Chapter 53 Flashcards
What is population ecology?
how biotic and abiotic factors influence density, distribution, size, and age structure of populations
How does population ecology vary?
in factos of 20x
What are three characteristics of a population?
Rely on the same resources,
are affected by the same environmental factors,
and are likely to breed and interact with each other
How are populations described?
by boundaries and size
what is density?
number of individuals per unit area or volume
what is dispersion?
the pattern of spacing among individuals within the boundaries of the population
three methods to estimate a population size
Extrapolating small samples
Index of population size (ex-number of nests)
Mark-recapture method
3 steps of mark and reacapture method
samples are captured, tagged, and released
time is given for individuals to mix back into the population
The second sample is captured to note how many are marked
Mark-recapture equation
N= sn/x
N= population size
n= second sample size
s= first sample size
x= marked amount in the second sample
What is density the result of?
interplay between processes that add individuals to a population and those that remove individuals
what is immigration?
the influx of new individuals from other areas
what is emigration?
movement of individuals out of a population
what adds new individuals to a population?
birth and immigration
what removed individuals from a population?
death and emigration
what influences spacing of individuals of a population?
environmental and social factors
what is clumped dispersion?
individuals aggregating in patches
what is clumped dispersion influenced by?
resource availability and behavior
what is uniform dispersion?
individuals are evenly distributed
what is uniform dispersion influenced by?
social interactions like territoriality
what is territoriality?
defense of a bounded space against other individuals
what is random dispersion?
the position of each individual is independent of other individuals
when does random dispersion occur?
in the absence of strong interactions or repulsions
what is demography, and examples?
study of vital statistics of a population and how they change over time
Ex- death and birth rates
what is a life table?
age-specific summary of the survival pattern of a population, following the fate of a cohort
what is a cohort?
a group of individuals of the same age
what does a life table provide?
Provides data about population, proportions of sex, and reproduction rate
what is survivorship curve?
graphic way of representing the data in a life table
What is type 1 survivorship curve?
low death rates during early and middle life, and an increase in death rates among older age
what is type 2 survivorship curve?
a constant death rate over the organism’s life span
what is type 3 survivorship curve?
high death rates for the young and a lower death rate for survivors
what type of survivorship curve are most species?
an intermediate
what do demographers focus on?
females in a population for species with sexual reproduction
what is a reproductive table?
age-specific summary of reproductive rates in a population
what does a reproductive table focus on?
a cohort from birth to deathw
what is reproductive output?
product of the fraction of female at a given age who are breeding and the number of female offspring they make
How is population growth studied?
in an idealized situation
what does population growth provide?
Helps us understand the capacity of species to increase and the conditions that may facilitate this growth
why doesn’t ideal population growth occur?
resource is limited
what is zero population growth?
when birth rate equals death rate
what is exponential population growth (2)?
population increase under idealized conditions
Results in a J-shaped curve
What is the rate of exponential population growth?
The rate of increase is constant but accumulates more new individuals when unit of time is large than when it is small
what is the issue of exponential population growth?
cannot be sustained indefinitely
what is carrying capacity?
maximum population size the environment can support
how does carrying capcity vary?
abundance of resources
what is the most realistic population model?
carrying capacity
what is logistic population growth?
per capita rate of increase declines as carrying capacity is reached
what makes it difficult to define carrying capacity>
when populations fluctuate
what is the Alle effect?
individuals have a more difficult time surviving or reproducing if the population size is too small
when is the logistical model used?
Can be used to estimate the size below which populations may become extinct
what is life history?
traits affecting its schedule of reproduction and survival
What is life history reflected in?
development, physiology, and behavior of an organism
what three variables entail life history?
When reproduction begins
How often the organism reproduces
How many offspring are produced per reproductive episode
what is semelparity?
reproduces once and die
when is semelparity favored?
Favored in variable or unpredictable environment
what is iteroparity?
produce offspring repeatedly
when is iteroparity favored?
Favored in a dependable environment
why do trade-offs occur?
due to finite resources, trade-offs between survival and reproduction cocur
