Lesson 1 (Chapter 53, Population Ecology) Flashcards
the study of populations in relation to their environment, including environmental influences on density and distribution, age structure, and population size
population ecology
a group of individuals of a single species living in the same general area; are described by their boundaries and size
population
the number of individuals per unit area or volume
density
the pattern of spacing among individuals within the boundaries of the population
dispersion
true or false: it is impractical or impossible to count all individuals in a population
true
can be used to estimate densities and total population sizes
sampling techniques
how can population size be estimated?
by either extrapolation from small samples, an index of population size, or the mark-recapture method
in which scientists capture, tag, and release a random sample of individuals (s) and capture a second sample of individuals (n) and note how many of them were already captured or marked before (x)
mark-recapture method
equation for population size (N) using mark-recapture method
N = (s*n)/x
the result of an interplay between processes that add individuals to a population and those that remove individuals
density
the influx of new individuals from other areas
immigration
the movement of individuals out of a population
emigration
what two factors add individuals to a population?
birth, immigration
what two factors remove individuals to a population?
death, emigration
factors that influence the spacing of individuals in a population
environmental and social factors
in which individuals aggregate in patches
clumped dispersion
may be influenced by resource availability and behavior
clumped dispersion
in which individuals are evenly distributed
uniform dispersion
may be influenced by social interactions such as territoriality
uniform dispersion
the defense of a bonded space against other individuals
territoriality
in which the position of each individual is independent of other individuals
random dispersion
occurs in the absence of strong attractions or repulsions
random dispersion
the study of how the vital statistics of a population and how they change over time
demography
are of particular interest to demographers
death rates, birth rates
an age-specific summary of the survival pattern of a population
life table
a group of individuals of the same age
cohort
a graphic way of representing the data in a life table
survivorship curve
can be classified into three general types
survivorship curve
low death rates during early and middle life and an increase in death rates among older age groups
type i curve
a constant death rate over the organism’s life span
type ii curve
high death rates for the young and a lower death rate for survivors
type iii curve
also known as a fertility schedule
reproductive table
an age-specific summary of the reproductive rates in a population
reproductive table
describes the reproductive patterns of a population
reproductive tab
true or false: it is useful to study population growth in an idealized situation
true
help us understand the capacity of species to increase and the conditions that may facilitate this growth
idealized situation
population growth rate
(births + immigrants entering population) - (deaths + emigrants leaving population)
occurs when the birth rate equals the death rate (r=0)
zero population growth
per capita rate of increase (r)
r = b - m, where b is the annua per capita birth rate, while m is the per capita death rate
change in population size
ΔN/Δt = r*N
instantaneous growth rate
dN/dT = r_inst*N, where r_inst is the instantaneous per capita rate of increase
population increase under idealized conditions, wherein the rate of increase is at its maximum
exponential growth
exponential growth rate
dN/dt = r_max*N, where r_max is the maximum rate of increase
shape of exponential population growth curve
j-shaped
true or false: exponential growth can be sustained for long in any population
false
true or false: a more realistic population model limits growth by incorporating carrying capacity
true
the maximum population size the environment can support
carrying capacity (K)
in which the per capita rate of increase declines as carrying capacity is reached
logistic population growth model
starts with the exponential model and adds an expression that reduces per capita rate of increase as N approaches K
logistic population growth model
logistic population growth model formula
dN/dT = r_max*N((K-N)/K)
shape of logistic population growth curve
s-shaped
true or false: some populations fluctuate greatly and make it difficult to define K
true
in which individuals have a more difficult time surviving or reproducing if the population size is too small
Allee effect
true or false: the logistic model fits few real population models and is not useful for estimating possible growth
false, it is useful for estimating possible growth
true or false: conservation biologists can use the model to estimate the critical size below which populations may become extinct
true
comprises the traits that affect an organism’s schedule of reproduction and survival
life history
examples of components of an organism’s life history
the age at which reproduction begins, how often the organism reproduces, and how many offspring are produced during each reproductive cycle
evolutionary outcomes reflected in the development, physiology, and behavior of an organism
life history traits
behavior of a species in which organisms reproduce once and die
semelparity or big-bang reproduction
behavior of a species in which organisms produce offspring repeatedly
iteroparity or repeated reproduction
highly variable or unpredictable environments are likely to favor this type of reproduction behavior
semelparity or big-bang reproduction
dependable environments are likely to favor this type of reproduction behavior
iteroparity or repeated reproduction
true or false: organisms have finite resources, which may lead to trade-offs between survival and reproduction
true
true or false: the correlation between the enlarged brood size and smaller survival rate of parent kestrels is NOT an example of a trade-off
false
true or false: plants that produce a large number of small seeds to ensure that some will grow and reproduce is an example of a trade-off
true
true or false: plants that produce a moderate number of large seeds that contain a large store of energy is NOT an example of a trade-off
false
selection for life history traits that are sensitive to population density
K-selection or density-dependent selection
selection for life history traits that maximize reproduction
r-selection or density-independent selection
true or false: the concepts of K-selection and r-selection are oversimplifications but have stimulated alternative hypotheses of life history evolution
true
one of the two general questions about regulation of population growth
what environmental factors stop a population from growing indefinitely?
one of the two general questions about regulation of population growth
why do some populations show radical fluctuations in size over time, while others remain stable?
populations in which birth rate and death rate do not change with population density
density-independent populations
populations in which birth rates fall and death rates rise with population density
density-dependent populations
an example of negative feedback that regulates population growth
density-dependent birth and death rates
any of the several factors that affect density-dependent populations
competition for resources, territoriality, disease, predation, toxic wastes, intrinsic factors
effect of competition for resources in density-dependent populations
in crowded populations, increasing population density intensifies competition for resources and results in a lower birth rate
effect of toxic wastes in density-dependent populations
accumulation of toxic wastes can contribute to density-dependent regulation of population size
effect of predation in density-dependent populations
as prey population builds up, predators may feed preferentially on that species
effect of intrinsic factors in density-dependent populations
for some populations, intrinsic or physiological factors appear to regulate population size
effect of territoriality in density-dependent populations
in many vertebrates and some invertebrates, competition for territory may limit density
effect of disease in density-dependent populations
in dense populations, pathogens can spread more rapidly
a study that focuses on the complex interactions between biotic and abiotic factors that cause variation in population size
population dynamics
true or false: long-term population studies reveal that populations of large mammals are relatively stable over time
false
two factors that affect population size over time
weather, predator population
population growth in which the number grows exponentially rapidly and is then followed by a period in which the population falls back to a minimal level
boom-and-bust cycle
groups of populations linked by immigration and emigration
metapopulations
true or false: high levels of immigration combined with higher survival can result in greater stability in populations
true
true or false: some populations such as of humans can grow indefinitely
false
year when the human population stopped increasing slowly and began to grow exponentially
1650
two configurations in which a regional population can exist while maintaining stability
high birth rate, high death rate; or
move from the first state to the second state
demographic transition
associated with an increase in the quality of health care and improved access to education, especially for women
demographic transition
true or false: most of the current global population growth is concentrated in developing countries
true
the relative number of individuals at each stage
age structure
one important demographic factor in present and future growth trends
age structure
can predict a population’s growth trends
age structure diagrams
can illuminate social conditions and help us plan for the future
age structure diagrams
true or false: infant mortality and life expectancy vary greatly among developed and developing countries
true
true or false: infant mortality and life expectancy capture the wide range of the human condition
false
how many humans can the biosphere support
7.8 billion - 10.8 billion in 2050
true or false: the carrying capacity of Earth for humans is uncertain
true
average estimate of carrying capacity
10 billion - 15 billion
summarizes the aggregate land and water area needed to sustain the people of a nation
ecological footprint
one measure of how close we are to the carrying capacity of Earth
ecological footprint
true or false: countries vary greatly in footprint size and available ecological capacity
true
factors that could potentially the carrying capacity of humans
food, space, nonrenewable resources, buildup of wastes
difference of humans from other organisms
we can regulate our population growth through social changes
