 Please pass back the new
objective sheet.
 Please get out your
signed permission slip
and $15 for pick up.
 Take your “TradeoffsSage Grouse and energy”
reading packet and
answers to the back lab
table. Staple them
together and put them in
the white bin.
Only 6 more days to
get that permission
slip turned in!
What do you think of this?
Population Ecology
WHAT ARE THE RULES? THEY DON’T APPLY
TO US, DO THEY?
Rule #1: Populations will grow
exponentially according to their
biotic potential
Linear growth vs. exponential growth
Biotic potential – capacity for growth
 Age at reproductive
maturity
 Generation time
 Time between
reproductive events
 Offspring per
reproductive event
Rule #2: Populations cannot
increase indefinitely
Sigmoidal growth – the S curve
Carrying capacity
 The number of
individuals of each
species that can survive
in an area indefinitely.
Subtle details!
 At carrying capacity (K),
individuals are still dying
and being born. The
total population size is
constant.
 Populations do not know
when they’ve reached K
 Populations cycle above
and below K several
times before leveling out.
Limiting factors set the carrying capacity
Two categories of limiting factors
 1. density-independent
limiting factors
Natural disasters
Clear cutting
 2. Density-dependent
limiting factors





Food
Mates
Space
Disease
predators
Rule#3: There is more than one
strategy for getting your genes
into the next generation
Reproductive similarities?
Reproductive similarities?
Opportunists vs. Competitors
Survivorship curves
Rule #4: Predator and prey
develop a predictable pattern.
Lotka-Volterra model
Soooo . . . Good thing we’re
human and these rules don’t
apply to us . . . Right?
Or do they?
 What part(s) of the
sigmoidal curve do
you see?
 Name two densitydependent and two
density-independent
factors that apply to
humans.
 Are we r- or Kstrategists? Defend
your answer.
 How do humans avoid
the Lotka-Volterra
model?