Wle200 Intraspecific Population Regulation

Front 1

Logistic Growth Equation

Back 1

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

Front 2

Density Dependent Regulation

Back 2

: impact a population in proportion to its density
Biotic Factors:
--predation** (more in later lecture)
--intraspecific competition
--disease
--stress
--reproductive inhibition
--territoriality
--dispersal * (does not regulate, but affects)

Front 3

Density Independent Regulation

Back 3

---acts independently of population size
---BUT can still result in regulation
Abiotic Factors:
--weather
--pollution
--disasters

Front 4

Scramble Competition

Back 4

---affects all individuals equally
…no interaction or interference
---”exploitative”…increased density results in decreased availability of resources
(spotted hyena)

Front 5

Contest competition

Back 5

…”interference”
…impacts only a fraction of the population
(polar bears, muskoxen, wolves)

Front 6

dispersal

Back 6

departure from territory or home range

Front 7

Self-thinning

Back 7

--high densities = low weight
--decline in survivors, but increase
in biomass

Front 8

presaturation dispersal

Back 8

--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

Front 9

saturation dispersal

Back 9

--at high density
--habitat may no longer support increased numbers
--usually sub-adults
--usually subordinate or less-healthy members

Front 10

Endocrine Disruption

Back 10

various chemicals including pesticides and industrial compounds can mimic hormones and result in reproductive anomalies