer
• Secondary – eats primary
• Tertiary
• Quaternary – not usually more than
a quaternary consumer
• Autotroph – make own food from
abiotic materials
– Photoautotroph – use sun
– Chemoautotroph – Use heat and
chemical compounds to make useable
energy
• Heterotroph – needs something
else for energy
Decomposers
• Use last energy from organic
matter that has died
• NOT shown on a food chain
• Trophic level (feeding level) – each
step in a food chain
Energy Transfer in a Food Chain
• Inefficient – some E lost in each step
• Only 10-20% of E passed to next level
• E loss due to:
– Some material not eaten
– Some not digested or assimilated
– Heat lost through cellular respiration
• Therefore, the E available to each
trophic level is always less than at
the previous level
• Results in less organisms at each
successive level
Ecological Pyramids
• Used to show overall E flow
• Numbers – can be inaccurate
(many insects on one tree)
• Biomass
• Energy – most accurate, biggest
pain to do
Food Webs
• Show alternative food chains
• Shows complexity of energy flow
Population Ecology
• Populations are described in terms
of:
• Size
• Distribution
• Density
• Diversity
Four main Factors affect
Population size
• Natality (birth rate)
• Mortality (death rate)
• Immigration (moving in)
• Emmigration (moving out)
Estimating Population size
• Mark and recapture method.
Population Growth
Represented on growth curves
• DIAGRIZZLE
Definitions
• Carrying capacity – number of
organisms an ecosystem can
support
• Reproductive potential – max
reprod. Rate under ideal conditions
Elephant - 2 years
Human - 9 months
Limiting factors
• Conditions that prevent population
growth
– Amount of food
– Space
– Waste
– Competition
– Predation
Limiting factors cont…
• Responsible for establishing the
carrying capacity
• Determine the distribution of org. in
ecosys.
• Plants: affected by temp., water, soil
pH, salinity, mineral nutrients
• Animals: affected by temp., water,
breeding sites, food supply, territory
Niche
• Total role of an organism in its
ecosystem including:
– Trophic level (food sources)
– Habitat used
– Interactions with biota and abiota
Competitive Exclusion Principle
• No two species can occupy the
same niche
• One always out competes the
other.
Biological Relationships
• Symbiotic – organisms living in
close association with each other
– Mutualism +/+: both benefit
(nitrogen fixing bacteria and bean
plant)
– Commensalism +/0: one benefits
other unaffected (shark and remora)
• Parasitism +/-: one benefits other
is harmed (tapeworm and human)
Competition
• Intraspecific = b/w members of the
same species (eg food, mates)
• Interspecific = b/w members of
different species (eg. Food, space)
• Competition creates selection
pressures that drive evolution
forward.
• Competition is reduced by resource
partitioning (making use of
different parts of the ecosystem
(I.e. niche specialization)
Succession
• Successive stages of development
in an ecosystem:
• Begins with pioneer species
• Develops through seral stages
• Ends with a climax community
Succession continued
• Primary succession: occurs in an
area where organisms have not
established themselves already
– lichens, moss on rocks exposed by a
retreating glacier
• Secondary succession: occurs in
an area where life has already been
but has been disturbed
– Forest after a forest fire
Why Succession Happens
• Organisms at each stage affect the
abiotic environment, altering the
conditions in such a way as to
allow other species to move in
• Abiotic changes include soil:
– development, accumulation of
minerals and reduced erosion
Productivity in the Ecosystem
• Gross Production (Gross Primary
Productivity –> GPP)
• Total amount of light E converted
to chemical E by the autotrophs of
an ecosystem over a given period
of time
• *some E from gross production is
used for cellular respiration
• Rest is converted to biomass and is
available to the next trophic level
Net Productivity (Net Primary
Productivity -> NPP)
• Gross production minus respiration
– GPP – Rs = NPP
• *net production can be expressed
as:
– Energy per area per time (J m-2 yr-1)
– Biomass (dry weight) expressed as
mass per area per time (g m-2 yr-1)
Biodiversity and Conservation
• Biodiversity: number and types of
organisms present in an area
(a.k.a. species richness)
• Wildlife conservation: efforts to
maintain high levels of biodiversity
Eg) With reference to rainforest
why attempt to conserve
biodiversity?
• Ethical concerns – responsibility
• Ecological concerns –
interrelationships between species
• Economic concerns – medicines,
drugs, pool of valuable resources
• Aesthetic concerns – beauty of the
rainforest worth saving.
In-situ vs ex-situ conservation
measures:
• In-situ – keeping organisms in their
natural habitat
– Eg creating nature reserves (aquatic
or terrestrial)
Ex-situ
• Ex-situ = conservation efforts
outside of their original habitat:
– Eg. Zoos (captive breeding
programs), aquaria, seed banks,
botanical gardens
In-situ
advantages/disadvantages
• Advantages:
• Natural habitat
• Maintains
ecological
relationships
• Protects from
human
exploitation
• Disadvantages:
• Need large tracts
of land
• Must control alien
species
• Must restore
degraded areas
Ex-Situ
Advantages/Disadvantages
• Advantages:
• Breeding ensured
even with low
population counts
• Animals released
where they are
lowest in
numbers
• Disadvantages:
• Animals not in
natural habitats
• Doesn’t maintain
ecological
relationships
• Doesn’t fix
original problem