Jonathan B. Losos
Autecology refers to how a single species interacts with the environment; its counterpart is synecology, which refers to how multiple species interact with each other. This latter term is mostly congruent with the field of community ecology, the subject of part III of this volume.
Integral to any discussion of autecology is the concept of the niche. This concept has a long and checkered history in the field of ecology, and the term itself has taken on different meanings through time (chapter I.1). In the most general sense, however, we may think of the niche of a population as the way members of that population interact with their environment, both biotic and abiotic. In other words, the term “niche” refers to where organisms live and what they do there.
The first step in considering how organisms interact with their environment is investigating how the specific phenotypic characteristics of members of a population allow them to exist in a particular environment. The environment poses a wide variety of challenges to organisms: for example, they must be able to obtain and retain enough water, withstand high or low temperatures, and obtain enough nutrients to survive. More than a century of research has revealed that species, and even populations of species, are often finely tuned to the specific conditions in the environment in which they live. In recent years, increasingly sophisticated approaches and instrumentation have allowed an exquisitely detailed understanding of the physiological basis of organismal function (chapters I.2–I.4).
Animals—and, in some sense, fast-growing plants— also can influence the way they interact with their environment through behavioral means. For example, animals can choose the habitat in which they occur and thus can determine, to some extent, the environment they experience throughout their lives (chapter I.5). Many organisms move from their birth site at a particular stage in life; although for plants and some animals, dispersal is passive, other species actively choose where to settle (chapter I.6).
Behavior, of course, is a key component of how most animals interact with their environment. Almost all aspects of the natural history of animals have a behavior component. In part I, we consider foraging (chapter I.7) and social behavior (chapter I.8). Other topics are included in parts II and VI of this volume.
Most plants have relatively little ability to determine the environmental conditions they experience. But plants often have another option available—they frequently exhibit substantial phenotypic plasticity, which allows a plant to alter its phenotype in an advantageous way to be better suited to its environment. Scientists have long appreciated this ability in plants, and zoologists have come to realize relatively recently that many animal species exhibit adaptive phenotypic plasticity as well (chapter I.9).
Organisms adapt in yet another way, by molding their life cycle—what is termed “life history”—to the particular environment in which they live (chapter I.10). Thus, species in environments in which resources are abundant and threats are common may have short generation times and early reproduction. Conversely, in environments in which resources are more scarce but threats are not as severe, a more successful strategy may be to defer reproduction and to invest in becoming better competitors for resources, delaying reproduction and ultimately producing fewer, but better provisioned, offspring.
No species occurs everywhere in the world. The behavior and physiological capabilities of a species determine where a species can and cannot occur. In the last few years, advances in remote sensing technology have provided the capability to visualize the distribution of environmental conditions with great precision over large spatial scales (chapter I.11). Combined with records of species occurrences and, ideally, an understanding of species’ physiological capabilities, these geographic information systems approaches have opened new vistas for understanding how and why species occur where they do; these approaches are also of great importance in predicting how species will respond to rapidly changing environmental conditions