Topic 5 Ecology and Evolution. Define Species Habitat Population Community Ecosystem Ecology...

Topic 5

Ecology and

Evolution

Define• Species

• Habitat

• Population

• Community

• Ecosystem

• Ecology

• Autotroph

• Heterotroph

• Consumer

• Detrivore

• Saphrotroph

5.1 Communities and Ecosystems Ecology is the study of relationships between

living organisms and between organisms and their environment.

This means the relationship of all the living things (biotic) to all the non living things (abiotic)

and their relationships to each other.

DefinitionsEcosystem—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

One of the most important relationships between living things is: who eats whom? Feeding relationships

Autotroph (producer) – organisms that use an external energy source to produce organic matter from inorganic raw materials

Examples: trees, plants, algae, bacteria

• Most autotrophs use carbon dioxide from the atmosphere along with energy from the sun to fix carbon into organic molecules through a process called photosynthesis.

• Other autotrophs fix organic material without the use of the suns energy. They are called chemoautotrophs.


Heterotroph (consumer) – organisms that use the energy in organic matter, obtained from other organisms

Examples: animals, protista, fungi


Types of heterotrophs:• Consumers – an organisms that ingests matter

from organisms that are living or recently killed • Detritivore – an organisms that ingests non-

living organic matter, examples: beetles, worms • Saprotroph- an organisms that lives on or in

non-living organic, secreting digestive enzymes into it and absorbing the products of that digestion, examples: fungi, mold


Describe what is meant by a food chain giving three examples, each with at least three linkages (four organisms).

A food chain is a sequence of relationships between trophic levels where each member feeds on the previous one.

The arrow from one organism to the other indicates the direction of energy

• Food chains

Review

• Define:• Ecology• Ecosystem• Biotic/abiotic• Species• Population community• Autotroph: 2 types• Heterotroph: 3 types• Food chain


Describe what is meant by a food web.

A food web is a a diagram that shows the feeding relationships in a community. The arrows indicate the direction of energy flow.

• Food web: make a food web including all of your organisms.


Define trophic level.

A trophic level is where an organism is positioned on a food web (it’s feeding relationship to other organisms).

Producer: 1st level

Primary consumer: 2nd level

Secondary consumer: 3rd level

Tertiary consumer: 4th level


Deduce the trophic level of organisms in a food chain and a food web.

Quaternaryconsumers

Tertiaryconsumers

Carnivore

Carnivore

Secondaryconsumers

Carnivore

Primaryconsumers

Herbivore

Primaryproducers

Plant

A terrestrial food chain


State that light is the initial energy source for almost all communities.

5.1.10

Explain the energy flow in a food chain.

Microorganismsand other

detritivores

Tertiaryconsumers

Secondaryconsumers

Detritus Primary consumers

Sun

Primary producers

Heat

Key

Chemical cyclingEnergy flow

Heat

Heat

Heat

5.1.11

State that energy transformations are 10–20% efficient. (1)

Growth (new biomass)

Cellularrespiration

Feces100 J

33 J

67 J

200 J

Plant materialeaten by caterpillar

5.1.12

Explain what is meant by a pyramid of energy and the reasons for its shape.

Notice the loss of energy with each transfer in a food chain


• Explain that energy can enter and leave an ecosystem, but that nutrients must be recycled

• 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

Ecology Investigation

Mighty Duckweed

Ecology and statistical analysis

• Ecologist often want to compare data from two populations to see if there are differences due to some biotic or abiotic factor

• Examples?

• So we could collect data on some aspect of the population, for instance mass of the organism.


• What statistical tests could we do to summarize the data? (these kinds of test are called descriptive tests- they help to describe the data)

• Mean, mode ,median, standard deviation• What test could we do to look at the differences

between the two populations?• t test- this is an example of inferential statistical test,

these help us to see if the differences we see on 2 groups of data are statistically significant.

• What other inferential test have we learned about?


• In ecology, as in most science experiments we are not going to measure every organism in the 2 populations in order to do any statistical analysis.

• We are going to sample the population.• We hope that the sample is representative

of the whole population.• What things can we do to get closer to the

real or parametric values?


• What is the starting hypothesis that will be tested with inferential statistics?

• Null hypothesis• The null hypothesis states that the differences

we see in the samples are just due to chance.• Because we don’t know the actual value, we

need a statistical test to know how different the values need to be to say with confidence that the actual values are different.


• Inferential statistical tests give us a value that we then have to associate with a P value.

• The P value tells us the probability that our differences are due to chance or some other factor.

• In biology if the P value is 0.05 or less, then the differences we see are real/significant and we reject the null hypothesis and come up with an alternate hypothesis.

• It means that we can be 95% sure that these differences are real so the smaller the P value the more sure we are that they are significant.


• To get data to practice calculating both descriptive and inferential statistics we are going to go to the lake and find 2 populations of organisms to get data on.

• In pairs, you will select 2 populations of the same organism, decide what you will measure and your sample size.

• You will then collect what you need or take measurements in the field.

• Then you will calculate the following for each group: mean, sd and variance. Present this date in an appropriate graph.

• Next you will calculate a t test on the two populations.• Use this site, or excel or your calculator.

http://www.graphpad.com/quickcalcs/ttest1.cfm


• T test: paired or unpaired, one tailed or two tailed. ?

• The website I gave you explains this well.• The short explanation: use paired if your data

for the two populations are paired, have a one to one correspondence, like if you measure a plant before and after a treatment. If not, use unpaired.

• Use one tailed if you are looking for a difference, but you don’t know which one will be greater.

• Energy flows through the ecosystem and must constantly be added.

• Nutrients , on the other hand are recycled.

• The organisms that do this are the saprotrophs and the decomposers.

• There are other biotic and abiotic mechanisms that cycle nutrients.

The Greenhouse effect

• How has the concentration of CO2 changed historically?

• Research data from Mauna Loa in Hawaii or Cape Grim in Tasmania.

CO2 levels in Hawaii

CO2 levels in Tasmania

The Greenhouse effect• The greenhouse effect describes the process of warming due to our

atmosphere.

• Like a greenhouse, when light enters the atmosphere, some of the heat energy is trapped. This causes the earth’s temperature to rise.

• Greenhouse gasses: water vapor, carbon dioxide, ozone, methane and oxides of nitrogen occur in the lower atmosphere- trophosphere.

• They absorb some of the infrared radiation that is radiated back from the earth’s surface.

• This causes their molecules to vibrate and transform the absorbed energy into longer infrared radiation (heat) in the trophosphere

• This is a natural phenomenon and if it wasn’t for the greenhouse effect, the earth would be in a perpetual ice age, mean temperature would be -18C

Precautionary Principle:better safe than sorry

• The precautionary principle states that if an action taken by humans MAY have some large,negative affect on the environment, then it should not be undertaken.

• Even if there is not solid scientific knowledge to say that it would have a bad effect.

• The person/s wanting to take the action must prove that it would not do harm

• Examples of use:

• 1994 the National Marine Fisheries Service adopted rules to prevent overfishing

• Protection of species such as elephants in Africa

• Protection of habitat example logging areas in the Pacific Northwest, wilderness areas in Alaska slotted for oil pipelines

Precautionary Principle

How is the PP applied to justify strong action in response to the threats posed by the enhanced greenhouse effect?

Greenhouse Effecthttp://www.ciel.org/Climate/Climate_Arctic.html

What are the consequences of the rise of global temperatures on artic ecosystems?•Average annual temperatures in the Arctic have increased by approximately double the increase in global average temperatures

•the Arctic has warmed at an alarming rate, and it is projected to continue to warm by as much as 18 degrees Fahrenheit by 2100

•This warming trend has had a devastating impact on Arctic ecosystems, including sea ice, permafrost, forests and tundra.

•Warming has contributed to increases in lake temperatures(5), permafrost thawing, increased stress on plant and animal populations(6) and the melting of glaciers(7) and sea ice.Research has revealed decreases in both sea ice extent (9) and cover.(10)

Greenhouse Effect

* Melting sea ice affects populations of marine mammals, caribou, polar bears and the subsistence livelihoods of people that depend on them. Because sea ice forms a natural breakwater against storm wave action, ice melting allows larger storm surges to develop and causes erosion, sedimentation, and coastal inundation.(11)

* Polar bears live on sea ice while hunting their prey and reductions in sea ice due to warming have resulted in shorter feeding periods and decreased accessibility to the seals that they hunt

* Walrus populations are suffering from the retreat of the sea ice and changes in food supply as is evident by their recently low juvenile survival rates

*Killer whales have been reported as feeding on sea otters since their prey of choice, sea lions and harbor seals, have followed changes in fish migration patterns and moved out of the killer whales' habitat range.(16)

*Local coastal losses to erosion of up to 100 feet per year have been observed in some locations in the Siberian, Alaskan and Canadian Arctic.(17)

Greenhouse Effect

*Rising temperatures have allowed spruce bark beetles to reproduce at twice their normal rate

*A sustained outbreak of the beetles on the Kenai Peninsula has caused over 2.3 million acres of tree mortality, the largest loss from a single outbreak recorded in North America.(21) Outbreaks of other defoliating insects in the boreal forest, such as spruce budworm, coneworm, and larch sawfly, also have increased sharply in the past decade.

*Climate warming and insect infestations make forests more susceptible to forest fire.

Greenhouse Effect

•Increased rate of decomposition of detritus

•Expansion of range of habitat

•Loss of ice habitat

•Changes in distribution of prey species--> affects higher trophic levels

•Increase numbers of pests and pathogens

Assimilation

N2 in atmosphere

DecomposersNitrifyingbacteria

Nitrifyingbacteria

Nitrogen-fixingsoil bacteria

Denitrifyingbacteria

NitrificationAmmonification

Nitrogen-fixingbacteria in rootnodules of legumes

NO3–

NO2–NH4

+NH3

Nitrogen Cycle

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.

• 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.


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


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


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


G.1.6 Outline the following interactions between species: competition, herbivory, predation, parasitism, and mutualism (with examples).


G.1.9 Define biomass - each tier represents the dry weight of all organisms in one trophic level

Trophic level Dry weight(g/m2)

Tertiary consumers

Secondary consumers

Primary consumers

Primary producers

1.5

11

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809

G2 Ecosystems and biomesG.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.


• 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


• 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

• 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 area2) Toss a 1 x 1 meter square into the grid area randomly3) Identify and count all the larger plant species first4) 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


• G.3.2 Analyze 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 Populations5.3.1Outline 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 (S-shaped) 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 increased predation and disease.

5.3 PopulationsPlateau PhaseNatality and mortality are equal so the population

size stays constant.

Limiting Factors:shortage of food or other resourcesincrease in predatorsmore diseases or parasites

If a population is limited, then it has reached its carrying capacity (K)

5.3 Populations

Define carrying capacity.

The maximum population size that can be supported by the environment

G.5 AHL

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.

G.5 AHL

population size =

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

3

21

n

xnn

G.5 AHL

• IA – Mark and Recapture

5.2 Greenhouse effect

5.2.1Draw 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

CausesLight 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


• 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.


• 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.


- 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


• 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.

Topic 5 Ecology and Evolution. Define Species Habitat Population Community Ecosystem Ecology...

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