SLOSS debate. reserve design principles. Caribbean Anolis. SLOSS debate- criticisms. Single large or several small Debate over reserve design

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1 SLOSS debate reserve design principles Single large or several small Debate over reserve design SLOSS debate- criticisms Caribbean Anolis Pattern not always supported Other factors may explain diversity Close-site problems (synchrony) Don t take species identity into consideration (and trophic levels) At particular sizes, no more species are added Patches more connected than assumed, function of matrix Losos and Schluter (2000) Nature The species-area relationship on islands Habitat heterogeneity and species diversity Variance = x Species 1 What is the relationship between habitat heterogeneity and island area? However, the species- area relationship is not always linear Variance x Species 1 Species 1 Species 2 Variance = (n)x( Courtesy of Jason Knouft Courtesy of Jason Knouft 1

2 Caribbean habitat data Shifting paradigms.. Elevation Temperature In 1980 s, under heavy criticism of TIB, metapopulation theory becomes the dominant theory Shift from community level to population level approach Landcover Precipitation Courtesy of Jason Knouft Metapopulations Population of populations Migration and extinction drive population dynamics Variations Examples Metapopulations r -- % occupancy b colonizations d extinctions P = 1 e/c e = extinctions c = colonizations Patch occupancy increases with decreasing e/c Metapopulations Simple: (true metapopulation) Source-sink: Patchy population: Variations 2

3 Examples Examples California mountain sheep California checkerspot butterfly Metacommunity Definition: A set of local communities linked by dispersal of multiple potentially interacting species (Leibold et al. 2004) Two distinct community scales: Local and Regional Local Communities competition predation disturbances abiotic factors Regional Community dispersal patch heterogeneity Species-specific traits (trade-offs) coexistence at local and regional community scales predicts type of species expected 3

4 Trade-off examples Dispersal Frequency and Diversity (based on Mouquet and Loreau 2002) Richness Kneitel and Chase (2004) Ecology Letters Regional Dynamics: Experimental Design Regional Dynamics: Local Richness X 3 Resource levels X 2 Predator levels X 3 Dispersal rates X 5 Replicates measured protozoan abundance and richness Local species richness b b a None Low High Dispersal frequency Kneitel and Miller (2003) American Naturalist Regional Dynamics: Protozoan Regional Diversity Regional Dynamics: Protozoan Abundance Square root (regional richness) b b a None Low High Dispersal frequency Kneitel and Miller (2003) American Naturalist Kneitel and Miller (2003) American Naturalist 4

5 Regional Dynamics: Protozoan Local Diversity Empirical Examples Harrison 1997, 1999 Shurin 2001, Cottenie et al Kneitel and Miller (2003) American Naturalist Bengtsson 1991, Therriault and Kolasa 2000 Lei and Hanski 1998, Amarasekare 2000 How do communities change with time?? Succession Sere Types of Succession Types of Succession Primary succesion (where no life existed before) Rotmoos Glacier on the Austria-Italian border Secondary succession (Post-disturbance) Bog succession 5

6 Disturbance an event that removes biomass from a community a disturbance will start/restart succession to an earlier stage Disturbances Gaps in rain forest floods in floodplain (Mississippi) boulder rolling through the intertidal zone fire unusual severe weather - or long term aberrant trend? Clearwater Riparian Area

7 1987 Pioneer species organisms that arrive early in succession r species produce many small seeds, may form a seed bank poor competitors good colonizers Pioneer Species Climax vegetation the final stage of a successional process, usually defined by the habitat type Climax Species Succession on Rocks K species produce few large seeds, no seed bank good competitors poor colonizers 7

8 Soil development Superorganism vs Individualistic (Clement 1936) (Gleason 1939) 8

9 Rivet Model Paul and Anne Ehrlich (1981) Species like rivets in airplane wings Not all necessary to hold wings together, but enough loss (species) will result in it falling apart (ecosystem functioning) Species Redundancy Walker (1991) Species and ecological processes redundant in community Those species lost will be replaced by others with similar function (guilds or functional groups) 9