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Unformatted text preview: EBIO 1220 General Biology L34 Community Ecology April 24-26, 2006 1 Community Ecology (Reading: Chap 53) I. Introduction II. Species control of community structure III.Disturbance and succession IV. Large scale patterns of diversity V. Views of community structure I. Introduction: What is a Community?? Any assemblage of populations in an area or habitat Community structure: interactions between species Figure 53.1 A. Community Interactions A. 2 key points on species interactions: 1. Affect distribution and abundance of interacting species. 2. Agents of natural selection and thus affect evolution of interacting species. I. Introduction I. Introduction: Community Interactions ii. Competition (-/-) When species compete for a particularly resource that is in short supply. Intra specific- remember the logistic curve?! Among individuals of one species Density dependence Inter specific Among individuals of different spp May restrict range of one or other spp Competitive Exclusion Principle Russian ecologist G.F. Gause in 1934 Two spp so similar that compete for same limiting resources and cannot coexist in same place Ricklefs Fig. 19.6 I. Introduction: Community Interactions Competitive exclusion and the niche Ecological niche: sum total of a species’ use of abiotic and biotic resources. Niches can’t overlap exactly or species can’t coexist (i.e., need resource partitioning ). Fundamental niche = potential Realized niche = actual I. Introduction: Community Interactions EBIO 1220 General Biology L34 Community Ecology April 24-26, 2006 2 As a result of competition . . . A species’ fundamental niche may be different from its realized niche Fig. 53.2 I. Introduction: Community Interactions In nature, Chthamalus restricted to high rocks With Balanus removed, shows realized niche of Chthamalus much smaller than its fundamental niche Resource partitioning Allopatric - closely related spp geographically separated Sympatric - closely related spp that overlap geographically I. Introduction: Community Interactions Fig. 53.3 Resource partitioning among Dominican Republic lizards Shady branches Sunny surfaces Character displacement Tendency for characteristics to be more divergent in sympatric populations Indirect evidence of past competition I. Introduction: Community Interactions Fig. 53.4 iii. Predation Where one species (predator) kills and...
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- Spring '07
- Ecology, I. Introduction, community structure, C. Community Structure, General Biology L34, Biology L34 Community