B 4.2 Ecological Niches PDF

B 4.2 Ecological Niches Essential idea: Dynamic biological processes impact population density and population growth. Fish populations, such as the schooling Anchovies (left) being hunted by the Bluefin Trevally (right) are an excellent example of how dynamic populations are. The process affecting...

B 4.2 Ecological Niches Essential idea: Dynamic biological processes impact population density and population growth. Fish populations, such as the schooling Anchovies (left) being hunted by the Bluefin Trevally (right) are an excellent example of how dynamic populations are. The process affecting population density here is mortality caused by predation. https://commons.wikimedia.org/wiki/File:Moofushi_Kandu_fish.jpg Each species plays a unique role within a community because of the unique combination of its spatial habitat and interactions with other species. Niches are restricted by the competition between species for resources. What is a fundamental niche? ● The resources and habitat that the species could theoretically use. ● Bigger What is a realized niche? ● The resources and habitat that the species is actually able to use. ● Smaller due to competition ○ within the same species (intraspecific) ○ between species (interspecific) Natural Selection and Niches Natural Selection can: ● Evolve species to have a broad range of tolerance. “Generalists.” Natural Selection and Niches Natural Selection can: ● Evolve species with morphological, physiological and/or behavioral specializations for a specific niche. “Specialists.” The result of natural selection Species are ADAPTED to fill a specific NICHE. Structural Adaptations Body anatomy adaptations that help the organism survive in the niche Physiological Adaptations Behavioral Adaptations Adaptations of the Behaviors that help processes within the organism the body that help survive in the niche the organism survive in the niche Two species cannot survive indefinitely in the same habitat if their niches are identical. Analysis of a data set that illustrates the distinction between fundamental and realized niche. C.1.U5 Two species cannot survive indefinitely in the same habitat if their niches are identical. C.1.S1 Analysis of a data set that illustrates the distinction between fundamental and realized niche. Expect : s ’ e s u a G r to a l i m i s s h p of the a r s n g o i e t s a l y u l ana he pop o t t m d o r e f k d s e to be a cies be deduc can t spe e n h e c r i e n f f l i a d t f ndamen ations o l u f u e p h o T p e • d by th cies e e c p u s d d e e d t a isol can be e h c i n d e s ali nteract i o t d e w • The re are allo y e h t r e t af C.1.U5 Two species cannot survive indefinitely in the same habitat if their niches are identical. C.1.U5 Two species cannot survive indefinitely in the same habitat if their niches are identical. C.1.U2 Community structure can be strongly affected by keystone species. A keystone species is one which has a disproportionate effect on the structure of an ecological community. keystone species exerts top-down influence on lower trophic levels and prevents species at lower trophic levels from monopolizing critical resources, such as competition for space or key producer food sources. http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/15829742/f1_wagner.jpg C.1.U2 Community structure can be strongly affected by keystone species. The term keystone species was first coined by Robert Paine (1966): • One of his study sites, located at Mukkaw Bay, contained a community consistently dominated by the same species of mussels, barnacles, and the starfish, Pisaster ochraceus, which preys upon the other species as a top predator. • He selected a "typical" piece of shoreline at Mukkaw Bay, about 8 meters long by 2 meters wide, that was kept free of starfish. • This area was compared to an adjacent, undisturbed control area of equal size. http://www.nature.com/scitable/knowledge/librar y/keystone-species-15786127 http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/15829742/f1_wagner.jpg C.1.U2 Community structure can be strongly affected by keystone species. The intertidal area where Pisaster had been removed was characterized by many changes: • Remaining members of the ecosystem's food web immediately began to compete with each other to occupy limited space and resources. • Within three months of the Pisaster removal, the barnacle, Balanus glandula, occupied 60 to 80% of the available space within the study area. • Nine months later, Blanus glandula had been replaced by rapidly growing populations of another barnacle Mitella and the mussel Mytilus. • This phenomenon continued until fewer and fewer species occupied the area and it was dominated by Mytilus and a few adult Mitella species. • Eventually the succession of species wiped out populations of benthic algae. • This caused some species, such as the limpet, to emigrate from the ecosystem because of lack of food and/or space. • Within a year of the starfish's removal, species diversity significantly decreased in the study area from fifteen to eight species. http://www.nature.com/scitable/knowledge/library/keystone-species-15786127 http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/15829742/f1_wagner.jpg C.1.U2 Community structure can be strongly affected by keystone species. Within a year of the starfish's removal, species diversity significantly decreased in the study area from fifteen to eight species. http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/15 829770/f2_wagner.jpg http://www.nature.com/scitable/knowledge/library/keystone-species-15786127 http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/15829742/f1_wagner.jpg C.1.U2 Community structure can be strongly affected by keystone species. Sea otters regulate sea urchin populations, which in turn feed upon kelp and other macroalgae (Duggins 1980). The otters keep the sea urchin populations in check, thus allowing enough kelp forests to remain as a habitat for a variety of other species. As a result, the entire ecosystem is kept in balance. http://www.nature.com/scitable/knowledge/library/keystone-species-15786127 http://www.vanaqua.org/files/1013/2018/0738/otter-eat.jpg C.1.U2 Community structure can be strongly affected by keystone species. Keystone modifier species, such as the North American beaver (Casor candensis), determine the prevalence and activities of many other species by dramatically altering the environment. http://www.nature.com/scitable/knowledge/library/keystone-species-15786127 http://commons.wikimedia.org/wiki/File:Beaver-Szmurlo.jpg C.1.U2 Community structure can be strongly affected by keystone species. Species like the Saguaro cactus (Carnegiea gigantea) in desert environments and palm and fig trees in tropical forests are called keystone host species because they provide habitat for a variety of other species. Keystone prey are species that can maintain their numbers despite being preyed upon, therefore controlling the density of a predator. http://www.nature.com/scitable/knowledge/library/keystone-species-15786127 http://commons.wikimedia.org/wiki/File:Carnegiea_gigantea_Saguaro_NP_1.jpg