populations in an ecosystem Flashcards
population
All the individuals of one species in the same area at the same time
habitat
The range of physical, biological and environmental factors in which a species can live
community
all the species in a particular area at a particular time
ecosystem
a community and the non-living components of an area
they can range from very small to very large in size
Niche
An organism’s role within an ecosystem
their position in the food web and their habitat
carrying capacity
The maximum population size an ecosystem can support
abiotic factors
Non-living conditions of an ecosystem
biotic factors
Impact and interactions between organisms
interspecific competition
Competition between members of different species
intraspecific competition
Competition between members of the same species
when would you use random sampling
when there is a uniform distribution of the plant species
to avoid bias
What must you do to ensure your samples are representative?
Take a large sample (at least 30)
randomly sample
when would you use a line transect
When sampling a non-uniform area
e.g. a rocky shore
Belt transect
one tape measure is placed through an ecosystem that is not uniform
the quadrat is placed at every position along a tape measure
interrupted belt transect
one tape measure is placed through an ecosystem that is not uniform
the quadrat is placed at set intervals along the tape measure
what are the 3 measurements you can take when counting plants in a quadrat?
density
percentage cover
frequency
density measurement
when you count the individualspresent
frequency measurement
count how many squares out of the 100 contain the species you are investigating
what is succession?
the change in an ecological community over time
percentage cover measurement
investigator estimates the percentage of the entire quadrat covered with the species that is being investigated
standardise by counting 1% for every small square that is at least half covered by the plant
when would you use mark-release-recapture?
Estimate the population size of motile organisms
what is secondary succession?
there is a disruption that causes plants to be destroyed succession starts again, but the soil is already formed
pioneer species
The first species to colonise an area
e.g. lichen
what is primary succession?
a succession with a pioneer species colonizing bare rock or sand
the first time the land is colonised
climax community
The final stage in succession
the most stable stage
Humus
a thin layer of soil that forms in early primary succession
Conservation of habitats
Protecting habitats as a means to protect species
maintains habitats and food sources
effects of stabilising selection
the middle trait has a selective advantage and continues to be the most frequent in the population
range decreases as the extreme traits are lost over time
what is the main advantage of managing succession?
conserves a range of habitats and a range of food sources
enables a wider range of species to survive
assumptions of mark-release-recapture
the marked individuals released distribute evenly after being released
no migration
no births or deaths
effects of directional selection
one of the extreme traits has a selective advantage
occurs when there is a change in the environment
the modal trait changes
effects of disruptive selection
alleles for the extreme traits and the middling trait allele becomes less frequent
leads to speciation
How would you randomly sample
place two tape measures at right angles to create a gridded area
use a random number generator to get coordinates
place the quadrate at the coordinates and collect the data
repeat at least 30 time
How would you sample using a line transect
Place a tape measure at a right angle to the road/river/shoreline
place quadrat every set distance meters (e.g. 5 metres)
collect the data in each quadrat
repeat placing the tape
measure in parallel 30 times
describe the mark-release-recapture method of sampling
an initial sample of the population is captured
individuals are marked and released
allow them time to randomly disperse
a second sample is captured
the total number captured in the second sample and the number recaptured with the marking are recorded
describe the changes you would see in a succession
abiotic factors become less hostile
biodiversity increases
becomes more stable
