4.1 Species, Communities and Ecosystems Flashcards
Ecological Organisation
Species
A group of organisms that can interbreed and produce fertile, viable offspring.
Ecological organisation
Population
Group of organisms of the same species, living in the same area at the same time.
Ecological organisation
Community
A group of different populations living together and interacting in a given area.
Ecological organisation
Habitat
The environment in which a species lives or the normal location of an organism.
Ecological organisation
Ecosystem
A community and also its environment
(all biotic and abiotic factors)
Modes of Nutrition
What are modes of nutrition?
Living organisms can obtain chemical energy by one of two
methods of nutrition (a few species can use both methods):
- Autotrophs
- Heterotrophs
Models of nutrition
Autotrophs
Autotrophs synthesise organic molecules from inorganic
nutrients within the environment, using energy from either:
* Light (photoautotrophs)
* Oxidation reactions (chemoautotophs)
Models of nutrition
Heterotrophs
Heterotrophs obtain their organic molecules from other
organisms via a variety of feeding methods and food sources
* Consumers ingest other living organisms
* Detritivores ingest detritus (decomposing matter and faeces)
* Saprotrophs externally digest dead organisms (decomposers)
Models of nutrition
Why are autotorophs often reffered to as “producers”?
Autotrophs are commonly referred to as producers, as they
are responsible for the production of organic molecules
* Heterotrophs could not survive without autotrophs
Nutrient Cycling
What are nutrients?
Materials required by organisms for survival.
Nutrient Cycling
The supply of inorganic nutrients within the environment is
finite and therefore must be constantly recycled:
- Autotrophs convert inorganic nutrients into organic
molecules (i.e. they are producers) - Heterotrophs ingest organic molecules and may release
inorganic byproducts (e.g. carbon dioxide) - Saprotrophs break down the nutrients in dead organisms
and return them to the soil (i.e. they are decomposers)
Mesocosms
What are the three conditions required for ecosystems to have the potential to be sustainable over long periods of time?
- Energy availability (e.g. light source)
- Nutrient availability (e.g. decomposers)
- Waste recycling (e.g. detoxifying bacteria)
Mesocosms
What are mesocosms?
Enclosed environments with controlled conditions (e.g. terrariums)
* They can be used to study sustainability
Species Associations
The presence of species in a habitat may be dependent on
the interactions between them can be either
Positive or negative
Species association
Positive association
If species are always found in the same habitat, this suggests
a positive association, e.g.:
- Predator / prey relationships
- Symbiotic interaction
Species associations
Negative association
If species do not share the same habitat, this suggests there
is a negative association, e.g.:
- competition
Quadrat Sampling
What is quadrant sampling?
The presence of a species in a given area can be determined
via quadrat sampling (to assess sessile/non-motile species)
* Rectangular frame placed in an area (+ repeat sampling)
* Species numbers within the frame are counted/estimated
Chi Squared Test
What is a chi squared test?
A chi-squared test can be applied to quadrat sampling data to determine if there is a statistically significant association between the distribution of two species.
Chi Squared Test
What is quadrat sampling used for?
Determining the presence of species within a given environment, particularly plants and sessile animals.
Chi Squared Test
How can a chi-squared test be applied in ecology?
To determine if there is a statistically significant association between the distribution of two species.
Chi Squared Test
What are the steps involved in a chi-squared test?
- Construct a table of frequencies (observed versus expected)
- Apply the chi-squared formula
- Determine the degree of freedom (df)
- Identify the p value (should be <0.05).
Chi Squared Test
What does a statistically significant chi-squared value indicate?
There is a significant difference between observed and expected frequencies, rejecting the null hypothesis.
