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Biology LibreTexts

24: Ecology

  • Page ID
    22634
  • This chapter introduces the fundamentals of ecology, describes terrestrial and aquatic biomes, and outlines ecosystem processes and their value to humans. The chapter also describes interspecific relationships in communities, how energy flows through ecosystems, and how matter is recycled through ecosystems.

    • 24.1: Case Study - The Web of Life
      Camille grew up in a rural farming community, and both of her parents worked on a local farm. When pesticides were being applied to the crops, as in the picture above, her parents had to use special protective equipment such as coveralls, gloves, and respirators. This is because many pesticides, which are substances that protect plants from damage and destruction by pests such as insects, can be hazardous to human health if inhaled, consumed, or absorbed through the skin. Camille began to wonder
    • 24.2: Introduction to Ecology
      You can certainly be excused for not recognizing the red-tipped organisms in this photo. They weren’t even discovered until 1977. Called tube worms, they live on the deep ocean floor, thousands of meters below the water’s surface.
    • 24.3: Ecosystems
      An ecosystem is a set of interacting components that form a complex whole including all of its living things and its nonliving environment. The nonliving environment includes such abiotic factors as temperature, water, sunlight, and minerals in soil. A community is the biotic part of an ecosystem. It consists of all the populations of all the species that live and interact in the ecosystem. The abiotic and biotic parts of an ecosystem are linked together by flows of energy and cycles of nutrient
    • 24.4: Community Relationships
      If you saw the movie Finding Nemo, then you probably recognize the colorful fish in this picture. The Marlin character in the movie was based on fish like these. Commonly referred to as clownfish, they are shown here swimming around the waving tentacles of animals called sea anemones. Sea anemones are predators that kill any prey that come too close by injecting poison with their tentacles. The anemones don’t harm the clownfish, perhaps because they are coated with mucus.
    • 24.5: Energy in Ecosystems
      It’s easy to see why the aquatic creature in this photo is commonly called a sea angel. It has gossamer-like “wings” that flutter gently and help it swim, and its diaphanous body gives it an otherworldly appearance. Although it appears angelic, this tiny invertebrate is actually a vicious predator.
    • 24.6: Cycles of Matter
      The water and chemical elements that organisms need continuously cycle through ecosystems, passing repeatedly through their biotic and abiotic components. These cycles are called biogeochemical cycles because they are cycles of chemicals that include both organisms (bio) and abiotic components such as the ocean or rocks (geo). As matter moves through a biogeochemical cycle, it may be held for various periods of time in different components of the cycle.
    • 24.7: Introduction to Human Populations
      It’s been called the world’s most successful weed species because it has grown so quickly in numbers and spread so far geographically. Everywhere this species has gone, it has taken over local ecosystems. Is the species in question a weedy plant like the dandelions pictured here? No; that dubious honor has been given to our own species, Homo sapiens.
    • 24.8: Population Dynamics
      Populations are dynamic. They are continuously gaining individuals through births and losing individuals through deaths. Populations may also gain or lose significant numbers of individuals through migration, when people either enter or leave a population. All of these factors together determine whether and how quickly a population grows. Population growth rates may change over time. Two well-studied patterns of change in population growth rates are exponential and logistic growth.
    • 24.9: Climate Change
      This image represents the biggest problem that the human species has ever faced: the current trend in global warming. There is no longer any doubt that our planet is growing warmer and that human actions are the primary cause. There is also no question that if we don’t do something about it soon, the consequences will be devastating.
    • 24.10: Case Study Organic Conclusion and Chapter Summary
      These organic tomatoes look delicious, but is it worth choosing them over less expensive conventionally-produced tomatoes? Camille, who you read about in the beginning of the chapter, asks herself questions like this whenever she goes food shopping. If organic agricultural practices are significantly better for the environment, she would like to buy organic food products at least some of the time. But are they better? And if so, how?

    Thumbnail: Bumblebee pollinating Aquilegia vulgaris. Image used with permission (CC BY-SA 3.0 Unported; Roo72).