chapter 16: Population Ecology Flashcards
ecology
subdiscipline of biology defined as the study of interaction between organisms and their environments
individuals
individual organisms
populations
groups of individual organisms that inter breed with each other
communities
population of different species that interact within a locale
ecosystems
all living organisms as well as non-living elements that interact in a particular area
population ecology
subfield of ecology that focuses on populations of organisms of a species and how they interact with environment
growth rate
change in number of individuals in the population in some unit of time
growth rate=Nxr
exponential growth
when a population size increases at a rate proportional to its current size (bigger population, faster growth)
what happens as population increases
- reduced food supplies
- diminished access to places to live and breed
- increased incidence of parasites and disease
- increased predation risk
population density
number of individuals in a given area
density-dependent factors
limitations on populations growth that are a consequence of population density
carrying capacity (k)
ceiling on growth - when a pop. cannot grow any larger
population growth = (r*N) * [(k-N)/k]
what happens as a population approaches k
- death rate increases
- emigration rate increases
- deduction in birth rate usually occurs
logistical growth
when a population grows exponentially at first but then its growth slows as the population size approaches k
density independent factors
limitations on a populations growth unrelated to population size
floods, earthquakes, fires, lightning
maximum sustainable yield
as many individuals as possible are removed from the population without impairing its growth
- halfway to k (point of fastest growth)
life history
species vital statistics, including age at first reproduction, probabilities of survival and reproduction at each age, litter size/frequency/longevity
reproductive investment
all of the material and energetic contributions that an individual will make to its offspring
variation in life histories
- big-bang reproduction
- reach sexual maturity 1 year
- mates intensely over a 3 wk period
- males die shortly after
- females usually die after first litter - fast, intense reproductive investment
- reaches SM after 1 mo.
- litters of 6-10 every month - slow gradual reproductive investment
- reaches SM at 1 year
- produces 1 offspring/yr
what are the trade-offs btwn growth reproduction and longevity
reproduction and survival
reproduction and growth
number and size of offspring
