exam 3 ppt 4 Flashcards
who was Thomas Malthus?
he was a British scholar, 1790; he influenced Darwin - resource limitation applies to all species
what is the fundamental unit of evolution?
populations
definition of populations
include all individuals of a species that live and reproduce in a certain place
definition of population ecology
the study of how and why a population changes over time
what are populations described in terms of?
size (N), geographic range, and spatial distribution (density)
can range be considered on different scales?
yes- can have local range, regional range, and global range
how would you measure the size of a population?
census, sampling
definition of census
a way to measure populations; count every individual; organisms must be easy to observe, not too numerous, and occur in an easily defined area
what are the requirements for taking a census?
organisms must be easy to observe, not too numerous, and occur in an easily defined area
different sections of sampling
quadrats, mark-and-recapture
definition of quadrats (sampling)
sessile of stationary organisms (ex: plants)
exp of an organism sampled by quadrats
plants
definition of mark-and-recapture (sampling)
mobile organisms
what type of distribution tells us more about a population?
spatial distribution
types of spatial distributions (listed)
uniform, random, clumped
what does uniform distribution look like?
all evenly distributed
what does random distribution look like?
some clumped, some fary away, randomly placed
what does clumped distribution look like?
all clumped together in a big group
exp of a clumped distribution
a herd of elephants
can spatial distribution change over time?
yes
exp of how spatial distribution changes over time in shrubs
small shrubs establish in high densities and produce a clumped distribution; mortality as the shrubs grow reduces clumping and produces a random distribution among medium shrubs; competition enforces a regular distribution among large shrubs
definition of demography
the statistical study of population dynamics over time
what things contribute to population decrease?
mortality (death) and emigration
definition of emigration
organisms leaving an area