Chapter 5: Population Dynamics Flashcards
What is a population?
A group of individuals of the same species living in the same area at the same time
What does population dynamics mean?
The forces of growth or change within a population
What are 4 reasons to study population dynamics?
- Allows us to determine a critical population size
- To determine whether a population is thriving, stable or nearly extinct
-Determine what factors are affecting the organisms - What we need to do to save the species and conserve wildlife
What is population density?
Number of individuals per unit area
What is abundance?
Number of organisms per unit area that live in a particualar part of the ecosystem
What is biomass?
Number of dry biomass per unit area
What is a critical population size?
The minimun size a population must be for it to surviv without help
Explain population growth in unstable environments
Unstable environments = ecosystems after natural disarsters. R-selected species inhabit quickly
Explain population growth in stable environments
Stable environments = consistent predictable pattens. Populated with K-selected species. Close to carrying capacity.
What are R-selected species?
Fast growing and reproducing species that quickly colonise an unstable environment, rapid population increase and decrease.
What are K-selected species?
Slow growing, long living species. Long term, sustainable population is maintained
Name 5 things that could limit population growth
- Predators
- Availability of resources
- Spread of disease
- Weather conditions
- Nutrient supply
What is density?
Number of individuals in a given area
What is the capture mark recapture equation?
Number caught and initially tagged x Total number recaptured / Number of tagged individuals recaptured
What are the 3 types of distribution?
- Random distribution
- Uniform distribution
- Clumped distribution
Explain random distribution
Organisms are spaced irregularly. The location of one does not affect the location of another
Explain uniform distribution
Organisms are evenly spaced, presence of one organism determines how close or distant others will be.
Explain clumped distribution
A number of individuals are grouped together and the groups make up the population as a whole, sometimes results from social behaviour
What is carrying capacity?
The maximum size of a population that an ecosystem can support, can be affected byu abiotic and biotic factors.
What are the 4 stages of population growth?
- Lag phase
- Acceleration phase (or exponential growth phase)
- Transitional phase
- Stationary phase (reached carrying capacity)
When will exponential population growth occur?
In the idea environment with unlimited resources and no competition to limit growth
When does logistical growth occur?
When a population nears carrying capacity
When does cylical population growth occur?
When a predator has 1 main prey species, the population numbers depend on eachother.
What is a pest?
A plant or animal that is detrimental to humans or human concerns, eg. livestock
What is an invasive species?
A non-native species that causes harm
What are 3 ways to control populations?
- Chemical pesrticides
- Biological control agents
- Culling
Name an advantage, disadvantage and example of a chemical pesticide.
Advantage: Quick and effective
Disadvantage: Often has ecological side effects and can damage non-target species
Example: 1080 Bait, used to control rabbit populations, not lethal to many native plants
What are the 4 types of biological control agents?
- General predators
- Specialised predators
- Parasites
- Microbial diseases
What are general predators in relation to biological control agents?
Organisms that consume a variaty of pest species, almost all biological control disatars are because of this
What are specialised predators in relation to biological control agents?
Organisms that target 1 pest species
What are microbial diseases in relation to biological control agents?
Bsacteria, fungi and viruses that target species and cause death
What is culling?
Killing the target species
What are 3 things that can cause native population decline?
- Lack of resourses
- Loss of habitat
- Predation
