Community Ecology I. Introduction II. Multispecies Interactions with a Trophic Level III. Multispecies Interactions acro

1. Community Ecology I. Introduction II. Multispecies Interactions with a Trophic Level III. Multispecies Interactions across Trophic Levels IV. Succession A. Definitions B. Types C. Mechanisms - facilitation, tolerance, and inhibition

2. Facilitated: early species change environment and increase the probability of successful colonization by later species. examples: colonization of bare rock: lichens, moss, herbs; colonization of carcasses: beetles, flies, etc. Aspen fix nitrogen that helps nitrogen-limited trees colonize

3. Tolerance: Tolerance: early species have no effect on later species. This occurs if there is 'ecological equivalence' among the species. Many stages in later forest succession seem dominated by this mechanism. Also, later species tolerate early species... so shade tolerant species come to dominate because they tolerate the shade of early species.

4. Inhibition: Early species retard the colonization success of later species. If these effects vary among early species, there can be "priority effects". The species that gets there first has a differential and deterministic effect on the subsequent structure of the community. Important where allelopathic interactions occur. Bryozoans block colonization of tunicates and sponges.

5. Community Ecology I. Introduction II. Multispecies Interactions with a Trophic Level III. Multispecies Interactions across Trophic Levels IV. Succession A. Definitions B. Types C. Mechanisms D. Model – Tilman 1985

6. 3. Model: Tilman (1985).... ready? A A,B B Our old 2-species model with stable coexistence possible.

7. 3. Model: Tilman (1985) A A,B B If resource supply rates are negatively correlated, then the community may succeed from A to A-B coexistence to B as concentrations change

8. 3. Model: Tilman (1985) A A,B B B, C C ...and then to B,C and C.... and etc....

9. 3. Model: Tilman (1985) A A,B B B, C C ...and then to B,C and C.... and etc.... C, D D

10. Community Ecology I. Introduction II. Multispecies Interactions with a Trophic Level III. Multispecies Interactions across Trophic Levels IV. Succession A. Definitions B. Types C. Mechanisms D. Model – Tilman 1985 E. Community Patterns

11. E. Community Patterns (From Morin, 1998) Variable Early Late Organism Size small large life history r K Biomass low high Richness, Diversity low high Structural complexity low high Niches broad narrow Nutrient cycles open closed Stability low high trophic relationships linear web-like connectance low high

13. BIODIVERSITY

14. Community Ecology • I. Introduction • II. Multispecies Interactions with a Trophic Level • III. Multispecies Interactions across Trophic Levels • IV. Succession • V. Biodiversity: Patterns and Processes • The Species-Area Relationship • 1. The pattern

15. "species - area relationship"

16. S = CAz log10S = log10C + z log10A where C is the y intercept and z is the slope of the line.

17. "species - area relationship" Breedings Birds - North Am.

18. "species - area relationship" Number of Bat Species log(N) Island Area log(square km)

22. Community Ecology • I. Introduction • II. Multispecies Interactions with a Trophic Level • III. Multispecies Interactions across Trophic Levels • IV. Succession • V. Biodiversity: Patterns and Processes • The Species-Area Relationship • 1. The pattern • 2. The Theory of Island Biogeography

23. MacArthur and Wilson (1967) THEORY OF ISLAND BIOGEOGRAPHY Edward O. Wilson Prof. Emer., Harvard Robert MacArthur 1930-1972

24. MacArthur and Wilson (1967) THEORY OF ISLAND BIOGEOGRAPHY - Species Richness is a balance between COLONIZATION (adds species) and EXTINCTION (subtracts species)

25. - Colonization Increases with Area - larger target - more habitats Mainland

26. confirmation: greater immigration rate on larger islands

27. - Colonization Increases with Area - larger target - more habitats

28. - Colonization Increases with Area - larger target - more habitats (except very small) Niering, W.A. 1963. Terrestrial ecology of Kapingamarangi Atoll, Caroline Islands. Ecological Monographs 33:131-160.

29. - Colonization Increases with Area - larger target - more habitats - Extinction Decreases with Area - more food means larger populations that are less likely to bounce to a size of "0" (extinction)

30. - Extinction Decreases with Area Reduced Turnover on larger islands Wright, S.J. 1980. Density compensation in island avifaunas. Oecologia 45: 385-389.     Wright, S. J. 1985. How isolation affects rates of turnover of species on islands. Oikos 44:331-340.

32. COL - large RATE EXT - small COL - small EXT - large SMALL LARGE species richness

33. - Colonization Decreases with Distance - fewer species can reach Mainland

34. - Colonization Decreases with Distance - fewer species can reach saturation is the % of species found on a patch of mainland that size

35. - Extinction Increases with Distance - recolonization less likely at distance Mainland "Rescue Effect"

36. - Extinction Increases with Distance - recolonization less likely at distance Wright, S.J. 1980. Density compensation in island avifaunas. Oecologia 45: 385-389.     Wright, S. J. 1985. How isolation affects rates of turnover of species on islands. Oikos 44:331-340.

37. COL - close RATE EXT - far COL - far EXT - close far close species richness

39. equilibria

40. equilibria and turnover

42. Dramatic evidence that, although the communities had recovered in terms of species richness, the composition was very different with typically about 80% of the species turning over.

43. Community Ecology • I. Introduction • II. Multispecies Interactions with a Trophic Level • III. Multispecies Interactions across Trophic Levels • IV. Succession • V. Biodiversity: Patterns and Processes • The Species-Area Relationship • 1. The pattern • 2. The Theory of Island Biogeography • 3. Why is this important? Fragmentation

44. - Why is this important? - all habitats except the atmosphere are islands. Continents - big islands

46. White-faced Saki (Pithecia pithecia)

47. Monk Saki (Pithecia monachus) White-faced Saki (Pithecia pithecia)

48. Monk Saki (Pithecia monachus) White-faced Saki (Pithecia pithecia) White-footed Saki (Pithecia albicans)

49. Monk Saki (Pithecia monachus) White-faced Saki (Pithecia pithecia) White-footed Saki (Pithecia albicans) Rio Tapajos Saki (Pithecia irrorata)

50. Minnesota: Land O'Lakes