C4.1 population and communities Flashcards
(46 cards)
population
interacting groups of organisms of the same species living in an area
what happens populations of the same species live far for long
they will develop new characteristics and become different species
estimation of population size by random sampling
instead of counting individuals, we can count a sample from a small area and multiply this by total area of habitat
quadrat sampling
method used to take a measurement of an area without systematically deciding where to take it. it eliminates bias which may influence the measurement. this can work out population size or stationary animals and plants
explain in detail random quadrat sampling to estimate population size for sessile organisms
- a base line along the edge of the habitat using measuring tape
- generation of random numbers using a table or generator
- first random number= distance along tape, 2nd random number is distance across the habitat at right angle from tape
- quadrat is places precisely at the distance
capture- mark- release- recapture
used to calculate population size
when measuring mobile organisms must use traps, nets, etc
population size
=n1xn2/n3
n1= 1st capture total
n2= total, marked + unmarked
n3= 2nd capture, marked only
carrying capacity
maximum size of a population that an enviorment can support
2 types of limiting factors
density dependant factors
density independant facotrs
density dependant factors
factors that depend on population size:
food and water
space for territories
availability of mates
diseases
density independant factors
factors that affect populations in similar ways, independant of population size:
enviormental change
injury
build up of toxic products
old age
how do dependant factors affect a population
dependant factors will cause the population size to fluctuate due to a negative feedback control. the population oscilates around its carrying capacity.
population size curve
exponential stage, transition stage, plateu stage
exponential stage
births+ immigration> mortality + emigration
there are lots of supplys, resources, growth limited by population size
transition stage
birth + mortality > mortality + emigration
population growth is slower than start since now there are limiting factors and competition
plateu stage
limiting factors have restricted growth
mortality= births
population size formula
mortality + imigration)- (mortality + emigration)
modelling a sigmoid curve
place plant in container
count number of leaves everyday until surface is covered
plot results
community
all of the interacting organisms in an ecosystem they have beneficial or harmful relationship
intraspecific interaction-
effects that individuals of the same species have on other members of that species eg: competing
interspecific
effect that individuals hof different species have on one another: prey x predetor
types of competition
- competing for resources
- competing for mates
- pollen distribution to pollenators
- space + nesting sighns
types of cooperative
comunal roosting
shared parenting
group hunting
social predation
interspecific relationships
herbivory, predation, competition, parasitism, mutualism, pathogency