Population Flashcards
population definition
a group of organisms which occupy the same environment and are of the same species
birth rate
the reproductive capacity of a population and the rate at which reproduction or cell division occurs
immigration
the movement of organisms for one population to another
equilibrium species
a species which relies on competition and predation for survival
fugitive species
species which relies on high reproduction rates and dispersal for survival
biotic factors
competition predation human activity pathogen nutrition
abiotic factors
sunlight water oxygen and co2 minerals temperature ph salinity
density dependent factors
factors which decrease and become more significant for survival as population increases
density independent factors
factors which influence on population size remains constant and never changes despite population growth or decline
environmental resistance
abiotic factors that reduce population growth
carrying capacity
the maximum population size which an environment can maintain, and fluctuate about
negative feedback at carrying capacity
the mechanism by which carrying capacity of an environment is maintained
when population exceeds carrying capacity, factors scarcity and increased competition reduce it back
when population falls below carrying capacity, factors are in abundance and competition is reduced so increases it
equation to measure population growht
(birth rate plus migration)-(death rate plus emigration)
factors regulating population size
density in/dependent factors
competition
population growth curve phases
lag
exponential
stationary
death
lag phase example in bacteria and organism
population growth is very slow
organisms are becoming sexually mature
finding mating partner
adaptation phase to the environment
gestation of young
high rates of metabolic activity
protein synthesis, dna replication, respiration to make atp for mitosis
exponential phase example in bacteria and organism
rapid population growth birth rate exceeds death rate no environmental resistance resources are in abundance / no density dependent factors restriction no overcrowding competition isn't limiting
stationary phase example in bacteria and organism
carrying capacity is met
birth rate = death rate
negative feedback operates to maintain carrying capacity
environmental resistance increases
density dependent factors become more significant
intraspecific competition increases as organisms of same species require same resources as they have same needs
death phase example in bacteria and organism
death rate exceeds birth rate density dependent factors most significant environmental resistance build up of waste products overcrowding
population explosion
rapid rise in population due to alleviation of a limiting factor EG predators
maintained by negative feedback to reduce it
measuring abundance methods
measuring distribution methods
ABUNDANCE
quadrat;
mark out a transect line
measure abundance at regular intervals
-% cover (estimate)
-% frequency (mark out tape squares and count how many squares are covered)
-mean area covered
random number generator used to pick coordinate of the quadrat square used
count organisms present in the square
repeat and calculate a mean
capture mark recapture
kick sampling
DISTRIBUTION
belt transect across irregular environment
line transect
repeat abundance measurements using quadrat at regular intervals, focusing on the number of organisms per species/in total as opposed to which species are present
kick sampling in a river
capture mark recapture method
place quadrat in sample space
count organisms and mark them with substance that doesn’t affect survival nor kill them
release into environment
redo after a set time period and count how many have the marking
belt transect
mark transect line across irregular environment
at regular intervals place down the quadrat
count how many organisms are present
abundance
the number of organisms per unit area
