Download 4-1 Species Comms Ecos notes - Mr Cartlidge`s Saigon Science Blog

4.1 Species, Communities and Ecosystems
Essential idea: The continued survival of living organisms including humans depends on
sustainable communities.
Understandings:
• Species are groups of organisms that can potentially interbreed to produce fertile offspring.
• Members of a species may be reproductively isolated in separate populations.
• Species have either an autotrophic or heterotrophic method of nutrition (a few species have
both methods).
• Consumers are heterotrophs that feed on living organisms by ingestion.
• Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.
• Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external
digestion.
• A community is formed by populations of different species living together and interacting with
each other.
• A community forms an ecosystem by its interactions with the abiotic environment.
• Autotrophs obtain inorganic nutrients from the abiotic environment.
• The supply of inorganic nutrients is maintained by nutrient cycling.
• Ecosystems have the potential to be sustainable over long periods of time.
Applications and Skills:
• Skill: Classifying species as autotrophs, consumers, detritivores or saprotrophs from a
knowledge of their mode of nutrition.
• Skill: Setting up sealed mesocosms to try to establish sustainability. (Practical 5)
• Skill: Testing for association between two species using the chi-squared test with data
obtained by quadrat sampling.
• Skill: Recognizing and interpreting statistical significance.
Key Words for the topic can be found here: https://quizlet.com/6396273/ecology-definitionsflash-cards/
●
●
●
Unscramble each of the clue words.
Copy the letters in the numbered cells to other cells with the same number to find a
quote on this topic
Now match the clue words to the definitions below:
Ecological Key Terms
_______________
The study of relationships between living organisms and between
organisms and their environment
_______________
The environment in which a species normally lives or the location of a
living organism
_______________
A community and its abiotic (non-living) environment
______________
A group of populations living and interacting with each other in an area
_______________
A group of organisms of the same species who live in the same area at
the same time
_______________
A group of organisms that can interbreed and produce fertile, viable
offspring
_______________
The role and space that an organism occupies in a given ecosystem
Feeding Methods
_______________
An organism that lives on or in non-living organic matter, secreting
digestive enzymes into it and absorbing the products of digestion
_______________
An organism that ingests non-living organic matter
_______________
An organism that obtains organic molecules from other organisms
(heterotrophs are consumers)
_______________
An organism that synthesises its organic molecules from simple inorganic
substances (e.g. CO2 and nitrates) (autotrophs are producers)
_______________
killed
An organism that ingests other organic matter that is living or recently
Complete the tree below with definitions and examples of each type of feeding strategy.
Distinguish between the feeding strategies at each level of the diagram.
Food chains represent the flow of energy and nutrients in a series of feeding relationships.
Give one example of a marine food chain (min. 4 organisms)
Give one example of a terrestrial food chain (min. 4 organisms)
Give one other example of a food chain (min. 4 organisms)
Describe what is meant by a food web.
The food web below shows some coral reef feeding relationships;
Identify species in the following trophic levels:
i.
Producers
ii.
Primary consumers
iii.
Secondary consumers
“Energy flows through an ecosystem, nutrients are recycled.”
Explain this statement with the aid of a flow chart. Include the roles of saprotrophic bacteria and
fungi.
Abiotic and Biotic Factors
Watch the video here:https://www.youtube.com/watch?v=woSO0D94VGA
Which of the following factors affects the distribution of plants and animals?
Factor
Plants
Animals
Temperature
Soil pH
Breeding sites
Salinity
Water
Mineral nutrients
Food supply
Territory
Light
How can we measure the distribution of plants and animals?
Describe how each of the following is used:
Quadrat
Random sampling
Skill: Testing for association between two species using the chi-squared test with data
obtained by quadrat sampling.
Go to this website and select Site A
http://www.saps.org.uk/secondary/teaching-resources/768-ecology-practical-abundancediversity-and-random-sampling
We are investigating if there is an association
between these two species:
If there is an association, we would expect them
to appear in the same places.
Record the number of quadrats that the species
appear in using the table below:
Lousewort
No Lousewort
Meadow buttercup
No Meadow
buttercup
Total
The null hypothesis (Ho) is that there is no association between the two species
Total
First calculate expected values: expected values = row total x column total/grand total
Add them to the table:
Lousewort
Observed
Expected
No Lousewort
Observed
Total
Expected
Meadow
buttercup
No Meadow
buttercup
Total
Now calculate chi squared using this formula:
Where o = observed and e = expected
Compare the chi squared value you calculated with the critical value in the table for the correct
degrees of freedom, calculated as follows:
Degrees of freedom = columns of observed value - 1) x (columns of observed value - 1
In this case (2-1) x (2-1) = 1
For our experiment we use probability p = 0.05 and 1 degree of freedom , so the critical value
is 3.84
There is no rule about this but with fieldwork data most people reckon that 5% significance is an
adequate level of acceptance or rejection of the null hypothesis. Remember this means that you
would expect to be correct in accepting or rejecting your null hypothesis 95% of the time, 5% of
the time you might get a different result due to chance.
Is there an association between the two species?
Use the chi squared value you calculated to explain how you know this.