Function  and  fitness  in  individual  niches  - Conceptual  and  explanatory  issues

The functions of the components - or organs - of an organism allow for its survival and reproduction under a range of environmental conditions. They contribute to the fitness of the organism in its environment and determine, to a large extent, its ecological niche. The new context of an individualised niche will help to sharpen both, the concept of a biological function and the concept of fitness, and to further work out their interdependence.

In order to delineate functioning from malfunctioning, the concept of function is usually defined as an average activity of a component or, in the case of so-called etiological concepts of function (Millikan 1984; Neander 1991), as its selected role. In both cases, the concept refers to a population as the standard for proper functioning; Functions cannot be assigned when an organism is considered individually. The concept of fitness is classically defined as well via reference to (sub)populations. Individualization of the niche deprives both concepts of their standard reference and thus demands for adapting the definitions.

This philosophical project aims at developing (i) an explication of the concept of function and (ii) a conception of fitness that both match the new context of an individualised niche. In order to account for functionality in individualised niches, it will bear on the non-populational concept of function as proposed by Krohs (2009, 2011). If required, the concept will be modified or specified. In order to test the range of adequate explications, additionally a non-orthodox modification of the etiological theory of function will be developed, which also might match the case of individual functions. This newly made-up concept will be tested for its applicability to cases of interest for the CRC. Further tests for applicability will be run with the non-normative concept of functions as actual systemic roles (Cummins 1975), and with a concept that considers functions as contributions to fitness (the so-called propensity view: Bigelow & Pargetter 1987).

A main focus of the project will be on the explanatory roles of the concepts of function and fitness in theories of niche choice, niche conformance, and niche construction, with a particular interest in cases of individualised niches. Consequently, we will also investigate how particular explanatory goals are reflected in the use of the concept of the individualised niche within the empirical projects of the CRC.

The project aims to answer the following main research questions:

  1. Which concepts of biological function can be used, or can be reshaped to be used, when the relevant context for the definition of functioning is an individualised niche?
  2. How are the concepts of function and of fitness related in settings of individualised niches?
  3. How do evolutionary explanations refer to processes of niche choice, niche conformance, and niche construction? Which of the possible combinations are used in actual explanations, based on the experiments performed in the CRC?
  4. Which concepts are actually used in the empirical projects of the CRC?
  5. How is the concept of fittedness related to the concept of fitness? Does the propensity interpretation play any role? How else is the statistical aspect of fitness as based upon the matching between organism and environment to be described?
  6. How can philosophy help sharpening the empiricist?s conceptions of fitness and niche?


Principle investigator

Prof. Dr. Ulrich Krohs

PhD student

Behzad Nematipour



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