Transcript Chapter 53
Chapter 53: Community Ecology Figure 53.2 Can a species’ niche be influenced by interspecific competition? EXPERIMENT Ecologist Joseph Connell studied two baranacle speciesBalanus balanoides and Chthamalus stellatusthat 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 Chthamalus Balanus RESULTS High tide Chthamalus realized niche Chthamalus fundamental niche Balanus realized niche Ocean Low tide In nature, Balanus fails to survive high on the rocks because it is unable 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. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ocean CONCLUSION Low tide The spread of Chtamalus when Balanus was removed indicates that competitive exclusion makes the realized niche of Chthamalus much smaller than its fundamental niche. Figure 53.4 Character displacement: indirect evidence of past competition G. fortis G. fuliginosa Percentages of individuals in each size class Beak depth Santa María, San Cristóbal Sympatric populations 40 20 0 Los Hermanos 40 20 0 G. fuliginosa, allopatric Daphne 40 20 0 G. fortis, allopatric 8 10 12 Beak depth (mm) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 14 16 Figure 53.5 Cryptic coloration: canyon tree frog Figure 53.6 Aposematic coloration: poison arrow frog Figure 53.7 Batesian mimicry: A harmless species mimics a harmful one (b) Green parrot snake (a) Hawkmoth larva Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 53.8 Müllerian mimicry: Two unpalatable species mimic each other (a) Cuckoo bee (b) Yellow jacket Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 53.9 Mutualism between acacia trees and ants Figure 53.10 A possible example of commensalism between cattle egrets and water buffalo Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 53.12 Examples of terrestrial and marine food chains Quaternary consumers Carnivore Carnivore Tertiary consumers Carnivore Carnivore Secondary consumers Carnivore Carnivore Primary consumers Zooplankton Herbivore Primary producers Plant A terrestrial food chain Phytoplankton A marine food chain Figure 53.13 An antarctic marine food web Humans Smaller toothed whales Baleen whales Crab-eater seals Birds Leopard seals Fishes Sperm whales Elephant seals Squids Carnivorous plankton Euphausids (krill) Copepods Phytoplankton Figure 53.18 Beavers as ecosystem “engineers” in temperate and boreal forests Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Rate of immigration or extinction Rate of immigration or extinction Rate of immigration or extinction Figure 53.27 The equilibrium model of island biogeography Equilibrium number Number of species on island (a) Immigration and extinction rates. The equilibrium number of species on an island represents a balance between the immigration of new species and the extinction of species already there. Small island Large island Number of species on island (b) Effect of island size. Large islands may ultimately have a larger equilibrium number of species than small islands because immigration rates tend to be higher and extinction rates lower on large islands. Far island Near island Number of species on island (c) Effect of distance from mainland. Near islands tend to have larger equilibrium numbers of species than far islands because immigration rates to near islands are higher and extinction rates lower. Table 53.1 Interspecific Interactions