The  ontological  status  of  individualised  niches

The central goal of this project is to explicate what individualised ecological niches are (i.e., what their ontological status is) and how they relate to mechanisms of niche choice, conformance, and construction. This project thus analyses three concepts that play a central role in the CRC: the concept of a biological individual and of individualisation, the concept of an ecological niche, and the concept of a mechanism. The aim is to specify the meaning of these concepts, their ontological presuppositions, and how they relate to each other. This project thus provides conceptual clarity and unification to the CRC, and it contributes to establishing the theoretical fundament of the novel synthesis of individualisation that the CRC develops.

The CRC draws attention to the fact that biological individuals differ and that different individual phenotypes have different effects on how an organism chooses, conforms to, or constructs its individualised ecological niche. Accordingly, all CRC research projects make heavy use of the concepts of biological individuality and of related concepts, such as animal personality. From a general perspective, however, it is far from clear whether the concepts of individuality applied in the different research contexts are all the same, and whether the different ways in which individualisation occurs can be unified conceptually.

The goal of this project is to develop an integrative concept of biological individuality and individualisation, which accounts for the (pre)conceptions of individuality that figure in the CRC projects as well as for the empirical findings about how individualisation (e.g., of phenotypes or of niches) occurs, which the other CRC projects deliver. The emerging concept of biological individuality shall be integrative in three ways.

  1. First, it connects ideas about what biological individuals are with ideas about individualisation (e.g., of phenotypes or of niches).
  2. Second, it integrates different theoretical and investigative contexts in the biological sciences (as the CRC does, in general).
  3. Finally, it brings together assumptions about individuality and animal personality that figure in studies of behaviour, ecology, and evolution on the one hand, and philosophical theories of individuality that are developed in the philosophy of biology and in general metaphysics on the other.

An important touchstone for my integrative concept of biological individuality is that it can be used to explain the concept of an individualised ecological niche, which is the second core research area of this project.

By elaborating the concept of an individualised niche and clarifying its ontological implications, this project contributes to providing a solid theoretical fundament of the new synthesis of the CRC. We focus on three sets of questions. First, to which ontological kind of entities do individualised niches belong? The working hypothesis is that contemporary biologists view ecological niches as spatially and temporally dynamic entities, not as functional roles in communities or as static (micro) habitats (as, e.g., historical niche concepts suggest). The goal of this project is to specify and scrutinise this thesis and to defend it against alternative suggestions, such as the idea that ecological niches à la Hutchinson are conglomerates of specific environmental factors, resources, fitness gradients, and interactions, and the idea that niches are abstract spaces that do not exist in nature. Second, what does it mean to speak about individualised ecological niches? One option is to understand the concept of an individualised niche in a radical way, as stating that (all) niches are defined with regard to a single individual. Alternatively, one might adopt a less radical reading, according to which individualised niches are subsets or parts of population or species niches. In close collaboration with other CRC projects, this project explores both readings and assesses which of them is most adequate to studies of behaviour, ecology, and evolution. Third, many CRC projects investigate social niches but it remains unclear what makes a niche social and distinguishes it from non-social niches. The working hypothesis is that niches are social only if the interactions between individuals affect the fitness of individuals.

The CRC studies three different types of mechanisms of how organisms relate to their individualised niches: mechanisms of niche choice, of niche conformance, and of niche construction. These are paradigmatic examples of ecological and evolutionary mechanisms, which have not been sufficiently philosophically analysed so far. This project investigates whether and how ecological and evolutionary mechanisms differ from other kinds of biological mechanisms, such as molecular or physiological mechanisms. From an ontological perspective, they seem to be of the same kind because ecological and evolutionary mechanisms also consist of entities and activities being spatially and temporally organised. Still, ecological mechanisms seem to be related to, for instance, molecular mechanisms in a specific way. For example, mechanisms of niche construction can but need not be investigated on a molecular level. Specifying the concept of an ecological and of an evolutionary mechanism also furnishes our understanding of the mechanisms by which individualisation (e.g., of phenotypes or niches) occurs and how mechanisms of niche choice, conformance, and construction relate to biological individuality and to individualised niches.


Principle investigator

Prof. Dr. Marie I. Kaiser

PhD student

Rose Trappes



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