Chapter 53: Population Ecology Flashcards Preview

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Flashcards in Chapter 53: Population Ecology Deck (59):
1

population ecology

study of population in relation to their environment
how abiotic and biotic factors influence density, distribution, size, age structure of populations

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natural selection changees frequencies of

alleles and traits

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population

group of individuals of same species living in same general area

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density

number of individuals per unit area or volume

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dispersion

pattern of spacing among individuals within boundaries of population

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mark-recapture method

capture and tag individuals of population and repeat process

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equation for mark-recapture method

N=sn/x
estimated population size = (#animals marked in first capture)(#animals captured in second sampling) / (#animals marked in second sampling)

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density changes as individuals are

added/removed from a population

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addition of animals

birth or immigration

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removal of animals

death or emigration

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local density patterns

clumped, uniform, random

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clumped local density

individuals in groups for environmental reasons, mating behavior, predation or defense

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uniform local density

evenly spaced individuals for territorial reasons

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territoriality

defense of bounded space against encroachment by other individuals

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random local density

unpredictable spacing when there is no strong attraction/repulsion among individuals

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demography

study of vital statistics of populations and how they change over time

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life tables

age specific summaries of survival pattern of population, follows fate of cohort until all are dead

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cohort

group of individuals of same age

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survivorship curve

plot of proportion or numbers in a cohort still alive at each age

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type I survivorship curve

usually few offspring, but provide care and many survive to old age

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type II survivorship curve

constant death rate over lifespan

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type III survivorship curve

usually many offspring but many die at early age

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reproductive table

age specific summary of reproductive rates in a population
measures reproductive output of a cohort from birth to death, tallies number of female offspring produced

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change in population size =

births + immigrants -deaths - emigrants

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per capita birth rate

# offspring produced per unit time by average member of population (b)

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equation to calculate expected number of births per year

B=bN

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per capita death rate

# individuals that die per unit time (m)

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equation to calculate expected number of deaths per year

D=mN

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per capita rate of increase (r)

difference between per capita birth and death rates

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equation for r

r=b-m

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r>0

growing population

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r

population declining

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ZPG

zero population growth when birth/death rates are equal

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change in population over change in time =

rN

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exponential growth

population growth under ideal conditions

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exponential growth occurs when

populations introduced into new environment
number drastically reduced by catastrophic event

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exponential growth equation

dN/dt = r(max)N

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carrying capacity (K)

max population size an environment can sustain

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carrying capacity equation

rmax x N x (K-N)/K

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allele effect

individuals may have more difficult time surviving/reproducing if population is too small

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life history

when reproduction begins, how often organism reproduces, how many offspring are reproduced

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semelparity

one reproductive episode in which thousands of offspring are produced

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heroparity

multiple reproduction episodes in which few offspring are produced

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what contributes to whether species is semelparity or heroparity

survival rate of offspring, likelihood that adult will survive and reproduce again

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K selection

selection for traits that are sensitive to population density and favored at high densities

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K selection occurs in populations

near carrying capacity where competition is stronger

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r selection

selection for traits that maximize reproductive success in uncrowded environments

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r selection occurs in populations

well below K with little competition

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density independent

a birth or death rate that does not change with population density

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density dependent

a birth or death rate that rises/falls inversely with population density

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examples of density dependent factors that regulate population growth

competition for resources, predation, toxic wastes, intrinsic factors (hormones), territoriality, disease

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population dynamics

population fluctuations from year to year or place to place
focuses on biotic/abiotic factors that influence population

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metapopulation

when local populations are linked by immigration and emigration

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demographic transition

change from high birth/death rates to low birth/death rates usually due to industrialization and improved living conditions, health care, education

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age structure

relative # of individuals of each age in the population

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infant mortality

# infant deaths per 1000 live births

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life expectancy at birth

predicted average length of life at birth

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ecological footprint

concept of summary of land/water area required by each person, city, or nation to produce all resources it consumes and absorb all waste it generates

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global carrying capacity could be limited by`

food, energy use, space, nonrenewable resources, etc.