This paper examines the empirical aspect of the debates over group selection. I argue that specific narrow readings of the notion of ‘group’ result in a deficient experimentation of the group selection process. Criteria for empirical testability are presented and used to reexamine two well-known experiments of group selection. I argue that the former holds a narrow image of ‘group’ that does not distinguish group selection from selection at other levels; while the latter holds a multifaceted image of ‘group’ that (...) offers a way to achieve substantive progress in the debate. However, most supporters and opponent of group selection maintain a narrow and restricted image of ‘group’, which implicitly undermines informative details regarding population dynamics and population structure. These details may improve our understanding of the evolution of altruism and the evolution of sociality. To conclude, adopting a wide-ranging meaning of ‘group’ may empirically advance the group selection debates. (shrink)

Biologists studying ecology and evolution use the term “population” in many different ways. Yet little philosophical analysis of the concept has been done, either by biologists or philosophers, in contrast to the voluminous literature on the concept of “species.” This is in spite of the fact that “population” is arguably a far more central concept in ecological and evolutionary studies than “species” is. The fact that such a central concept has been employed in so many different ways is potentially problematic (...) for the reason that inconsistent usages (especially when the usage has not been made explicit) might lead to false controversies in which disputants are simply talking past one another. However, the inconsistent usages are not the only, or even the most important reason to examine the concept. If any set of organisms is legitimately called a “population,” selection and drift processes become purely arbitrary, too. Moreover, key ecological variables, such as abundance and distribution, depend on a nonarbitrary way of identifying populations. I sketch the beginnings of a population concept, drawing inspiration from the Ghiselin-Hull individuality thesis, and show why some alternative approaches are nonstarters. (shrink)

The word ``deme'' was coined by the botanists J.S.L. Gilmour and J.W.Gregor in 1939, following the pattern of J.S. Huxley's ``cline''. Its purposewas not only to rationalize the plethora of terms describing chromosomaland genetic variation, but also to reduce hostility between traditionaltaxonomists and researchers on evolution, who sometimes scorned eachother's understanding of species. A multi-layered system of compoundterms based on deme was published by Gilmour and J. Heslop-Harrison in1954 but not widely used. Deme was adopted with a modified meaning byzoologists (...) leading the evolutionary synthesis – Huxley, Simpson, Wright,and Mayr. Connections are shown between Gilmour's ideas around definingthe deme, his role in founding the Systematics Association, and his chapter``Taxonomy and Philosophy'' in the book The New Systematics. Thishistorical episode raises questions about the role of carefully-definedwords in scientific practice. (shrink)

Biologists studying short-lived organisms have become aware of the need to recognize an explicit temporal extend of a population over a considerable time. In this article we outline the concept and the realm of populations with explicit spatial and temporary boundaries. We call such populations “temporally bounded populations”. In the concept, time is of the same importance as space in terms of a dimension to which a population is restricted. Two parameters not available for populations that are only spatially defined (...) characterise temporally bounded populations: total population size, which is the total number of individuals present within the temporal borders, and total residence time, which is the sum of the residence times of all individuals. We briefly review methods to estimate these parameters. We illustrate the concept for the large blue butterfly (Maculinea nausithous) and outline insights into ecological and conservation-relevant processes that cannot be gained without the use of the concept. (shrink)

The concept of individuality as applied to species, an important advance in the philosophy of evolutionary biology, is nevertheless in need of refinement. Four important subparts of this concept must be recognized: spatial boundaries, temporal boundaries, integration, and cohesion. Not all species necessarily meet all of these. Two very different types of pluralism have been advocated with respect to species, only one of which is satisfactory. An often unrecognized distinction between grouping and ranking components of any species concept is necessary. (...) A phylogenetic species concept is advocated that uses a grouping criterion of monophyly in a cladistic sense, and a ranking criterion based on those causal processes that are most important in producing and maintaining lineages in a particular case. Such causal processes can include actual interbreeding, selective constraints, and developmental canalization. The widespread use of the biological species concept is flawed for two reasons: because of a failure to distinguish grouping from ranking criteria and because of an unwarranted emphasis on the importance of interbreeding as a universal causal factor controlling evolutionary diversification. The potential to interbreed is not in itself a process; it is instead a result of a diversity of processes which result in shared selective environments and common developmental programs. These types of processes act in both sexual and asexual organisms, thus the phylogenetic species concept can reflect an underlying unity that the biological species concept can not. (shrink)

Biologists and philosophers have been extremely pessimistic about the possibility of demonstrating random drift in nature, particularly when it comes to distinguishing random drift from natural selection. However, examination of a historical case-Maxime Lamotte's study of natural populations of the land snail, Cepaea nemoralis in the 1950s - shows that while some pessimism is warranted, it has been overstated. Indeed, by describing a unique signature for drift and showing that this signature obtained in the populations under study, Lamotte was able (...) to make a good case for a significant role for drift. It may be difficult to disentangle the causes of drift and selection acting in a population, but it is not impossible. (shrink)

Biological species have been treated traditionally as spatiotemporally unrestricted classes. If they are to perform the function which they do in the evolutionary process, they must be spatiotemporally localized individuals, historical entities. Reinterpreting biological species as historical entities solves several important anomalies in biology, in philosophy of biology, and within philosophy itself. It also has important implications for any attempt to present an "evolutionary" analysis of science and for sciences such as anthropology which are devoted to the study of single (...) species. (shrink)

This collection of essays by Robert Brandon spans two decades and most of the important problems in the philosophy of biology. Four of his five most important contributions to the philosophy of biology can be found here: the concept of relative adaptedness and its role in the propensity interpretation of fitness; the principle of natural selection; the use of the screening-off relation in defense of organismic selection; and the distinction between units of selection and levels of selection. The fifth major (...) contribution, an analysis of the concept of "environment," mentioned briefly in an essay on the co-evolution of organisms and environment, is given an extended treatment in his 1990 book, Adaptation and Environment. (shrink)

Biologists have recently found it useful to give a prominent place in their theories to the concept of a plant or animal population. Genetics, ecology, paleontology, and especially the theory of evolution have been able to make notable advances as a result of employing the concept in their interpretations and inferences. The concept has not, however, first been rigorously defined and then put to work. That is rarely the way fruitful scientific notions develop. On the contrary, in most discussions the (...) term “population” has a large degree of vagueness about it. This is due in part to the fact that the term has been taken over from ordinary language and employed in a number of novel contexts. But some of the vagueness also seems to be an unavoidable consequence of the immensely intricate phenomena to which the term refers. In any case, the role played by the concept of a population in evolutionary theory makes even a brief inquiry into its meaning worthwhile. The present paper is concerned with such an inquiry. What I wish to do is, first, to review the major ways in which the concept has been used by biologists in connection with recent formulations of the theory of evolution; and secondly, to comment on a few misleading issues which may arise if care is not taken to observe certain logical and linguistic distinctions. (shrink)

At least below the level of species, biological populations are not mind‐independent objects that scientists discover. Rather, biological populations are pragmatically constructed as objects of investigation according to the aims, interests, and values that inform particular research contexts. The relations among organisms that are constitutive of population‐level phenomena (e.g., mating propensity, genealogy, and competition) occur as matters of degree and so give rise to statistically defined open‐ended biological systems. These systems are rendered discrete units to satisfy practical needs and theoretical (...) preferences associated with specific contexts of investigation. While it may be possible to defend a realist position regarding biological relations among organisms, biological populations are “made” when contextual features determine which kinds and degrees of relations to privilege over others, and so how to bound genes in space and time. Consequently, the objectivity of population‐based approaches to species genome diversity cannot rest in the mind‐independence of populations themselves. (shrink)

This paper takes up the cause of species pluralism. An argument for species pluralism is provided and standard monist objections to pluralism are answered. A new form of species pluralism is developed and shown to be an improvement over previous forms. This paper also offers a general foundation on which to base a pluralistic approach to biological classification.

Robert Brandon is one of the most important and influential of contemporary philosophers of biology. This collection of his recent essays covers all the traditional topics in the philosophy of evolutionary biology and as such could serve as an introduction to the field. There are essays on the nature of fitness, teleology, the structure of the theory of natural selection, and the levels of selection. The book also deals with newer topics that are less frequently discussed but are of growing (...) interest, for example the evolution of human language and the role of experimentation in evolutionary biology. A special feature of the collection is that it avoids jargon and is written in a style that will appeal to working evolutionary biologists as well as philosophers. (shrink)

_This sweeping discussion of the philosophy of evolutionary biology is based on the revolutionary idea that species are not kinds of organisms but wholes composed of organisms._.

The book presents a new way of understanding Darwinism and evolution by natural selection, combining work in biology, philosophy, and other fields.

Traditionally, species have been treated as classes. In fact they may be considered individuals. The logical term “individual” has been confused with a biological synonym for “organism.” If species are individuals, then: 1) their names are proper, 2) there cannot be instances of them, 3) they do not have defining properties, 4) their constituent organisms are parts, not members. “ Species " may be defined as the most extensive units in the natural economy such that reproductive competition occurs among their (...) parts. Species are to evolutionary theory as firms are to economic theory: this analogy resolves many issues, such as the problems of “reality” and the ontological status of nomenclatorial types. (shrink)