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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