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Demography and Population Sizes Cheat Sheet by

Gr 12 Bio


study of changes in the charac­ter­istics of a population

Surviv­orship Curves

Type I Surviv­ors­hip
child surviv­orship high, old mortality high
Type II Surviv­ors­hip
die at equal rates despite age
Type III Surviv­ors­hip
child mortality high, adult surviv­orship high
Surv­ivo­rship Charac­ter­ist­ics
Mortality, # offspring, gestation period, parental care, organism size


It is...
Potential for species to produce offspring
Factors Affecting It
age of sexual maturity, max reprod­uctive age, length of gestation, offspring per pregnancy, parental care

Measuring Population Change

ΔN = ( B + I ) - ( D + E )
B = births
D = deaths
I = immigr­ation
E = emigra­tion

Population Growth Rate

r = ΔN / N1

Per Capita Growth Rate

during specific period of time
r = b - d
b = # of births / population size
d = # of deaths / population size
r > 0 pop. growing, if less, declining
Max per capita growth rate
ideal condit­ions, expone­ntial growth model

Logistics Growth Model

Expone­ntial growth model not realistic.
has carrying capacity

Types of Density

Crude Density
number of indivi­duals in habitat
Ecol­ogical Density
number of individual in the area actually used by them, not random space


Schools, herds, colony, flock

Sampling Methods - to find average pop. size

Quadrant Sampling
placed randomly to avoid bias, many small square sections
Mark Recapt­ure
capture organisms, mark them, release them, recapture set of organisms

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