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

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

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.

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.

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

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

3. Model: Tilman (1985) AA, 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

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

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

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

E. Community Patterns (From Morin, 1998) VariableEarlyLate Organism Sizesmalllarge life historyrK Biomasslowhigh Richness, Diversitylowhigh Structural complexitylowhigh Nichesbroadnarrow Nutrient cyclesopenclosed Stabilitylowhigh trophic relationshipslinearweb-like connectancelowhigh

BIODIVERSITY

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

"species - area relationship"

S = CA z log 10 S = log 10 C + z log 10 A where C is the y intercept and z is the slope of the line.

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

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

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

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

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

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

confirmation: greater immigration rate on larger islands

- Colonization Increases with Area - larger target - more habitats

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

- 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)

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

RATE species richness COL - small EXT - small COL - large EXT - large SMALLLARGE

- Colonization Decreases with Distance - fewer species can reach Mainland

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

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

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

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

Equilbrium Island Biogeography & Turnover Turnover on "Landbridge" islands (California Channel Islands) Island Area km2 Distance km Bird Spp Bird Spp Extinctio ns Human Introd. Immigratio ns Turnover % Los Coronados San Nicholas San Clemente Santa Catalina Santa Barbara San Miguel Santa Rosa Santa Cruz Anacapa Diamond, J.M Avifaunal equilibria and species turnover rates on the Channel Islands of California. Proc. Natl. Acad. Sci 64: Jones, H.L. and Diamond, J.M Short-time-base studies of turnover in breeding bird populations on the Channel Islands of California. Condore 73: [+] + equilibria

Equilbrium Island Biogeography & Turnover Turnover on "Landbridge" islands (California Channel Islands) Island Area km2 Distance km Bird Spp Bird Spp Extinctio ns Human Introd. Immigratio ns Turnover % Los Coronados San Nicholas San Clemente Santa Catalina Santa Barbara San Miguel Santa Rosa Santa Cruz Anacapa Diamond, J.M Avifaunal equilibria and species turnover rates on the Channel Islands of California. Proc. Natl. Acad. Sci 64: Jones, H.L. and Diamond, J.M Short-time-base studies of turnover in breeding bird populations on the Channel Islands of California. Condore 73: [+] + equilibria and turnover

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.

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

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

White-faced Saki (Pithecia pithecia)

Monk Saki (Pithecia monachus)

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

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

Minnesota: Land O'Lakes

"Sky Islands" High elevation habitats separated by inhospitable (desert) habitat.

- Why is this important? - all habitats except the atmosphere are islands. - human activity fragments a landscape, making lots of islands, too.

Bolivia has lost 50% of its rainforest in last 30 years

Even Costa Rica has lost 95% of its old growth forest that is outside of national parks...