Download Trophic Levels - International School Bangkok

Biology 1
Introduction to Ecology
Ecology: the study of the relationships
living things have with each other and
their non-living environment.
Biotic Factors: all the living things in an
environment
What biotic factors can you identify?
Abiotic Factors:
All the non-living
factors in an
environment.
The soil (dirt) in an
environment cannot be
called simply abiotic or
biotic. Discuss.
Species: a group of organisms that can
interbreed and produce fertile offspring in
nature.
A few shark species
What does it mean that these sharks are
different species?
Vocabulary
Habitat (address)
The place an organism lives.
Think of a zoo. There is usually an attempt to mimic the
organism’s “habitat.”
Niche (occupation)
The role that an organism plays in its environment.
How does the organism obtain food? What are some of
its relationships with other organisms?
Can you describe the habitat and niche of some organisms?
Vocabulary: Levels of Ecology
Organism (any single living thing)
Population (members of same species living in
one place)
Community (different populations interacting
in an area)
Ecosystem (a complete community + its
abiotic environment)
 Biosphere (all parts of Earth where life
exists, both biotic and abiotic)
Population: a group of the same
species living in the same area at the
same time.
Community: interacting groups of
populations
Ecosystem: a community and its
abiotic environment.
humidity
light
Water temperature
Mineral
content
A Freshwater
Pond
Biomes (not required): Large, ecologically similar areas.
Biosphere: all the interdependent and
interrelated ecosystems of the earth
Population Ecology: the interactions of one
population, especially relating to population
size
What increases population size?
• Natality (births)
• Immigration (moving into a
population)
What decreases population size?
• Mortality (deaths)
• Emigration (moving out of a
population)
What are some factors that would influence natality and
mortality rates? Immigration and emigration?
Natural Resources:
• Things organisms need to survive
Limiting Factors (environmental resistance):
• When resources are in short supply (or
too abundant) and impact population
growth.
Carrying capacity: the maximum population
than an environment can sustainably support
Compare
and
contrast
these
graphs.
A population may plateau OR temporarily overshoot the
carrying capacity. If overshot, survival depends of severity
of overshoot and speed of environmental recovery.
Apply population ecology ideas to
the global human population.
COMMUNITY INTERACTIONS:
Relationships between species
3 types of
Symbiosis:
A continuing and
close relationship
between species
Relationship
Mutualism
Effect
+ / +
Commensalism
+ / 0
Parasitism
+ / -
Pathogen / Host
Predator / Prey
Not considered
symbiosis
Herbivore / Plant
Competition
+ / + / + / - / -
MUTUALISM: a + / + interaction
Lichens: an alga and
a fungus!
What benefit does each species receive?
MUTUALISM: a + / + interaction
Cleaner Wrasse and
Parrot Fish
Ants and Acacia
Trees
What benefit does each species receive?
MUTUALISM: a + / + interaction
Ants and Aphids
PARASITISM: a + / - interaction
PARASITISM: The Cuckoo
PATHOGEN / HOST: a + / - interaction
COMMENSALISM: a + / 0 interaction
Scavengers benefit
from dead organisms
that are not
affected.
Cattle Egrets eat
the insects that
these cattle scare
up.
COMMENSALISM: a + / 0 interaction
Shark and Remora
PREDATION: a + / - interaction
HERBIVORY: a + / - interaction
COMPETITION: a - / - interaction
Male weaver birds: compete
to attract a mate. This is
INTRASPECIFIC
competition: competition
within the same species
COMPETITION: a - / - interaction
Invasive starlings will out-compete
native bluebirds for nesting holes.
This is INTERSPECIFIC
competition: competition between
different species
Energy and Ecology:
ALL living things need both matter and energy.
Matter and energy are transferred:
• between organisms
• between organisms and the abiotic environment
What is different between the transfer of
ENERGY and the transfer of MATTER?
ENERGY: flows one-way through the
biosphere and leaves the Earth. A new
input of energy is continually needed.
MATTER: the same atoms are use over and
over again. Matter is recycled, not “lost”.
Energy and Ecology
All organisms need energy to live.
Where do you get your energy?
How did the things you eat get their energy?
Trace the energy back to its source. What is the
source of energy for (almost) all living things?
Ecology Vocabulary
Tip: Learn word parts to help you understand new terms:
Prefixes:
“Auto” = by itself
“Hetero” = from others
Base-word:
“Troph” = energy (obtaining food)
Sometimes you see the suffix:
“ic” = pertaining to
Can you think of examples of words that have these parts?
Trophic Levels: how organims obtain energy (their food)
All organisms need energy to live.
AUTOTROPHS (producers): Most use
energy directly from the sun
produce their own food
by photosynthesis in
chloroplasts
often plants (also some
bacteria, lichens, etc)
Also break down food
when and where needed
to release energy
(respiration)
All organisms need energy to live.
HETEROTROPHS get energy from
consuming other organisms
often animals that release energy by
respiration in their mitochondria
Two major types of Heterotrophs:
Consumer -
a living thing that eats other
living things to survive. It cannot make its own
food.
Examples…humans, fish, spiders
Decomposer -
an organism that
breaks down and digest the remains of
organisms.
Examples…. fungi and some bacteria
Decomposers are essential
because they are the
nutrient recyclers!
Kinds of Decomposers:
1.) detritovore: (have a mouth)
feed on dead organisms or their wastes
eg. worms, millipedes, dung beetles
2.) Saprotroph: (without a mouth)
secrete digestive enzymes into their
environment and absorb the nutrients.
eg. Bacteria, fungi
What is the difference
between Detritivores and Saprotrophs?
• Detritivores usually have mouths, Saprotrophs do not.
• Detritivores are mostly animals while saprotrophs are
mostly bacteria and fungi.
• Detritivores consume lumps of dead organic matter
separately, while saprotrophs absorb chemically
digested food.
• Saprotrophs digest their food externally, whereas
detritivores do it internally in their digestive system.
Remember to follow the
energy!
Find several major errors / omissions in this diagram
(from a respected publisher!)
Food chain: One possible energy
pathway through an ecosystem.
Shows who eats whom.
Let’s play “follow the energy!”
The arrows show you where it goes!
Food web: All possible energy
pathways through an ecosystem.
Shows alternative food choices.
Trophic Levels and
Levels of Consumers
Fourth Trophic
Level
Third Trophic
Level
Second Trophic
Level
First Trophic
Level
Note that the trophic level is always one more than
the consumer level. Why?
Food Web: Problems with Trophic Levels
What is the trophic
level of the fox?
3 4 5
4 3
3
2
1
2 2
1
1
We know that energy is transferred. How much?
About 10% between trophic levels.
Trophic Level:
Position in a
food chain
Energy Efficiency in Food Consumption
Why is it said that eating vegetarian food
can reduce food shortages and starvation?
Energy is not created or destroyed. If only 10% of energy
is transferred to the next trophic level, where is the rest?
Why can only 10% of
energy be transferred
to the next trophic
level?
• Not all organisms are
eaten
• Not all parts of
organisms can be
digested
• Converting energy
for the functions of
life is not 100%
efficient (some is
always) lost as heat
Cycles in Nature:
ALL living things need both matter and energy.
Matter and energy are transferred:
• between organisms
• between organisms and the abiotic environment
What is different between the transfer of
ENERGY and the transfer of MATTER?
ENERGY: flows one-way through the
biosphere and leaves the Earth. A new
input of energy is continually needed.
MATTER: the same atoms are use over and
over again. Matter is recycled, not “lost”.
Cycles of Matter:
Water, Carbon, Nitrogen, etc.
CARBON CYCLE
Follow the
carbon atoms.
Where do they
go?
combustion
Biodiversity
What does “Bio” mean?
Bio =
Biodiversity
What does “Diversity” mean?
Diversity = Variety
There are 3 components of biodiversity
1. Diversity within genes
Chihuahuas, beagles, and Rottweilers are all dogs—
but they're not the same because their alleles are
different.
Chihuahua
Beagle
Rottweilers
3 components of biodiversity
2. Diversity of species
For example, there about 260 species of
monkeys, 5,000 species of dragonflies,
and 350,000 species of flowering plants.
Saki Monkey
Golden Skimmer
Meadow Beauty
3 components of biodiversity
3. Variety of ecosystems
Prairies, Ponds, and tropical rain forests are all
ecosystems. Each one is different and supports a
unique set of species.
Paines Prairie
Florida Sand hill Pond
Hoh Rain Forest
Which has more biodiversity?
A
B
Threats to biodiversity
1. Habitat destruction or loss including
1.
2.
3.
Land cleared for agriculture, construction,
resource extraction, etc.
Climate change impacts
Pollution
2. Invasive Species
3. Direct hunting or exploitation
For a video about biodiversity watch
“Extinction!” video from the evolution unit.
Why do we want biodiversity?
1. Intrinsic Value = Something that has value
in and of itself. Do we value all life?
2. Utilitarian Value = Something that has value
as a means to an end. What do we get from
biodiviersity?
• Food, shelter, medicine, and other
products
• Stable ecosystems and epidemicresistant species
• Ideas for research and sources of new
information
The Earth is losing species at an alarming rate
• Some scientists estimate that dozens of species are going
extinct each day, many of which humans never studied
This periwinkle was used in traditional
medicine and became endangered due
to habitat destruction. Scientists
found that it has anti-cancer
properties. It now gives us cisplatin,
one of our best treatments for
leukemia.
Madagascan Rosy
Periwinkle
We came close to losing this species.
What else might we be losing every
day without knowing it?
Solutions, not just problems
• Eco-Tipping Points
– Small actions that lead to large positive
changes
– For more information
• A Thailand case study
– Reversing Tropical Deforestation
– Video presentation