Populations Flashcards
What is a population?
a group of individuals of one species
occupying the same habitat
What method can be used to determine the mean percentage cover of a species?
Random number generator
use a large number of quadrats
divide total percentage by number of quadrats
What is a community?
all the populations of different species occupying the same habitat at the same time
What is a niche?
how an organism fits into an environment
no two species can occupy the same niche
What determines the population size?
carrying capacity
- the max size a habitat can support
What is the standard population curve?
increases and enough resources
starts to level off as increased competition
What are some abiotic factors?
temp, light intensity, pH, water, humidity
Why does temp affect growth?
enzymes (for photosynthesis) denature in high temps
reactions slower as less KE in low temps
Why does light affect growth?
photosynthesis limited in low light
Why does pH affect growth?
enzymes denature at wrong pH
Why does water and humidity affect growth?
high humidity = decrease in transpiration - less water for photosynthesis
photosynthesis limited with low levels water -> used for support (turgidity)
What are biotic factors?
intraspecific competition - same species
interspecific competition - different species
predation
How can the size of a population be estimated?
mark-release-recapture for motile organisms
What are the limitations and assumptions for mark-release-recapture?
‘mark’ isn’t lost
no births/deaths
no immigration/migration
equally likely to get caught
how do you calculate pop. size after mark-release-recapture?
no. in 1st sample x no. in 2nd sample / no. in 2nd sample marked
What is an abiotic factor?
non-living factor of environment
Describe mark-release-recapture
capture, count, release
mark carefully to avoid detection
recapture, count marked and unmarked
What is spearmans rank?
use when two sets of numerical data may be correlated
values must be paired so their ranks can be compared
must be enough data to make judgement (10-15)
What does it mean if the test value> critical values?
probability that difference in… was due to chance is less than (p value)
so reject null hypothesis
What does it mean if the test value< critical values?
probability that the difference in… was due to chance is more than (p value)
so accept null hypothesis
What is uniformly distributed?
organisms evenly spread between regions
How do the assumptions for proportional sampling differ from mark-release-recapture?
suggest organisms are evenly distributed
mark suggests size of total area not required
How are the assumptions for proportional sampling and mark-release-recapture the same?
animals are apart of same population
What information do standard deviations give?
values spread around mean
