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Presentation on theme: "Species Diversity in Communities Photo from Wikimedia Commons."— Presentation transcript:

1 Species Diversity in Communities Photo from Wikimedia Commons

2 Community Assembly – Ecological Filters Cain, Bowman & Hacker (2014), Fig. 19.4

3 Co-occurrence  Coexistence Species “able to persist indefinitely together are deemed to ‘coexist’…” “If some mechanism promotes the coexistence of two or more species, each species must be able to increase when it is rare and the others are at their typical abundances; this invasibility criterion is fundamental evidence for species coexistence regardless of the mechanism.” “some subset of the co-occurring species are either slowly being driven extinct by others in the assemblage… stochastically [drifting] to extinction via neutral dynamics… or maintained in a local area by dispersal from other areas (i.e., sink populations…)…” Quotes from Siepielski & McPeek (2010) Ecology

4 Species-packing mechanisms that illustrate “resource-partitioning” or “niche-differentiation” explanations for differences in diversity between two sites Coexistence – Resource Partitioning Figure from Remsen (1991) Univ. Calif. Publ. Zool.

5 Coexistence – Resource Partitioning Species-packing mechanisms that illustrate “resource-partitioning” or “niche-differentiation” explanations for differences in diversity between two sites Figure from Remsen (1991) Univ. Calif. Publ. Zool.

6 Coexistence – Resource Partitioning Species-packing mechanisms that illustrate “resource-partitioning” or “niche-differentiation” explanations for differences in diversity between two sites Figure from Remsen (1991) Univ. Calif. Publ. Zool.

7 Coexistence – Temporal Variability Quote from Chesson (2000) Ann. Rev. Ecol. Syst. G. E. Hutchinson’s (1961) “Paradox of the Plankton” i.e., that many more species of plankton apparently coexist in lakes than there are limiting nutrients; concluded that plankton rarely achieve equilibrium owing to ever-changing environmental conditions Storage Effect “models in which stable coexistence results from environmental fluctuations are models of temporal niches: species are not distinguished by the resources they use but by when they are most actively using them…” (Chesson 2000) Temporal variability can foster coexistence

8 Coexistence – Intermediate Disturbance Hypothesis Cain, Bowman & Hacker (2014), Fig , after Connell (1978) Science Disturbance can foster coexistence

9 Coexistence – Intermediate Disturbance Hypothesis Cain, Bowman & Hacker (2014), Fig , after Sousa (1979) Ecology Disturbance can foster coexistence

10 Coexistence – Dynamic Equilibrium Model Cain, Bowman & Hacker (2014), Fig , after Huston (1979) The American Naturalist Disturbance can foster coexistence

11 Coexistence – Keystone Predation Enemies can foster coexistence “The removal of Pisaster has resulted in a pronounced decrease in diversity… from a 15 to an eight-species system” Quote from Paine (1966) The American Naturalist; photo of Paine from

12 Coexistence – Janzen-Connell Model Enemies can foster coexistence Adapted from Janzen (1970) The American Naturalist

13 Coexistence – Facilitators Cain, Bowman & Hacker (2014), Fig , after Hacker & Gaines (1997) Ecology Positive interactions can foster coexistence

14 Coexistence – Facilitators Positive interactions can foster coexistence Cain, Bowman & Hacker (2014), Fig , after Hacker & Gaines (1997) Ecology

15 Coexistence – Facilitators Cain, Bowman & Hacker (2014), Fig , after Menge & Sutherland (1987) The American Naturalist A combination of predators and disturbance/stress can foster coexistence

16 Long-term co-occurrence: Lottery and Neutral Models Cain, Bowman & Hacker (2014), Fig , after Sale (1979) Oecologia Experimental removal and numbers of replacements by 3 species of fishes

17 Diversity-Ecosystem Function (e.g., Productivity) Relationships Cain, Bowman & Hacker (2014), Fig A after Tilman & Downing (1994), Fig B after Tilman et al. (1996) Drought resistance (measured as biomass change) in plots that varied in pre-drought species richness Separate experiment in which plots were constructed with varying numbers of species and cover after 2 yr was measured

18 Cain, Bowman & Hacker (2014), Fig , after Peterson et al. (1998) Ecosystems Diversity- Ecosystem Function Relationships


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