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Ch 18: Principles of Ecology

About This Chapter

Watch interesting ecology video lessons with quick quizzes to measure your understanding. Learn about ecosystems, biomes, changing populations and more.

Principles of Ecology

Welcome to the the world of ecology. Actually, there's no escaping it, since it encompasses the interactions of organisms with their environments, which includes you. In terms of scale, we'll look at individual organisms, populations, communities, ecosystems and the biosphere. Along with organisms, you'll examine abiotic factors that also make up an ecosystem. From tundras to tropical rainforests, parts of the Earth with similar abiotic and living factors are classified as biomes. How are they classified, and which biomes have the most biomass? Our lessons will teach you all this and more.

We'll also address the stunning diversity of species that can be found in ecosystems both large and small. For example, how is it possible for lions, leopards and cheetahs to coexist in the Serengeti? Each species has a suitable habitat within an ecosystem. Each species also carves out a niche that allows them to play a specialized role in that habitat. See how a variety of habitats and niches can allow many species to coexist within a single ecosystem.

You'll see the big picture and its individual components as we work through the trophic levels of a food chain. You'll meet autotrophs, herbivores, carnivores, omnivores and detrivores while we navigate a food web, a combination of interconnected food chains. Our lessons will also dive further into the connections between species, from competition to symbiosis, by looking at predators and prey, parasites and hosts as well as native and invasive species.

An ecosystem constitutes a complex, dynamic balance, and it can only support so many organisms. We'll cover population density and carrying capacity. Learn which limiting factors depend on population density and which factors operate independently of it. Populations grow, shift and disperse, so we'll enter the arena of biogeography and examine migration, emigration and immigration. Just like populations, ecosystems aren't static, so one of our lessons will cover ecological succession, the changes that ecosystems and their communities undergo.

You, and humans in general, are perhaps the most influential animal. Our growing population has spread across the Earth, and we have a greater capacity than ever before to manipulate many different ecosystems, including the biosphere. Unfortunately, we may be the ultimate invasive species. We'll examine the phosphorus, carbon and nitrogen cycles in the context of ecological balance and environmental pollution. We weren't kidding when we said welcome to world of ecology. It's a vast field, but our lessons will give you a deeper understanding of this awesome realm and your place in it.

18 Lessons in Chapter 18: Principles of Ecology
The Environment, Levels of Ecology and Ecosystems

1. The Environment, Levels of Ecology and Ecosystems

Do you know the difference between an environment and an ecosystem? In this lesson, you'll find out what makes an environment, and what makes an ecosystem. You'll also learn what ecology is and some of the ways that scientists study ecology using organisms, populations, communities, ecosystems and even the entire biosphere.

Ecosystems, Habitats and Ecological Niches

2. Ecosystems, Habitats and Ecological Niches

Check out this video lesson to understand the many complex aspects of an ecosystem. See how animals live in habitats and survive amongst their surroundings.

Food Chains, Trophic Levels and Energy Flow in an Ecosystem

3. Food Chains, Trophic Levels and Energy Flow in an Ecosystem

In this lesson, you'll learn about food chains, food webs, and the different roles that organisms play in an ecosystem. You'll also learn about how energy flows through an ecosystem.

Interspecific Competition, Competitive Exclusion & Niche Differentiation

4. Interspecific Competition, Competitive Exclusion & Niche Differentiation

What happens when two similar species that consume the same resources occupy the same space? Interspecific competition, that's what! Watch our video lesson to learn about the outcomes of this ecological battle.

Predator/Prey Interactions, Camouflage, Mimicry & Warning Coloration

5. Predator/Prey Interactions, Camouflage, Mimicry & Warning Coloration

You probably know that skunks can be quite stinky, bees sting and monarch butterflies are pretty, but do you know why? This lesson will introduce you to the reasons why some animals look or act the way they do and how these things relate to the predator/prey relationship.

Symbiotic Relationships: Mutualism, Commensalism & Parasitism

6. Symbiotic Relationships: Mutualism, Commensalism & Parasitism

If your cat or dog has ever had fleas, you've witnessed symbiosis in action. In this lesson, learn the many types of symbiosis in biology, and how these relationships can have a positive, negative, or neutral effect on the individual species.

Populations: Density, Survivorship and Life Histories

7. Populations: Density, Survivorship and Life Histories

Have you ever wondered how biologists determine the populations of animals in a particular geographic area? Watch this video lesson to find out, and discover how scientists look at the survivorship and life histories of many different species.

Carrying Capacity, Migration & Dispersion

8. Carrying Capacity, Migration & Dispersion

Have you ever wondered why some types of birds fly south in the winter or why some animals form territories? Watch this video to learn about a species' maximum growth capabilities, the way its members group themselves and why they might migrate to new locations every year.

Dispersal, Colonization, and Island Biogeography

9. Dispersal, Colonization, and Island Biogeography

Have you ever gone in your backyard and discovered a wild raspberry bush that has never been there before? How did it get there? Why is there only one bush year after year? In this lesson, you'll study how plant and animal species colonize in new areas through dispersal and immigration and how some species thrive in a new area while others fail.

Conservation Biology, Habitat Fragmentation, and Metapopulations

10. Conservation Biology, Habitat Fragmentation, and Metapopulations

It's becoming harder to conserve large, unbroken tracts of wilderness. Is there another way for conservation biologists to ensure the survival of a species? In this lesson, you'll learn about habitat fragmentation and metapopulations.

Ecological Succession: From Pioneer to Climax Communities

11. Ecological Succession: From Pioneer to Climax Communities

Just as people grow and change so, too, do ecosystems. Watch this lesson to learn about ecological succession from the beginning stages of development to a community's ultimate destination, or climax.

How Introduced and Invasive Species Alter Ecological Balance

12. How Introduced and Invasive Species Alter Ecological Balance

What happens to your block when a new neighbor moves in? Something changes, right? Now think about that on an ecological scale: what happens to an environment when a new SPECIES moves in?

Biomes: Desert, Tropical Rainforest, Savanna, Coral Reefs & More

13. Biomes: Desert, Tropical Rainforest, Savanna, Coral Reefs & More

Take a trip around the world and learn all about different biomes. Why can you only find certain plants and animals in specific places? What are the most fertile climates on Earth? Watch on to answer these and other questions.

Biomes: Tundra, Taiga, Temperate Grassland, and Coastlines

14. Biomes: Tundra, Taiga, Temperate Grassland, and Coastlines

Take a trip with us in this lesson, starting in the Pacific Ocean, traveling across California through the Central Valley and up to the peaks of the Sierra Nevada mountains. We'll learn how oceans, elevation, and people can determine which types of biomes are found in different areas and check out the Earth's most massive and oldest organisms.

Biogeochemical Cycling and the Phosphorus Cycle

15. Biogeochemical Cycling and the Phosphorus Cycle

In this video lesson, we'll take a look at how elements large and small use other elements to grow. This is achieved through cycles. We'll look at macronutrients, trace elements and the biogeochemical and phosphorous cycles.

The Nitrogen Cycle, Acid Rain and Fossil Fuels

16. The Nitrogen Cycle, Acid Rain and Fossil Fuels

Do you know the difference between nitrite and nitrate? Do you have any clue how all the nitrogen in the atmosphere becomes usable? If you can't answer these questions, then you need to watch this lesson on the nitrogen cycle.

The Carbon Cycle and Long-Term Carbon Storage

17. The Carbon Cycle and Long-Term Carbon Storage

All living organisms have a role in the carbon cycle. Do you know you understand how humans, animals and plants use carbon? This lesson will introduce you to the carbon cycle and explain how it functions on a global scale.

Fossil Fuels, Greenhouse Gases, and Global Warming

18. Fossil Fuels, Greenhouse Gases, and Global Warming

In this video lesson, you'll learn what roles fossil fuels and greenhouse gases play in global warming, as well as what life on Earth can expect due to rising carbon dioxide levels within Earth's atmosphere.

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