p2: investigating populations Flashcards
ecology
study of organisms and the environment in which they live.
species
closely related individuals, which are capable of interbreeding and producing a fertile offspring
population
all individuals of a species
- living together in the same area
- at the same time
carrying capacity
maximu, equilibrium number of organisms of a particular species
- supported in each stable environment
- birth and death rates are in equilibrium
community
all individuals of all species
living together in same area
at same time
habitat
place organisms live
niche
where an organisms lives and what it does
what is the difference between interspecific competittion and intraspecific competition?
INTER: competition for resources between different species for territory (eg: lions and hyenas for food)
inTRA: competition between individuals of same species for food, amtes and resources
ecosystem
community if living organisms
- and interactions with abiotic components
- air, water and soil
biotic factors
- mate availability
- invasive species
- competition
- predation
- disease
- human impact
abiotic factors
- temperature
- light intensity
- wind speed
- water pH
- salinity of water
- pesticides
the ecologists found that each species of fish had adaptations to its niche. one of these adaptations was the shape of its mouth. suggest and explain how the shape of its mouth is an adaptation to its niche.
- niches increase competiton between species for food
- different mouth shapes = different food eaten so interspecific competition is reduces
why do no 2 species have exactly the same niche?
- competitive niche exclusion principle: more successful will outcompete
what happens when niches overlap?
– one species has adaptations that outcompete other species
- second species is outcompeted
why is it incorect to say that no two species have the same niche?
- different organisms occupy same niches
- compete until one species is eliminated
how to make estimating populations more reliable?
- random sampling so avoids bias so more representative
- ## large so stats test can be done so representative so reliable
density
- actual count of ALL individuals
- time consuming
- most accurate
- hard to count
percentage cover
- area of quadrat covered by one species taken as percentage of total area
- used when too many to count
- percentage may exceed 100% due to overlaying
frequency
proportion of quadrats containing species
- if species present in 30 out of 100 quadrats, 30%
- least accurate
when is random sampling/ random quadrating used?
- measure relative abundance in an area
- compare species abundance in 2 different areas
- compare species abundance in one area at different times of year
dexcribe random sampling
- used for slow moving organisms with uniformed distribution in area
- use a grid to split area
- use a random number generator to obtain random co-ordinates
- count frequency in quadrat
- ## large sample (20+) and calculate a mean
how many quadrats should you use in the sample?
- calculate running mean
- stop sampling if little change
- enough to carry out a stats test
- large enough number to make sure mean is reliable
systematic sampling
- across an area (eg: does population change over a dune?)
- transect from one side to another
- place quadrats at regular intervals along the line
- count percentage cover/ abundance
- count plants and record when touch transect
measuring population density
- count total number of all individuals in area
measuring frequency
- count number in quadrat area
- calculate average frequency per meter squared
percentage cover
total area covered by species / total area of quadrats x100
describe how you would determine the mean percentage cover for beach grass on a sand dune
- random sampling
- randomly generate co-ordinates
- large number of samples (20+)
- total percentage by number of quadrats
describe a method that can be used to determine the mean percentage cover of algae on a coral reef
- use a random generator to randomly generate some random co ordinates
- large number of samples (20+)
- total percentage by number of quadrats
describe the mark release and recapture technique to estimate the size of a fish sample
- capture sample, mark and release
- ensure marking is not harmful for the fish
- allow time for fish to randomly distribute and repopulate before collecting a second sample
population size: (N1 x N2) / N2m
n1: first time
n2: population second time
n2m: population marked second time
suggest why the mark release recapture method can produce unreliable results in very large lakes
- less chance of recapturing fish
- unlikely fish distribute evenly
- fish may remain in one area
ethical way to treat animals (MCR method)
- collect via net
- paint dots
- UV dye tagged
abiotic factors
- temperature: affect enzymes and metabolism. too cold then no kinetic energy. if too high, enzymes denature
- light intensity: required for PS, more then more spores production so mre population increase
- water availability and humidity
- pH
equipment used to measure abiotic factors
- wind speed: anemometer m/s
- soil pH: pH probe, pH
- temperature: digital termometer ( degrees)
- light intensity: lux meter, Lx
biotic factors
- competition: intra more fiercer.
- predation: mechanisms to improve capturing ( high sped, venomous secretions) and prey have defence mechanisms (camoflage, protective spines)
