topic 4 - Ecology Flashcards
Define Species.
Species:
A group of organisms that can interbreed and produce fertile, viable offspring
Define population.
Population:
Group of organisms of the same species, living in the same area at the same time
Define Community.
Community:
A group of different populations living together and interacting in a given area
Define Habitat.
Habitat:
The environment in which a species lives or the normal location of an organism
Define Ecosystem.
Ecosystem:
A community and also its environment (all biotic and abiotic factors)
True or False?
Living organisms can obtain chemical energy by one of two methods of nutrition (a few species can use both methods)
True
Living organisms can obtain chemical energy by one of two methods of nutrition (a few species can use both methods). One of these species is Autotrophs. What are autotrophs?
Autotrophs synthesise organic molecules from inorganic nutrients within the environment, using energy from either:
• Light (photoautotrophs)
• Oxidation reactions (chemoautotophs)
Living organisms can obtain chemical energy by one of two methods of nutrition (a few species can use both methods). Heterotrophs are one these species. What are 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)
True or False?
Autotrophs are commonly referred to as producers, as they are responsible for the production of organic molecules
• Heterotrophs could not survive without autotrophs
True
Nutrients are materials required by organisms for survival
The supply of inorganic nutrients within the environment is finite and therefore must be constantly recycled. How do autotrophs do this?
Autotrophs convert inorganic nutrients into organic molecules (i.e. they are producers)
Nutrients are materials required by organisms for survival
The supply of inorganic nutrients within the environment is finite and therefore must be constantly recycled. How do heterotrophs do this?
Heterotrophs ingest organic molecules and may release inorganic byproducts (e.g. carbon dioxide)
Nutrients are materials required by organisms for survival
The supply of inorganic nutrients within the environment is finite and therefore must be constantly recycled. How do saprotrophs do this?
Saprotrophs break down the nutrients in dead organisms and return them to the soil (i.e. they are decomposers) by external digestion (use of enzymatic secretion)
Ecosystems have the potential to be sustainable over long periods of time, however this requires three conditions. What are these 3 conditions? Give an example for each condition.
Energy availability (e.g. light source)
• Nutrient availability (e.g. decomposers)
• Waste recycling (e.g. detoxifying bacteria)
What are mesocosms?
Mesocosms are enclosed environments with controlled conditions (e.g. terrariums)
• They can be used to study sustainability
The presence of species in a habitat may be dependent on the interactions between them (either positive or negative).
What does a positive association suggest? Give an example.
If species are always found in the same habitat, this suggests a positive association.
Example:
Predator / prey relationships
OR
Symbiotic interaction (mutualism, commensalism, parasitism
The presence of species in a habitat may be dependent on the interactions between them (either positive or negative). What does a negative association suggest? Give an example.
If species do not share the same habitat, this suggests there is a negative association (such as):
• Competition (niche partitioning or competitive exclusion)
What is Quadrat Sampling? How does it work?
The presence of a species in a given area can be determined via quadrat sampling (to assess sessile/non-motile species)
How does it work?
Rectangular frame placed in an area (+ repeat sampling) • Speciesnumberswithintheframearecounted/estimated
What is a chi-squared test conducted?
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
How do you conduct a chi-squared test?
Step 1: Identify Expected Frequencies
Expected frequency = (Row total × Column total) ÷ Grand total
a) hypothesis: Null Hypothesis (H0) – There is no association (i.e. distribution is random) Alternative Hypothesis (H1) – There is an association (positive or negative)
b) construct table
compares expected frequencies v.s. observed values (present, absent. total)
Step 2: Apply the Chi-Squared Formula
a) calculate: x^2 = sum of (O-E)^2/E
b) find df = (#of rows -1) multiplied by (#of columns -1)
Step 3: Determine Significance
a) significance is based on p-value p<0.05 = significant
b) state conclusion based on hypothesis
Define Ecology.
The study of the relationship between living organisms, or between living organisms and their environment
True or False?
Autotrophs obtain inorganic nutrients from the abiotic environment
TRUE
Autotrophs obtain inorganic nutrients from the abiotic environment
True or False?
Consumers are heterotrophs that feed on living organisms by ingestion. Heterotrophs obtain organic molecules from other organisms via different feeding mechanisms and different food sources.
TRUE
Define scavengers.
Opportunistic animal that feeds on dead or decaying matter rather than hurting live prey
Define Detritivores. Give an example.
Detritivores are heterotroph that obtains organic nutrients from non-living organic sources, such as detritus (dead, particulate organic matter) and humus (decaying leaf litter intermixed w/ soil) via internal digestion
The supply of inorganic nutrients is maintained by nutrient cycling. Describe this nutrient cycles of recycling chemical elements is in terms of autotrophs, heterotrophs and saprotrophs.
Chemical elements are constantly recycled after they are used:
Autotrophs obtain inorganic nutrients from the air, water and soil and convert them into organic compounds
Heterotrophs ingest these organic compounds and use them for growth and respiration, releasing inorganic byproducts
When organisms die, saprotrophs decompose the remains and free inorganic materials into the soil
The return of inorganic nutrients to the soil ensures the continual supply of raw materials for the autotrophs
What is an ecological niche?
An ecological niche describes the functional position and role of an organism within its environment
What are the components that an ecological niche is composed of?
The habitat in which the organism lives
The activity patterns of the organism (e.g. periods of time during which it is active)
The resources it obtains from the environment (e.g. food source, territorial boundaries, etc.)
The interactions that occur with other species in the region (e.g. competition / predator-prey relationships)