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10 Cards in this Set

  • Front
  • Back
Logistic Growth Equation
dN/dt = rN {(K-N)/K} or rN = (1 – N/K)
dN/dt = rate of change in population size over time
rN = rate of increase of the population
K = carrying capacity…(maximum the environment can sustain)
(K-N)/K = unutilized opportunity for population growth
Density Dependent Regulation
: impact a population in proportion to its density
Biotic Factors:
--predation** (more in later lecture)
--intraspecific competition
--reproductive inhibition
--dispersal * (does not regulate, but affects)
Density Independent Regulation
---acts independently of population size
---BUT can still result in regulation
Abiotic Factors:
Scramble Competition
---affects all individuals equally
…no interaction or interference
---”exploitative”…increased density results in decreased availability of resources
(spotted hyena)
Contest competition
…impacts only a fraction of the population
(polar bears, muskoxen, wolves)
departure from territory or home range
--high densities = low weight
--decline in survivors, but increase
in biomass
presaturation dispersal
--often to avoid inbreeding
--may be to find better or more mates
--occurs prior to saturation level
--usually healthy, fit members…may be juveniles
--not forced out
--may be sex-biased
--in birds..usually females
--in mammals..usually males
saturation dispersal
--at high density
--habitat may no longer support increased numbers
--usually sub-adults
--usually subordinate or less-healthy members
Endocrine Disruption
various chemicals including pesticides and industrial compounds can mimic hormones and result in reproductive anomalies