Copyright Pearson Prentice Hall Biology Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 5-1 How Populations Grow Photo Credit: © Frans Lanting/Minden Pictures, Inc. Copyright Pearson Prentice Hall

Characteristics of Populations What characteristics are used to describe a population? Copyright Pearson Prentice Hall

Characteristics of Populations Three characteristics of a population: geographic distribution population density growth rate Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Population Growth Population Growth Three factors can affect population size: the number of births the number of deaths the number of individuals that enter or leave the population A population can grow when its birthrate is greater than its death rate. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Population Growth Immigration - the movement of individuals into an area, is another factor that can cause a population to grow. Emigration- the movement of individuals out of an area, can cause a population to decrease in size. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Exponential Growth Types of Growth Exponential Growth: If unlimited resources, a population will grow exponentially. Logistic Growth: As resources become limited, the growth of a population slows or stops. . Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Carrying Capacity Largest numbers of individual a given environment can support Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Limiting Factors Limiting Factors a factor that causes population growth to decrease. Can be Density dependent – factor depends on number of individuals in area Density Independent – factor is not affected by number of individuals in area Copyright Pearson Prentice Hall

Density-Dependent Factors Density-dependent limiting factors include: competition predation parasitism disease Copyright Pearson Prentice Hall

Density-Dependent Factors Competition Compete for food, water space, sunlight and other essentials. Competition can occur within a species or between species - Could result in species evolving to occupy new niches Copyright Pearson Prentice Hall

Density-Dependent Factors Predation Predator-prey relationship: Populations in nature are often controlled by predation. Copyright Pearson Prentice Hall

Density-Dependent Factors Wolf and Moose Populations on Isle Royale The relationship between moose and wolves on Isle Royale illustrates how predation can affect population growth. In this example, the moose population was also affected by changes in food supply, and the wolf population was also affected by disease. Moose Wolves Copyright Pearson Prentice Hall

Density-Independent Factors Density-independent limiting factors affect all populations in similar ways, regardless of the population size. Copyright Pearson Prentice Hall

Density-Independent Factors Examples of density-independent limiting factors include: Weather, natural disasters, and seasonal cycles Certain human activities—such as damming rivers and clear-cutting forests Environmental conditions - climate, pollution Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Is humans hunting deer a density dependent or independent factor? Copyright Pearson Prentice Hall