Chapter 24

Summary		Questions		Media Resources
24.1 Populations are individuals of the same species that live together.
• Populations are individuals of the same species living together in one place. A population's range, the area in which the population exists, can change over time. • Populations may be dispersed in a random, uniform, or clumped manner.		1.  What are the three types of dispersion in a population? Which type is most frequently seen in nature? Why? 2.  What are some causes of clumped distributions?		• Introduction to Populations •Population Characteristics •Snakes in Ireland
24.2 Population dynamics depend critically upon age distribution.
• The growth rate of a population depends on its age structure, and to a lesser degree, sex ratio. • Survivorship curves describe the characteristics of mortality in different kinds of populations.		3.  What is survivorship? Describe the three types of survivorship curves and give examples of each. 4.  What is demography? How does a life table work?		•Deer Hunting •Survivorship Curves
24.3 Life histories often reflect trade-offs between reproduction and survival.
• Organisms balance investment in current reproduction with investment in growth and future reproduction.		5.  Why do some birds lay fewer than the optimal number of eggs as predicted by David Lack?		• Tropical Songbirds Lay Fewer Eggs
24.4 Population growth is limited by the environment.
• Population size will change if birth and death rates differ, or if there is net migration into or out of the population. The intrinsic rate of increase of a population is defined as its biotic potential. • Many populations exhibit a sigmoid growth curve, with a relatively slow start in growth, a rapid increase, and then a leveling off when the carrying capacity of the environment is reached. • Density-dependent factors affect a population that is approaching its carrying capacity. • Density-independent factors have the same impact on a population no matter what its density. • Large broods and rapid rates of population growth characterize r-strategists. K-strategists are limited in population size by the carrying capacity of their environments; they tend to have fewer offspring and slower rates of population growth.		6.  Define the biotic potential of a population. What is the definition for the actual rate of population increase? What other two factors affect it? 7.  What is an exponential capacity for growth? When does this type of growth naturally occur? Give an example. 8.  What is carrying capacity? Is this a static or dynamic measure? Why? 9.  What is the difference between r- and K-selected populations?		•Stages of Population Growth • Size Regulation •Coral Reefs Threatened •Prairie Habitat Fragmentation •Was Malthus Mistaken? •Population Growth
24.5 The human population has grown explosively in the last three centuries.
• Exponential growth of the world's human population is placing severe strains on the global environment.		10.  How do population pyramids predict whether a population is likely to grow or shrink?		•Exponential Population Growth •Population Growth •Human Population • Class of 2000 Science for the Future •History of Human Population •Population Pyramids from 1990

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