Chapter 5 Flashcards
Define population
A group of individuals belonging to the same species living in a particular area at the same time
Why is it important for scientists to know the size of a population?
To understand the habitats and needs of organisms. This enables humans to sustain and ensure that vulnerable species persist and contribute to the planets biodiversity
Define r selection
species quickly colinising an unstable ecosystem, leading to a pattern of rapid population increase and decrease and eventual take over by competitors
what is a r-selected species
A fast growing and reproducing organism, often the first to occupy unused resources and living space
What are the characteristics of an r selected species
Smaller size, short life cycles and a lack of parental care in young
What are some examples of an r selected species
Mice, rats, frogs, toads, weeds and oysters
Define k selection
While some individuals may not survive initially, over the long term a sustainable population can be maintained
What is k selected species
A slow growing, long lived species typical of those in a climax community
What are the characteristics of a k selected species
Live longer, breed later, have fewer offspring and devote their lives to ensuring the survival of offspring
Examples of a k selected species
birds, larger mammals and larger plants.
Define carrying capacity
The maximum population size of a species that can be supported in a given environment
What is the equation for population growth rate?
Population growth rate = (Birth rate + Immigration rate) - (death rate + emigration rate)
Explain the equation that calculates population growth rate
A population is increasing if the birth/immigration rate exceeds the death/emigration rate. Therefore, a population decreases when the death/emigration rate exceeds birth/immigration rate
What is an open ecosystem
Where migration between populations of animals can occur but will affect the overall numbers in the ecosystem involved
What is a closed ecosystem
Where migration doesn’t impact population size at all
What is random distribution and an example
When organisms are spaced irregularly, the location of an organism does not affect the location of another. EG. Specific tree species in a forest.
what is uniform distribution
Organisms are evenly spaced, the presence of one organism determines how close another will be. Common in high density populations like Penguins
What is clumped distribution
A number of individuals are grouped together which make up the population as a whole
Why is knowing the distribution of a species important
Knowledge of particular plant species can give glues about the distribution and abundance of animals that depend on them
Disadvantages and advantages of direct observation
- Time consuming, dangerous
+ Satellites can be used in inaccessible regions
What is direct observation
A method used to measure abundance. Eg, recording sightings at particular intervals
What is a quadrat and the advantages and disadvantages
Where a square is placed on the ground to count each individual of a species. Useful for stationary organisms and faster. Needs to have appropriate number of quadrats, wont be accurate
Population size equation
Total number of individuals counted / area of each quadrat x number of quadrats
What is a transect and their advantages and disadvantages
Where a line is drawn through a community to determine the distribution of species. Get a good picture of the landscape over a distance. Can’t be used in marine ecosystems and if a large sampling interval is used, wont be accurate
What is the capture mark recapture method and their advantages and disadvantages
When individuals are captured, marked and released and after time are recaptured to indicate population size.
Easier than sampling every single member of the population
Time, costly, species die, needs large sample size
Equation for capture mark recapture
Total population = Number marked in first sample (M) x Number of animals recaptured (n) divided by number of recaptured animals that are marked (m)
Advantages and disadvantages of telemetry
Shows pattern and behavior of animals
Time consuming and costly
What is species distribution modeling
An attempt to predict future needs and resource management using computer technology
What is an example of the carrying capacity theory
100 km^2 of eucalyptus forest is the minimum area possible to support 10 000 sugar gliders as a viable population. This info acts as a guide to the minimum size a park or any closed ecosystem needs to be to conserve animals. The area needs to be sufficient for a significant number of top carnivores to survive
What is environment resistance
Happens when populations exceed carrying capacity. Leads to competition, disease, parasites, increase in predation, decrease in food supply
What are density dependent factors
The greater the density of a population, the more individuals die or fail to reproduce. Eg. Competition, disease, parasites, predation, food supply
What are density independent factors
Those that affect all individuals in a population regardless of age or stage. Eg, severe weather, volcanic activity, habitat destruction
When is controlling populations needed
When one species increases at the expense of others. Can be controlled chemically or biologically
What is chemical control
The chemical pesticides used to control pest species. Quick and effective but can be ecologically damaging and costly
What is biological control
When living organisms are used to control pest species
What are the four types of biological control
- General predators - Organisms that consume a great variety of pest species. Eg, ladybirds target aphids, caterpillars, mites and beetles
- Specialized predators - Organisms that target one pest species. Eg, dragonflies and mosquitoes
- Parasites - organisms that lay their eggs in the bodies of hosts. Eg, wasps, flies
- Microbial diseases - caused by bacteria, fungi and viruses that target species and cause death through illness
Example of unsuccessful biological control
Cane toads were introduced to north east Queensland to control cane sugar beetle pests. Cane toads have rapidly expanded north and south of the original site
Successful biological control
Wasps are being used to control the native stem-girdler moths that can decimate crops in Queensland. The wasps lay their eggs in the moth eggs, which are then consume by the wasp larvae
Pest
Any species causes harm or death to other organisms
