CH19 Populations in ecosystems Flashcards
Define community
All the different species that live in one area and interact with each other
Define ecosystem
All the living organisms found in one area, combined with non-living aspects of their environment
Describe biotic factors
Living features of an ecosystem
Predators, disease
Describe abiotic factors
Non-living features of an ecosystem
Light and temperature
Define habitat
The place where an organism lives within an ecosystem
Define niche
The role of a species within its habitat, consisting of both its biotic interactions and abiotic interactions
What is carrying capacity
The maximum size of population an ecosystem can support
Name 4 abiotic factors that affect population growth
Temperature
Light
pH
Water
What is intraspecific competition
Competition between organisms of the same species
What is interspecific competition
Competition between organisms of different species
What resources might organisms compete for
Food Water Shelter Minerals Light Mates
Pattern of typical predator-prey relationship in terms of population change
Prey is eaten by predator, resulting in predator population increasing and prey population decreasing
Fewer prey means increased competition for food so predator population decreases
Fewer predators means more prey survive, cycle begins again
How are quadrats used to estimate population size
Can be placed on grid coordinates
Results reported as either % cover or frequency
For slow-moving or non-motile organisms
How is mark-release-recapture used to estimate population size
Sample of species is captured, marked and released into the same area that are they were caught
After certain period of time another sample of species captured and number of marked organisms counted
Motile organisms
Equation for mark-release-capture
Estimated pop. size =
(total num of individuals in sample 1 x total num of individuals in sample 2) / number of marked individuals recaptured
What assumptions are made
Marked individuals distribute evenly No migration in or out of the population Few births or deaths Method of marking does not affect survival Mark does not come off
Why are ecosystems described as being dynamic
Populations constantly rise and fall
Any small change can have a large effect
Biotic and abiotic factors may alter the conditions of the ecosystem
What is meant by primary succession
Where an area previously devoid of life is colonised by a community of organisms
Process of primary succession
Pioneer species can survive harsh conditions and colonise the area
They change abiotic factors of their environment
Over time, this allows more complex organisms to survive
What is climax community and how is it reached
The final stage of succession where the ecosystem is balanced and stable
Reached when the soil is rich enough to support large trees and the environment is no longer changing
How might a species alter the environment that develops during succession
A species may improve the environment to make it more suitable for other species
A species may worsen the environment by making it less suitable for other species
Define conservation
The protection and management of species and habitats, in order to maintain biodiversity
