Species Diversity in Communities Photo from Wikimedia Commons

Species Diversity in Communities Photo from Wikimedia Commons

Community Assembly – Ecological Filters Cain, Bowman & Hacker (2014), Fig. 19. 4

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 & Mc. Peek (2010) Ecology

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.

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.

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.

Coexistence – Temporal Variability Temporal variability can foster coexistence 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 Photomontage of plankton from Wikimedia Commons

Coexistence – Temporal Variability Temporal variability can foster coexistence 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) Quote from Chesson (2000) Ann. Rev. Ecol. Syst.

Coexistence – Intermediate Disturbance Hypothesis Disturbance can foster coexistence Cain, Bowman & Hacker (2014), Fig. 19. 14, after Connell (1978) Science

Coexistence – Intermediate Disturbance Hypothesis Disturbance can foster coexistence Cain, Bowman & Hacker (2014), Fig. 19. 15, after Sousa (1979) Ecology

Coexistence – Dynamic Equilibrium Model Disturbance can foster coexistence Cain, Bowman & Hacker (2014), Fig. 19. 12, after Huston (1979) The American Naturalist

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 Pisaster consuming a Mytilus from Wikimedia Commons; photo of Paine from http: //naturalhistoriesproject. org/conversations/anemone-like

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

Coexistence – Facilitators Positive interactions can foster coexistence Cain, Bowman & Hacker (2014), Fig. 19. 17, after Hacker & Gaines (1997) Ecology

Coexistence – Facilitators Positive interactions can foster coexistence Cain, Bowman & Hacker (2014), Fig. 19. 18, after Hacker & Gaines (1997) Ecology

Coexistence – Facilitators Positive interactions can foster coexistence “reefs with (closed symbols) and without (open symbols) cleaner fish at Casuarina Beach (circles) and Lagoon (squares) sites Figure from Grutter et al. (2003) Current Biology; photo of cleaner wrasse & client from Wikimedia Commons

Coexistence – Relative Importance of Factors A combination of predators and disturbance/stress can foster coexistence Cain, Bowman & Hacker (2014), Fig. 19, after Menge & Sutherland (1987) The American Naturalist

Long-term Co-occurrence: Lottery and Neutral Models Experimental removal and numbers of replacements by 3 species of fishes Cain, Bowman & Hacker (2014), Fig. 19. 20, after Sale (1979) Oecologia

Diversity-Ecosystem Function (e. g. , Productivity) Relationships 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 Cain, Bowman & Hacker (2014), Fig. 19. 21 A after Tilman & Downing (1994), Fig. 19. 21 B after Tilman et al. (1996)

Diversity. Ecosystem Function Relationships Cain, Bowman & Hacker (2014), Fig. 19. 22, after Peterson et al. (1998) Ecosystems