Transcript Topic 4 - Ecology

Topic 5 and Option G Ecology
5.1 Communities and Ecosystems
5.1.1
Define: (1)
Ecology—the study of relationships between living organisms and
between organisms and their environment.
Ecosystem—a community and its abiotic environment.
Population—a group of organisms of the same species who live in the
same area at the same time.
Community—a group of populations living and interacting with each
other in an area.
Species—a group of organisms which can interbreed and produce
fertile offspring.
Habitat—the environment in which a species normally lives or the
location of a living organism.
5.1 Communities and Ecosystems
5.1.2
autotroph (producer) – organisms that use
an external energy source to produce
organic matter from inorganic raw
materials
Examples: trees, plants, algae, blue-green
bacteria
What process are they doing????
5.1 Communities and Ecosystems
heterotroph (consumer) – organisms that
use the energy in organic matter,
obtained from other organisms
Examples: ????
5.1 Communities and Ecosystems
1. consumers – feed on other living things
2. detritivore – feed on dead organic matter
by ingesting it
3. saprotroph (decomposer) – feed on dead
organic material by secreting digestive
enzymes into it and absorbing the
products
So, what’s the difference here???
5.1 Communities and Ecosystems
5.1.4
Describe what is meant by a food chain
giving three examples, each with at least
three linkages (four organisms). (2)
A food chain is a sequence of relationships
between trophic levels where each
member feeds on the previous one.
Don’t include decomposers in your food
chain in your notes.
5.1 Communities and Ecosystems
5.1.5
Describe what is meant by a food web. (2)
A food web is a a diagram that shows the
feeding relationships in a community. The
arrows indicate the direction of energy
flow.
5.1 Communities and Ecosystems
5.1.6
Define trophic level.
(1)
A trophic level is where an organism is positioned
on a food web (it’s feeding relationship to other
organisms).
Producer
Primary consumer
Secondary consumer
Tertiary consumer
5.1 Communities
and Ecosystems
Quaternary
consumers
Carnivore
Tertiary
consumers
5.1.7
Deduce the trophic level
of organisms in a food
chain and a food web.
(3)
Carnivore
Secondary
consumers
Carnivore
Primary
consumers
Herbivore
Primary
producers
Plant
A terrestrial food chain
5.1 Communities and Ecosystems
5.1.9
State that light is the initial energy source for
almost all communities. (1)
What process???
5.1.10
Explain the energy flow in a food chain. (3)
Tertiary
consumers
Microorganisms
and other
detritivores
Heat
Secondary
consumers
Heat
Detritus
Primary consumers
Heat
Primary producers
Heat
Key
Chemical cycling
Energy flow
Sun
5.1.11
State that energy transformations are 10–20%
efficient.
(1)
Plant material
eaten by caterpillar
200 J
67 J
Feces
100 J
33 J
Growth (new biomass)
Cellular
respiration
5.1.12
Explain what is meant by a pyramid of
energy and the reasons for its shape. (3)
Notice the
loss of
energy with
each
transfer in
a food chain
5.1 Communities and Ecosystems
5.1.13
Explain that energy can enter and leave an
ecosystem, but that nutrients must be recycled.
(3)
Energy enters as light and usually leaves as heat.
Nutrients do not usually enter an ecosystem and
must be used again and again. Nutrients
include: Carbon, Nitrogen, and Phosphorus
Nitrogen Cycle
N2 in atmosphere
Assimilation
Nitrogen-fixing
bacteria in root
nodules of legumes Decomposers
Ammonification
NH3
Nitrogen-fixing
soil bacteria
NO3–
Nitrifying
bacteria
Nitrification
NO2–
NH4+
Nitrifying
bacteria
Denitrifying
bacteria
G1 Community Ecology
• G.1.1 Outline the factors that affect the
distribution of plant species, including
temperature, water, light, soil pH, salinity,
and mineral nutrients.
G1 Community Ecology
• G.1.2 Explain the factors that affect the
distribution of animal species including
temperature, water, breeding sites, food
supply and territory.
Internal Assessment
Think about what will effect how plants
are distributed in an ecosystem….
First IA pause and Statistics Pause.
G1 Community Ecology
G.1.5 Explain what is meant by the niche
concept.
The total of a species’ use of biotic and
abiotic resources is called the species’
ecological niche.
- Habitat
- Feeding relationships
- Symbiotic/other interactions with
organisms
G1 Community Ecology
G.1.7 Explain the principle of competitive
exclusion.
• two species competing for the same
limiting resources cannot coexist in the
same place – one must leave or becomes
extinct
G1 Community Ecology
G.1.8 Fundamental vs Realized Niches
Fundamental = where the species is designed
to live the best
Realized = where the species actually resides
because of competition
G1 Community Ecology
G.1.6 Outline the following interactions
between species: competition, herbivory,
predation, parasitism, and mutualism (with
examples).
G1 Community Ecology
G.1.9 Define biomass - each tier represents
the dry weight of all organisms in one
trophic level
Trophic level
Tertiary consumers
Dry weight
(g/m2)
1.5
Secondary consumers
11
Primary consumers
37
Primary producers
809
G2 Ecosystems and biomes
G.2.1 Define gross production and net
production.
Gross Production = the amount of light energy
converted to chemical energy by autotrophs
in an ecosystem
Net Production = Energy able to be passed on
by producers to consumers
G.2.2 GP – R (Respiration) = NP
G2 Ecosystems and biomes
• G.2.5 Construct a pyramid of energy,
given information.
G2 Ecosystems and biomes
• G.2.6 Distinguish between primary and
secondary succession.
• Primary succession occurs where no soil
exists when succession begins
• Secondary succession begins in an area
where soil remains after a disturbance
G2 Ecosystems and Biomes
• G.2.7 Outline the
changes in species
diversity and
production during
primary succession.
• Not very diverse:
Lichen pioneer
species
• Very diverse: Forest
climax community
G2 Ecosystems and Biomes
• G.2.8 Explain the effects of living organisms on
the abiotic environment, with reference to the
changes occurring during primary succession.
• Small amount of soil formed by the lichens is
colonized by mosses, which do not have roots
and require little soil
• As the seedless plants live and die
decomposition increases the richness of the soil
• Grasses can successfully grow
G2 Ecosystems and biomes
• G.2.9 Distinguish between biome and
biosphere.
• Biome = Communities on earth that
contain similar plant and animal
inhabitants
• Biosphere = part of Earth that can contain
life
G2 Ecosystems and Biomes
• G.2.11 Outline the characteristics (temperature,
moisture, vegetation) of six major biomes.
• Desert
• Grassland
• Shrubland
• Temperate deciduous forest
• Tropical rainforest
• Tundra
G1 Community Ecology
• G.1.3 Describe one method of random
sampling, based on quadrat methods, that
is used to compare the population size of
two plant or two animal species.
1) Mark off a large 10 x 10 meter grid area
2) Toss a 1 x 1 meter square into the grid area randomly
3) Identify and count all the larger plant species first
4) Smaller plant species, like grass, divide your square into
several smaller 10 x 10 cm squares. Count the number of
individual plants in several of those smaller squares, average,
and multiply by 100 to get an estimate.
5) Toss the 1 x 1 m square to obtain more data.
G3 Impacts of humans on
ecosystems
• G.3.1 Calculate the Simpson diversity
index for two communities.
• N – total number of individual organisms
(all species combined)
• n – number of individuals of a particular
species
G3 Impacts of humans on
ecosystems
• G.3.2 Analyse the biodiversity of the two
local communities using the Simpson index.
• High Index (closer to one) – Higher the
biodiversity
• This index ranges from zero to one and is
literally a measure of the probability that two
organisms taken at random from the sample
are different species. A number close to zero
means low diversity and it is likely you will
get the same species of organism and a
number close to one means high diversity.
Internal Assessment
Quadrat Lab
5.3 Populations
5.3.1
Outline how population size can be affected by
natality, immigration, mortality and emigration.
• Natality – offspring are produced and added to
the population
• Mortality – individuals die and are lost from the
population
• Immigration – individuals move into the area
from somewhere else and add to the population
• Emigration – individuals move out of the area
and are lost from the population
5.3 Populations
5.3.2
Draw a graph showing
the sigmoid (Sshaped) population
growth curve.
5.3 Populations
Exponential Phase
Population increases exponentially because
the natality rate is higher than the mortality
rate. This is because there is an
abundance of food, and disease and
predators are rare.
5.3 Populations
Transitional Phase
Difference between natality and mortality
rates are not as great, but natality is still
higher so population continues to grow,
but at a slower rate.
Food is no longer as abundant due to the
increase in the population size. May also
be increase predation and disease.
5.3 Populations
Plateau Phase
Natality and mortality are equal so the population
size stays constant.
Limiting Factors:
shortage of food or other resources
increase in predators
more diseases or parasites
If a population is limited, then it has reached its
carrying capacity
5.3 Populations
Define carrying
capacity.
The maximum
population size that
can be supported by
the environment
5.3 Populations
In a random sample, every individual in a
population has an equal chance of being
selected.
Describe one technique used to estimate the
population size of an animal species based on a
capture-mark-release-recapture method.
(2)
• Various mark and recapture methods exist.
• Knowledge of the Lincoln index (which involves
one mark, release and recapture cycle) is
required.
5.3 Populations
population size =
n1xn 2
n3
where . . .
• n1= number of individuals initially caught, marked and released
• n2 = total number of individuals caught in the second sample
• n3 = number of marked individuals in the second sample
5.3 Populations
• IA – Mark and Recapture
5.2 Greenhouse effect
5.2.1
Draw the carbon cycle to show the
processes involved.
• The details of the carbon cycle should
include the interaction of living organisms
and the biosphere through the processes
of photosynthesis, respiration, fossilization
and combustion. Recall of specific
quantitative data is not required.
5.2 Greenhouse Effect
5.2.2
Analyze the changes in concentration of
atmospheric carbon dioxide using
historical records.
What’s happening to carbon dioxide levels?
5.2 Greenhouse effect
• Explain the relationship between rises in
concentrations of atmospheric carbon
dioxide, methane and oxides of nitrogen
and the enhanced greenhouse effect.
Greenhouse Effect
Causes
Light from the sun has short wavelengths
and can pass through most of the
atmosphere.
This sunlight warms the earth which in turn
emits long wave radiation.
This long wave radiation is bounced back by
the greenhouse gases, such as carbon
dioxide, methane, water vapour, and
sulphur dioxide
5.2 The greenhouse effect
5.2.6 Outline the
consequences of a
global temperature
rise on artic
ecosystems.
- Loss of ice habitat
- Increased success of
pests
G3 Impacts of humans of
ecosystems
• Ozone layer absorbs
UV radiation
• CFCs are causing a
hole in the ozone
layer
• Excessive UV
radiation can cause:
– Skin cancer
– Vital bacteria would
die
G3 Impacts of humans on
ecosystems
• G.3.4/5 List 3 examples of introduced/alien
species and discuss the impact.
-Purple Loosestrife
-spread alarmingly fast,
- removed from their natural controlling
agents.
- dramatic disruption in water
flow in rivers and canals,
- Native food and cover plant species,
notably the cattails, are crowded out.
G3 Impacts of humans on
ecosystems
• Zebra mussels were first
detected in the Great Lakes
in 1988 and have caused
widespread damage in the
ecosystem.
• Zebra Mussels are edible, but
most experts advise against
eating any found in areas of
pollution concern since zebra
mussels accumulate
contaminants and toxins from
the water that they filter.
G3 Impacts of humans on
ecosystems
- Round Goby
- Survives well in
degraded environmental
conditions
-Competitive advantage
compared to native
species.
-Heavy feeding on
invasive mussels
(zebra and quagga)
results in greater
biomagnification
- No predators due to
defensive mechanism
Define biomagnification –
At each trophic level, toxic substances (Hg, pesticides, TCDD, etc.)
become more concentrated
G3 Impacts of humans on
ecosystems
• How can we keep invasive species in check
via a biological mechanism?
– Decide on a local area that is currently being
impacted negatively by an invasive species.
– Find out what that negative impact is and which of
the invasive species is causing it.
– Research a BIOLOGICAL means of controlling
that species in order to stop the negative impact.
– Put together a proposal illustrating your method of
restoring the ecosystem.