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Species Diversity in Communities
Photo from Wikimedia Commons
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Community Assembly – Ecological Filters
Cain, Bowman & Hacker (2014), Fig. 19.4
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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
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Species-packing mechanismsthat 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.
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Coexistence – Resource Partitioning
Species-packing mechanismsthat illustrate
“resource-partitioning” or “niche-differentiation”
explanations for differences in diversity
between two sites
Figure from Remsen (1991) Univ. Calif. Publ. Zool.
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Coexistence – Resource Partitioning
Species-packing mechanismsthat illustrate
“resource-partitioning” or “niche-differentiation”
explanations for differences in diversity
between two sites
Figure from Remsen (1991) Univ. Calif. Publ. Zool.
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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
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Coexistence – Intermediate Disturbance Hypothesis
Cain, Bowman & Hacker (2014), Fig. 19.14, after Connell (1978) Science
Disturbance can foster coexistence
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Coexistence – Intermediate Disturbance Hypothesis
Cain, Bowman & Hacker (2014), Fig. 19.15, after Sousa (1979) Ecology
Disturbance can foster coexistence
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Coexistence – Dynamic Equilibrium Model
Cain, Bowman & Hacker (2014), Fig. 19.12, after Huston (1979) The American Naturalist
Disturbance can foster coexistence
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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 http://naturalhistoriesproject.org/conversations/anemone-like
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Coexistence – Janzen-Connell Model
Enemies can foster coexistence
Adapted from Janzen (1970) The American Naturalist
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Coexistence – Facilitators
Cain, Bowman & Hacker (2014), Fig. 19.17, after Hacker & Gaines (1997) Ecology
Positive interactions can foster coexistence
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Coexistence – Facilitators
Positive interactions can foster coexistence
Cain, Bowman & Hacker (2014), Fig. 19.18, after Hacker & Gaines (1997) Ecology
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Coexistence – Facilitators
Cain, Bowman & Hacker (2014), Fig. 19.19, after Menge & Sutherland (1987) The American Naturalist
A combination of predators and disturbance/stress can foster coexistence
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Long-term co-occurrence:Lottery and Neutral Models
Cain, Bowman & Hacker (2014), Fig. 19.20, after Sale (1979) Oecologia
Experimental removal and numbers of replacements by 3 species of fishes
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Diversity-Ecosystem Function (e.g., Productivity) Relationships
Cain, Bowman & Hacker (2014), Fig. 19.21A after Tilman & Downing (1994), Fig. 19.21B 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
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Cain, Bowman & Hacker (2014), Fig. 19.22, after Peterson et al. (1998) Ecosystems
Diversity-Ecosystem Function
Relationships