1 Mon. Tues. Wed. Thurs. Fri. Week of Nov. 10 Week of Nov. 17 River ecology lab – dress for weather Lab Exam (bring calc.) Week of Nov. 24 No lab – Thanksgiving No lecture Week of Dec. 1 Independent project presentations Exam 3

2 Ecology does not roll over into Genetics Last chance to take Genetics.

3 Sp. interactions – (through fig. 18.7), (only covering p. 391) Community ecology – 21 22

4 Structure of course Environmental variability Organisms Ecosystems Populations Species interactions Communities Applied Ecological Issues

5 + + Mutualistic interactions AB

6 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?

7 Lichens

8 Obligate mutualism – species are so dependent on each other that they cannot live without each other

9 Acacia trees and acacia ants

10 Trees without ants Trees with ants % of shoots with herbivores on them

11 May 25 June 16 Aug. 03 Acacia height (cm)

12 Which are more general? seed dispersal or pollination mutualisms

13 Figure 20.16

14 Structure of course Environmental variability Organisms Ecosystems Populations Species interactions Communities Applied Ecological Issues

15 Communities What is a community? How are communities described? How are species organized within a community? How do communities change over time?

16 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

17 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?

18

19 Figure 21.6a Ecotone- zone of transition between 2 distinct communities

20 Figure 21.9 boundaries less distinct

21 Communities What is a community? How are communities described? How are species organized within a community? How do communities change over time and space?

22 How are communities described? number of species = species richness evenness = # individuals/species diversity = richness and evenness relative abundance

23 Figure Relative abundance few dominant many rare

24 5 species high evenness 5 species lower evenness

25 Diversity = combination of richness and evenness - contribution of species weighted by relative abundance

26 5 species high evenness 5 species lower evenness Which has higher diversity?

27 What determines diversity of a community?

28 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

29 Figure one of the most common patterns in ecology

30 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

31 Figure 23.5

32 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

33 Figure 21.21

34 Communities What is a community? How are communities decribed? How are species organized within a community? How do communities change over time?

35 How are species organized within a community?

36 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.Species A is a predator of species B. b.Species A is a prey of species C. c.Species B is a competitor of species C. d.All of these are possible.

37 Figure 21.12

38 Connectedness web Starfish Snail ChitonsLimpetsMusselsBarnacles

39 Energy web Starfish Snail ChitonsLimpetsMusselsBarnacles

40 Functional/interaction web Starfish Snail ChitonsLimpetsMusselsBarnacles