Test 4: Ecology and Ecotoxicology Flashcards
What is a community?
It is a “group” formed when all the different populations of species share the same habitat.
When a group of organisms share an environment.
How do you measure biodiversity?
Species richness and relative abundance.
What is species richness?
It is the total number of species in a community.
What is relative abundance?
It is the number of species in relation to the total organisms in the community.
When is there a high biodiversity?
When the species richness is high and the relative abundance is similar (relatively equal).
What are interspecific interactions?
They are relationships between individuals of different species.
What are the types of interspecific interactions?
- Competition
- Predation (sub-set parasitism(symbiosis))
- Mutualism (symbiosis)
- Commensalism (symbiosis)
What is symbiosis?
It is close and often long-term interactions between 2 or more different biological species.
What is competition?
It is a relationship where different species compete for the same limited food resources.
Which type of species will profit the best from the available resources?
The species that can adapt.
What can strong competition limit?
Strong competition can limit the presence of a species.
What is predation?
It is when one species kills another for food (hunting). The predator feeds on the prey.
What is parasitism?
It is a relationship in which one species benefits while harming another.
What is commensalism?
It is a relationship in which one species benefits without helping or harming the other.
What is mutualism?
It is a relationship in which both species benefit.
What is a population?
It is a group of organisms of the same species living in a shared habitat (defined space) at a given point in time.
What is the population characterized by?
- Size
- Growth
- Density
- Distribution
What is population size?
It is the number of individuals in a population. It can increase, decrease or stay constant over time.
What are factors that affect population size?
- Natality
- Mortality
- Immigration
- Emigration
How do we estimate the size of a population?
- Counting
- Random Sampling (sample area)
- Mark and recapture
How to do to random sampling?
Divide areas of land into equal plots, count the number of individuals in each plot, calculate average, multiply by total area then divide by area per plot.
Average # of individuals / Area per plot = Total population / Total area
How to do mark and recapture?
Capture and mark, release, recapture. # marked in sample 1 (M) / Size of whole population (N) = # marked in sample 2 (r) / Total caught in sample 2 (n)
What is population growth?
It is the increase, decrease or consistency in the growth of a population.
When does the population increase?
When natality + immigration > mortality + emigration
When does the population decline?
When natality + immigration < mortality + emigration
When does the population size stay constant?
When natality + immigration = mortality + emigration
What affects population?
Time affects population.
What is carrying capacity?
It is when the resources in an area are limited there is a limited population that can be supported.
It is the maximum number of individuals that can be supported in a given area.
Population will grow over time, until carrying capacity is reached, once exceeded what will happen to the population?
The population will decline.
What are limiting factors? Give examples.
Factors that limit the growth and survival of a population.
Examples: Biotic and Abiotic factors.
What are biotic factors? Give examples.
They are living factors that can have an impact on (influence) a population.
Examples:
- Food - Humans
- Bacteria - Parasites
- Predation (predators) - Limited plants
What are abiotic factors? Give examples.
They are non-living ecological factors of physical or chemical nature that can affect (influence) a population.
Examples:
- Sunlight - Storms
- Atmospheric composition - Droughts
- pH - Floods
- Temperature - Volcanic activity
- Pheromones - Deforestation
- Water - Pollution
How to calculate population density?
D= number of individuals of a species (n) /
surface area or volume occupied (a or v)
What is population distribution?
It is the way in which individuals are spread out over a territory.
What is population density?
It is the number of individuals of a species counted divided by surface area or volume
What are the three ways in which individuals are spread out in a territory?
- Clumped
- Uniform
- Random
What is clumped distribution?
It is when individuals form clumps that improve chance of survival. The most common.
What is uniform distribution?
It is when individuals maintain an equal distance between each other, this indicates a strong competition for space and resources.