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What is population growth?
an increase in the size of a population over time, changes caused by different factors
What are the factors that regulate population growth and decline?
growth: birth and immigration
decline: death and emigration
What is the population size formula?
N(t) = (Bt + It) - (Dt + Et)
What is immigration? Emigration?
immigration: moving into a population
emigration: moving out of a population
What is fertility rate? When does replacement level fertility occur?
the average number of offspring a female will have in her lifetime; when the fertility rate and death rate are EQUAL
What is the human population replacement level fertility?
about 2.1 children
What is exponential growth? Example?
the rapid growth of a population when it is provided with unlimited resources, growth rate is proportional to its size and it continually increases, no carrying capacity; bacteria dividing rapidly 3x an hr
What is logistic growth?
the initial rapid growth of a population that is limited by the carrying capacity of the environment, begins exponentially but tapers off due to limited resources
Which growth is J vs S curve?
exponential, logistic
What is the carrying capacity?
the maximum number of organisms that an environment can sustainably support with available resources (water, physical space, soil, etc.)
What are the types of limiting factors?
density-dependent: factors increase as the population density does, competition, predation, parasitism, disease
density-independent: factors are independent of the density population, human disturbances, drought, climate extremes
How does the carrying capacity affect the population organisms?
causes the population to taper off or crash, not enough resources to sustain, can lead to higher competition
What is the boom and bust cycle?
repeated cycles of growth (boom) and decline (bust), typical of predator-prey interactions as a large number of predators means less prey, which means less predators due to competition
What are the different survivorship curves? Examples?
Type I: high survival and rapid die off in old age, maintain population at carrying capacity, invest into offspring to ensure their long survival; humans, large mammals
Type II: constant decline in survivorship; squirrels, fish, lizards
Type III: rapid die off in early life followed by high survivorship with those who survived, ensure quantity over quality; plants, insects
Which type of survivorship is r-selected species and K-selected species?
Type III, Type I
What are the different types of species interactions?
amensalism, commensalism, mutualism, predation, parasitism, competition
Amensalism + ex
one organism is harmed and the other is unaffected; ruminants walking on grass
Commensalism + ex
when one organism is benefitted and the other is unaffected; barnacles on whales
Mutualism + ex
both organisms benefit; clownfish hiding in sea anemones and also protecting them
Predation
one organism benefits and the other is killed, can affect where prey spend time
Parasitism + ex
one organism benefits from living on or inside other which is harmed; tapeworms, fleas, ticks
What is competition? What is interspecific competition vs intraspecific?
when more than one organism tries to use the same limited resources in the same place at the same time with one winner and one loser
intraspecific: competition among members of the same species
interspecific: competition between members of different species
What is the Competitive Exclusion Principle?
no two species can occupy the same niche in the same habitat at the same time, one winner and one loser who dies out
What is resource partitioning? Example? Why did it form?
when species divide their shared resources based on the different portions/areas or times used; birds dividing tree by area of branches; formed as a result of competition in the past
What does competition do as a result of dividing resources?
helps to determine the numbers and kinds of species as well as their niches in the communities
What is a keystone species?
a species on which other species largely depend so that if it were removed the ecosystem would change drastically, helps to maintain balance and structure