Transcript biology
biology Slide 1 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Slide 2 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Limiting Factors What factors limit population growth? Slide 3 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Limiting Factors Limiting Factors The primary productivity of an ecosystem can be reduced when there is an insufficient supply of a particular nutrient. Ecologists call such substances limiting nutrients. Slide 4 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Limiting Factors A limiting nutrient is an example of a more general ecological concept: a limiting factor. In the context of populations, a limiting factor is a factor that causes population growth to decrease. Slide 5 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Density-Dependent Factors A limiting factor that depends on population size is called a density-dependent limiting factor. Slide 6 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Density-dependent limiting factors include: • competition • predation • parasitism • disease Slide 7 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Density-dependent factors operate only when the population density reaches a certain level. These factors operate most strongly when a population is large and dense. They do not affect small, scattered populations as greatly. Slide 8 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Competition When populations become crowded, organisms compete for food, water space, sunlight, and other essentials. Competition among members of the same species is a density-dependent limiting factor. Slide 9 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Competition can also occur between members of different species. This type of competition can lead to evolutionary change. Over time, the species may evolve to occupy different niches. Slide 10 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Predation Populations in nature are often controlled by predation. The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanisms of population control. Slide 11 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Wolf and Moose Populations on Isle Royale Moose Wolves Slide 12 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Dependent Factors Parasitism and Disease Parasites can limit the growth of a population. A parasite lives in or on another organism (the host) and consequently harms it. Slide 13 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Independent Factors Density-Independent Factors Density-independent limiting factors affect all populations in similar ways, regardless of the population size. Slide 14 of 21 Copyright Pearson Prentice Hall 5-2 Limits to Growth Density-Independent Factors Examples of density-independent limiting factors include: • unusual weather • natural disasters • seasonal cycles • certain human activities—such as damming rivers and clear-cutting forests Slide 15 of 21 Copyright Pearson Prentice Hall 5-2 Click to Launch: Continue to: - or - Slide 16 of 21 Copyright Pearson Prentice Hall 5-2 A limiting factor that affects all populations in similar ways regardless of their size might be a. drought. b. disease. c. predation. d. crowding. Slide 17 of 21 Copyright Pearson Prentice Hall 5-2 Which of the following would be a limiting factor affecting the panda population of China? a. programs that educate people about endangered species b. capture of some pandas for placement in zoos c. laws protecting habitat destruction d. a disease that kills bamboo plants Slide 18 of 21 Copyright Pearson Prentice Hall 5-2 Density-dependent factors operate most strongly when a population is a. large and dense. b. large but sparse. c. small and sparse. d. small, but growing. Slide 19 of 21 Copyright Pearson Prentice Hall 5-2 Within a limited area, if the population of a predator increases, the population of its prey is likely to a. increase. b. decrease. c. remain about the same. d. become extinct. Slide 20 of 21 Copyright Pearson Prentice Hall 5-2 Which of the following is a density-independent factor affecting populations? a. predation b. disease c. a destructive hurricane d. parasites Slide 21 of 21 Copyright Pearson Prentice Hall END OF SECTION