Download Community

Mon.
Tues.
Wed.
Thurs.
Fri.
Week of
Nov. 10
Week of
Nov. 17
River ecology lab – dress for weather
Week of
Nov. 24
No lab – Thanksgiving
Lab
Exam
(bring calc.)
No
lecture
Week of
Exam 3
Dec. 1
Independent project presentations
1
Ecology does not roll over into
Genetics
Last chance to take Genetics.
2
Sp. interactions –
17
18 (through fig. 18.7),
19
20 (only covering p. 391)
Community ecology –
21
22
3
Structure of course
Environmental variability
Organisms
Ecosystems
Populations
Species interactions
Communities
Applied Ecological Issues
4
Mutualistic interactions
+
A
B
+
5
Different types of mutualisms
1. Those involving energy, nutrients,
and/or water
(Trophic mutualisms)
Examples?
2. Those involving defense
(Defensive mutualisms)
Examples?
3. Those involving dispersal
(Dispersive mutualisms)
Examples?
6
Lichens
7
Obligate mutualism – species are so dependent
on each other that they cannot live without each
other
8
Acacia trees and
acacia ants
9
Trees
without
ants
Trees
with
ants
10
% of shoots with
herbivores on them
Acacia height (cm)
120
60
0
May
25
June
16
Aug.
03
11
Which are more general? seed dispersal or
pollination mutualisms
12
Figure 20.16
13
Structure of course
Environmental variability
Organisms
Ecosystems
Populations
Species interactions
Communities
Applied Ecological Issues
14
Communities
What is a community?
How are communities described?
How are species organized
within a community?
How do communities change over
time?
15
Community: an association of populations of
different species living in a particular area
Community ecology: focus is understanding the
diversity and relative abundance of species in
the community
16
Questions asked by community ecologists
What determines the number of species in a community?
How does disturbance affect community structure?
Does adding new species change the way a
community functions?
17
18
Figure 21.6a
Ecotone- zone of
transition between 2
distinct communities
19
Figure
21.9
boundaries less distinct
20
Communities
What is a community?
How are communities described?
How are species organized
within a community?
How do communities change over
time and space?
21
How are communities described?
number of species = species richness
evenness = # individuals/species
diversity = richness and evenness
relative abundance
22
Figure
21.18
many rare
few
dominant
Relative abundance
23
5 species
high evenness
5 species
lower evenness
24
Diversity = combination of richness and
evenness
- contribution of species weighted
by relative abundance
25
5 species
high evenness
Which has
higher diversity?
5 species
lower evenness
26
What determines diversity of a community?
27
What determines diversity of a community?
1. diversity is related to area
2. diversity is related to variability
Lots of other theories that attempt to explain
controls on diversity
28
Figure 21.20
one of the most
common
patterns in ecology
29
What determines diversity of a community?
1. diversity is related to area
2. diversity is related to variability
Lots of other theories that attempt to explain
controls on diversity
30
Figure 23.5
31
Hard to separate variability and area
- typically larger areas have more habitat
variability
Lesser Antilles – island size and habitat
diversity vary independently
- two kinds of islands
- tall volcanic – diverse habitats
- low raised seabed – 1 habitat
- both kinds of islands come in all sizes
32
Figure 21.21
33
Communities
What is a community?
How are communities decribed?
How are species organized
within a community?
How do communities change over
time?
34
How are species organized within a community?
35
Suppose there are 3 species in a community,
species A, B, and C. When you remove
species A from the community, species C
goes extinct. What can you conclude
about the relationship between species?
a.
b.
c.
d.
Species A is a predator of species B.
Species A is a prey of species C.
Species B is a competitor of species C.
All of these are possible.
36
Figure 21.12
37
Connectedness web
Starfish
Snail
Chitons
Limpets
Mussels
Barnacles
38
Energy web
Starfish
Snail
Chitons
Limpets
Mussels
Barnacles
39
Functional/interaction web
Starfish
Snail
Chitons
Limpets
Mussels
Barnacles
40