Population Ecology 4 CHAPTER Big Question: How do changes in population size relate to environmental conditions? Placeholder opening page, but maybe we can duplicate the look of the SE chapter opener page by using the same fonts and colors (and maybe that Ch 14 icon?)

Finding Gold in a Costa Rican Cloud Forest Golden toads lived in Costa Rica’s Monteverde cloud forest. Golden toads were first described in 1964. They were extinct by 1989. Talk About It Why is the extinction of the golden toad a global concern?

Lesson 4.1 Studying Ecology Ernst Haeckel defined ecology in 1866 as “the body of knowledge concerning the economy of nature—the total relations of the animal to both its inorganic and organic environment.”

Lesson 4.1 Studying Ecology Objectives Describe the different levels of organization studied by ecologists. Explain the difference between biotic an abiotic factors. Discuss how an organism’s habitat relates to its survival.

Ecology Ecologists study life at many levels, from individual organisms to the entire biosphere. The study of how organisms interact with each other and with their environments.

Levels of Ecological Organization Lesson 4.1 Studying Ecology Levels of Ecological Organization The study of how organisms interact with each other and with their environments Scientists study ecology at various levels of organization.

Biotic and Abiotic Factors Lesson 4.1 Studying Ecology Biotic and Abiotic Factors Biotic factors: Parts of an ecosystem that are living or used to be living Abiotic factors: Parts of an ecosystem that have never been living Did You Know? Decaying organisms are biotic factors as long as their structure remains cellular.

Habitat The specific environment in which an organism lives Lesson 4.1 Studying Ecology Habitat The specific environment in which an organism lives Habitats provide an organism with resources—anything an organism needs to survive and reproduce, including food, shelter, and mates.

Lesson 4.1 Studying Ecology Assessments Apply Concepts: Would all the different kinds of organisms in a pond be considered a population or a community? Explain. Explain: In your own words, explain how an organism can be dead, yet still considered a biotic factor. Apply Concepts: Why do different organisms live in different habitats? Big Question: For each of the levels of ecological organization, state whether it contains only biotic factors, only abiotic factors, or both biotic and abiotic factors.

Lesson 4.2 Describing Populations From 1900 to 2000, the white-tailed deer population of New York state grew from about 20,000 to more than 1 million. Densities of more than 100 deer per sq mi occur in some metropolitan areas.

Lesson 4.2 Describing Populations Objectives Explain the usefulness of tracking population size. Define population density. Describe the three ways populations can be distributed. Explain what age structure diagrams tell you about a population.

Lesson 4.2 Describing Populations Population Size The number of individuals in a population at a given time Sudden and dramatic decreases in population size can indicate an unhealthy population headed toward extinction. Ecologists often use sampling techniques to estimate population size. Did You Know? The passenger pigeon was once North America’s most abundant bird. Hunting drove them to extinction in less than 100 years. Counting Laysan Albatross Nests

Population Density Measure of how crowded a population is Lesson 4.2 Describing Populations Population Density Measure of how crowded a population is Larger organisms generally have lower population densities. Low population density: More space, resources; finding mates can be difficult High population density: Finding mates is easier; tends to be more competition; more infectious disease; more vulnerability to predators Northern pintail ducks

Population Distribution Lesson 4.2 Describing Populations Population Distribution How organisms are arranged within an area: Random distribution: Organisms arranged in no particular pattern Uniform distribution: Organisms evenly spaced Clumped distribution: Organisms grouped near resources; most common distribution in nature

Name that distribution type! Clumped!

Name that distribution type! Random !

Name that distribution type! Uniform!

Lesson 4.2 Describing Populations Age Structure Relative number of organisms of each age group within population Can be used to predict future population growth of a population

Sex Ratios Proportion of males to females Lesson 4.2 Describing Populations Sex Ratios Proportion of males to females Age structure diagrams give information about sex ratios. For a monogamous species, the ideal sex ratio is 50:50.

Lesson 4.2 Describing Populations Assessments Relate Cause and Effect: How is a population’s size related to its well-being? Calculate: Which population of flamingos is more dense: 15 flamingos in a 5-square-meter area, or 40 flamingos in a 10-square-meter area? Apply Concepts: Describe the three patterns of population distribution. Which of these is the most common distribution in nature? Infer: Which of the populations shown in Figure 6 do you think is most likely to get bigger in size? Explain your reasoning.

Lesson 4.3 Population Growth From 1800 to today, the human population has grown from about 1 billion to more than 6.8 billion—an exponential rate of increase.

Lesson 4.3 Population Growth Objectives Describe the factors that influence a population’s growth rate. Explain exponential growth and logistic growth. Explain how limiting factors and biotic potential affect population growth.

Lesson 4.3 Population Growth Birth and Death Rates A population’s relative birth and death rates (mortality and natality) affect how it grows. Survivorship curves show how the likelihood of death varies with age.

Birth or death rate per 1,000 population Birth and death rates and age structure affect population growth The demographic transition Is the shift from high birth rates and death rates to low birth rates and death rates 50 40 30 20 10 1900 1925 1950 1975 2000 2025 2050 Year Birth rate Death rate Birth or death rate per 1,000 population Figure 36.10A

Immigration and Emigration Lesson 4.3 Population Growth Immigration and Emigration In addition to births and deaths, population growth is affected by immigration and emigration—individuals moving into and out of a population. Migration, seasonal movement into and out of an area, can temporarily affect population size.

Calculating Population Growth Lesson 4.3 Population Growth Calculating Population Growth Determined by the following equation: (birthrate + immigration rate) – (death rate + emigration rate) Growing populations have a positive growth rate; shrinking populations have a negative growth rate. Usually expressed in terms of individuals per 1000

Did You Know? Immigration contributes more than 1 million people to the U.S. population per year.

Lesson 4.3 Population Growth Exponential Growth Population increases by a fixed percentage every year. Normally occurs only when small populations are introduced to an area with ideal environmental conditions Rarely lasts long

Logistic Growth and Limiting Factors Lesson 4.3 Population Growth Logistic Growth and Limiting Factors Growth almost always slows and stops due to limiting factors. Limiting factors: Environmental characteristics slow population growth and determine carrying capacity.

What can Impact the Carrying Capacity of a Population Density Dependent Limiting Factors Density-dependent: Influence changes with population density. Density Independent Limiting Factors Density-independent: Influence does not change with population density.

Identify if the following are DENSITY-DEPENDENT OR DENSITY-INDEPENDENT LIMITING FACTORS: Humans altering ecosystem Not enough food Predators Parasites Not enough space Construction Diseases Build-up of wastes

Lesson 4.3 Population Growth Biotic Potential An organism’s maximum ability to produce offspring in ideal conditions Many factors influence biotic potential, including gestation time and generation time. Organisms with high biotic potential can recover more quickly from population declines than organisms with low biotic potential.

Lesson 4.3 Population Growth Assessments Calculate: A population has a birthrate of 10/1000, a death rate of 9/1000, an immigration rate of 3/1000, and an emigration rate of 7/1000. What is the population’s growth rate? Is the population getting larger or smaller? Compare and Contrast: What is the difference between exponential growth and logistic growth? Which is more common over long terms in nature? Apply Concepts: In your own words, define limiting factor and biotic potential.