1291903
Biology A2- 4.1
- Statistics
- Standard deviation and standard error-
used to look for differences between mean
values
- Standard deviation and standard error-
used to look for differences between mean
values
- ECOLOGICAL TERMS
- Population: All the
organisms of one species in
a habitat
- Ecosystem: An ecological
unit with biotic and abiotic
components
- Community: All the individuals of all
species in an ecosystem
- Niche: The role of an
organism within an
ecosystem; what it does, what
it eats, and what eats it
- Intraspecific competition: Competition
between members of the same species for
a resource eg food, light
- Biotic: All the living
components of an ecosystem
- Interspecific competition: Competition between
members of different species for a resource eg
food, light
- Abiotic: all the non-living components of
an ecosytem eg. temp, light intensity, pH
- Habitat: Place where an organism lives
- Abundance: The number of individuals of a species within a given space
- Predators: organisms that kill their prey
- Predators feed on other organisms
- Predators feed on other organisms
- Parasite: live in/on host
- eg. Flatworm- gains nutrients/ shelter/ oxygen from host
- eg. Flatworm- gains nutrients/ shelter/ oxygen from host
- Population: All the
organisms of one species in
a habitat
- Random Sampling
- Used to avoid any bias in collecting data
- Makes sure the results are valid
- Makes sure the results are valid
- Try and reduce an soil, climatic
and other abiotic differences when
comparing test areas
- Generate random numbers
from calculator/ computer, using grid
that has been set up, use
the numbers as
coordinaates
- Place quadrat at intersection of each pair
of coordinates, record the sample of
species that you are investigating
- Lay out two long tape measures
at right angles, along two sides of
study area
- Used to avoid any bias in collecting data
- Transects
- Sometimes more informative to
measure the abundance and
distribution of a species in a
systematic, not random order
- Especially important to see transition of
animal and plant species in the community
- Can be used to see things such as succession
- Tape stretched across the ground in a straight line, any
organism within the quadrat after generating the coordinates
from computer is recorded.
- Sometimes more informative to
measure the abundance and
distribution of a species in a
systematic, not random order
- Measuring abundance
- Abundance is the number of
individuals of a species in a given
space
- Measured in several ways, depending on size of species
being counted and the habitat
- Frequency: the likelihood of a particular
species occurring in a quadrat
- for example: a species occurs in 15 out of 30 quadrats- frequency of its occurrence is 50%
- Useful where a species is hard to count- eg. grass
- Quick idea of how the species present and their general distribution
- DOES NOT: provide information on density and detailed distribution of a species
- DOES NOT: provide information on density and detailed distribution of a species
- Quick idea of how the species present and their general distribution
- Useful where a species is hard to count- eg. grass
- for example: a species occurs in 15 out of 30 quadrats- frequency of its occurrence is 50%
- Percentage cover: estimate of the area
within a quadrat that a particular plant
species covers
- Useful where a species is particularly abundant or difficult to count
- Data collected rapidly, individual plants need not be counted
- LESS USEFUL: where organisms occur in overlapping areas
- LESS USEFUL: where organisms occur in overlapping areas
- Data collected rapidly, individual plants need not be counted
- Useful where a species is particularly abundant or difficult to count
- Frequency: the likelihood of a particular
species occurring in a quadrat
- To obtain reliable results- need large sample size, so
the mean can be found. The larger the number of
samples, the more representative of the community
as a whole the results will be
- Abundance is the number of
individuals of a species in a given
space
- Mark- release- recapture techniques
- Used for animals
- most animals are mobile and move away when approached
- others hide and therefore more hard to identify
- others hide and therefore more hard to identify
- most animals are mobile and move away when approached
- a known number of animals are
caught, marked and then released
back into the community
- After some time, a given number of individuals is
collected randomly and the number of marked
animals are recorded
- SIZE OF POPULATION then calculated
- estimated population size= (total no.individuals in
first sample X total no.of individuals in second
sample) / no. of marked individuals recaptured
- estimated population size= (total no.individuals in
first sample X total no.of individuals in second
sample) / no. of marked individuals recaptured
- SIZE OF POPULATION then calculated
- After some time, a given number of individuals is
collected randomly and the number of marked
animals are recorded
- Relies on assumptions: 1) the proportion of marked to unmarked
individuals in second sample is the same as the population as a
whole 2) marked individuals from first sample distribute
themselves evenly amongst remainder of population ans have
had sufficient time to do so 3) population has a boundary- no
immigration of emigration 4) few births/ deaths 5) method of
marking is not toxic and does not make it more identifiable to
predators 6) the marker doesn't rub off
- Used for animals
- Ethics and field work
- where possible the organisms should be
studied in situ (if necessary to move them, the
numbers need to be at a minimum.)
- any organism removed from site
should be returned to original habitat
as soon as possible
- Even if dead
- Even if dead
- a certain amount of time should
pass before the site is used
again
- Disturbance to habitat
should be avoided
- where possible the organisms should be
studied in situ (if necessary to move them, the
numbers need to be at a minimum.)
Media attachments
Want to create your own Mind Maps for free with GoConqr? Learn more.