Community Ecology A biological community is an assemblage of populations of various species living close enough for potential interaction © 2011 Pearson Education, Inc.

Resource partitioning Figure 54.2 A. distichus perches on fence posts and other sunny surfaces. A. insolitus usually perches on shady branches. Resource partitioning A. ricordii Figure 54.2 Resource partitioning among Dominican Republic lizards. A. insolitus A. aliniger A. christophei A. distichus A. cybotes A. etheridgei

Resource Partitioning Figure 54.3 EXPERIMENT Resource Partitioning Realized v Fundamental Niches Competitive Exclusion High tide Chthamalus Balanus Chthamalus realized niche Balanus realized niche Ocean Low tide RESULTS High tide Figure 54.3 Inquiry: Can a species’ niche be influenced by interspecific competition? Competitive Exclusion Resource Partitioning Realized v Fundamental Niches Chthamalus fundamental niche Ocean Low tide

Character Displacement Figure 54.4 G. fuliginosa G. fortis Beak depth 60 Los Hermanos 40 G. fuliginosa, allopatric 20 60 Daphne 40 Percentages of individuals in each size class G. fortis, allopatric 20 Figure 54.4 Character displacement: indirect evidence of past competition. Character Displacement 60 Santa María, San Cristóbal Sympatric populations 40 20 8 10 12 14 16 Beak depth (mm)

Figure 54.5 Examples of defensive coloration in animals. (a) Cryptic coloration (b) Aposematic coloration Canyon tree frog Poison dart frog (c) Batesian mimicry: A harmless species mimics a harmful one. (d) Müllerian mimicry: Two unpalatable species mimic each other. Hawkmoth larva Cuckoo bee Yellow jacket Green parrot snake Figure 54.5 Examples of defensive coloration in animals.

Interspecific competition © 2011 Pearson Education, Inc.

Facilitation (b) (a) Salt marsh with Juncus (foreground) Figure 54.9 Facilitation 8 6 Number of plant species 4 2 Figure 54.9 Facilitation by black rush (Juncus gerardi) in New England salt marshes. (a) Salt marsh with Juncus (foreground) With Juncus Without Juncus (b)

Species Richness and Relative Abundance Figure 54.10 Species Richness and Relative Abundance A B C D Figure 54.10 Which forest is more diverse? Community 1 Community 2 A: 25% B: 25% C: 25% D: 25% A: 80% B: 5% C: 5% D: 10%

RESULTS 3.6 3.4 3.2 Shannon diversity (H) 3.0 2.8 2.6 2.4 2.2 3 4 5 6 Figure 54.11 RESULTS 3.6 3.4 3.2 Shannon diversity (H) 3.0 2.8 Figure 54.11 Research Method: Determining Microbial Diversity Using Molecular Tools 2.6 2.4 2.2 3 4 5 6 7 8 9 Soil pH

A terrestrial food chain A marine food chain Figure 54.13 Carnivore Quaternary consumers Carnivore Carnivore Tertiary consumers Carnivore Carnivore Secondary consumers Carnivore Figure 54.13 Examples of terrestrial and marine food chains. Herbivore Primary consumers Zooplankton Plant Primary producers Phytoplankton A terrestrial food chain A marine food chain

Humans Smaller toothed whales Baleen whales Sperm whales Elephant Figure 54.14 Humans Smaller toothed whales Baleen whales Sperm whales Elephant seals Crab- eater seals Leopard seals Birds Fishes Squids Figure 54.14 An Antarctic marine food web. Carniv- orous plankton Euphau- sids (krill) Cope- pods Phyto- plankton

Figure 54.17 EXPERIMENT RESULTS Figure 54.17 Inquiry: Is Pisaster ochraceus a keystone predator? Keystone species exert strong control on a community by their ecological roles, or niches In contrast to dominant species, they are not necessarily abundant in a community Field studies of sea stars illustrate their role as a keystone species in intertidal communities Dominant species are those that are most abundant or have the highest biomass Dominant species exert powerful control over the occurrence and distribution of other species For example, sugar maples have a major impact on shading and soil nutrient availability in eastern North America; this affects the distribution of other plant species 20 15 With Pisaster (control) Number of species present 10 Without Pisaster (experimental) 5 1963 ’64 ’65 ’66 ’67 ’68 ’69 ’70 ’71 ’72 ’73 Year

Otter number (% max. count) Grams per 0.25 m2 Number per 0.25 m2 Figure 54.18 100 80 60 Otter number (% max. count) 40 20 (a) Sea otter abundance 400 300 Grams per 0.25 m2 200 100 (b) Sea urchin biomass Figure 54.18 Sea otter as a keystone predator in the North Pacific. 10 8 Number per 0.25 m2 6 4 2 1972 1985 1989 1993 1997 Year (c) Total kelp density Food chain

Ecosystem Engineers Figure 54.19 Figure 54.19 Beavers as ecosystem engineers.

Glacial retreat and primary succession: Glacier Bay, Alaska. Figure 54.22-4 1941 1907 2 Dryas stage 1 Pioneer stage, with fireweed dominant 5 10 15 1860 Kilometers Glacier Bay Alaska Figure 54.22 Glacial retreat and primary succession at Glacier Bay, Alaska. 1760 4 Spruce stage 3 Alder stage Glacial retreat and primary succession: Glacier Bay, Alaska.

60 50 40 Soil nitrogen (g/m2) 30 20 10 Pioneer Dryas Alder Spruce Figure 54.23 60 50 40 Soil nitrogen (g/m2) 30 20 Figure 54.23 Changes in soil nitrogen content during succession at Glacier Bay. 10 Pioneer Dryas Alder Spruce Successional stage

Island Equilibrium Model Island Biogeogrpahy: Island Equilibrium Model Figure 54.27 Immigration Extinction Immigration Extinction Immigration (small island) (near island) Extinction (large island) (far island) Extinction Immigration Rate of immigration or extinction Rate of immigration or extinction (large island) Rate of immigration or extinction (far island) Immigration Extinction (near island) Figure 54.27 The equilibrium model of island biogeography. (small island) Equilibrium number Small island Large island Far island Near island Number of species on island Number of species on island Number of species on island (a) Immigration and extinction rates (b) Effect of island size (c) Effect of distance from mainland

Number of plant species Area of island (hectares) Figure 54.28 Species Richness v Island Size in the Galapagos RESULTS 400 200 100 Number of plant species (log scale) 50 25 10 Figure 54.28 Inquiry: How does species richness relate to area? 5 10 100 103 104 105 106 Area of island (hectares) (log scale)

How is Lyme Disease a question for Community Ecologists? The Lyme disease bacterium, Borrelia burgdorferi, is spread through the bite of infected ticks. The blacklegged tick (or deer tick, Ixodes scapularis) spreads the disease in the northeastern, mid-Atlantic, and north-central United States.