CUMULATIVE textbook and lecture notes for the class BIOLOGY281: General Ecology at the University of Michigan. Notes were taken WN2024 under Prof. Christopher Dick.
Chapter
1:
What
is
Ecology
in
Action?
1.1
Ecological
Questions
●
2
basic
questions
asked
by
population
ecologists:
○
What
is
the
abundance
of
a
population?
○
What
is
the
distribution
of
the
population?
1.2
Testing
Hypotheses
●
To
be
study-worthy,
hypotheses
must
be
plausible
and
generate
testable
predictions
●
Consider
all
hypotheses
when
attempting
to
understand
a
biological
process
●
Hypotheses
for
buffalo/wildebeest
population
increase
in
the
1960s/1970s:
○
Food
Availability
Hypothesis:
food
was
better
in
quality
or
more
abundant
■
Rainfall
influences
grass
production
■
To
test:
established
exclosures
(experimental
fenced
areas
that
reduces
unwanted
factors)
●
Harvested
vegetation
within
exclosures
regularly
and
measured
the
amt
of
grass
that
grew
compared
to
the
amt
of
rainfall
●
Predicted
positive
correlation
between
rainfall
and
grass
production
■
As
rainfall
increased,
grass
production
also
increased
–
significant
positive
effect
on
grass
availability
■
Rainfall
records
were
the
same
as
historical
averages
→
likely
not
the
reason
for
population
increase
○
Predator
Release
Hypothesis:
reduction
(release)
from
high
levels
of
predation
■
To
test:
compared
previous
surveys
of
predator
levels
■
Found
that
predator
populations
also
increased
during
this
time
○
Rinderpest
Release
Hypothesis:
rinderpest
is
a
virus
that
attacks
cattle
and
other
ruminants
(mammals
who
digest
plant-based
food
by
softening
it
within
the
rumen
where
it
ferments)
■
Great
Rinderpest
Plague
of
1890
killed
95%
of
cattle
in
southern/eastern
Africa
■
Hypothesized
that
rinderpest
was
keeping
wildebeest
and
cattle
populations
unnaturally
low
in
the
50s,
and
that
they
were
recovering
in
the
60s
●
When
both
variables
are
numeric
or
continuous,
use
correlation
analysis
to
eval
relationship
b/n
them
●
Statisticians
use
the
correlation
coefficient
(r)
to
describe
correlation
strength
○
1.0
=
strong
positive,
-1.0
=
strong
negative,
0
=
no
correlation 1.3
Observation,
Modeling,
and
Experimentation
●
Ecology
happens
in
the
real
world
○
Controlling
variables
is
difficult
○
Replication
of
experiments
may
be
impossible
●
Must
be
able
to
observe
and
pick
up
on
small
nuances
●
3
types
of
observations
○
Observe
actual
processes
with
their
senses
○
Learn
from
published
literature
○
Observe
what
other
people
are
doing
or
saying
■
Local
communities,
other
scientists/experts
from
other
fields,
bouncing
ideas
off
of
other
ecologists
●
Scientific
models
seek
to
describe
a
system
or
predict
what
it
will
do
in
the
future
●
Ecologists
differ
from
other
biology
fields
because
their
research
spans
and
integrates
many
levels
of
the
biological
hierarchy
1.4
Linking
the
Biological
Hierarchy
●
Ecologists
study
interactions,
so
must
understand
all
levels
of
the
biological
hierarchy
but
usually
focus
on
the
level
of
the
organism
and
above,
up
to
the
biosphere
●
Can
use
the
Serengeti
to
represent
the
different
levels
of
the
biological
hierarchy
●
Organism:
individual
life
form
○
At
this
level,
can
ask
how
individual
buffalo
forages
in
a
manner
that
meets
its
daily
energy
and
nutritional
needs
●
Can
explore
distribution
and
abundance
of
populations
at
a
location
○
Wildebeest,
zebra,
and
Thompson
gazelle
migrations
●
Populations
interact
to
form
communities
○
Wildebeest
grazing
stimulates
regrowth
of
grasses/plants
→
gazelles
and
other
populations
can
eat
them
○
Communities
of
wildebeest,
gazelles,
grasses,
and
plants
all
interact
●
The
ecosystem
includes
all
communities
and
abiotic
features
that
interact
with
each
other
●
Landscapes
are
interacting
and
spatially
connected
ecosystems
○
West
of
the
Serengeti,
ecosystem
is
dominated
by
agriculture
○
Humans
hunt
elephants,
wildebeests,
etc
●
Landscapes
are
parts
of
larger
regions
with
common
set
of
environmental/evolutionary
influences
○
On
this
level,
look
at
abundance
and
species
richness
●
The
biosphere
is
the
highest
level;
the
part
of
the
world
that
supports
life
●
3
primary
abiotic
factors
studied
in
the
Serengeti:
○
Nutrients
■
Highest
levels
in
the
southeastern
plain
■
Lowest
in
the
northwest
○
Fire ■
Almost
all
started
by
humans
●
Improve
grazing
pastures,
park
management,
honey
hunters
smoking
out
bees
■
Only
occur
in
dry
season
but
in
typically
wetter
areas
●
Wetter
area
→
more
grass
growth
→
more
dry
grass
for
fuel
in
the
dry
season
○
Rain
■
Lowest
levels
in
the
southeastern
plain
■
Highest
in
the
northwest
●
Due
to
rain/nutrient
levels,
migrating
animals
spend
the
wet
months
in
the
southeast,
then
move
to
the
northwest
in
the
dry
season
○
Distribution
of
abiotic
factors
influences
distribution
of
organisms
●
Much
of
the
western/northern
portion
of
the
Serengeti
is
open
woodland
with
canopy
cover
b/n
2%
and
30%
○
Grass
grows
easily
between
the
trees
●
El
Nino
Southern
Oscillation
(ENSO)
:
a
large-scale
atmospheric
system
that
affects
the
global
climate
○
Associated
with
high
temperature
and
low
pressure
in
the
Pacific
region
○
Affects
Serengeti
climate
○
Fluctuates
~5
years
Lecture
–
1/16
●
Scientific
Method
○
Make
observations,
ask
questions
○
Previous
knowledge/intuition
→
form
hypotheses
○
Evaluate
hypotheses
by
experiment,
observation,
or
modeling
○
Use
results
to
modify
hypothesis,
pose
new
questions,
or
draw
conclusions
●
Scientific
method
is
iterative
and
self-modifying
●
Serengeti:
79
large
mammal
species
○
Southeast
and
northwest
corners
=
wet
areas
■
In
between
is
very
dry
■
Breeding
season
spent
in
southeast,
migrate
to
northwest
during
dry
season
●
60s-70s:
wildebeest
population
growing
rapidly…
why?
●
Tony
Sinclair’s
hypotheses:
○
Food
availability:
more
rain
=
more
food/higher
quality
food
available
■
Prediction:
food
quality
and
abundance
increased
in
early
60s
and
remained
high
throughout
the
decade
■
Test:
●
Use
exclosures
to
test
productivity
of
grasslands
in
areas
with
increased
rainfall
●
Determine
if
rainfall
had
increased
significantly
over
the
period
of
population
increase ■
Was
not
found
to
be
true
○
Predator
release:
less
predators
=
more
survival
■
Prediction:
large
predators
declined
in
the
60s
■
Test:
look
at
records
of
predator
populations
■
Not
found
to
be
true
○
Rinderpest
release:
rinderpest
was
a
disease
that
affected
cattle
and
other
ruminants,
rinderpest
eradicated
so
wildebeest
populations
rebounded
■
Predictions:
●
Negative
correlation
between
rinderpest
infection
and
ruminant
abundance
●
No
correlation
between
rinderpest
infection
and
non-ruminant
abundance
●
Increased
survival
rate
in
juvenile
ruminants
●
Kinds
of
experiments
○
Lab:
control
everything,
possibly
reductionistic
○
Field:
can
manipulate
things
but
maybe
not
“natural”
○
Natural:
may
have
confounding
factors
●
Rules
of
experimental
design
○
Replication
○
Randomization
○
Avoid
pseudoreplication
●
False
positive
→
type
I
error
○
Incorrectly
reject
the
null
●
False
negative
→
type
II
error
○
Incorrectly
accept
the
null
●
Types
of
data
○
Categorical:
finite
number
of
categories/groups
○
Discrete:
numeric
variables
that
have
countable
number
of
values,
no
decimals
○
Continuous:
numeric
variables
w/
infinite
number
of
values
between
any
two
values
●
What
kind
of
test?
○
Independent:
Quantitative;
Dependent:
quantitative
→
correlation
or
regression
○
Ind:
Categorical;
Dependent:
quantitative
→
T-test,
ANOVA
○
Ind:
categorical;
dependent:
categorical:
chi-squared
Chapter
2:
The
Physical
Environment
Intro
●
Biome:
large
geographical
area
w
characteristic
groups
of
organisms
adapted
to
that
particular
environment
○
Terrestrial
biomes
influenced
by
temp,
moisture,
and
soil
○
Aquatic
biomes
influenced
by
temp,
chemical
composition
of
water,
and
currents
Les avantages d'acheter des résumés chez Stuvia:
Qualité garantie par les avis des clients
Les clients de Stuvia ont évalués plus de 700 000 résumés. C'est comme ça que vous savez que vous achetez les meilleurs documents.
L’achat facile et rapide
Vous pouvez payer rapidement avec iDeal, carte de crédit ou Stuvia-crédit pour les résumés. Il n'y a pas d'adhésion nécessaire.
Focus sur l’essentiel
Vos camarades écrivent eux-mêmes les notes d’étude, c’est pourquoi les documents sont toujours fiables et à jour. Cela garantit que vous arrivez rapidement au coeur du matériel.
Foire aux questions
Qu'est-ce que j'obtiens en achetant ce document ?
Vous obtenez un PDF, disponible immédiatement après votre achat. Le document acheté est accessible à tout moment, n'importe où et indéfiniment via votre profil.
Garantie de remboursement : comment ça marche ?
Notre garantie de satisfaction garantit que vous trouverez toujours un document d'étude qui vous convient. Vous remplissez un formulaire et notre équipe du service client s'occupe du reste.
Auprès de qui est-ce que j'achète ce résumé ?
Stuvia est une place de marché. Alors, vous n'achetez donc pas ce document chez nous, mais auprès du vendeur gloriakawai. Stuvia facilite les paiements au vendeur.
Est-ce que j'aurai un abonnement?
Non, vous n'achetez ce résumé que pour 23,53 €. Vous n'êtes lié à rien après votre achat.
