Biol Theory DOI 10.1007/s13752-017-0263-9

ORIGINAL ARTICLE

On the Definition of Ecology Mark Sagoff1   

Received: 27 October 2016 / Accepted: 8 March 2017 © Konrad Lorenz Institute for Evolution and Cognition Research 2017

Abstract  In this article I discuss the proposition that ecologists may place restrictions on the kinds of plants and animals and on the kinds of systems they consider relevant to assessing the resiliency of ecological generalizations. I argue that to restrict the extension of ecological science and its concepts in order to exclude cultivated plants, captive animals, and domesticated environments ecologists must appeal either (1) to the boundaries of their discipline; (2)  to the idea that the effects of human activity are rare and unusual enough to count as ceteris paribus conditions; or (3) to the nature/culture divide. The boundaries of their discipline, however, are practical, not epistemological. The effects of human activity are ubiquitous and profound. And the nature/culture divide, as far as I know, has been infra dignitatem in the natural sciences at least since Charles Darwin and John Stuart Mill. Ecologists may reason, moreover, that organisms and systems that have the kind of history that interests them must as a result possess a kind of organization or some other general biological property that distinguishes them from those that do not. This is to commit a genetic fallacy. Keywords  Definition of ecology · Ecological generalizations · Genetic fallacy · Habitat · Invasive species · Philosophy of ecology A lot is known about the abundance and distribution of cultivated animals and plants. In 2014, scientists using * Mark Sagoff [email protected] 1



satellite data and building on earlier studies by the United Nations Food and Agriculture Organization, mapped standing populations of 1.43  billion cattle, 1.87  billion sheep and goats, a billion pigs, and 20  billion chickens (Robinson et al. 2014). According to three conservation biologists, “Of the global terrestrial vertebrate biomass, only about 3% are wild living animals” (Smil 1991; Haberl et  al. 2004). According to other studies, “Farm animals … already make up two-thirds of terrestrial vertebrates by weight, with most of the rest being humans and only three percent wildlife” (WSPA 2008, p. 4). Marine and freshwater environments are also intensively farmed. The FAO updates “Fact Sheets” on fin and shellfish production in aquaculture, “probably the fastest growing food-producing sector [which] now accounts for nearly 50 percent of the world’s food fish” (FAO 2014). In addition, the Zoological Information Management System (ZIMS) (http://www.isis.org/Pages/zims.aspx) provides data (according to its web page) on 3.5 million animals—10,000 species—in captivity. An FAO consortium maintains “an interactive webbased information system on land use which contains statistics on primary food crops, aggregated by sub-national administrative districts, on crop production, area harvested, and crop yields” (http://www.fao.org/agromaps/). The US Department of Agriculture (USDA) also provides an annual census of food production (http://www.agcensus.usda. gov/). The abundance and distribution of pasture and crop plants, which cover more than a third of the world’s icefree surface, is well inventoried year after year. Although huge data sets about the abundance and distribution of cultivated plants and animals are available at local to global scales, few if any ecologists make use of them.

Institute for Philosophy and Public Policy, George Mason University, Fairfax, VA, USA

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Ecology Defined All prominent definitions of ecology I have been able to find refer to organisms generally and do not distinguish explicitly between those that are domesticated and those that are wild. Ecology is defined as the “scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance” (Begon et al. 2006, p. xi; see also Andrewartha 1961; Krebs 1972; Courchamp et  al. 2015). This definition apparently refers to all organisms. “Traditional biological ecology is defined as the scientific study of the interactions that determine the distribution and abundance of organisms” (Jelinski et  al. 1992, p. 793). “A working definition of biological ecology is that it is the study of the distribution and abundance of organisms and of the interactions and flows of resources among them” (Graedel 1996, p. 70). More broadly, ecology has been defined as “the scientific study of the relationships between organisms and their environments” (McNaughton and Wolf 1973); “the study of the relationship between organisms and their physical and biological environments” (Ehrlich and Roughgarden 1987); “the study of interactions between organisms and between organisms and their environments” (Stiling 1992); “the study of the relationships, distribution, and abundance of organisms, or groups of organisms, in an environment” (Dodson et al. 1998); and “the study of the spatial and temporal patterns of the distribution and abundance of organisms, including causes and consequences” (Scheiner and Willig 2008). Inkpen (2017, p. 51) has noted, “definitions of ecology contain no fundamental distinction between human and natural.” He quoted the statement of the Ecological Society of America, which defines ecology as the scientific discipline “concerned with the relationships between organisms and their past, present, and future environments. These relationships include physiological responses of individuals, structure and dynamics of populations, interactions among species, organization of biological communities, and processing of energy and matter in ecosystems” (ESA 2016). This definition apparently refers to plants and animals generally. In spite of these definitions, ecology plainly does not see itself as the science of the distribution and abundance of plants and animals generally; otherwise ecologists would make use of the data sets I described. I did the best I could to Google search the Journal of Animal Ecology, in publication since 1932, and found almost nothing about animals in cultivation or captivity. Why is it that definitions of ecological science refer to species, populations, and environments in general, although ecological science itself concerns only a subset, for example, only the three percent of terrestrial vertebrates (by weight) that is “natural” and

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not the 97 percent that comprises human beings and their chattel? One may answer that the proposition that ecology concerns only relatively “natural” organisms and environments is so obvious that any definition of the science may simply assume this fact without having to make it explicit. If this is true, however, one might fairly ask what is being assumed and how ecologists would define their science if this assumption were made explicit. What entitles ecologists to exclude cultivated plants and animals from the domain of their science? There are at least three possibilities which, following Inkpen (2017), I call disciplinary, empirical, and methodological. The first is based on the practice or on the professional interests and preferences of ecologists. The second treats human action or influence as a disturbing condition or as an intervening force. The third constructs ecological models and methods to theorize an ideal natural order in which humanity does not intrude or even exist—an ontological realm untrammeled by man where he takes only measurements and leaves not even footprints. In the following pages I propose that none of these three options provides a defensible reason to believe that whatever general truths, principles, or processes ecologists study are not equally valid and testable in cultivated as in “natural” populations and places. As to the first approach, I shall argue that the disciplinary boundaries of ecology do not necessarily coincide with its epistemic boundaries. Just because ecologists aren’t interested in them, in other words, does not show that cultivated organisms fall outside the reach of concepts used in the discipline, such as “animal” and “plant,” or beyond the extensions of generalizations based on those concepts. The second or empirical approach treats anthropogenic causes, such as those found in agriculture, as disrupting conditions (ceteris paribus conditions) that restrict the domain of ecological generalizations. Anthropogenic causes, however, operate nearly everywhere and not just down on the farm. Human influence is not an aberrant, sudden event, like an earthquake or a volcano, that intrudes so rarely on ecological phenomena that it may be treated as an exceptional disturbance. Climate change is only an example. Just as it has become hard for anthropologists to locate “uncontacted” tribes, so has it become difficult or impossible for ecologists to find “unaffected” populations of plants and animals. To construct them experimentally is to court contradiction. The third or methodological approach to ecological theory posits an ideal natural order in which (unlike the second approach) humans have no presence. This way of theorizing ecology constructs the natural as an “ideal type” in the sense of Weber (1949) by contrasting it with its opposite, i.e., the artificial. This approach to theory in ecology reflects the view of 17th and 18th century natural theology,

On the Definition of Ecology

a belief system that remains influential today, which represents Nature and Man as opposing wills, entelechies, or global controllers—the res cogitans of nature versus the res cogitans of humanity. The distinction between nature and art is fundamental. At best Man can try to imitate Nature but Man more often seeks to thwart Nature and replace its processes and purposes with his own ends. The proposition that humanity constitutes an externality a priori contrasts with the a posteriori or empirical approach which regards humanity as a condition, like an earthquake or a volcano, that may be disruptive in nature, but remains a part of it. As Inkpen (2017) has suggested, ecologists who investigate “how nature works" mean nonhuman nature. Ecologists recognize, as most of us do, that lands that are “untouched” by human influence, i.e., pristine places, are far and few, like the lands where Edward Lear’s Jumblies live, but this may be beside the point. What is fundamental is the nature/culture dichotomy however it is construed. Ecological theory may explain the opposition of nature and artifice as a difference in degree or in kind. Either way, ecological theory envisions a nature/culture dichotomy (even as a spectrum) and dedicates itself to understanding those phenomena that lie closer to the Nature end than to the Artifice end of the spectrum. On this basis ecological theory could exclude cultivated plants and domesticated environments from its reach because these occur at the culture extreme of the nature/culture divide. Ecological theory could possibly extend in some way, on this view, to species that colonize a site with human assistance but become naturalized. What is important is not at what point on the nature/culture spectrum the phenomenon of interest lies, or whether the nature/culture dichotomy is understood as a matter of kind or of degree. What is important is that the methodological approach rests on a fundamental ontological divide.

Disciplinary Boundaries I have asked how one would define ecological science to make explicit the assumption that it does not include domesticated or cultivated species or environments. The first way—the disciplinary approach—makes the assumption explicit by defining ecology as the scientific study of the abundance, the distribution, and the relationships between the kinds of organisms and environments that interest ecologists. Alternatively: ecology is scientific study of the distribution and abundance of the organisms ecologists prefer to study and which therefore lie within the disciplinary boundaries of their science. As Linquist et al. (2016, p. 124) have written, “Ecology, like other disciplines, is interested in certain kinds of systems and not others.”

On this approach, the reason ecological science excludes cultivated or domesticated plants and animals is that ecologists are not interested in them. There are many incentives, from the aesthetic to the athletic, that lead ecologists as a matter of disciplinary practice to study organisms and environments relatively free of human influence. As Vellend (2014, p.  138) has written, “Like many ecologists, I was drawn to ecology in large part by an abiding love of nature. To think that I could work outdoors (fun) and at the same time contribute to the understanding and thereby protection of nature (rewarding) was a huge draw.” This way of restricting ecological science argues essentially that the generalizations of ecology (principles, patterns, processes) are true only of the plants and animals ecologists prefer to study because ecologists prefer to study only those plants and animals. This way of defining ecology depends on the a posteriori practice of an academically entrenched, historically informed, and socially supported discipline of empirical inquiry that investigates some organisms and environments but not others. This first approach to limiting the science of ecology in order to exclude cultivated plants raises an important problem. Even if ecologists are not interested in domesticated and cultivated organisms, ecological generalizations about plants and animals nevertheless include them. As a practical matter ecologists ignore certain kinds of plants and animals. This does not show that as a logical matter the concepts they use, such as “plant” and “animal,” exclude domesticated organisms. To be sure, ecological science may and does in its disciplinary practice restrict the kinds of organisms and of systems against which it tests the resilience of a given generalization. This does not restrict the logical extension of that generalization. The living world includes cultivated plants and animals. There seems no obvious reason to suppose that the principles, truths, processes, forces, or other generalizations ecologists seek to discover in the living world are true of and testable in only “wild” nature, even if ecologists are not concerned with cultivated organisms or environments. If domesticated organisms pose counterexamples to (or even if they confirm) ecological truths, ecologists must include them in the scope of their science even if, in the immortal words of Bartleby the Scrivener, they would prefer not to. Agriculture may provide the best setting for testing ecological generalizations since experimenters can control for the contingencies that make it so difficult to test these generalizations in the wild. It is usual to think that human agents can apply the forces, processes, and principles of nature. When they do, these cannot differ between the natural and the artificial biological production. The mechanisms are the same in both: predation, competition, parasitism, disease, the availability of food and water, weather, and so on. Agriculturalists who manipulate the natural world,

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for example, by suppressing some forces (such as predation and competition) to encourage others (population size) apply only the principles or forces nature makes available to them. They reveal mechanisms at work throughout the biological world (Litrico and Violle 2015; Milla et al. 2015, p. 463). Agriculture may test ecological theory by applying it. By the beginning of this century most of the terrestrial biosphere had been transformed by human use, with more than 50% in agricultural production and much of the rest in human settlement. Perhaps a quarter of the ice-free land surface of the planet remains arguably wild; anthropogenic causes largely determine which plants and animals are found where in the rest (Ellis et  al. 2010; Ellis 2015). These anthropogenic plants and animals either conform to the laws, forces, or theoretical generalizations of ecology or they do not. If they do, then these truths can be investigated and tested in anthropogenic systems. If they do not, they are counterexamples to them. Disciplinary boundaries are one thing; epistemic boundaries are another. The interests of ecologists and the extensions of ecological concepts do not necessarily coincide.

Empirical Boundaries A second way to restrict ecological science in order to exclude cultivated plants and animals is to distinguish between those forces or causes that are endogenous and those that are exogenous to the kinds of models ecologists propose. One could then define ecology as the scientific study of the abundance and distribution of plants and animals, and the interactions between them, except insofar as they are caused by factors that lie outside of and interfere with the forces or mechanisms ecologists model and seek to understand. All or nearly all scientific generalizations come with ceteris paribus conditions, and those of ecology are no different in this respect. No one would cavil with the argument that a rare event, such as an earthquake, volcano, or cyclone, may disrupt ecological forces in ways that produce outcomes that differ from those that a model or a generalization predicts. This in itself would not disconfirm the model or the generalization. The philosopher Marc  Lange (2002, 2005) uses the theory of island biogeography as an example. The relation of the number of species to the area of an island is often used to illustrate a putative law or generalization in ecology. Lange (2005, p.  398) characterizes the “area law” as follows: “the number S of species of a given taxonomic group on an ‘island’ (as far as creatures of that group are concerned) in a given ‘archipelago’ increases, ceteris paribus, with the island’s area A in accordance with a power function (S = cAz).” The size of an island,

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then, is said to be related to the number of species found there relative to other islands similarly situated, ceteris paribus. As Lange explains, the area law is coupled with other candidate laws to produce predictions. “For example, the ‘distance law’ says that ceteris paribus, islands farther from the mainland equilibrate at lower biodiversity” (2005, p. 399). MacArthur and Wilson (1967, p.  21) argued that the number of species that will come to an island (the “immigration rate”) will fall over time “because as more species become established, fewer immigrants will belong to new species.” They reasoned, “The extinction curve must on the other hand rise,” since the more species colonize, the more there are to become extinct and the more likely each will succumb to “ecological and genetical accident.” As Inkpen (2016, p.  37) has explained, “MacArthur and Wilson further reasoned that since rates of immigration depend on distance from the mainland (i.e., an increase in distance ‘lowers’ the immigration curve), and since rates of extinction depend on the size of an island (i.e., an increase in size ‘lowers’ the extinction curve),” the species richness of an island will reach an equilibrium where these curves intersect, i.e., at a number of species that reflects both the size of an island and its distance from the mainland. Consider a counterexample to this theory. Ascension Island, a tiny landmass of about thirteen kilometers by eight wide, is as isolated as anywhere can be, sitting midway between the horn of South America and Africa at the equator. According to Simberloff (2010, p. 227): Before discovery by humans, Ascension Island had 25–30 vascular plant species, of which the largest were ferns and an uncommon endemic shrub; Darwin described the island as a “cinder” entirely destitute of trees. By the 1920s, the vegetation, dominated by introduced species from Africa, Asia, Australia, Europe, North America, South America, Madagascar and Bermuda, with eucalyptus, conifer and palm trees, was an “almost dense jungle” that persists to this day. The “area law” coupled with the “distance law” predicts that the species richness of Ascension Island would equilibrate at some small number, perhaps a few more than the paucity Darwin found when he visited in 1839, given the remoteness of the island and its small size. Instead, what we observe is a teeming, blooming, buzzing confusion of species, orders of magnitude more than in 1839, because the British Marines and others brought in plants from the four corners of the Earth. If one includes not only species intentionally introduced by British naturalists to build up a lush verdant environment but also those cultivated on the island, there may be no limit to the species richness there, if by that concept one means the number of species.

On the Definition of Ecology

The empirical approach to ridding ecological science of counterexamples of this sort would explain the biodiversity on Ascension Island in terms of ceteris paribus exceptions to the species-area rule. Many of the species on the island are cultivated directly; many more were introduced because they were likely to (and did) spread on their own; but in either case, they are there because of human activity. As much on Ascension Island as down on the farm, human activity interferes with the forces ecological theory seeks to model and to understand. If one construes anthropogenic activity as an intervening variable or disturbing force, the plants and animals on this island, although they exceed by orders of magnitude the number the species-area law would predict, would not constitute legitimate counterexamples to that law, since they result from human activity, an externality. This is the empirical as distinct from the disciplinary way of setting the boundaries of ecology.

An Objection to the Empirical Approach The empirical approach to setting the boundaries of ecological science may make explicit the exclusion of cultivated plants and domesticated environments in the following way. It may define ecology as the scientific study of the abundance and distribution of plants and animals and the relations among them insofar as they are not strongly determined by anthropogenic causes, along with other ceteris paribus conditions. This approach faces the following objection. Nearly all islands are like—or becoming like—Ascension Island. It may be hard to find a significant island on which the majority of plants and animals have not arrived with human assistance. The diversity of plants has approximately doubled in insular habitats in recent centuries. “Within the last few centuries following European colonization, relatively few insular endemic plant species have become extinct, whereas invading species have approximately doubled the size of island floras—from 2000 to 4000 on New Zealand; 1300–2300 on Hawaii; 221–421 on Lord Howe Island, Australia; 50–111 on Easter Island; and 44–80 on Pitcairn Island” (Brown and Sax 2004, p.  534). In Great Britain almost 1800 non-native plant species have become naturalized and many more have resulted from hybridization, since 1700, while no island-wide extinction of any plant species is known to have occurred (Thomas and Palmer 2015). The rate of plant speciation during the Anthropocene, moreover, because of hybridization may be orders of magnitude greater than background or “natural” rates of speciation (Thomas 2015, p. 448). Harmon and Harrison (2015, p. 589) have described the openness of communities to new species traveling in the wake of commerce, “even at the small spatial scales where

species interact and the influences of competition and resource supply should be strongest.” Helmus et al. (2014) have proposed that the primary driver of biodiversity on islands is the extent of economic activity. The more commerce, the more species; the rate of immigration increases. The “rich get richer” (Stohlgren et  al. 2003). Ecologists have even noted the phenomenon of “reverse colonization”; species that arrive as stowaways on cargo ships and become naturalized on islands go on from there to colonize the mainland (Bellemain and Ricklefs 2008). The theory of island biogeography predicts that the biodiversity of an island will equilibrate at some number of species that reflects both the size of an island and its distance from the mainland. Every island seems to disconfirm this prediction. This would include all sizeable islands except a few that are sedulously protected from economic activity, such as nature reserves, which may require a lot of weeding and other kinds of human attention. If the number of species on major oceanic islands has doubled or more in recent centuries and if the distance between those islands and the mainland has not changed, then distance has little effect on the number of species. The species richness of Cuba is expected to grow, though the size of the island remains constant, when the U.S. embargo ends (Helmus et al. 2014). If the theory of island biogeography “saves the phenomena” by putting in a ceteris paribus clause about any species that migrates to an island with human assistance it turns into a tautology. It cannot pass the laugh test. The empirical approach to bounding the subject matter of ecology to exclude cultivated organisms and domesticated environments fails because it confuses the signal with the noise. The signal is human activity; in the Anthropocene, anthropogenic causes are the principal drivers of ecological change. The noise includes the distance of islands from the mainland, the oscillation of predators and prey, the competitive exclusion of organisms that use the same resources, and any of a number of other chestnuts of theoretical ecology that are so swamped by anthropogenic and other contingent factors that they are impossible to detect (Sagoff 2016). To this, a supporter of the theory of island biogeography may reply that the species-area relationship is “one of ecology’s few ironclad laws” (Pounds and Puschendorf 2004, p.  108). Two ecologists have written, “The species-area curve is one of the few universally accepted generalizations in community ecology” (Hanski and Gyllenberg 1997, p.  397). Ecologists agree, “The relationship between the number of species and the area sampled is one of the oldest and best-documented patterns in community ecology” (Crawley and Harral 2001, p.  864). Rosenzweig (1999, p. 276) has written, “The great 19th-century scientist Alexander von Humboldt gave ecology its oldest law: Large areas harbor more species than smaller ones…” That this

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truism, hardly different from common sense, is touted as one of the great intellectual discoveries of theoretical ecology should tell you something.

The Methodological Approach I have now discussed two ways ecologists may restrict the reach of their theory to “natural” organisms. The first or disciplinary approach argues that cultivated organisms and domesticated environments, even if they lie within the logical extensions of the concepts and thus generalizations of ecological science, do not count as exceptions to them because ecologists are not interested in them or prefer not to think about them. The second or empirical approach removes from the explanatory reach of ecological theory species whose abundance and distribution are strongly influenced by human activity. This perspective treats human influence as an intervening force, like a rare weather event, rather than as an unnatural force, like divine retribution. The third or methodological approach invokes the ontological nature/culture divide. This tack excludes from the reach of ecological generalizations domesticated organisms and environments by categorizing them as “unnatural.” This view expresses a division of substance between nature and culture and not a division of labor between ecologists and other scientists. In this definition of ecology “culture and nature are distinguished from each other as if they were two separate realms of reality” (Haila 2000, p. 55; Alberti et al. 2003). To suppose otherwise “would be to confound the entire tradition that takes human agency or intentionality as a priori unnatural, and accordingly pits natural against artificial design” (Keller 2005, p. 1073). As Inkpen (2017) has pointed out, ecologists who investigate “how nature works” take this methodological tack because by “nature” they refer to nonhuman nature, thus deploying the nature/culture divide. It is as if biotechnologists, agronomists, and environmental engineers can’t tell you “how nature works.” This way of excluding the cultivated and the domesticated from ecological science defines ecology as “the scientific study of the abundance, distribution, and relationships between the kinds of organisms and environments that are not the result of human agency or under the control of human beings.” Or: “Ecology is scientific study of the distribution and abundance of natural organisms in natural environments.” The concept natural organism or natural environment represents an idealization, or what Max Weber has identified as an “ideal type” that helps to set boundaries to separate kinds of disciplines. Weber characterizes an ideal type as a “mental construct” (Weber 1949, p. 90) or as a “conceptual construct” (Weber 1949, p. 93), that is, a theoretical

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abstraction that may not be entirely descriptive of anything in the world but serves the analytical purposes of the scientist. “An ideal type is formed by the one-sided accentuation of one or more points of view and by the synthesis of a great many diffuse, discrete, more or less present and occasionally absent concrete individual phenomena … into a unified analytical construct” (Weber 1949, p. 90). According to Angner (2015, p.  3560), “Scientists construct ideal types by exaggerating or idealizing features of the world that, for whatever reason, are of interest to them.” An example of an ideal type outside ecology might be the idea of the primitive, which determined the object of cultural anthropology at least through the 19th century (Voget 1975). The idea of primitive society, with an inherent order to be understood by the ethnologist before it disappeared, persisted at least through the 1940s, when Malinowski in his influential book, The Dynamics of Culture Change (1945), extolled the “pristine fullness” of tribal culture, the “grace of original tribalism,” and the “conditions of pre-European tribal equilibrium” (p.  27). Cultural anthropologists committed to the construct of the “uncontacted tribe” have lamented “the loss of subject matter. Untouched simple societies are fewer and fewer …” (Jarvie 1975, p. 255). In ecology, nature can be an ideal type in the way primitive is an ideal type in anthropology. In ecology the concept of nature constructs an untouched, unspoiled, or pristine world for theoretical purposes. This concept of nature may or may not include preliterate hunter-gatherers; ecologists ask, “Should the reference condition include or exclude the human impact of indigenous people?” (Wagner et  al. 2000, p. 26). This question arose very early in the history of ecological science in the United States. “When the white man first appeared near Chicago no secondary community existed, as the aborigines lived almost entirely by hunting and fishing. They cultivated the land only a little, and are accordingly to be ranked with the larger animals as a part of the original communities” (Shelford 1913, p. 13). Whether ecologists include indigenous peoples among the larger animals in the realm of nature is immaterial; what is fundamental to ecological method is the dichotomy between nature and culture, however drawn. From this perspective ecological models—logistic curves, Lotka–Volterra predator–prey equations, and species-area laws, for example—construct nature as an ideal type, in a way that makes it intelligible and amenable to mathematical exploration. In the ideal systems theoretical ecology posits domesticated plants and animals are not exceptions; rather they are absent: they have no place. They are abnormal, unnatural; there is something wrong about them as they stand. They are not present enough even to be ignored. The essential aspect of the methodological approach is that it conceives nature as having its own agency—a

On the Definition of Ecology

“self” of its own; what makes nature natural is the opposing agency of humanity, other than those people counted among the larger animals because of their lack of culture or, at least, our culture. The mechanisms and processes theoretical ecologists model show how nature “works” when left to itself, that is, when it operates apart from our influence or intent. (One may think by analogy of the stuffed tiger Hobbes, in the Calvin and Hobbes cartoon, who comes to life or into action just when adults are not present.) Ecological science presupposes “a basic conflict between the strategies of man and of nature” (Odum 1969, p.  266). Humanity defines the “natural” by replacing nature’s purposes with its own ends (for discussion see Daston 1995).

The Nature‑Culture Divide The “nature” ecology studies represents a kind of being or existence that can be understood only in opposition to the “artifice” of human agency and intention. The concept of the natural is meaningful, in other words, only in a dichotomy with the artificial. It is only in terms of this fundamental dichotomy that nature is natural, that is, that some things (i.e., wild things) are found in nature and others (i.e., cultural things) are not. Ecology on this approach relies on the nature-artifice dichotomy to limit its subject matter to exclude the domesticated and the cultivated. From this methodological perspective human beings constitute not an intervening ceteris paribus variable but a corrupting and defying outside agency, something like the wrath of God. An example may help. Consider the statement, “Natural selection is the prototypical example of the autonomous process … Artificial selection is not; it is not autonomous because it relies on a global controller” (Levin 1998, p.  432). It is one thing to say, as Darwin did, that evolutionary forces produce biological species; this is consistent with the idea that plant and animal breeders can use those same forces to produce other biological species. It is another thing to say that the process of natural selection is “autonomous”; this is inconsistent with plant and animal breeding, which relies on a global controller in conflict with the natural order of things. In 1860, Asa Gray, a botanist at Harvard, reviewed The Origin of Species. Gray quoted The Winter’s Tale to explain that what Darwin described as “artificial selection” adds nothing new to the natural force or principle of descent with modification but simply instantiates, applies, or exemplifies it. According to Gray, artificial selection reveals rather than distorts what goes on in the natural world. Gray (1860, p.  27) wrote that “‘the art itself is Nature,’ since the whole art consists in allowing the most universal of all natural tendencies in organic things (inheritance) to operate

uncontrolled by other and obviously incidental tendencies. No new power, no artificial force, is brought into play.” Similarly, Darwin (1838 or 1839) wrote, “It is a beautiful part of my theory that domesticated races of organics are made by precisely the same means as species ….” One might argue that since cultivation reveals so much about how nature works, it may be thought to be more natural than nature itself. “The fancier’s view of the pigeon, Darwin thought, was not so much like a naturalist’s as like that of nature herself” (Secord 1981, p. 178). It is the same with ecosystems. Consider the statement, “Ecosystems are dynamic assemblages of interacting components, self-organized into evanescent patterns of interaction on multiple scales of space and time” (Levin 1999, citing, 1992). If ecological networks are organized by forces or principles human beings can master and apply, these forces, not an autonomous “self,” organize them, insofar as they are organized at all. Human agents by employing these same forces or principles could reorganize and create ecosystems—hence farms. If ecosystems are selforganized, in contrast, human beings, since they represent a different kind of agency, a different “self,” can create only socio-technological-economic systems. It is conceptually impossible for two autonomous selves to organize the same self-organized system; this would amount to schizophrenia. If human agency represents a force outside of nature, this makes domesticated and cultivated organisms “unnatural” and puts them outside the scope of ecology. A vast literature in theoretical ecology nevertheless seeks to account for the way cultural and natural systems interact or how social and ecological systems can “couple” given that each is organized by its own autonomous self (for review see Binder at al. 2013). As Walker et al. (2006) pose this problem, “Coupled social-ecological systems may have very different dynamics when compared to the ecological component, because the social domain contains the element of human intent.” Having divorced nature from humanity, theoretical ecologists have to reintegrate it to make their work fundable because relevant to the ecological crises. This has produced a vast amount of mathematical modeling that seeks to bridge the nature/culture divide (Berkes et al. 2008), and thus offer a theoretical fix for the impending downfall of civilization (Ehrlich and Ehrlich 2013). There is no branch of biology other than ecology that invokes the nature/artifice divide or suggests that different general biological truths extend to organisms and environments depending on their relation to human influence and activity. No one believes that cytology, for example, should treat wild organisms differently from cultivated organisms with respect to their cell structure, function, and chemistry. Plant physiology, according to Wikipedia, studies “photosynthesis, respiration, plant nutrition, plant

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hormone functions, tropisms, nastic movements … circadian rhythms, environmental stress physiology, seed germination, dormancy and stomata function and transpiration,” among other processes. No one suggests that these processes differ between wild and cultivated vegetation. It is the same with genetics. The manner, the extent, or the mechanism by which genotypes determine (or do not determine) phenotypes does not distinguish between organisms that are wild and those that are not. Darwin used artificial selection to exemplify the process and power of heredity in the theory of evolution. Genetics is the same science whether it is studied in the context of wild or domestic organisms, and its discoveries are equally relevant to both. Mill (1875) wrote that there is no difference between the mechanisms that govern wild versus domesticated organisms or environments. “The corn which men raise for food, grows and produces its grain by the same laws of vegetation by which the wild rose and the mountain strawberry bring forth their flowers and fruit” (p.  5). According to Mill, the wild and the cultivated are not different kinds of things to which different principles or powers apply. “Art is as much Nature as anything else, and everything which is artificial is natural. Art has no independent powers of its own: Art is but the employment of the powers of Nature for an end” (p. 7).

Are Zoos Habitats? Any definition of ecology, I have argued, if it is to exclude cultivated plants and animals from its extension, must refer either (1) to the practice of ecologists; (2) to ceteris paribus clausality; or (3) to the nature/culture divide. I believe that many or perhaps most of the basic concepts of ecology take the third approach, that is, they invoke the nature/culture divide. I will now offer an ostensive argument for this proposition. By this I mean I will consider a number of examples. In each case, I try to show that the concept in question can be defined without contradiction or absurdity only if it refers explicitly or implicitly to human agency, usually in terms of its absence. The concept, in other words, either makes this reference and thus invokes the nature/culture divide, or it cannot avoid blatant counterexamples. I have mentioned that the logical extensions of concepts such as “plant,” “animal,” and “organism” include domesticated varieties. When ecologists use these concepts, they rely implicitly on the nature/culture dualism to include only “natural” plants and animals, however construed. I now try to show concepts more specific to ecology rely on the nature/culture dichotomy to exclude artificial species and environments from their extensions. Consider the concept habitat. According to Mitchell (2005, p. 634), “The concept of habitat is possibly the

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most fundamental and unquestioned paradigm in ecology.” Few ecologists, I believe, would say that a zoo represents the habitat of any animal exhibited there. Why are zoos not habitats? Many, indeed most, tigers live in zoos, game farms, and other domesticated settings. On what basis do ecologists exclude these domesticated settings from the concept tiger habitat? There are two possible ways to explain why zoos are not habitats. First, one may describe or point to a general biological factor or condition that distinguishes a zoo from the habitat of an animal. I will argue this cannot be done. This leaves the second way of explaining the difference. Zoos are unnatural. This explanation relies on the nature/culture dichotomy. Elton (1966) wrote that the “definition of habitats, or rather lack of it, is one of the chief blind spots in Zoology.” Mitchell commented that while there is no authoritative definition of the concept habitat, one of the most cited is that of Odum (1971, p.  234), “the place where an organism lives, or the place where one would go to find it.” The zoo is a place an organism, such as a panda, lives, and certainly the place where most people would go to find it. A zoo meets Odum’s definition of “habitat.” Odum’s definition implies that zoos are habitats. Accordingly ecological generalizations about habitats extend to and are testable in zoos. No definition of “habitat” that does not invoke a culture-nature divide avoids this outcome. According to Whittaker et  al. (1973, p.  328; see similarly the proposal of Bamford and Calver 2014), “Habitat is usually conceived as the range of environments or communities over which a species occurs ….” For tigers, zoos and game farms meet this condition. Most tigers alas are found in captivity and increasingly so. According to a Wall Street Journal report, “China today has about 6000 tigers bred in captivity; world-wide, there are around 3500 tigers in the wild” (Oster 2010). The World Wildlife Fund (2014) estimates the global population of wild tigers to be 3200, less than the captive population in the United States alone. Knox (2010) follow Odum in defining “habitat” as, “The environment of an organism; the place where it is usually found.” In their textbook, Campbell et  al. (2009) define “habitat” as, “A place where an organism lives; an environmental situation in which an organism lives.” Krebs (2001) identifies “habitat” as “any part of the biosphere where a particular species can live, either temporarily or permanently.” All of these definitions have the same implication: zoos handily meet the criteria for habitat. Ecological generalizations that refer to habitat therefore logically extend to and would therefore be testable in zoos and in captive populations. Definitions of “habitat” try to avoid this implication by invoking the concept nature. For example, Villee (1972) has defined habitat as “The natural abode of an animal

On the Definition of Ecology

or plant species.” The question then arises, what property makes an abode “natural”? Every abode is “natural” in the sense of consistent with the laws of nature. The zoo and the game farm are “natural” if the same laws of nature apply to them as to wild habitats. Mader (2004) in her popular textbook avoids the term “natural,” and thus tries to skirt a commitment to the ontological nature/culture divide. She has defined “habitat” as the “[p]lace where an organism lives and is able to survive and reproduce.” The phrase “able to survive and reproduce,” is ambiguous. On August 23, 2013, the David M. Rubenstein Family Giant Panda Habitat at the National Zoo welcomed the birth of panda cub Bao Boa to panda parents Mei Xiang and Tian Tian. The cub, conceived via artificial insemination and attended by a team of veterinarians, is evidence that pandas, like many, most, or perhaps all animals, are able to live and reproduce nearly anywhere if they are provided with enough human assistance. When scientists assist populations to live and reproduce they do not defy but apply the laws of nature. Mader’s definition has to be spelled out: the “habitat” of an organism refers to the place or places where it lives and is able to survive and reproduce without human assistance. Mader excludes zoos from the extension of habitat only by referring to the way organisms and environments are related to human agency. This is to invoke the culture/ nature divide. All or nearly all organisms require other organisms if they are to survive and reproduce; what difference does it make that they rely on humans rather than on other species? The difference between a habitat and a zoo may depend not on any biological property of an organism or its environment but on where it ought to be or where it is thought to belong (Thompson 2014). The tiger has its habitat “in the wild” for our moral and aesthetic, not for its biological, reasons. If ecological generalizations do not extend to domestic collections of plants or to animals in captivity, then a fundamental concept like habitat has to be defined in terms of biological properties that exclude zoos from its extension but do not circle back to a reference to human agency and thus to the ontological divide. I am unable to think of a definition of “habitat” that does not refer, explicitly or implicitly, to human agency and yet keeps zoos, farms, concentrated animal feeding operations, etc., out of its extension. It may be easy to show I am wrong. All that is required is a definition of “habitat” that (1) excludes zoos from its extension and (2) does not refer to human agency and thus to the nature/culture divide. If the difference between wild and cultivated amounts to the difference between what is unintended and intended, however, it is reasonable to believe that the distinction, for all its moral, social, and spiritual importance, lacks a biological difference.

Are Crops Invasive Species? I believe the same argument mutatis mutandis may be presented with respect to most of the fundamental concepts of theoretical ecology—for example the concept niche is open to the same line of argument as habitat. Consider the concept species richness. If this refers to the number of species at a place and time, then zoos and botanical gardens are hotspots of species richness. If the concept includes only those organisms that occur “naturally” at a place, there must be some intrinsic property they possess that the denizens of zoos and gardens lack. I do not think there is such a property. One could easily show I am wrong by identifying a property that distinguishes between those species that legitimately add to species richness and those that do not without referring to (1) the disciplinary interests or preferences of ecologists or (2) the presence or absence of human agency. No one denies the importance of human agency and its absence, i.e., intention versus accident, in making moral, aesthetic, and spiritual judgments, but this does not show that it correlates with a general or a fundamental biological difference. The concept “community” is typically “defined as a collection of species occurring in the same place at the same time” (Fauth et  al. 1996, p.  283; see also Schoener 1986; Magnusson 2013). A petting zoo and a botanical garden meet this definition. If special assembly rules or other general properties apply to ecological communities but not to zoos and gardens, then ecologists could refer to these rules or properties to define “community” in a way that excludes cultivated settings from its extension but does not refer to human agency. I do not think this can be done. I know of no property other than human intention or disciplinary interest (or the lack thereof) that distinguishes ecological entities, such as natural communities, from non-ecological entities, such as aquariums. I would include the concept ecosystem in this argument except that it defies definition (Jax 2006), and ecologists have suggested it be buried (O’Neill 2001). Consider the concept invasive species. I know of no invasion biologist who would say that crops, if they stay put, are invasive species. Reichard and Hamilton (1997, p.  193) have written, “Most intentionally introduced species remain in their cultivated settings, but some invade natural areas.” If they remain in their cultivated settings, they are not invasive. They can “escape cultivation and become invasive ….” How is the boundary between “cultivated settings” and “natural areas” drawn? If this has to do with a biological distinction, one should be able to describe how organisms that “remain in their cultivated settings” differ in their general properties from those that “escape.” They do not seem to differ; they could be the same organisms. The distinction between the cultivated and the invasive may depend less on

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what an organism is like than on where ecologists think it belongs. If there were an intrinsic or internal biological difference between crops in place and invasive species, ecologists should be able to refer to this difference in defining “invasion” to exclude crops. Richardson and Ricciardi (2013, p. 1461) propose that “research on invasions is invaluable for understanding how most ecosystems work.” Critics contend that invasion biology is so beset with contingency it is not worth pursuing (Valéry et al. 2013). If crops are biologically no different from invasive species—other than that crops qua crops are deemed “unnatural”—then research on crops is invaluable for understanding how most ecosystems work. Didham et  al. (2007, p.  489) define “invasive species” as “Non-native organisms (excluding humans) that become established in a location outside their natural geographical range and cause, or have the potential to cause, environmental, social or economic change.” It may be hard in the Anthropocene, when species migrate easily in the wake of human activity, to make sense of their “natural geographic range,” but major crops in the United States have become established in place of native species. They cause a lot of environmental, social, and economic change. The Didham et al. definition implies that crops are invasive. This contradicts the assumption that crops are not invasive as long as they remain where they belong. Pyšek et al. (2008, p. 237) have written, “Invasive species are those that overcome barriers to dispersal.” Crops and livestock have done that; otherwise they would not be where they are. Similarly, Ricciardi (2014, p.  154) characterizes a biological invasion as “the introduction and establishment of a species beyond its natural range, where it may proliferate and spread dramatically.” Cultivated species have been introduced and they proliferate and spread dramatically where they are cultivated. In Iowa, nothing is more productive, stable, extensive, and predictable than maize, even without the Energy Security and Independence Act. Richardson et al. (2000, p. 93) have plausibly proposed that “the term ‘invasive’ should be used without any inference to environmental or economic impact.” They suggested the following definition: “The species establishes new self-perpetuating populations, undergoes widespread dispersal and becomes incorporated within the resident flora” (p. 94). Similarly, Reichard and White (2001, p. 103) define “an invasive plant species as one that has or is likely to spread into native flora and managed plant systems, develop self-sustaining populations, and become dominant or disruptive (or both) to those systems.” Invasion biologists, by and large, speak in the same voice, i.e., “to be classified as ‘invasive’ the introduced species must be capable of establishing self-sustaining populations ….” (Macdonald

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et  al. 1989). Simberloff and coauthors define an “invasive population” as one “that spreads and maintains itself without human assistance” (Simberloff et al. 2013, p. 58). Ecologists have proposed the concept self-sustaining or self-perpetuating as naming a biological property that distinguishes wild from cultivated populations and environments. An immigrant population is established in the wild if its “individuals reproduce and found a self-sustaining population” (Estrada et  al.  2016, p.  2). Simberloff et  al. (2012, p. 600), while discussing non-native plants, contrast those “maintained by deliberate, ongoing human activity (e.g., many horticultural varieties and agricultural plants)” with “naturalized nonnative plants, as these are the ones that, like the vast majority of native species, are established and self-perpetuating in nature.” The concept wild refers “to organisms that have … a self-sustaining population” (Falk-Petersen et al. 2006, p. 1414). These authors suggest that the intrinsic property that distinguishes wild organisms from cultivated ones lies in their ability to establish self-sustaining populations. This criterion makes little sense because no organism is self-sustaining or self-perpetuating. Every plant and animal, no matter how wild it may be, depends on something, some source of energy or food, to sustain itself and its population. Wild organisms depend on other organisms to perpetuate themselves; for example, flowering plants depend on pollinators. If generalizations in ecology extended only to organisms that establish self-sustaining populations, they would extend to the null set. The concept invasive species, like the concept habitat, cannot be defined without reference to human intention and still exclude cultivated plants and animals. (It would be easy to show I am wrong; all that is required is a definition of “invasive species” that does not refer to human agency and still excludes crops.) If the concept invasion entails a reference to human intention or its absence, as I believe it must if it is to exclude crops from its extension, one may wonder if invasion biology is more a kind of social or moral than a kind of natural science (Davis 2009; Valéry et al. 2013; Thompson 2014).

Conservation as Agency Ecologists often cite as a reason to support their research the need to preserve threatened species. As ecology becomes the science of conservation it becomes the science of maintaining and sustaining—and sometimes translocating and establishing—organisms. This presents a paradox since the maintenance of those populations, which might otherwise go extinct, depends on human agency. Since the concept of the natural entails the absence of human agency,

On the Definition of Ecology

how can ecologists, who are human agents, help to sustain natural species? This paradox is particularly poignant in the use of biotechnology to support the wild salmon fishery in the Pacific Northwest (PNW). According to one fisheries biologist, “Hatcheries have for many years provided up to 80% of the fish in key PNW salmon fisheries and have greatly benefited commercial, sport, tribal, and nontribal fishers” (Flagg 2015, p. 367). According to earlier data, “each year hatcheries along the west coast of the United States release nearly 1.2 billion juvenile salmon, with 200 million salmon released into the Columbia River alone” (Levin and Williams 2002, p. 1581; citations omitted). Wild salmon depend not only on hatcheries; juveniles after imprinting on native waters are often trucked to the sea to avoid hazards en route. “In an act that is equal parts despair and hope, the government is transporting the salmon by truck and barge, trying to imitate nature so that in 3  years some fully grown fish will find their way back upstream” (Barringer 2014, p. A1). Scientists analyze “each salmon’s DNA before breeding them to make sure that the fish they match have no genetic relationship to each other” (American Fisheries Society 2016). Scientists who rear salmon in tanks apply principles, powers, processes, mechanisms, and generalizations that are to be discovered and also operate in the wild. There is no nature/culture divide. If projects that breed, hatch, raise, and truck salmon are effective, the fish will return after they mature at sea. The fish that receive human help may become interspersed with those that do not. Are their offspring wild or cultivated? This is a question science need not answer and cannot ask. If scientists who assist wild populations got hung up on this question, they could not do their work. Nature is all one to them.

A Genetic Fallacy In this article I have discussed the proposition that ecologists may place restrictions on the kinds of plants and animals and on the kinds of systems they consider relevant to assessing the resiliency of ecological generalizations. I have argued that to restrict the extension of ecological science and its concepts in order to exclude cultivated plants, captive animals, and domesticated environments ecologists must appeal either (1) to the boundaries of their discipline; (2) to the idea that the effects of human activity are rare and unusual enough to count as ceteris paribus conditions; or (3) to the nature/culture divide. The boundaries of their discipline, however, are practical, not epistemological. The effects of human activity are ubiquitous and profound. And the nature/culture divide, as far as I know, has been infra

dignitatem in the natural sciences at least since Charles Darwin and John Stuart Mill. This leaves the question whether ecologists need to place restrictions on the kinds of organisms and systems they consider relevant to assessing the resiliency of ecological generalizations. By this, I mean to ask whether ecologists might accept the idea that the concepts and generalizations they model and test apply as well to cultivated as to “natural” environments. One might suggest ecologists accept the idea, for example, that the concept of density-dependence, which may be hard to tease out amid the sturm und drang of natural environments, is easily illustrated by row crops. If farmers could plant them any closer they would. According to Hubbell (2001, pp.  10–11) the number of cases in which local extinction can be attributed to the idea of competitive exclusion is “vanishingly small.” Yet gardeners deal with competitive exclusion all the time, for example, when a weed wipes out their impatiens plants. I believe there are at least two reasons ecologists may resist the idea that whatever laws, forces, patterns, and processes they study are found as well (and more easily) in cultivated organisms and domesticated environments. First, they may point out that ecology is a long-established academically entrenched discipline with clear empirical boundaries. These boundaries exclude cultivated or domesticated organisms and systems. Ergo ecological generalizations exclude cultivated or domesticated organisms and systems. This is plainly a non sequitur. Consider a second reason that ecologists may want to place restrictions on the kinds of plants and animals and on the kinds of systems they consider relevant to assessing the resiliency of ecological generalizations. Ecologists prefer to study the kinds of organisms and the kinds of places that have a certain kind of history—one that may be characterized by an absence of human agency. (What this requires in extent or in substance will vary with the individual ecologist.) Ecologists may reason, however, that the kinds of organisms and systems that have the kind of history that interests them must as a result possess a kind of organization or some such property that separates them from organisms and systems with histories in which human intention or influence is more prevalent. Organisms that are swept together, in some way or other, outside of human agency, on this view, must differ in a general way from organisms that are where they are because of human agency. The resilience of ecological generalizations, therefore, may be assessed in terms of “natural” organisms and systems not because they possess a different kind of ontology, but because they have a kind of different history. The term “genetic fallacy” is used to refer to an inference from how a thing is caused to the kind of thing it is. “In philosophy the genetic fallacy is the mistake of allowing the question ‘How come?’ to preempt the question

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‘What?’” It is “the fallacy of forgetting that the primary value or meaning of an event has no necessary connection with its genesis in history or its causal explanation” (Bradley 1998, pp. 71–72). The false reasoning goes from (1) the causes that bring or continue a thing in existence to (2) the structural constitution of that thing. As a theoretical science, ecology may depend on a fallacious inference from (1) a difference in the way organisms and environments come into being to (2) a difference in how they work or the kinds of things they are. The wild and the cultivated are not different kinds of things even if they come into being in different ways. Beneath the complexity of nature, the same underlying patterns apply to both, although these may be more isolated and thus more apparent in cultivated settings. One may wonder if ecology has a separate theoretical task. If it does, then there must be some mechanism or principle that works in wild settings and but eludes discovery, isolation, or application in cultivated ones. Whether any generalization meets this condition is an empirical question although it is usually treated as a conceptual one. That the wild and the cultivated have different kinds of histories explains the disciplinary boundaries of ecology. It does not show, however, that different biological generalizations are true of them or explain how they work. Acknowledgements  I thank Andrew Inkpen for many helpful suggestions.

References Alberti M, Marzluff JM, Shulenberger E et  al (2003) Integrating humans into ecology: opportunities and challenges for studying urban ecosystems. Bioscience 53(12):1169–1179 American Fisheries Society (2016) Researchers play matchmaker to save fish population. https://fisheries.org/2016/01/researchersplay-matchmaker-to-save-fish-population/. Accessed 15 Mar 2017 Andrewartha HG (1961) Introduction to the study of animal populations. University of Chicago Press, Chicago Angner E (2015) To navigate safely in the vast sea of empirical facts. Synthese 192(11):3557–3575 Bamford M, Calver M (2014) A precise definition of habitat is needed for effective conservation and communication. Aust Zool 37(2):245–247 Barringer F (2014) Swim to sea? These salmon are catching a lift. New York Times, April 18 Begon M, Townsend CR, Harper JL (2006) Ecology: from individuals to ecosystems. 4th edn. Blackwell Publishing, Malden Bellemain E, Ricklefs RE (2008) Are islands the end of the colonization road? Trends Ecol Evol 23(8):461–468 Berkes F, Colding J, Folke C (eds) (2008) Navigating social-ecological systems: building resilience for complexity and change. Cambridge University Press, Cambridge Binder CR, Hinkel J, Bots PWG, Pahl-Wostl C (2013) Comparison of frameworks for analyzing social-ecological systems. Ecol Soc 18(4):26. 10.5751/ES-05551-180426

13

Bradley B (1998) Two ways to talk about change: ‘The child’ of the sublime versus radical pedagogy. In: Bayer BM, Shotter J (eds) Reconstructing the psychological subject: bodies, practices and technologies. Sage Publications, London, pp 68–93 Brown JH, Sax DF (2004) An essay on some topics concerning invasive species. Austral Ecol 29(5):530–536 Campbell NA, Reece JB, Taylor MR, Simon EJ, Dickey JL (2009) Biology: concepts and connections, 6th edn. Pearson/Benjamin Cummings, New York Courchamp F, Dunne JA, Le Maho Y, May RM, Thébaud C, Hochberg ME (2015) Fundamental ecology is fundamental. Trends Ecol Evol 30(1):9–16 Crawley MJ, Harral JE (2001) Scale dependence in plant biodiversity. Science 291:864–868 Darwin C (1838–39) Notebook. http://darwin-online.org.uk/converted/published/1960_Notebooks_F1574d.html. Accessed 15 Mar 2017 Daston L (1995) How nature became the other: anthropomorphism and anthropocentrism in early modern natural philosophy. In Biology as society, society as biology: metaphors, pp.  37–56. Springer, Netherlands Davis MA (2009) Invasion biology. Oxford University Press, Oxford Didham RK, Tylianakis JM, Gemmell NJ, Rand TA, Ewers RM (2007) Interactive effects of habitat modification and species invasion on native species decline. Trends Ecol Evol 22(9):489–496 Dodson SI et al (1998) Ecology. Oxford University Press, Oxford Ehrlich PR, Ehrlich AH (2013) Can a collapse of global civilization be avoided?. In Proceedings of the Royal Society B, vol  280, No. 1754, p. 20122845. The Royal Society, London Ehrlich PR, Roughgarden J (1987) The science of ecology. Macmillan, New York Ellis EC (2015) Ecology in an anthropogenic biosphere. Ecol Monogr 85(3):287–331 Ellis EC, Klein Goldewijk K, Siebert S et  al (2010) Anthropogenic transformation of the biomes, 1700 to 2000. Global Ecol Biogeogr 19(5):589–606 Ellis EC, Kaplan JO, Fuller DQ et al (2013) Used planet: a global history. Proc Natl Acad Sci USA 110(20):7978–7985 Elton C (1966) The pattern of animal communities. Methuen, London ESA (2016) About. Ecological society of America. ESA.org. http:// www.esa.org/esa/about. Accessed 26 Oct 2016 Estrada A, Morales-Castilla I, Caplat P, Early R (2016) Usefulness of species traits in predicting range shifts. Trends in ecology evolution 31(3):190–203 Falk-Petersen J, Bøhn T, Sandlund OT (2006) On the numerous concepts in invasion biology. Biol Invasions 8(6):1409–1424 Fauth JE, Bernardo J, Camara M et  al (1996) Simplifying the jargon of community ecology: a conceptual approach. Am Nat 147(2):282–286 Flagg TA (2015) Balancing conservation and harvest objectives: a review of considerations for the management of salmon hatcheries in the US Pacific Northwest. North Am J Aquac 77(3):367–376 Food and Agriculture Organization of the United Nations (FAO) (2014) Global aquaculture production. http://www.fao.org/ fishery/collection/global-aquaculture-production/en Foucault M (1986) The care of the self: the history of sexuality, vol 3. Pantheon Books, New York Graedel TE (1996) On the concept of industrial ecology. Annu Rev Energy Env 21(1):69–98 Gray A (1963) [1860] The origin of species by means of natural selection. In: Dupree AH (ed) Darwiniana. Harvard University Press, Cambridge Haberl H, Wackernagel M, Wrbka T (2004) Land use and sustainability indicators. An introduction. Land Use Policy 21(3):193–198

On the Definition of Ecology Haila Y (2000) Beyond the nature-culture dualism. Biol Philos 15(2):155–175 Hanski I, Gyllenberg M (1997) Uniting two general patterns in the distribution of species. Science 275:397–400 Harmon LJ, Harrison S (2015) Species diversity is dynamic and unbounded at local and continental scales. Am Nat 185(5):584–593 Helmus MR, Mahler DL, Losos JB (2014) Island biogeography of the Anthropocene. Nature 513(7519):543–546 Hubbell SB (2001) The unified neutral theory of biodiversity and biogeography. Princeton University Press, Princeton Inkpen SA (2016) Like Hercules and the Hydra: trade-offs and strategies in ecological model-building and experimental design. Stud Hist Philos Sci Part C 57:34–43 Inkpen SA (2017) Are humans disturbing conditions in ecology? Biol Philos 32(1):51–71 Jarvie IC (1975) Epistle to the anthropologists. Am Anthropol 77(2):253–266 Jax K (2006) Ecological units: definitions and application. Q Rev Biol 81(3):237–258 Jelinski LW, Graedel TE, Laudise RA et al (1992) Industrial ecology: concepts and approaches. Proc Natl Acad Sci USA 89(3):793–797 Keller EF (2005) Ecosystems, organisms, and machines. Bioscience 55(12):1069–1074 Knox B, Ladiges P, Evans B, Saint R (2010) Biology: an Australian focus. McGraw-Hill, North Ryde Krebs CJ (1972) Ecology. Harper & Row, New York Krebs CJ (2001) Ecology. Benjamin Cummings, an imprint of Addison Wesley Longman, Inc, Menlo Park Lange M (2002) Who’s afraid of ceteris-paribus laws? Or: how I learned to stop worrying and love them. Erkenntnis 57:407–423 Lange M (2005) Ecological laws: what would they be and why would they matter? Oikos 110:394–403 Levin SA (1992) The problem of pattern and scale in ecology. Ecology 73:1943–1967 Levin SA (1998) Ecosystems and the biosphere as complex adaptive systems. Ecosystems 1(5):431–436 Levin SA (1999) Towards a science of ecological management. Conserv Ecol 3(2):6. http://www.consecol.org/vol3/iss2/art6/ Levin PS, Williams JG (2002) Interspecific effects of artifically propagated fish: an additional conservation risk for salmon. Conserv Biol 16(6):1581–1587 Linquist S, Gregory TR, Elliott TA et  al (2016) Yes! There are resilient generalizations (or “laws”) in ecology. Q Rev Biol 91(2):119–131 Litrico I, Violle C (2015) Diversity in plant breeding: a new conceptual framework. Trends Plant Sci 20(10):604–613 MacArthur RH, Wilson EO (1967) The theory of island biogeography. Princeton University Press, Princeton Macdonald IA, Loope LL, Usher MB, Hamann O (1989) Wildlife conservation and the invasion of nature reserves by introduced species: a global perspective. In: Biological invasions: a global perspective. Wiley, New York, pp 215–255 Mader SS (2004) Biology. 8th edn. McGraw-Hill, North Ryde Magnusson WE (2013) The words “population” and “community” have outlived their usefulness in ecological publications. Natureza e Conservação 11(1):1–8. doi:10.4322/ natcon.2013.007 Malinowski B (1945) In: Kaberry PM (ed) The dynamics of cultural change: an inquiry into race relations in Africa. Yale University Press, New Haven McNaughton SJ, Wolf LL (1973) General ecology. Holt, Rinehart and Winston, New York

Mill JS (1875) Nature, the utility of religion, and theism. Longmans, Green, Reader, and Dyer, London. Mill’s “Essay on Nature” is available at https://archive.org/details/a592828200milluoft Milla R, Osborne CP, Turcotte MM, Violle C (2015) Plant domestication through an ecological lens. Trends Ecol Evol 30(8):463–469 Mitchell SC (2005) How useful is the concept of habitat?–a critique. Oikos 110(3):634–638 O’Neill RV (2001) Is it time to bury the ecosystem concept (with full military honors, of course!). Ecology 82(12):3275–3284 Odum EP (1969) The strategy of ecosystem development. Science 164(3877):262–270 Odum EP (1971) Fundamentals of ecology, 3rd edn. WB Saunders Company, Philadelphia Oster S (2010) China’s tiger farms spark a standoff. Wall Street J. http://online.wsj.com/article/SB1000142405274870345580457 5057101418533006.html Pounds JA, Puschendorf R (2004) Ecology: clouded futures. Nature 427:107–109 Pyšek P, Richardson DM, Pergl J, Jarošík V, Sixtová Z, Weber E (2008) Geographical and taxonomic biases in invasion ecology. Trends Ecol Evol 23(5):237–244 Reichard SH, Hamilton CW (1997) Predicting invasions of woody plants introduced into North America. Conserv Biol 11(1):193–203 Reichard SH, White P (2001) Horticulture as a pathway of invasive plant introductions in the United States most invasive plants have been introduced for horticultural use by nurseries, botanical gardens, and individuals. Bioscience 51(2):103–113 Ricciardi A (2014) Biological invasions simply explained. Bioscience 64(2):154–155 Richardson DM, Ricciardi A (2013) Misleading criticisms of invasion science: a field guide. Divers Distrib 19(12):1461–1467 Richardson DM, Pyšek P, Rejmánek M et  al (2000) Naturalization and invasion of alien plants: concepts and definitions. Diver Distrib 6(2):93–107 Robinson TP, Wint GW, Conchedda G et  al (2014) Mapping the global distribution of Livestock. PLoS One 9(5):e96084 Rosenzweig M (1999) Heeding the warning in biodiversity’s basic law. Science 284(5412):276–277 Sagoff M (2016) Are there general causal forces in ecology? Synthese 193:3003–3024 Scheiner SM, Willig MR (2008) A general theory of ecology. Theor Ecol 1(1):21–28 Schoener TW (1986) Mechanistic approaches to community ecology: a new reductionism. Am Zool 26(1):81–106 Secord JA (1981) Nature’s fancy: Charles Darwin and the breeding of pigeons. Isis 72:163–186 Shelford MB (1913) The decline of primeval communities at the head of Lake Michigan. In: Shelford VE (ed) Animal communities in temperate America. University of Chicago, Chicago Simberloff D (2010) Invasions of plant communities–more of the same, something very different, or both? Am Midl Nat 163(1):220–233 Simberloff D, Souza L, Nuñez MA, Barrios-Garcia MN, Bunn W (2012) The natives are restless, but not often and mostly when disturbed. Ecology 93(3):598–607 Simberloff D, Martin JL, Genovesi P et al (2013) Impacts of biological invasions: what’s what and the way forward. Trends Ecol Evol 28(1):58–66 Smil V (1991) General energetics: energy in the biosphere and civilization. Wiley, New York Stiling P (1992) Ecology. Prentice Hall, Upper Saddle River Stohlgren, T.J., Barnett, D.T. and Kartesz, J.T., 2003. The rich get richer: patterns of plant invasions in the United States. Front Ecol Environ 1(1):11–14

13

M. Sagoff Thomas CD (2015) Rapid acceleration of plant speciation during the Anthropocene. Trends Ecol Evol 30(8):448–455 Thomas CD, Palmer G (2015) Non-native plants add to the British flora without negative consequences for native diversity. Proc Natl Acad Sci 112(14):4387–4392 Thompson K (2014) Where do camels belong? The story and science of invasive species. Profile Books, London Valéry L, Fritz H, Lefeuvre JC (2013) Another call for the end of invasion biology. Oikos 122(8):1143–1146 Vellend M (2014) The value of biodiversity: a humbling analysis. Trends Ecol Evol 29:138–139 Villee CA (1972) Biology. WB Saunders Compamy, Philadelphia Voget FW (1975) A history of ethnology. Holt, Rinehart and Winston, New York Wagner MR, Block WM, Geils BW, Wenger KF (2000) Restoration ecology. J For 98(10):22–27 Walker BH, Gunderson LH, Kinzig AP et  al (2006) A handful of heuristics and some propositions for understanding resilience

13

in social-ecological systems. Ecol Soc 11(1):13. http://www. ecologyandsociety.org/vol11/iss1/art13/ Weber M (1949) [1904] Objectivity in social science and social policy. In: Shilsand EA, Finch HA (eds) The methodology of the social sciences. Free Press, New York Whittaker RH, Levin SA, Root RB (1973) Niche, habitat, and ecotope. Am Nat 107(955):321–338 World Society for the Protection of Animals (WSPA) (2008) Eating our future: the environmental impact of industrial animal agriculture. http://www.fao.org/ag/againfo/themes/animal-welfare/ news-detail/en/c/12203/. Accessed 15 Mar 2017 World Wildlife Fund (2014) More tigers in American backyards than in the wild. https://www.worldwildlife.org/stories/more-tigersin-american-backyards-than-in-the-wild. Accessed 15 Mar 2017