humans, depends on sustainable communities topic 4...

Topic 4: Ecology4.1 Species and Ecosystems

The continued survival of living organisms, including humans, depends on sustainable communities

4.2 Energy FlowEcosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat.

4.3 Carbon CyclingContinued availability of carbon in ecosystems depends on carbon cycling.

4.4 Climate ChangeConcentrations of gases in the atmosphere affect climates experienced at the Earth’s surface.

Topic 4: Ecology4.1 Species and Ecosystems

Essential Question: The continued survival of living organisms, including

humans, depends on sustainable communities

What is Ecology?Eco derived from the Greek “oikos” which means home/environment. “ology” is the greek suffix for “study of”

• A branch of biology that studies ecosystems.

• Usually we study ecosystems on Earth, which is a Biosphere.– The global ecosystem,

including all the earth's regions that support life (land, water, air)

How do we define ecosystems?

Which photo(s) represent an ecosystem?

How do we define ecosystems?

All the photos represent ecosystems!● Ecosystem: All of

the living things in a defined area that interact with each other, as well as the physical environment surrounding the living things.

What is Ecology?

Abiotic: non-living chemical and physical factors of the environment

(e.g temperature, water, light, soil, nutrients)

Biotic: living organisms that are part of the environment

Biosphere: the global ecosystem, including all the earth's regions that support life (land, water, air)

Ecosystem: all interacting communities of organisms and abiotic factors of the environment within a defined area

Community: all interactive populations living in the same geographic location

Population: a group of individuals of the same species living in the same geographic area

Species: A group of organisms that can potentially interbreed to produce fertile, viable offspring

From i-biology.net

PracticeThink of a different organism for each feeding method found in a kelp forest.

Autotroph- Photoautotroph- Chemoautotroph

Heterotroph- Consumer

- Primary- Secondary

- Decomposer- Detritivore- Saprotroph

Ecosystem SustainabilityThe various feeding methods allow for nutrient recycling.• Inorganic nutrient supplies on Earth are finite – new

elements cannot simply be created (ex. Calcium and Zinc).

• Hence why nutrient recycling is important.

Ecosystem Sustainability

Heterotrophs ingest these organic compounds and use them for growth and respiration, releasing inorganic byproducts

Autotrophs obtain inorganic nutrients from the air, water and soil and convert them into organic compounds

When organisms die, decomposers free inorganic materials into the soil

Ecosystems have the potential to be sustainable over long periods of time.

• Ecosystems are largely self-contained and have the capacity to be self-sustaining over long periods of time.

• Main components of an ecosystem:

1. Energy Availability• Light from the sun provides the initial energy source for almost all

communities

2. Nutrient Availability• Saprotrophic decomposers ensure the constant recycling of

inorganic nutrients within an environment

3. Recycling of wastes • Certain bacteria can detoxify harmful waste byproducts

Biosphere 2

Why did it fail?● Microbes in the soils had produced carbon dioxide at a greater rate than the

young plants could produce oxygen via photosynthesis. ● CO2 was absorbed by the unsealed concrete and the amount of oxygen

decreased.

Setting Up a Mesocosm

• Enclosed environment that allows a small part of a natural environment to be observed under controlled conditions.– A terrarium (glass or plastic container) that holds select plants and

animals to be observed.

http://cbricknell2015.weebly.com/

Setting Up a MesocosmStep 1 - add a thin layer of pebbles to use as a drainage layer. It was approximately 2 cm thick.


Setting Up a MesocosmStep 2 - Add a layer of activated charcoal.

This is to aid with the hygiene of the mesocosm, as the charcoal would prevent mold and aerate the soil. Charcoal should be about 2 cm thick and should completely cover the pebbles.


Setting Up a MesocosmStep 3 - Add a layer of sphagnum moss.This is to keep the soil in place and stop it from settling at the bottom of the container.


Setting Up a MesocosmStep 4 - Add a layer of soil.


Setting Up a MesocosmStep 5- Add the plants in the soil. Make a hole in the soil for the plant (blue bell fern) and just placed the moss on top of the soil. Misted the surface of the soil with water using a spray bottle until the surface appeared to be damp without being soaked and pour approximately two tablespoons of water directly onto the plant’s (fern's) roots.


Setting Up a MesocosmStep 6 - Place mesocosm in a suitable location. The location needs to fulfil the requirements for the plant. The plant require indirect sunlight and a warm environment. Near a window on a desk is a suitable location.


Ecological Relationshipswhen studying an ecosystem, we want to understand how the different species, populations, and communities interact.

Some Examples:competition—when two or more organisms rely on the same environmental resourcepredation—behavior of one animal feeding on anothersymbiosis—the close relationship of two dissimilar organismsmutualism—a symbiotic relationship where both organisms benefitparasitism—a symbiotic relationship where one organism benefits and one is harmed

Chi Squared Test• Test of independence: evaluates

whether two variables are associated statistically.

• Finds if there is a significant association between the distribution of two species.

OR

• Test for goodness of fit: compares an experimental result with an expected theoretical outcome

• will revisit later on in genetics.

Chi Squared Test

• If two species are typically found within the same habitat, they show a positive association.

• If two species tend not to occur within the same habitat, they show a negative association

• If distribution of two species is independent of one another, there is no association between them.

Steps for Chi Squared Test

1. Identify your hypothesis.a. Need a null and alternative hypothesis.

Null Hypothesis (H0): There Is no significant difference/association between specified populations.

Alternative Hypothesis(H1): There is a significant difference/association between specified populations.

Example:Null: There is no relationship between Oregon Forest Snails and Stinging Nettle

Alternative: There is a relationship between Oregon Forest Snails and Stinging Nettle


2. Identify your Observed values in a contingency table.• What did your data collection tell you?

Snails present no snails total

stinging nettle present 20 9 29

no stinging nettle 6 15 21

total 26 24 50


3. Identify your Expected values.• If there are no relationships in your data, what would you

expect to observe?


stinging nettle present

(29 x 26)/50= 15.1

(29 x 24)/50= 13.9 29

no stinging nettle

(21 x 26)/50= 10.9

(21 x 24)/50= 10.1 21

total 26 24 50

E = (Rtotal x Ctotal) / Total

Steps for Chi Squared Test4. Find our Chi Square (𝝌2) value• In theory, if your observed and expected values were equal

(“no difference”) then chi-square would be zero

Snails present no snails

stinging nettle present

O 20 9

E 15.1 13.9(O-E)^2/E 1.59 1.73

no stinging nettle

O 6 15

E 10.9 10.1

(O-E)^2/E 2.20 2.38Total (𝝌2) 1.59 + 1.73 + 2.20 + 2.38 = 7.90


5. Find your degrees of Freedom• the number of values involved in the calculations that have

the freedom to vary.

DF = (rows(r) - 1) x (column(c) - 1) = (2-1) x (2-1) = 1


stinging nettle present 20 9 29

no stinging nettle 6 15 21

total 26 24 50

Steps for Chi Squared TestDepending on your Degrees of Freedom (DF) your Chi Square distribution curve will appear differently

Steps for Chi Squared Test6. Use the calculated chi-square and DF to find the p-value on a chi-square table.DF = 1 𝝌2 = 7.90

There is less than a 0.5% chance that our null hypothesis is correct, Therefore we can assume our alternate hypothesis is correct. There is a relationship between Oregon Forest Snails and Stinging Nettle

ACCEPT NULL HYPOTHESIS REJECT

Quadrat Sampling• A method by which a

certain sample of organisms are counted directly.

• Used to estimate population abundance, density, frequency and distribution.

Quadrat Variables• size of the quadrat• what is being surveyed• size of the area• randomization process

Procedure● Each individual is

counted within the quadrat and those numbers are used to extrapolate population size and distribution.

Our Procedure● Use 1m2 quadrats to count the number of

buttercups within a designated area.

● To observe if there is a relationship between presence of moss and buttercups.

Write Up Must Include:

● Null and Alternate Hypothesis● Contingency Table● Chi Squared Value → Show your work!● Degrees of Freedom Calculation● Your conclusion based on the data and P

value.

Example

https://www.biologyforlife.com/x2-test-for-independence.html

Population Density● The population density is

expressed in # of individuals/sample area (buttercups/m2).

● Population size can be estimated using the formula:

N = (A/a) * n

where: N = the estimated total population size A = the total study area a = the area of the quadratn = the mean number of organisms per quadrat

Population Density N = (A/a) * n

where: N = the estimated total population size A = the total study area a = the area of the quadratn = the mean number of organisms per quadrat

N = 80m2/1m2 * 5 (F) 8 (E) buttercups N = 400 buttercups (Block F)N = 615 buttercups (Block E)

humans, depends on sustainable communities topic 4...

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