Autecology

by

G.H. Walter

• LAST REVIEWED: 26 August 2021
• LAST MODIFIED: 30 July 2014
• DOI: 10.1093/obo/9780199830060-0102

Introduction

Ecology’s central question is the distribution and abundance of organisms. To this end, autecology quantifies the survival and reproductive consequences of the interactions of individual organisms with their immediate environment, as mediated by their species-specific adaptations. Autecology is, nevertheless, commonly perceived as anecdotal natural history rather than general theory (see History of Autecology) and is consequently poorly developed. The impact of autecology in practice therefore does not reflect its potential. Few textbooks deal solely or even explicitly with autecology, and no journals are dedicated to autecology. Early-21st-century developments should, however, settle these issues (see General Overviews). Autecology, to its advantage, is widely seen to produce useful information, so resolution of these issues should see it put to more-effective use in applied ecology (see Applications of Autecological Knowledge). Autecological theory is based on the following key premises: (1) the environment is structured (seasonally, mostly) and it varies stochastically, (2) each environmental variable may affect organisms in various ways, and each such basis for interaction represents a specific axis of environmental differentiation, (3) the life cycle and seasonal cycle of species must match with the seasonal structure of the environment and its variance if the species is to persist in a locality (Autecological Concept of Environment expands these points), (4) the adaptations of organisms are complex mechanisms that mediate the organism-environment interaction, (5) each species is adapted to a subset of such environmental influences (or axes of differentiation) in any particular locality (hence the individualistic ecology of species), and (6) organisms shift spatially in response to changed environmental conditions to achieve environmental matching (Autecological Perspective on Species and Speciation and Autecological Interactions expand on these last three points). Autecology is thus the investigation and interpretation of the spatio-temporal dynamics of species. The spatial scale is geographic, which accords with the recognition concept of species, as follows. Species are expected to be under stabilizing selection in their usual environment. Adaptive change takes place only under unusual circumstances, when directional selection from the new environment influences the entire population when it is trapped in a different environment. The newly adapted population may then expand into areas of suitable environment. This explains the geographical emphasis of the recognition concept and autecology, and the stability of the primary adaptations of species. In general, organisms are subject to stabilizing selection rather than local, optimizing (or competitive) selection (see Autecological Perspective on Species and Speciation).

General Overviews

Relatively few books deal explicitly with autecology, and these have tended to focus on plants or animals, for no good reason. A vast yet scattered literature started developing in the late 19th century on the environmental variables that influence the changing numbers of organisms. The focus was mainly organisms of economic interest, including many plants and insects, but also various aquatic organisms. Synthesizing this knowledge presented a massive challenge, well illustrated by compilations in Uvarov 1931; Daubenmire 1947; Allee, et al. 1949; and Andrewartha and Birch 1954. Modern revelations of the climatic influences on changing distributions, in Parmesan 2006 and other studies, justify the relevance of the autecological approach, as does the strongly building body of Quaternary ecology data, as detailed in Elias 2010, for example. Andrewartha and Birch 1954 and Andrewartha and Birch 1984, extensive treatments of the distribution and abundance of animals, are the conceptual developments most strongly associated with autecology, even though these authors did not favor the term. They focused on “environment” as a central concept in its influence on the numbers of animals in natural populations, and their ultimate conceptualization of environment into the “envirogram” was intended as a guide to the investigation of any species of interest. Plant autecology followed a slightly different path, perhaps best represented by the synthesis in Daubenmire 1947. The author equated autecology to a consideration of “those phases of geology, soils, climatology, zoology, chemistry, and physics which are more or less directly connected with the welfare of living organisms . . .” (p. ix) and, thus, the “environmental complex” (see Autecological Concept of Environment). The geographic aspects to autecology were, by then, not explicitly articulated. The emphasis on spatial adjustment by organisms (plants and animals) has more recently been fully incorporated into the principles of autecology in Walter and Hengeveld 2014. In short, the evidence and interpretations from Quaternary ecology and dynamic biogeography are bound up in the recognition concept of species, and the whole is explicitly geographic (Autecological Perspective on Species and Speciation). Organisms track the environmental conditions to which they are primarily adapted (Autecological Concept of Environment). The individuals that make up the species’ gene pool are therefore usually under stabilizing selection, and adaptive change and speciation require special conditions (see Autecological Perspective on Species and Speciation). The theory of autecology is expanded in Walter and Hengeveld 2014, which also explains how autecology is linked mechanistically to the other subdisciplines in biology.

• Allee, W. C., A. E. Emerson, O. Park, T. Park, and K. P. Schmidt. 1949. Principles of animal ecology. Philadelphia: W. B. Saunders.

  This monumental volume covers a lot of ground, in depth. Autecology and synecology (here, includes both population and community ecology) are seen as complementary, as in most other texts. You will have to use the index to find specific reference to autecology.

• Andrewartha, H. G., and L. C. Birch. 1954. The distribution and abundance of animals. Chicago: Univ. of Chicago Press.

  This massive interpretive survey has been the text for autecology for over half a century. It analyzes, in depth, the causes of changing abundance in natural populations. Deals with physiological aspects of ecology (innate capacity for increase, diapause, and dispersal) and analysis of environment. Covers a diversity of illustrative examples.

• Andrewartha, H. G., and L. C. Birch. 1984. The ecological web: More on the distribution and abundance of animals. Chicago: Univ. of Chicago Press.

  Notable for extending the authors’ original interpretation of environment (almost one-third of the book) and their general theory of population ecology. They outline a “pragmatic approach to density” in which “spreading of risk” plays a key role. Detailed, illustrative treatment of a few species (insects, birds, rabbits, humans) follows.

• Daubenmire, R. F. 1947. Plants and environment: A textbook of plant autecology. New York: Wiley.

  Details the numerous facets of each environmental variable that affects, in general, the life of plants in nature, and the particular aspects of those impacts. Soil, water, temperature, light, atmospheric influences, biotic influences, and fire are covered in substantial detail, as is the “environmental complex” (see “Autecological Concept of Environment”). Third edition (1974) did not differ much in structure and content.

• Elias, S. A. 2010. Advances in Quaternary entomology. Developments in Quaternary Science 12. Amsterdam: Elsevier.

  Summarizes a large literature on Quaternary insects. The evidence, across many systems and numerous species, shows that species shift geographically as climate changes and that they remain unchanged morphologically, as judged against extant material (because the Quaternary insect fauna has persisted in this way through the various ice ages).

• Parmesan, C. 2006. Ecological and evolutionary responses to recent climate change. Annual Review of Ecology, Evolution, and Systematics 37:637–669.

  DOI: 10.1146/annurev.ecolsys.37.091305.110100

  This work is not explicitly autecological, but it does illustrate the complex ways in which various facets of climatic change affect organisms in nature, focusing on studies of long time series and those that provide a good mechanistic understanding of causes of responses to climate.

• Uvarov, B. P. 1931. Insects and climate. Transactions of the Royal Entomological Society of London 79.1: 1–232.

  DOI: 10.1111/j.1365-2311.1931.tb00696.x

  This massive compendium on the influence of climatic variables on insect abundance works from the principle that even when the existence of an insect depends on conditions other than climatic (e.g., presence of its food plant), climate “remains as a definite, if not dominant, factor,” a crucial point of departure for autecology.

• Walter, G. H., and R. Hengeveld. 2014. Autecology: Organisms, interactions and environmental dynamics. Boca Raton, FL: CRC Press.

  DOI: 10.1201/b16805

  The theory of autecology is developed with numerous illustrative examples. It emphasizes the role of the adaptive mechanisms of organisms and the way in which these mediate interactions with the environment. The final chapter synthesizes the material and contrasts the autecological paradigm with the demographic (population plus community ecology) paradigm.