Bio. Populations (Ch.45)

Front 1

demographics

Back 1

statistics that describe a population (ex. size, age structure)

Front 2

population size

Back 2

the number of individuals that actually or potentially contribute to the gene pool of a population

Front 3

age structure

Back 3

of a population, the number of individuals in each age category

Front 4

reproductive base

Back 4

the number of actually and potentially reproducing individuals of a population

Front 5

population density

Back 5

number of individuals of a population in a specified volume or area of a habitat

Front 6

population distribution

Back 6

the pattern in which individuals of a population are dispersed through their habitat

Front 7

quadrats

Back 7

one of the number of sampling areas of the same size and shape used to estimate population size

Front 8

capture-recapture methods

Back 8

individuals of a mobile species are captured (or selected) at random, marked, then released so they can mix with unmarked individuals. one or more samples are taken. the ratio of marked to unmarked individuals is used to estimate total population size.

Front 9

immigration

Back 9

one or more individuals move and take up residence in another population of its species

Front 10

emigration

Back 10

permanent move of one or more individuals out of a population

Front 11

migration

Back 11

of many animals, a recurring pattern of movement between two or more regions in response to seasonal change or other environmental rhythms

Front 12

per capita growth rate

Back 12

the rate obtained by subtracting a populations per capita death rate from per capita birth rate

Front 13

zero population growth

Back 13

no net increase or decrease in population size during a specified interval

Front 14

exponential growth

Back 14

population increases in size by the same proportion of its total in each successive interval

Front 15

doubling time

Back 15

the time it takes for a population to double in size

Front 16

biotic potential

Back 16

the maximum rate of increase per individual for a population growing under ideal conditions

Front 17

limiting factors

Back 17

any essential resource that limits population growth when scarce

Front 18

logistic growth

Back 18

population growth pattern. a population grows exponentially when small, then levels off in size once carrying capacity has been reached.

Front 19

carrying capacity

Back 19

maximum number of individuals of a species that a particular environment can sustain

Front 20

density-depedent factors

Back 20

a factor that slows population growth, and either appears or worsens with crowding (ex. disease, competition for food)

Front 21

density independent factor

Back 21

a factor that slows population growth; its likelihood of occurring and magnitude of effect does not vary with population density

Front 22

life history pattern

Back 22

of a species, pattern of when and how many offspring are produced during a typical lifetime

Front 23

cohort

Back 23

a group of individuals of the same age

Front 24

survivorship curves

Back 24

plot of age-specific survival of cohort, from the time of birth until the last individual dies.

Front 25

r-selection

Back 25

selection that favors traits that maximize number of offspring; operates when the population is well below its carrying capacity

Front 26

k-selection

Back 26

selection for traits that make offspring better competitors; occurs in a population near carrying capacity.

Front 27

total fertility rate (TFR)

Back 27

for humans, the average number of children born to a female during her lifetime

Front 28

demographic transition model

Back 28

model that correlates in population growth with stages of economic development