Population ecology Flashcards
group of organisms of the same species who live in a specific location and breed with one another more often than they breed with other members of population
population
When studying a population, ecologists collect information about its…?
gene pool, reproductive traits, and behavior of its component individuals
vital statistical data that describe the population
demographics
number of individuals in a population
population size
number of members of a population in a given area
population density
Formula for population density?
(Population / area)
describes where individuals are and
where are the others
population distribution
usually symbolized as N
population size
large populations may be more stable than smaller populations because of greater genetic diversity
population size
Applied for immobile organisms such as plants or very small and slow-moving organisms
quadrat method
plots called ____ are used to determine the population size and even density
quadrats
each quadrat marks off an area of the same size – typically, a ______ – within the habitat
square area
can be made by staking out an area with sticks and string or by using a wood, plastic, or metal square placed on the ground
quadrat
calculate population, use the quadrat equation
N = (A/a) x n
N is estimated population
A is the total study area,
a is the area of the quadrat,
n is the population density.
technique is for organisms that move around
mark-recapture method
Involves capturing a sample of animals and marking them in some way – for instance, using tags, bands, paint, or other body markings
mark-recapture method
What happens after animals are marked?
They are released back into the wild, and allowed to mix with the rest of the population
What is the formula for total pop. with the mark-recapture method?
of marked animal / % of marked
animal in the sample
member of low-density population have more trouble finding a mate than an individual in a high-density population
population density
Most common population distribution
clumped dispersion
Members are closer to each other because of an essential resource
clumped distribution
Individuals are evenly spaced out
uniform dispersion
result of competition in resources
uniform dispersion
Rare, only occurs if the resources is uniformly available and the proximity of resource to others does not matter
random dispersion
explains how fast a given population grows
population growth rate (PGR)
the number of individuals born (Birthrate)
natality
the number of deaths that occur in the population during a given time period
mortality
number of individuals moving away from a population
emigration
number of individuals moving into a population
immigration
population grows when…?
birth rate exceeds its death rate
obtained when per capita death rate is subtracted from per capita birth rate
per capita growth rate
describes how a population’s size changes over time if its per capita growth rate is constant and its resources are unlimited
exponential growth model
population growth rate increases as the population gets larger
exponential growth model
population would grow if there were no limits placed on it by the environment
exponential growth model
J-shaped growth curve is made
exponential growth model
resources are always limited
logistic growth model
Exponential growth happens for a while, when number of individuals gets large enough, resources get used up, slowing growth rate
logistic growth model
the growth rate will plateau, or level off, making an S-shaped curve
logistic growth model
population size at which it levels off, which represents the maximum population size a particular environment can support, is called the…?
carrying capacity (K)
maximum number of individuals that a particular environment can sustain indefinitely
carrying capacity
carrying capacity is not constant
logistic growth model
may depend on physical and biological factors that may change over time
logistic growth model
Change in population density that alters how an environmental factor affects that population
density-dependent limiting factors
Biotic or have to do with living organisms
density-dependent limiting factors
increase of population encourage rise in competition in food, hiding places, nesting sites, and other essential resources
density-dependent limiting factors
competition, predation, diseases and parasitism
density-dependent limiting factors
Any environmental factor that affects the size of a population but is not influenced by changes in population density
density-independent limiting factors
Generally abiotic
density-independent limiting factors
random weather events such as killing frost, severe blizzard, hurricane, extended drought and other natural disaster or calamities
density-independent limiting factors
