Populations And Communities Flashcards
What is a population
A group of organisms of the same species living in a particular habitat
What are the 4 phases of population growth
Lag phase
Exponential phase
Stationary phase
Decline phase
What is the lag phase
This is the time for nutrient assimilation or egg production or egg/ larvae development to occur
What is the exponential phase
When reproduction creates new members at an exponential rate
What is the stationary phase
When the population numbers stay around the same, reaching its carrying capacity
What is the decline phase
When the population has exhausted all resources, numbers drop at a high rate
What are R-selected species
The populations of species increase rapidly as a resource becomes available and crash as the resource is used up
What are K-selected species
The populations of the species remain at the carrying capacity of the environment
What are some features of R-selected species
Short lifespan
Short generation time
Many offspring
Highly variable population density
High disperability
Weak competitive ability
Little parental care
Unstable habitat
What are some features of K-selected species
Long lifespan
Long generation time
Little offspring
Low variable population density
Low disperability
Strong competitive ability
Considerable parental care
Stable habitat
What are the 3 types of interaction
Mutualism (+/+)
Predation (-/+)
Competition (-/-)
What is mutualism
When both species benefit from the interaction
What is an example of mutualism
Rhizobium and Trifolium
What is predation
When the predator gains, the prey losses
What is a predator prey interaction
When prey numbers are high, predator numbers increase
When predator numbers increase, prey numbers decrease
When prey numbers decrease, predator numbers decrease
When predator numbers decrease, prey numbers increase
What is inter-specific competition
When two species require a common resource in limited supply
What are some characteristics of inter-specific competition
Both species tend to do less well
One species is completely eliminated
One species tends to use the resources better
The winner may well be decided by the environmental conditions
What is the competitive exclusion principle
That two species cannot share the same niche, without one being completely eliminated
What is a pest
An organism that affects the population of plants or animals that is economically beneficial to humans
What are some advantages of biological control
They target only the pest species
They don’t negative affect biodiversity
Unlikely to develop pest resistance
They are self-perpetuating over time
It is relatively cheap
What is a disadvantage of biological control
It requires a lot of a lot more research
What are some features of primary succession
Soil depth and fertility increases
Plant biomass and height increases
Number of food chains increase
As plant height increases, less sunlight reaches the ground, which decreases plant biodiversity
What is a climax community
The stable end-stage when a community is in dynamic equilibrium with its environment
What is a climatic climax
When the climax community is determined by the environment
