6.6 Populations And Sustainability Flashcards
Population
number of organisms existing in a particular area
Growth curve
A = lag phase
B = log phase
C = stationary phase
Lag phase
when there are few individuals who get used to their habitat and start reproducing while the rate of reproduction is still low
Log phase
when there are lots of resources, conditions are good (reproduction is favoured), rate of reproduction>rate of death
Stationary phase
when rate of reproduction = rate of death, because the population has reached its carrying capacity
Carrying capacity
maximum population size that can be maintained over a period of time in a habitat (based on biotic and abiotic factors)
What happens if you exceed the carrying capacity
there will be a decline phase = bc there’ll be a limiting factor
Why do you reach carrying capacity
Bc of limiting factors
2 types of limiting factors
Density dependent and density independent
Density dependent factors
limiting factors whos power increases when density of the population increases e.g. predators, food, water, oxygen
Density independent factors
limiting factors that do not depend on the population size e.g. temperature, natural disasters
2btypes of strategists to reach carrying capacity
R strategists and K strategists
K strategists
growth curve = closer the population reaches to carrying capacity, the stronger the effect of limiting factors = gradual levelling out, system followed by populations like large mammals, humans
Features that allow us to follow K system
low reproduction rate, slow development, late reproductive age, longer life span, large body mass
R strategists
population size increases so quickly it exceeds carrying capacity, then limiting factors start to have an effect, then it goes back down. Usually bacteria or pioneer species
R strategists population growth curve
Features that cause people to follow the R system
high reproductive rate, short life span, long reproductive age, quick development, small body mass
2 types of competition
Interspecific and intraspecific
Interspecific competition
Between individuals of different species
Intraspecific competition
between individuals of same species
What is intraspecific competition proportional to
Most intraspecific competition is proportional to population size
If population size goes down, competition goes down, which then means the population size goes back up again
Effect of interspecific competition
Within interspecific population bc it’s impossible for 2 species to occupy the exact same niche, one species will often out compete the other species = 2nd species levels will be rlly low