population ecology Flashcards
what is a population?
group of same species living in a defined area
some natural reasons that cause change in population size
food, water, living space, predators
population size
number of individuals in a population
minimum viable population
smallest group needed to sustain population
population density
member of individuals per unit area
plot sampling estimation
-choose size the plot will be
-choose located plots within population area
-count individuals in plots
-determine total population area
-average plot population x total area
mark recapture method of population estimation
- capture a number of animals, mark them in some way and then release them.
- After a while, you capture a second group of animals and see how many of them have the mark.
- By comparing the marked animals in the second group to the total captured, you can estimate the total population size.
what does it mean if you mark 10 and then recapture 10 but only 1 is marked ?
10 is 10% of the population, so there is 100 total
mark recapture method assumes that…
equal proportion is captured each time
population distribution
where individuals are found within the population area
3 population distribution patterns:
clumped, uniform, or random
clumped distribution
-individuals are found in groups
-may cluster around needed resources (abiotic factor)
-may group together socially (biotic factor)
grouping together (biotic factor) gives protection from
predators
most common population distribution pattern
clumped distribution
uniform distribution
-individuals are spaced evenly
-often from negative interactions between individuals (biotic)
creosote bushes use up all water and inhibit growth of nearby individuals
this is an example of what?
uniform distribution
random distribution
-individuals spread out without a pattern
-resources are evenly distributed
-little social interactions
example of random distribution
dandelion seeds grow wherever they fall
least common population distribution pattern?
random distribution
growth rate (r)
how quickly a population is growing or shrinking
r =
r = birth rate + immigration – death rate – emigration
maximum biotic potential (Rmax)
the highest possible reproductive capacity of a species under optimal conditions
-females reproduce as much as possible
-no offspring die
exponential growth is based on
current population size
exponential growth: growth as a …
percentage of population
graph of exponential growth:
J shaped graph
constant growth at Rmax
biotic factors
the living or biological components of an ecosystem
abiotic factors
the non-living or physical components of an ecosystem
____ rarely happens in nature
exponential growth
exponential growth assumes…
o Population reaches maximum biotic potential
o Resources are unlimited
logistic growth takes _____ into account
limited resources
carrying capacity (k)
maximum population size environment can support
____ result as populations pass carrying capacity
Carrying capacity____ as environment changes
death; changes
limiting factor
primary thing limiting population growth
logistic growth:
Growth rate starts almost as _____
Rate slows as population nears __________________
Growth ____at carrying capacity
Makes a vaguely __ shaped graph
exponential
carrying capacity
stops
S
density dependent factors
impact increases as population size goes up
what helps determine carrying capacity?
density dependent factors
Disease, Competition for resources, Buildup of wastes, Predation, Territoriality, Intrinsic limitations
these are all..?
density dependent factors
density INDEPENDENT factors
impact is NOT affected by population size
____ does NOT impact carrying capacity
density independent factors
fires, storms, natural disasters
these are all
density independent factors
life history
pattern of significant events in an individual’s life
some examples of life history
o Development level at birth
o Parental care or lack
o When reproduction begins
o How many offspring are produced
o How often organisms reproduce
semelparity
one reproductive event at end of life
iteroparity
repeated reproductive events throughout life
survivorship curves:
likelihood of survival throughout life
survivorship curves: type 1
most dangerous things happen late in life
*Die in old age (humans)
survivorship curves: type 2
equally likely to die at any age
survivorship curve: type 3
most dangerous part of life is the beginning
*Most die early on (trees)
These species are characterized by their ability to reproduce rapidly and produce a large number of offspring in a short period of time.
r adapted species
hese species are characterized by their ability to maintain stable populations near the carrying capacity (K) of their environment
k adapted species
______ -strategists typically have small body sizes, short lifespans, and invest relatively little parental care in each offspring.
r adapted
______ -strategists typically have larger body sizes, longer lifespans, and invest more parental care and resources into raising each offspring.
k adapted
r adapted:
___ environments
niche _______
unstable
generalists
k adapted species:
___ environments
niche ____
stable
specialists
