restricted access What Is Ecology?
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What Is Ecology? Mark A. McPeek Before you begin reading this,take a few minutes to use all your senses and find out as much as you can about your surroundings. How well did you take in your surroundings? Are you warm, chilled, or comfortable right now? Does the air feel dry or damp? Is the breeze moving air past you, and, if so, in what direction? Do you see or smell any food around you, and if so, is it something you’d like to eat? Are other people near you who might also like to eat that food? Can they potentially get to it before you do? Do you see any place where you could get water or something else to drink? Are any potential threats near you, like a street with traffic, a tree that’s just about to fall over, a wasp that might sting you, or a large, threatening dog? Any question about your surroundings and about how well or poorly you might do in the surroundings in which you find yourself is a question about your ecology.The study of ecology is the inquiry into organisms and their environment. Where are particular species found? What makes them successful in the places where they are found, and what prevents them from inhabiting other places? Which species can live together and which cannot? How do collections of species found in a particular location alter that environment? These are the major questions addressed by scientists who study ecology—ecologists.Questions about the species that inhabit these environment—Why these species and not others? Where did the dinosaurs go?—raise questions related to evolution.Ecology and evolution are fascinating subjects, and here we’ll explore them both. What Is Ecology? 109 What Is Ecology? Imagine that you are a cheetah on the Serengeti evaluating your surroundings. What questions would you have about your surroundings that would be important to you? Is it so hot that you need to seek shade? Is there water nearby where you can get a cool drink? What prey is around you that you might be able to subdue? What prey must you ignore because they are too well protected by their herd? Are other cheetahs present that might get to that vulnerable prey before you? Are there other larger predators that may be a threat to you personally? In fact,just about any organism—a plant in a field,a fish in a lake,a salamander in a creek, an octopus in the sea, an earthworm in the dirt—has the same questions about its environment. Some subdisciplines of ecology study the fit of an individual organism to its environment. As an illustration of this, let me first ask you what may initially seem a silly question. Why do fish live in the water? If you put a fish on the ground under a tree, it would die in only a few minutes, because many of its essential environmental requirements are missing. Foremost among those requirements is water as a medium and not air. The fish must be in a water medium because its body is built to extract essential oxygen from water and not air, namely through its gills. This may seem a ludicrous question to ask, but it illustrates a broader issue. This question illustrates how scientists approach these questions.No fish species lives in every environment in which water is the medium. Some fish species are found only in small creeks, some only in large rivers, some only in freshwater lakes, some only in saline lakes, some in the open ocean, and some only in the polar oceans, some only where freshwater rivers enter the ocean. Most of these species are restricted to particular environments because their physiological systems operate best in only a limited range of environmental conditions defined by temperature, water salinity, or oxygen concentration. Species are not just limited in their distribution by their physiological capabilities . For example, many salamander species live in small ponds and creeks, but are never found in larger ponds or streams where fish are present.Ecologists have examined the causes for these types of checkerboard species distributions in many environments with many different types of species. Let’s briefly explore how an ecologist might go about determining why salamanders and fish do not live together. The first thing an ecologist would do is develop a set of hypotheses that she could test. Then for each hypothesis she 110 Mark A. McPeek would...