Populations in Ecosystems Flashcards
What is community?
All different species that live in one area and interact with each other
What is an ecosystem?
All living organisms found in one area, combined with non-living aspects of their environment. Can vary from very large to very small
What are biotic factors?
Living features of an ecosystem
What are abiotic factors?
Non-living features of an environment
What is an example of biotic factors?
Predators, disease
What is an example of abiotic factors?
Light, temperature
Give an example of how an organism has become adapted to abiotic factor
Otters have webbed paws so they can work on the land and swim
Give an example of how an organism has become adapted to biotic factor
Otters use rocks to smash open shellfish
What is a niche?
The role of a species within its habitat, consisting of both its biotic interactions
What is carrying capacity?
The maximum size of population an ecosystem can support without environmental degradation
What is intraspecific competition?
Competition between organisms of the same species
What is interspecific competition?
Competition between organisms of different species
What are the abiotic factors that affect population size?
Temperature
Light
pH
Water/humidity
How are quadrats used to estimate population size?
Placed on grid coordinates or at intervals along transect
Results reported as either a percentage cover or frequency
For slow moving/ non-mobile organisms
What should samples be?
Random and repeated to avoid bias
Describe the predator-prey relationship patterns
Prey eaten = predator population increases + prey decreases
Fewer prey = increased competition for food so predator population decreases
Fewer prey = prey population increases
Cycle begins again
What resources do organisms compete for?
Food Water Shelter Light Mates (intraspecific only)
How is the mark-release-recapture used to estimate population size?
Sample of species collected Marked in harmless way Released back into habitat Wait a week then take 2nd sample from population Count how many of 2nd sample are marked
What is the mark-release-recapture equation?
No. marked in 2nd sample
What happens if two species are competing for a resource?
The one better adapted to its surroundings will survive
What assumptions are made for the mark-release-recapture method?
Marked individuals distributed evenly No migration in or out of population Few births or deaths Method of marking does not affect survival Mark does not come off
Why are ecosystems described as dynamic?
Populations constantly rise + fall
Any small change can have a small effect
Biotic + abiotic factors may alter conditions of ecosystem
Describe population growth
Population increases = resources plentiful
= more organisms competing for same amount of food/space
= resources limited = decline in population
= less competition for resources
= population grows
Describe the process of primary succession
Pioneer species colonies harsh conditions + area
Change abiotic factors of environment
The die and decomposed = adds nutrients to soil
This repeats = soil deep + nutritious
Allows more complex species to survive
What is a climax community?
The final stage of succession, where the ecosystem is balanced and stable
How is a climax community reached?
Soil rich enough to support large trees or shrubs
Environment no longer changing
What is conservation?
The protection and management of species and habitats, in order to maintain biodiversity
Describe an example of pioneer species (bare rock to woodland)
Pioneer species (lichens) grow + break rock
Lichens die + decompose = soil thickens are decomposes more
Larger plants grow = soil deepens as they decompose
Shrubs+ small tress grow = out-compete grass
Diversity increases
Large trees become dominant species
Climax community
What is plagioclimax?
When succession is stopped artificially to stop a climax community from developing
How might succession be managed i order to aid conservation?
Sometimes succession needs to be prevented in order to observe an ecosystem
eg. stopping moorland from progressing into spruce forest = plagioclimax
What is sustainability?
Using enough resources to meet the needs of today’s society, without reducing the ability of people in the future to meet their own needs
What is the opinion of conservation?
Not everyone agrees with every conservation measure so often conflict between human needs and conservation
= careful management used to find a balance
How a species might alter the environment that develops during succession?
Species might improve it to make it more suitable for other species
Species may worsen it by making it less suitable for other species
What ways are used to manage succession in the moorland ecosystem?
Animals allowed to graze = they eat growing points of shrubs = stops vegetation establishing + vegetation low
Managed fires are lit = secondary succession will occur = species grow back first (pioneer species) conserved
= large species will not grow back
What is a limiting factor?
Environmental conditions that limit the growth, abundance or distribution of an organism or population of organisms in an ecosystem
What is competitive exclusion principle?
Two species competing for the same limited resource, cannot coexist at constant population values as one will always out compete the other
What are examples of conservation techniques?
National parks protect habitats = restrict urban development, industrial development + farming
Endangered species bred in captivity
Fishing quotas limit amount of certain fish species you can catch
When is it best to use a log scale?
Rapid growth
Studying a long period of time
Why would you use a log scale?
Reduces wide range quantities to tiny scopes
Clearer pattern shown
What are factors that increase population growth?
Health care Infrastructure + resources Economy Food availability Better quality of life Industrial revolution
What is the equation for population growth?
(Births + immigration) - (deaths + emigration)
What is the equation for the percentage growth rate of population?
Population change during time period
——————————————————- X 100
Population at start of time period
What are sampling methods?
Random
Systematic
Why may a population fluctuate other then prey-predator relationship?
Disease
Climate change
What are the two forms of active human conservation management?
Ex-situ
In-situ
What is primary succession?
Where an area previously devoided of life s colonised by a community of organisms
What is secondary succession?
Where land has been cleared of all plants but soil remains
What is a habitat?
The place where an organism lives within an ecosystem
What is a population?
Group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed
What are the characteristics of organisms present during early stage of succession
Produce wind dispersed seeds Survive in harsh conditions Fast germination Photosynthesise Nitrogen-fixing Produce asexually
What is ex-situ?
Outside of natural habitats (eg. zoos)
What in-situ?
Whole ecosystems and landscapes
Why do populations not grow indefinitely?
Competition for space then reach carry capacity
Why do species present during succession change?
Soil deepens as organisms grow, which allow for larger species to grow = increased competition
What is a limitation of using the mark-release-recapture method?
Disturbance of habitat
What is a species?
A group of organisms that can breed to produce fertile offspring
Why are most characteristics distributed normally?
Result of polygenes (multiple genes each affected by the environment)
What is a selection pressure?
Environmental pressure that is alternating the frequency of alleles in the population
What is ecology?
The study of inter-relationships between organisms and their environment
What is the biosphere?
The regions of the surface (land) and atmosphere (air) and Earth occupied by living organisms
Describe a stable population - population pyramid
Birth + death rate are balanced
No change in population size
Typical of developed countries
Describe increasing growth - population pyramid
High birth rate = wide base
Few old people = narrow apex
Typical of developed countries
Describe decreasing growth - population pyramid
Low birth rate = narrow base
Low mortality rate = more elderly = wide apex
Applies to certain developed countries eg. Japan
What is demographic transitions?
As countries develop economically, their human population display a patter of growth
What are the four stages that demographic transitions are divided into?
Small and stable
Early expansion
Late expansion
Large and stable
What do the stages depend on in demographic transition?
Death rate
Birth rate
Total population
What are the adaptations of predators?
Fast
Camouflage
Sense of smell/sight
What are the adaptions of prey?
Camouflage
Concealing behaviour
Speed
Protective features
What is a stable community?
Where all species and environmental factors are in balance so that population size remains fairly constant
Why is intraspecific population important?
Availability of resources determine population size
Greater availability = larger population size
More resources to grow + breed
Why is it difficult to prove competition is factor affecting population size?
Many factors involved (abiotic)
Causal link has to be established
Lag time
Data on population size hard to obtain
What are the difficulties of using quadrats?
Time consuming
May damage habitat
Element of personal bias
Difficult to identify + count every organism
What are the advantages of point quadrats?
Smaller organisms
Smaller area
Specific detail
What are the disadvantages of point quadrats?
Tedious
Hard to use
Time consuming
When is systematic sampling important?
Gradual changes across habitat
Transitions within communities occur
What are line transects?
Tape
Use quadrats
What are belt transects?
Two tapes
Organisms recorded between two belts
What are the advantages and disadvantages of line transects?
Quick -A Easily shows species - A Clear visual of species change -A Harder to see range across large area -D Less data collected -D
What are the advantages and disadvantages of belt transects?
More data-A Tell you more about abundance + range -A Shows change clearly-A Larger area -A Time consuming -D
What are the two methods to measure abundnace?
Frequency
Percentage cover
What is the per quadrat equation?
No.of squares species occurs in
———————————————- X100
No.of squares in total
What is the advantages and disadvantages of using frequency to measure abundance?
Useful where species easier to count -A
Quick idea of species present -A
No detailed info on distribution -D
Time consuming-D
What is the advantages and disadvantages of using % cover to measure abundance?
Useful when specie hard to count -A Quick -A Representation of density -A Less precise -D Subjective -D
What are the disadvantages of the mark, recapture and release method?
Risk of predation changing sample size
Disturbance of habitat
Trauma or injury to organism
What is preservation?
Maintaining individuals, populations and ecosystems in their current state without the exploitation of their natural resources
What is species diversity?
The number of different species and numbers of individuals of each species within only one community
What is genetic diversity?
The variety of genes possessed by the individuals that make up any one species
What is ecosystem diversity?
The range of different habitats within a particular area
