Chapter 53: Population Ecology Flashcards
population ecology
study of population in relation to their environment
how abiotic and biotic factors influence density, distribution, size, age structure of populations
natural selection changees frequencies of
alleles and traits
population
group of individuals of same species living in same general area
density
number of individuals per unit area or volume
dispersion
pattern of spacing among individuals within boundaries of population
mark-recapture method
capture and tag individuals of population and repeat process
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)
density changes as individuals are
added/removed from a population
addition of animals
birth or immigration
removal of animals
death or emigration
local density patterns
clumped, uniform, random
clumped local density
individuals in groups for environmental reasons, mating behavior, predation or defense
uniform local density
evenly spaced individuals for territorial reasons
territoriality
defense of bounded space against encroachment by other individuals
random local density
unpredictable spacing when there is no strong attraction/repulsion among individuals
demography
study of vital statistics of populations and how they change over time
life tables
age specific summaries of survival pattern of population, follows fate of cohort until all are dead
cohort
group of individuals of same age
survivorship curve
plot of proportion or numbers in a cohort still alive at each age
type I survivorship curve
usually few offspring, but provide care and many survive to old age
type II survivorship curve
constant death rate over lifespan
type III survivorship curve
usually many offspring but many die at early age
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
change in population size =
births + immigrants -deaths - emigrants
per capita birth rate
offspring produced per unit time by average member of population (b)
equation to calculate expected number of births per year
B=bN
per capita death rate
individuals that die per unit time (m)
equation to calculate expected number of deaths per year
D=mN
per capita rate of increase (r)
difference between per capita birth and death rates
equation for r
r=b-m
r>0
growing population
r
population declining
ZPG
zero population growth when birth/death rates are equal
change in population over change in time =
rN
exponential growth
population growth under ideal conditions
exponential growth occurs when
populations introduced into new environment
number drastically reduced by catastrophic event
exponential growth equation
dN/dt = r(max)N
carrying capacity (K)
max population size an environment can sustain
carrying capacity equation
rmax x N x (K-N)/K
allele effect
individuals may have more difficult time surviving/reproducing if population is too small
life history
when reproduction begins, how often organism reproduces, how many offspring are reproduced
semelparity
one reproductive episode in which thousands of offspring are produced
heroparity
multiple reproduction episodes in which few offspring are produced
what contributes to whether species is semelparity or heroparity
survival rate of offspring, likelihood that adult will survive and reproduce again
K selection
selection for traits that are sensitive to population density and favored at high densities
K selection occurs in populations
near carrying capacity where competition is stronger
r selection
selection for traits that maximize reproductive success in uncrowded environments
r selection occurs in populations
well below K with little competition
density independent
a birth or death rate that does not change with population density
density dependent
a birth or death rate that rises/falls inversely with population density
examples of density dependent factors that regulate population growth
competition for resources, predation, toxic wastes, intrinsic factors (hormones), territoriality, disease
population dynamics
population fluctuations from year to year or place to place
focuses on biotic/abiotic factors that influence population
metapopulation
when local populations are linked by immigration and emigration
demographic transition
change from high birth/death rates to low birth/death rates usually due to industrialization and improved living conditions, health care, education
age structure
relative # of individuals of each age in the population
infant mortality
infant deaths per 1000 live births
life expectancy at birth
predicted average length of life at birth
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
global carrying capacity could be limited by`
food, energy use, space, nonrenewable resources, etc.
