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FINAL OUTLINE - Chapter Learning Objectives Chapter 39...

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Chapter Learning Objectives Chapter 39: Population Growth and Regulation Define ecology and population - Ecology : the study of interrelationships between living things and their nonliving environment. - Population : all the members of a particular species within an ecosystem and can potentially interbreed. 39.1 How does population size change? - Three factors determine whether and how much the size of a population changes: Births , Deaths , and Migrations (immigration= migrate in , emigration= migrate out ) - (births – deaths) + (immigrants – emigrants) = change in population size Distinguish between biotic potential and environmental resistance Biotic potential : the maximum rate at which the population could increase, assuming ideal conditions that allow a maximum birth rate and a minimum death rate. FACTORS 1. The age at which the organism first reproduces 2. The frequency at which reproduction occurs 3. The average number of offspring produced each time 4. The length of the organism’s reproductive life span 5. The death rate of individuals under ideal conditions Environmental resistance : Limits set by the living and nonliving environments (biotic and abiotic). Environmental resistance is imposed by the availability of food, space, competition with other organisms, and certain interactions among species such as predation and parasitism. FACTORS 1. Food 2. Space 3. Competition with other organisms 4. Certain interactions among species 5. Predation 6. Parasitism 7. Natural disasters Describe the variables involved in the exponential model of population growth The graph of an exponential model is J-shaped. The growth rate (r) of a population is the change is a measure of the change in population size per individual during a given unit of time. Growth rate (r) = birth rate (b) – death rate (d) Birth rate (b) is the average number of births per individual per unit time.
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Death rate (d) is the proportion of individuals dying per unit time. Population growth rate = (r)( N ); growth rate time original population size respectively. 39.2 How is population growth regulated? Exponential growth cannot continue indefinitely. Compare the exponential model of population growth with the S-curve model of population growth - S-curve: the population grows exponentially at first, and then fluctuates around the carrying capacity. The growth is driven by biotic potential, but levels off because of environmental resistance - Exponential growth model results in a J-shaped growth curve, even if the population is increasing at a constant rate, the population accumulates more new individuals per unit of time when it is large than when it is small. (this creates the J-shape) Explain how an environment’s carrying capacity affects the per capita rate of increase of a population - Carrying capacity is the maximum population size that a particular environment can support.
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