populations and ecosystems 3.7 Flashcards
define population
a group of individuals of the same species that occupy the same habitat at the same time
define community
all living things present in an ecosystem at a given time
define ecosystem
all living and non living components of a particular area
define habitat
the place where an organism normally lives and which is characterised by physical conditions and the types of other organisms present
define ecological niche
describes how an organism fits into its environment. describes what a species is like, where is occurs, how it behaves, interactions with others, how it responds to its environment
define abiotic
an ecological factor that makes up a part of the non biological environment of an organism
define biotic
an ecological factor that makes up part of the living environment of an organism
define carrying capacity
population size that can be sustained over a relatively long period. determined by limiting factors such as predation and disease
define interspecific competition
competition between organisms of different species
define intraspecific competition
competition between organisms of the same species
define predation
one organism is consumed by another
what are the two types of migration
internal and external
what are the four stages of a population growth curve
lag phase
log phase
stationary phase
decline phase
what is the lag phase
population is slowly increasing as organisms adjust to the new environment and start to reproduce
what is the log phase
high availability of nutrients and space leads to exponential growth
what is the stationary phase
population reaches its maximum as it is limited by the resources available
what is the death phase
where lack of nutrients and toxic waste products cause death rate > birth rate
examples of limiting factors
predation
light
oxygen
disease
competition
water
humidity
toxic waste
temperature
pH
food availability
nutrients
habitats
why is low temperature an issue
slows enzyme activity and reduces the metabolic rate
what is the competition exclusion principle
states that 2 species cannot coexist if they occupy the same niche (if they compete for identical recourses)
effect of predator prey relationship on population size
predators eat prey
reduces prey population
predators in greater competition for prey
predator population is reduced
less prey eaten
prey population increases
predator population then increases
what are quadrats used for
used for non mobile/sessile organisms
what is mark release recapture used for
used for mobile animals
random sampling method
use transects
random number generator for coordinates
quadrat at intersections
when would you use systematic sampling
to investigate changes in habitats, along lines of succession or where there are environmental gradients
when is a line transect used
records species which actually touch the transect
how is a belt transect used
a frame quadrat is laid down along a straight line and species recorded in the transect
when is an interrupted belt transect used
records all those species present in a number of quadrats places at fixed points along a line stretched across the habitat
