chapter 37: populations Flashcards
Ecology
the study of the relationships among organisms and the environment
population
consists of interbreeding organisms of one species occupying the same area at the same time
community
includes all populations, representing multiple species, in the same region
ecosystem
the biotic community plus the abiotic environment
biotic
living
abiotic
nonliving
biosphere
all parts of the planet where life exists
habitat
the physical location where the members of a population live
population density
the number of individuals of a species per unit area of unit volume of a habitat
population distribution
describes how individuals are scattered through the habitat
the three types of population distribution
uniform, clumped, and random
three ways of estimating population size
aerial photos, sampling small subset, and mark-recapture
The separated populations are local [blank]. If separated for a long period of time, they may become [blank]
subpopulations
new species
what factors affect population size
births, deaths, immigration, and emigration
birth rate
the number of individuals produced per unit of time
immigration
the movement of individuals into a population
death rate
the number of deaths per unit of time
emigration
the movement of individuals out of a population
age structure
helps determine whether a population is growing, stable, or declining
survivorship curves
shows the proportion of surviving individuals at each age
It is especially useful to determine what percentage of individuals survive to reproductive age, since…
only they will contribute to the size of the next generation
life tables
follow a group of individuals within a population from birth to death
the three types of survivorship curves
type I, type II, and type III
the type of survivorship curve that includes humans and other large vertebrates
type I
the type of survivorship curve that includes many birds and mammals
type II
the type of survivorship curve that includes many fishes, most invertebrates, and plants
type III
type I (late loss)
representative of species that invest much energy caring for young and have low death rates early in life. Most individuals survive to reproduce
type II (constant loss)
species have approximately equal probability of dying at any age
type III (early loss)
representative of species that invest little energy raising their young and have high death rates among offspring. Few individuals survive to reproductive age
population growth is calculated using this equation
G = rN
what do the letters in the population growth equation stand for?
G = the growth rate r = the per capita rate of increase N = the initial size of the population
since r is [blank], G increases as N [blank]
constant
increases
a population is growing exponentially when…
its growth rate increases over a given time period
Exponential growth curves are [blank] shaped
J
A population is growing [blank] if the number of new individuals is proportional to the size of the population
exponentially
can exponential growth continue indefinitely?
no
population growth levels off when
resources become limited or when any factor happens that increases death rate or reduces birth rate
environmental resistance
the combination of factors that keeps a population from reaching its maximum growth rate
Environmental resistance tends to increase as [blank] size increases due to…
population
competition, predation, and anything else that reduces birth rates or increases death rates
carrying capacity
the maximum number of individuals that the ecosystem can support indefinitely
as the population size approaches carrying capacity, the growth rate [blank].
slows
populations approaching carrying capacity follows a [blank] growth model
logistic or s-shaped
logistic growth equation
G = rN (K - N/ K)
what does K represent in the logistic growth equation?
the carrying capacity
As the population size gets close to the carrying carrying capacity, the growth rate approaches [blank]
zero
do factors limiting a population size depend of the density of the population?
yes and no
the effects of density-dependent factors increase as the population density [blank]
rises
density-independent factors
exert effects that are unrelated to population density
