1 Mon. Tues. Wed. Thurs. Fri. 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 Week of Dec. 8 Final Exam Dec. 11

2 Sp. interactions – (through fig. 18.7), (only covering p. 391) Community ecology – Don’t read 23,25, and 26 just yet

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

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

5 cod seals

6 How are species organized within a community? Webs! Connectedness webs Energy webs Functional webs (interaction webs) (these are what we drew when talking about species interactions)

7 Figure 21.12

8 Connectedness web Starfish Snail ChitonsLimpetsMusselsBarnacles

9 Energy web Starfish Snail ChitonsLimpetsMusselsBarnacles

10 Functional/interaction web Starfish Snail ChitonsLimpetsMusselsBarnacles

11 How are species organized within a community? Webs Keystone species Top-down vs. bottom-up

12 Keystone species – species that have large impacts on structure of the community they inhabit despite having relatively low biomass

13 Impact of species Proportional biomass of species

14 Figure bottom- up top- down Trophic cascade What is size of trophic level determined by?

15 Bottom – up – increasing primary producer increases production at all levels Top-down – increasing biomass of top consumer increases production in every other level

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

17 Succession – gradual change in plant and animal communities in an area following a disturbance or the creation of a new substrate primary vs. secondary

18 Primary succession – occurs on new geological substrates Secondary succession – occurs after destruction of aboveground community but substrate is still intact Examples??

19 Figure 22.2

20 New substrate Climax community Disturbed area Multiple successional stages Multiple successional stages Primary succession Secondary succession

21 Figure 22.9

22 Figure 22.5 Lake Michigan

23 Why does succession occur??? 1.Organisms change environment during succession - how? 2.Organisms face trade-offs

24 Why does succession occur??? 1.facilitation 2.inhibition 3.tolerance Mechanisms for species establishment

25 Figure 22.11

26 Figure 22.10

27 Why does succession occur??? 1.facilitation 2.inhibition 3.tolerance Mechanisms for species establishment

28 Figure 22.13

29 Why does succession occur??? 1.facilitation 2.inhibition 3.tolerance – establishment not dependent on which species are already there Mechanisms for species establishment

30

31 1. Annual plants 2. Herbaceous perennials 3. Early sucessional trees/shrubs 4. Late successional trees Succession on abandoned fields

32 Figure tolerance inhibition