3.5 POPULATION Flashcards
definition of population
- an interbreeding group of organisms of the same species occupying a particular habit
why do organisms live in population
- more successful in breading and rearing their young
- gaining protection from predators by living in groups (safety in numbers)
- working as a group to locate new food sources
problems with living in a population
-intraspecific competition (food/space)
-could make the group more vulnerable
some individuals better adapted than others and more likely to survive
what increases population sizes
more births
immigration
what decreases population sizes
death
emigration
what’s an equillibrium species
where the control of their population is by competition within a stable habitat
carrying capacity
the maximum number around which a population fluctuates in a given environment
what should a growth curve for an equilibrium species look like
sigmoid shape curve
what;s environmental resistance
environmental factors that slow down population growth
explain negative feedback in terms of population size
regulates population sizes. it is a change in response to a first change to bring numbers back to the original levels. negative feedback always brings about change to return levels to optimum. always be fluctuations in population numbers but around the set points
density
number of species in a particular area
what type of factors affect population size
biotic/abiotic factors
what are biotic factors
living and are part of the environment of an organism
e.g predators, parasites and competitors
density-dependent
what are abiotic factors
non-living parts of the environment of an organism
e.g. temperature, oxygen, shelter, pollution
what does being density-dependent mean
they affect a higher proportion of the population when there is a high population density
