Chapter 53: Community Ecology

1. Chapter 53: Community Ecology

2. EXPERIMENT RESULTS Ecologist Joseph Connell studied two baranacle speciesBalanus balanoides and Chthamalus stellatusthat have a stratified distribution on rocks along the coast of Scotland. When Connell removed Balanus from the lower strata, the Chthamalus population spread into that area. High tide High tide Chthamalus Chthamalusrealized niche Balanus Chthamalusfundamental niche Balanusrealized niche Ocean Ocean Low tide Low tide In nature, Balanus fails to survive high on the rocks because it isunable to resist desiccation (drying out) during low tides. Its realized niche is therefore similar to its fundamental niche. In contrast, Chthamalus is usually concentrated on the upper strata of rocks. To determine the fundamental of niche of Chthamalus, Connell removed Balanus form the lower strata. CONCLUSION The spread of Chtamalus when Balanus wasremoved indicates that competitive exclusion makes the realizedniche of Chthamalus much smaller than its fundamental niche. Figure 53.2 Can a species’ niche be influenced by interspecific competition?

3. G. fortis G. fuliginosa Beak depth Santa María, San Cristóbal Sympatric populations 40 20 0 Los Hermanos 40 G. fuliginosa, allopatric Percentages of individuals in each size class 20 0 Daphne 40 G. fortis, allopatric 20 0 8 10 12 14 16 Beak depth (mm) Figure 53.4 Character displacement: indirect evidence of past competition

4. Figure 53.5 Cryptic coloration: canyon tree frog

5. Figure 53.6 Aposematic coloration: poison arrow frog

6. (b) Green parrot snake (a) Hawkmoth larva Figure 53.7 Batesian mimicry: A harmless species mimics a harmful one

7. (a) Cuckoo bee (b) Yellow jacket Figure 53.8 Müllerian mimicry: Two unpalatable species mimic each other

8. Figure 53.9 Mutualism between acacia trees and ants

9. Figure 53.10 A possible example of commensalism between cattle egrets and water buffalo

10. Quaternary consumers Carnivore Carnivore Tertiary consumers Carnivore Carnivore Secondary consumers Carnivore Carnivore Primary consumers Zooplankton Herbivore Primary producers Plant Phytoplankton A terrestrial food chain A marine food chain Figure 53.12 Examples of terrestrial and marine food chains

11. Humans Smaller toothed whales Baleen whales Sperm whales Elephant seals Leopard seals Crab-eater seals Squids Fishes Birds Carnivorous plankton Euphausids (krill) Copepods Phyto-plankton Figure 53.13 An antarctic marine food web

12. Figure 53.18 Beavers as ecosystem “engineers” in temperate and boreal forests

13. Extinction Immigration Extinction (small island) Immigration Immigration (far island) Extinction (near island) (large island) Extinction Immigration (far island) Rate of immigration or extinction Rate of immigration or extinction Rate of immigration or extinction (large island) Extinction Immigration (near island) (small island) Small island Equilibrium number 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. The equilibrium number of species on anisland represents a balance between the immigration of new species and theextinction of species already there. (b) Effect of island size. Large islands may ultimately have a larger equilibrium num-ber of species than small islands because immigration rates tend to be higher and extinction rates lower on large islands. (c) Effect of distance from mainland. Near islands tend to have largerequilibrium numbers of species thanfar islands because immigration ratesto near islands are higher and extinctionrates lower. Figure 53.27 The equilibrium model of island biogeography

14. Table 53.1 Interspecific Interactions