Lecture Exam 2 (Chapters 4–6) – Study Guide

I. Species Interactions and Community Ecology (Chapter 4)

Competition

• Occurs when organisms use the same limited resource.

• Intraspecific = within the same species.

• Interspecific = between different species.

• Be able to clearly distinguish between these two types.

• Limited resources (food, space, light) drive competition.

• Resource partitioning reduces competition by allowing species to use resources

differently.

Predation and Trophic Structure

• Predation = one organism consumes another.

• Producers capture energy through photosynthesis.

• Energy decreases as it moves through an energy pyramid.

• A trophic cascade occurs when changes at the top (e.g., predator removal) affect lower

levels.

• Understand cause-and-effect relationships in trophic cascades.

Keystone Species

• A species with a disproportionately large effect on its ecosystem.

• Removing a keystone species can dramatically alter community structure.

Disturbance, Resistance, and Resilience

• Disturbance = rapid, drastic change (fire, storm, human impact).

• Resistance = ability to remain stable during disturbance.

• Resilience = ability to recover after disturbance.

• Be able to distinguish resistance from resilience.

Succession

• Primary succession occurs where soil has been removed (e.g., glacier retreat).

• Secondary succession occurs where soil remains (e.g., after fire).

• Secondary succession generally proceeds more quickly.

• Over time, species composition and biodiversity change.

Invasive Species

• Non-native species that spread rapidly in new environments.

• Prevention is emphasized because eradication is difficult and costly.

• Understand why invasive species can disrupt ecosystem balance.

Biomes

• Large ecological regions defined primarily by climate and dominant vegetation.

• Temperature and precipitation determine biome distribution.

• Be able to recognize general characteristics of major biomes shown in lecture.

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II. Economics and the Environment (Chapter 5)

Economic Systems

• Economies convert natural resources into goods and services.

• Ecosystem services include benefits such as soil formation, water purification, and

pollination.

• Understand that natural systems support economic systems.

Market Failure

• Occurs when prices do not reflect true environmental costs or benefits.

• External costs (negative externalities) affect people not involved in a transaction.

• Environmental problems often arise when these costs are not included in prices.

Tragedy of the Commons

• Shared resources can be overused when individuals act in their own interest.

• Understand why common resources are vulnerable to depletion.

Free Riders

• Individuals who benefit from a shared resource without contributing.

• Recognize examples of free-rider problems.

Internalizing Costs

• Including environmental costs in product pricing.

• Full cost accounting evaluates all costs and benefits.

• Understand why internalizing costs can change behavior.

GDP vs GPI

• GDP measures economic output only.

• GPI adjusts for environmental and social factors.

• Understand why GDP alone may not reflect overall well-being.

Environmental Policy

• Requires scientific input, ethical considerations, and economic analysis.

• Congress creates legislation.

• The Executive branch (including EPA) implements laws.

• Courts interpret laws.

• Be able to identify the role of each branch.

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III. Human Population and Demography (Chapter 6)

Exponential Growth

• Occurs when growth rate remains constant as a percentage.

• Doubling time can be estimated using the Rule of 70.

• Be able to recognize exponential growth on a graph.

Fertility and Mortality

• Total fertility rate (TFR) = average number of children per woman.

• Replacement fertility ≈ 2.1 in developed nations.

• Infant mortality rate reflects health care and living conditions.

• Understand how fertility and mortality influence population growth.

Demographic Transition Model

• Pre-industrial: high birth and death rates.

• Transitional: death rates decline; birth rates remain high.

• Industrial/Post-industrial: both birth and death rates low.

• Understand why death rates decline first in the transitional stage.

• Be able to recognize stages if shown a population graph.

Population and Development

• As nations become wealthier and more educated, fertility rates tend to decline.

• Family planning allows individuals to control number and spacing of children.

• Education of women is strongly linked to lower fertility rates.

Ecological Footprint and Overshoot

• Ecological footprint = amount of biologically productive land and water needed to support

consumption.

• Biocapacity = available productive area.

• Overshoot occurs when footprint exceeds biocapacity.

• Understand what overshoot implies for long-term sustaina