International Society for History, Philosophy, and Social Studies of Biology

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MONDAY, JULY 6  /  15:30 - 17:00  /  DS-M340
Organized session / standard talks
What are ecological communities, and are they preservable?

Christopher Lean (Australian National University, Australia); Alkistis Elliott-Graves (Rotman Institute, Canada)

The aim of community ecology is to explain ecological communities (i.e., assemblages of populations), how they influence each other and how they co-exist. The ontological status of ecological communities has been energetically contested within the ecological sciences for almost 90 years, with battle lines drawn up between realist and anti-realist camps. Providing a substantive account of what ecological communities are has ramifications that extend beyond the practice of ecological science. Conservation efforts often focus on the preservation of ecological communities and/or describe ecological communities as nodes of normative worth. As a result, the philosophical debate over ecological communities has become a practical issue confronting conservation workers and governmental agencies attempting to preserve biotic communities. Recently, philosophers have started to take notice of these foundational debates within ecology and contribute. This session will further this inquiry with three new papers on ecological communities.

Ecological community identity is not a function of emergent properties

Christopher Eliot (Hofstra University, United States)

Ecological communities are units of description in biological ecology. They consist of more than one population and generally do not include abiotic components. Whether communities exist as such is of interest to conservation policy, conservation biology, and scientific realists. I'm aware of 6 general positions on whether ecological ecological communities exist, and to the extent that something is a community, what criteria it can be recognized by: (1) eliminativist accounts (defended by Gleason, for one example, on one reading), suggesting that no communities exist as such; (2) co-occurrence accounts (Shrader-Frechette and McCoy), suggesting that communities are generally merely statistical associations; (3) place-based accounts (Odum), attending to location alone, to the exclusion of any membership or interaction criteria; (4) interaction strength accounts (Odenbaugh) recognizing communities above a threshold of interaction strength among populations; (5) causal-perspectival accounts (Lockwood, Eliot), embracing pluralism about kinds of communities based on the kinds of causation knitting them together; (6) emergentist accounts (Mikkelson, Sterelny, perhaps Mitchell), recognizing communities as such when they reveal emergent properties including top-down self-regulation. In this paper I assess the strengths of emergentist accounts of communities against the others. They are well-motivated, and I accept the capacity of emergent properties to ground identities, but I am skeptical that any naturally-occurring communities meet such criteria for identity or derive their identities from their possession of any emergent properties.

Ecological communities are robust population networks

Christopher Lean (Australian National University, Australia)

The task of providing a substantive description of ecological communities bears upon hypotheses in both ecology and conservation science. Ecologists have frequently questioned whether ecological communities ‘exist’ or are just observer defined with the scientist or conservation worker dictating the boundaries of the community. Richard Levins and Richard Lewontin provided an early reply to such scepticism, proposing that ecological communities are causal networks of populations. I develop an allied view which recruits the Woodwardian 'difference-making' account of causation to define ecological communities as causal networks of populations. I propose that a ‘real’, and distinguishable, ecological community is a robust causal network of populations. The network is identified via the counterfactual effects of intervention on a single population radiating through other local populations. This network is bound by the dissipation of the force of the initial intervention through the other populations. If intervention on different populations that are spatially and temporally proximate yield the same or similar population networks, then this network can be considered robust. Network robustness can also be identified through varying the type of intervention on a population and the strength of intervention. This account has the virtue of being able to exclude ephemeral networks that appear through transiently interacting populations and captures how communities appear to have a stable identity without being beholden to the stability-diversity hypothesis in its various guises. Accordingly, this account offers a schematic for distinguishing between simple aggregates of populations and communities. A distinction which, I argue, is supported by empirical evidence from community ecology.

Is Aldo Leopold's "Biotic Community" an individual?

Roberta L. Millstein (University of California, Davis, United States)

Aldo Leopold’s Land Ethic has often been interpreted as ascribing intrinsic value to what he calls the biotic community. But what is the biotic community? Is it actually an entity at all, which might seem necessary (albeit not sufficient) for it to be intrinsically valuable; more precisely, is it an individual? Some authors equate Leopold’s “biotic community” with “ecosystem.” It is true that Leopold’s concept of “biotic community” is similar to that of “ecosystem,” since like an ecosystem it includes abiotic components and like an ecosystem it is at least partially characterized in terms of energy flow. However, Leopold also emphasizes that a biotic community is composed of interdependent parts. By underscoring the interactions between species and the way in which changes in some species affect other species, his concept of “biotic community” sounds a bit more like the concept of “community” studied by community ecologists. So, perhaps Leopold’s “biotic community” blends the concepts of “ecosystem” and “community” in some fashion. But this blending raises a complication, which is illuminated nicely by considering a recent essay by Jay Odenbaugh. Odenbaugh invokes a “causal relations” criterion of individuality; the relevant causal relations for communities are interactions between species whereas the relevant causal relations for ecosystems consist of nutrient and energy cycling. If this is right, what sense can be made, if any, of a blended community-ecosystem? Would it be an individual as well? I explore answers to these questions, considering, e.g., recent attempts to integrate community and ecosystem ecology. My goal is to shed light on what an integrated community-ecosystem might look like and how to make sense of the relationship between a community-individual, an ecosystem-individual, and a community-ecosystem-individual, helping to provide a solid basis for Leopold’s Land Ethic.