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Limits to Growth Vocabulary • There are many different factors that can limit the population growth. Limiting factor • A factor that causes population growth to decrease is called limiting factor. Types of Limiting factors Vocabulary Density-dependent limiting factors 1. Density-Dependent limiting factors. a) They depend on population size. b) They become limiting only when the population density reaches a certain level. c) They include competition, predation, parasitism, and disease. Vocabulary • Density-Dependent Limiting Factors 1. Competition: When a population becomes crowded, organisms compete, or struggle, with one another for food, water, space. Competition can also occur between members of different species. Two species cannot occupy the same niche at the same place and time. Predator-prey 2. Predation: Populations in nature are often controlled by predation. relationship Predator-prey relationship 3. Parasitism and disease: Parasites and disease are easier to transmit in a large, and dense population Figure 5-7 Wolf and Moose Populations on Isle Royale Predator-Prey Relationship Section 5-2 60 2400 50 2000 40 1600 30 1200 20 800 10 400 0 1955 1960 1965 1970 1975 Moose Go to Section: 1980 Wolves 1985 1990 1995 0 Vocabulary 2. Density-independent limiting factors. Density-Independent limiting factors a) They affect all populations in similar ways regardless on the population size. b) They include unusual weather, natural disasters, seasonal cycles, and certain human activities (damming rivers, and clear-cutting forests). Populations DensityDependent factors Predation Density-Independent factors Competition Parasitism and disease Unusual weather Natural disasters Some human activities