22nd Lecture – November 17, 2011
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Assignment 3 is posted. This will be due Tues. Nov. 29th.
Read Kneitel and Miller for after T-day.
Note that you are running out of talks!
Dr. Iliana B. Baums
Pennsylvania State University, University
Park
Local adaptation in the face of
large scale gene flow
Friday 4:00, King 1024
V. Community ecology
A. What is community ecology?
1. What is a community - "An assemblage of
populations of living organisms in a prescribed area or
habitat that interact with one another, directly or indirectly”
Similar terms:
ecosystem: all the interacting parts of the physical and
biological worlds.
association: group of species living in the same place.
guild: species in the same community utilizing resources in
the same way, often competitors.
V. Community ecology
A. What is community ecology?
1. What is a community - "An assemblage of
populations of living organisms in a prescribed area or
habitat that interact with one another, directly or indirectly”
A caution that ecologists use “community” to mean two
different things:
--
as described above, all the species in an area
or
--
what might more properly be called a guild, which is all the
species that share a resource base (e.g., birds, rodents, or
plants)
V. Community ecology
A. What is community ecology?
1. What is a community?
2. Approaches to studying communities
a. Descriptions - associations between different species and
between different species assemblages and climate. Biomes,
Holdridge classification, now GIS.
Phytosociology - the study of the composition and structure of plant
communities.
b. Population-based approaches - reductionist view, using
individuals and species as building blocks and units. Stresses
biotic interactions such as predation and competition.
c. Ecosystem ecology - also can be reductionist, using energy and
nutrients as units instead of individuals and populations.
Holdridge Classification Scheme
Example of Phytosociology
Some Floristic provinces of NA:
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
Tundra
Northern conifer
Eastern deciduous
Coastal Plains
West Indian
Grassland
Cordilleran Forest
Great Basin
California
Sonoran
V. Community ecology
A. What is community ecology?
1. What is a community?
2. Approaches to studying communities
a. Descriptions - associations between different species
and between different species assemblages and
climate. Biomes, Holdridge classification, now GIS.
b. Population-based approaches - reductionist view, using
individuals and species as building blocks and units.
Stresses biotic interactions such as predation and
competition.
c. Ecosystem ecology - also can be reductionist, using
energy and nutrients as units instead of individuals
and populations.
V. Community ecology
A. What is community ecology?
1. What is a community?
2. Approaches to studying communities
a. Descriptions - associations between different species
and between different species assemblages and
climate. Biomes, Holdridge classification, now GIS.
b. Population-based approaches - reductionist view, using
individuals and species as building blocks and units.
Stresses biotic interactions such as predation and
competition.
c. Ecosystem ecology - also can be reductionist, using
energy and nutrients as units instead of individuals
and populations.
c.
Ecosystem ecology - also can be reductionist, using
energy and nutrients as units instead of individuals
and populations.
Odum’s model of the
Silver Springs ecosystem
IV. Community ecology
A. What is community ecology?
B. How do we quantify communities?
IV. Community ecology
A. What is community ecology?
B. How do we quantify communities?
1. Tools of community ecology
a.
b.
c.
d.
e.
growth form and structure
number of species vs. diversity of species
dominance/ relative abundance:
rank abundance curves
food or trophic webs
IV. Community ecology
A. What is community ecology?
B. How do we quantify communities?
1. Tools of community ecology
a. growth form and structure
prairie vs. forests, coral reef vs. sandy bottom
b.
c.
d.
e.
number of species vs. diversity of species
dominance/ relative abundance:
rank abundance curves
food or trophic webs
S = 13 spp.
IV. Community ecology
A. What is community ecology?
B. How do we quantify communities?
1. Tools of community ecology
a.
b.
c.
d.
e.
growth form and structure
number of species vs. diversity of species
dominance/ relative abundance
rank abundance curves
food or trophic webs
S = 12 spp.
IV. Community ecology
...
a. growth form and structure (sedans, trucks, etc.)
b. number of species vs. diversity of species (10 vs. 9 species)
Here is a list of car
colors from FSU lots,
which we can treat
like “communities”
and compare. Since
students and faculty
have a very similar
number of species,
are they really similar
communities?
Car color
(species)
Faculty
Student
Blue
16
7
Grey/silver
13
5
Red
13
18
Tan/brown
8
5
Black
8
17
White
7
9
Green
4
7
Two-tone
3
2
Orange
2
0
Purple/pink
2
1
V. Community ecology
...
a. growth form and structure (sedans, trucks, etc.)
b. species number, diversity, or eveness
n
H¢ = -å pi log e pi
Shannon-Weiner diversity index:
i=1
Car color
(species)
Faculty
Proportion
(%) = p
ln(p)
pln(p)
Blue
16
0.21
-1.56
-0.33
Grey/silver
13
0.17
-1.77
-0.30
Red
13
0.17
-1.77
-0.30
Tan/brown
8
0.11
-2.25
-0.24
Black
8
0.11
-2.25
-0.24
7
0.09
-2.38
-0.22
Green
4
0.05
-2.94
-0.15
Two-tone
3
0.04
-3.23
-0.13
Orange
2
0.03
-3.64
-0.10
Purple/pink
2
0.03
-3.64
-0.10
V. Community ecology
...
a. growth form and structure (sedans, trucks, etc.)
b. species number, diversity, or eveness
Shannon-Weiner diversity index:
Car color
(species)
Faculty
Student
Blue
16
7
Grey/silver
13
5
Red
13
18
Tan/brown
8
5
Black
8
17
White
7
9
Green
4
7
Two-tone
3
2
Orange
2
0
Purple/pink
2
1
n
H = -å pi log e pi
i =1
FACULTY = 2.10
STUDENT = 1.94
V. Community ecology
...
a. growth form and structure (sedans, trucks, etc.)
b. species number, diversity, or eveness
Shannon-Weiner diversity index:
Car color
(species)
Faculty
Student
Blue
16
7
Grey/silver
13
5
Red
13
18
Tan/brown
8
5
Black
8
17
White
7
9
Green
4
7
Two-tone
3
2
Orange
2
0
Purple/pink
2
1
n
H = -å pi log e pi
i =1
FACULTY = 2.10
STUDENT = 1.94
Indices are handy, but
confound species number
with eveness of abundance.
b. number of species (S) and diversity of species (H’)
Both can also be measured at different spatial scales:
-- alpha diversity is within-habitat diversity, number of
species in local, small areas of uniform habitat
-- beta diversity is between habitat diversity, the variation
in species composition from one habitat to another within a
region. This is really a measure of variation in diversity, not
diversity directly.
-- gamma diversity is regional diversity, number of
species in a larger area of interest across habitats or local
areas
Consider three different regional communities, each with five
different local populations and maximum of five species:
1
A, B, C, D, E
A
A, B
2
A, B, C, D, E
B
B, D
3
A, B, C, D, E
C
E, A
4
A, B, C, D, E
D
B, D
5
A, B, C, D, E
E
B, C
High alpha
low beta
High gamma
Consider three different regional communities, each with five
different local populations and maximum of five species:
1
A, B, C, D, E
A
A, B
2
A, B, C, D, E
B
B, D
3
A, B, C, D, E
C
E, A
4
A, B, C, D, E
D
B, D
5
A, B, C, D, E
E
B, C
High alpha
low beta
High gamma
Low alpha
high beta
High gamma
Consider three different regional communities, each with five
different local populations and maximum of five species:
1
A, B, C, D, E
A
A, B
2
A, B, C, D, E
B
B, D
3
A, B, C, D, E
C
E, A
4
A, B, C, D, E
D
B, D
5
A, B, C, D, E
E
B, C
High alpha
low beta
High gamma
Low alpha
Mod alpha
high beta
mod beta
High gamma High gamma
Consider three different regional communities, each with five
different local populations and maximum of five species:
1
A, B, C, D, E
A
A, B
2
A, B, C, D, E
B
B, D
3
A, B, C, D, E
C
E, A
4
A, B, C, D, E
D
B, D
5
A, B, C, D, E
E
B, C
High alpha
low beta
High gamma
Low alpha
Mod alpha
high beta
mod beta
High gamma High gamma
It may be helpful to think of the relationship between these measures
as alpha * beta = gamma though this is not totally accurate.
3
2
1
0
log (Relative abundance x 100
4
IV. Community ecology
...
a. growth form and structure (sedans, trucks, etc.)
b. diversity or species number (10 vs. 9)
c. dominance/ relative abundance (blue/grey vs. red/black)
d. rank abundance curves.
0
5
10
Species rank
15
20
Note the log scale!
Rank abundance curves have been measured for lots of communities and
seem to fall into several different sorts of shapes.
Why? What do these curves tell us about communities?
prpl_pink
orange
two_col
green
white
black
tan
red
grey
blue
number of cars of each color
15
Rank-abundance curves
for faculty/staff car, based
on abundance
10
5
0
prpl_pink
orange
two_col
green
white
black
tan
red
grey
blue
Proportion of cars of each color
0.20
Rank-abundance curves
for faculty/staff car, based
on proportion
0.15
0.10
0.05
0.00
Rank-abundance curves
for faculty/staff car, based
on log (proportion)
3.0
2.5
2.0
1.5
1.0
0.5
rpl_pink
orange
two_col
green
white
black
tan
red
grey
0.0
blue
log(Proportion of cars of each color*200)
3.5
10
9
8
7
6
5
4
3
2
1
log(Proportion of cars of each color*200)
3.0
faculty/staff
students
2.5
2.0
1.5
1.0
0.5
0.0
IV. Community ecology
...
a. growth form and structure (sedans, trucks, etc.)
b. diversity or species number (10 vs. 9)
c. dominance/ relative abundance (blue/grey vs. red/black)
d. rank abundance curves.
Now, back to our list of
car colors. Another
way to describe these
communities be based
on the dominant
species (in red). Even
better would be to
somehow describe the
rankings of species in
each community. We
can do that with a
graph.
Car color (species)
Faculty
Student
Blue
16
7
Grey/silver
13
5
Red
13
18
Tan/brown
8
5
Black
8
17
White
7
9
Green
4
7
Two-tone
3
2
Orange
2
0
Purple/pink
2
1
-- geometric assumes division of
resource in regular, sequential way.
-- broken stick model assumes
division of a single resource, but
random.
-- log-normal distribution also. In
this case, it is likely that multiple
factors are affecting the distribution
of species abundances (such as
competing for multiple resources).
Most communities fit a log-normal
distribution.
10
9
8
7
6
5
4
3
2
1
log(Proportion of cars of each color*200)
3.0
2.5
2.0
1.5
1.0
0.5
0.0
--- Faculty
--- Students
Example questions from past exams over this material
Example questions from past exams over this material
Example questions from past exams over this material
Study Guide Items from Lecture 22
Terms:
•Community
•Ecosystem
•Association
•Guild
•Phytosociology
•Diversity
•Richness
•
•
•
alpha diversity
beta diversity
gamma diversity
Concepts:
•3 approaches to studying communities
•Different ways to describe a community
•Species diversity includes richness plus the eveness of relative abundance.
•Shannon-Weiner index of diversity
•Alpha, beta, and gamma diversity – different spatial scales
•Rank-abundance curves
•The meaning of shapes of the rank-abundance curves (e.g., broken stick model)
Case Studies:
•Hubbell’s graph of tree diversity in different forests