Unit 1: Population Dynamics Flashcards
How can a population continue growing when the birth rate is constant?
Mortality rates have gone done and immigration.
What factors could contribute to a low birth rate?
A developing country (healthcare, modern farming ect.) and cultural values (smaller families and educated women)
Does population decline automatically translate to a lower ecological footprint?
No, because the amount of waste and materials people need to live has increased.
How does the quadrant sampling technique work?
- Map out the area of your population
- Place a grid over the map
- Choose random grid squares to sample
- Count all the individuals in a quadrant. Sum up the total and find the average.
When should you use quadrant sampling?
Use for a large population, that don’t move much and can be easily seen.
e.g Plants or earthworms.
What assumptions are you making with Quadrant sampling?
- The population is evenly spread out
- The area of sampling is representative of the whole area.
What is the mark-recapture technique?
It is a population measuring technique that is best used for populations that move around.
e.g. Fish or birds.
How does the mark and recapture technique work?
- Take a sample and mark some individuals and return to the population.
- Take a second sample (recapture)
- The ratio of marked to unmarked gives the estimate of population size
What assumptions are made with mark-recapture?
- The # of marked individuals will be the same for each sample.
- That tagging the individual does not affect its likely-hood of recapture.
What are the 3 ways in which populations change?
Death, immigration and emigration.
What is a survivorship curve?
It is the pattern of how mortality rates change because of age.
What is survivorship curve: Type 1?
E.g. Humans, whales and birds
Species with few offspring and have a low risk of dying until they are old.
What is survivorship curve: Type 2?
E.g. Insects, bees
Species with equal chance of dying young OR old. Parents do not protect their young.
What is survivorship curve: Type 3?
E.g. Sea turtles, maple trees
Species with a very high death rate when young but not when they are old. Tend to produce many young.
What is Mutualism?
E.g. Bees and flowers
Both species benefit from a relationship.
What is Commensalism?
e.g. Clownfish and Sea anemones
One species benefits from the relationship and the other in unaffected.
What is Parasitism?
e.g. Bacteria and host
Were one species benefits at the expense of another.
How could the disappearance of bass from the lakes ecosystem cause the population of insect larvae to decrease?
Food webs are sensitive to change. The insect larvae will have more predators to contend with since the bass eat and control the amount of frogs and beetles.
How could you help a fish population recover?
Reintroduce more adult cod into areas where their population is low .
Symbiosis
When two species live closely together and interact in ways that benefit at least one of them.
Predation
When a predator feeds on its prey
Competition
When species use the same set of resources in the same area and is bad for both parties.
Interference Competition
e.g. Lions fighting over food.
When individuals directly interact over resources
Exploitative Competition
Indirect competition for resources
