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
the number of individuals per unit area or volume
density
patterns of spacing of individuals within a population
dispersion
how can population size be estimated?
- extrapolation from small samples (quadrad method)
- and index of population size (e.g., number of nests)
- the mark-recapture method
mark-recapture formula
N=sn/x
N-population size
s-tagged samples
n-second set of samples
x-how many are marked in the second sample
scientists capture, tag, and release a random sample of individuals (s) in a population
marked individuals are mixed back into the population
they capture a second sample of individuals (n) and note how many of them are marked (x)
mark-recapture method
3 patterns of dispersion
- clumped dispersion
- uniform
- random dispersion
- the study of the vital statistics of a population and how they change over time
- death rates and birth rates are of particular interest to demographers
demography I
- an age-specific summary of the survival pattern of a population
- it is best made by following the fate of a cohort (a group of individuals of the same age)
life tables
a graphic way of representing the data in a life table
survivorship curves
what are the three types of survivorship curves?
- type1: low death rates during early and middle life and an increase in death rates among older age groups
- type2: a constant death rate over the organism’s life span
- type 3: high death rates for the young and a lower death rate for survivors (large number of offspring, little to no care to offspring)
age-specific summary of the reproductive rates in a population
it describes the reproductive patterns of a population
often concentrate on females in the population
reproductive table or fertility schedule
Per Captita rate of increase
change in population = births + immigrants entering - deaths - emigrants leaving
results when population increase is under idealized conditions
growth results in a j-shaped curve
ex: rebounding populations
exponential growth
the maximum population size the environment can support
carrying capacity (K)
the per capita rate of increase ________ as carrying capacity is reached
declines
the ________ of population growth produces a sigmoid (s-shaped) curve
logistic
an organism’s _________ comprises the traits that affect its schedule of reproduction and survival
- the age at which reproduction begins
- how often the organism reproduces
- how many offspring are produced during each reproductive cycle
life history
are evolutionary outcomes reflected in the development, physiology, and behavior of an organism
species that reproduce once and die
ex: salmon and some plants
semelparity or big-bang reproduction
species that produce offspring repeatedly
iteroparity
organisms have finite resources, which may lead to ________ between survival and reproduction
trade-offs
ex: survival and parental care in European kestrel birds. the more offspring the less chance of survival
- when birth and death rates do not change with population density
- selects for life-history traits that are sensitive to population density and favored at higher density*
- operates in populations near the limit imposed by their resources (the carrying capacity, k)
K-selection or density-dependent selection
- selects for life history traits that maximize reproduction
- occurs in environments in which population densities that are bellow carrying capacity*, and there is little competition
r-selection or density-independent selection
two general questions about regulation of population growth…
- what environmental factors stop a population from growing indefinitely? (carrying capacity)
- why do some populations show radical fluctuations in size over time, while others remain stable?
in density-_______ populations, birth rate and death rate do not change with population density
ex: temperature, precipitation
independent
In density-_______ populations, birth rates fall and death rates rise with population density
ex: food resources
example of negative feedback that regulates population growth
dependant
density-dependent birth and death rates are affected by what factors?
- competition for resources
- toxic wastes
- predation
- intrinsic factors (physiological factors)
- territoriality
- disease
the study of __________ focuses on the complex interactions between biotic and abiotic factors that cause variation in population size.
population dynamics
what can influence population dynamics?
- the population of large mammals can fluctuate over time and are not always relatively stable
- weather and predator population can change over time
- some populations undergo regular boom-and-bust cycles
a group of Dictyostelium amoebas can emigrate and forage _______ than individual amoebas.
better
groups of populations linked by immigration and emigration
-high levels of immigration combined with higher survival can result in greater stability in populations
metapopulations
