I defend a view of the species category, pluralistic realism, which is designed to do justice to the insights of many different groups of systematists. After arguing that species are sets and not individuals, I proceed to outline briefly some defects of the biological species concept. I draw the general moral that similar shortcomings arise for other popular views of the nature of species. These shortcomings arise because the legitimate interests of biology are diverse, and these diverse interests are reflected (...) in different legitimate approaches to the classification of organisms. In the final section, I show briefly how the pluralistic approach can help to illuminate some areas of biological and philosophical dispute. (shrink)

Evolutionary biology is a field currently animated by much discussion concerning its conceptual foundations. On the one hand, we have supporters of a classical view of evolutionary theory, whose backbone is provided by population genetics and the so-called Modern Synthesis (MS). On the other hand, a number of researchers are calling for an Extended Synthe- sis (ES) that takes seriously both the limitations of the MS (such as its inability to incorporate developmental biology) and recent empirical and theoretical research on (...) issues such as evolvability, modularity, and self-organization. In this article, I engage in an in-depth commentary of an influential paper by population geneticist Michael Lynch, which I take to be the best defense of the MS-population genetics position published so far. I show why I think that Lynch’s arguments are wanting and propose a modification of evolutionary theory that retains but greatly expands on population genetics. (shrink)

We distinguish dynamical and statistical interpretations of evolutionary theory. We argue that only the statistical interpretation preserves the presumed relation between natural selection and drift. On these grounds we claim that the dynamical conception of evolutionary theory as a theory of forces is mistaken. Selection and drift are not forces. Nor do selection and drift explanations appeal to the (sub-population-level) causes of population level change. Instead they explain by appeal to the statistical structure of populations. We briefly discuss the implications (...) of the statistical interpretation of selection for various debates within the philosophy of biologythe `explananda of selection' debate and the `units of selection' debate. (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)

Recent discussions in the philosophy of biology have brought into question some fundamental assumptions regarding evolutionary processes, natural selection in particular. Some authors argue that natural selection is nothing but a population-level, statistical consequence of lower-level events (Matthen and Ariew [2002]; Walsh et al. [2002]). On this view, natural selection itself does not involve forces. Other authors reject this purely statistical, population-level account for an individual-level, causal account of natural selection (Bouchard and Rosenberg [2004]). I argue that each of these (...) positions is right in one way, but wrong in another; natural selection indeed takes place at the level of populations, but it is a causal process nonetheless. (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)

I defend a view of the species category, pluralistic realism, which is designed to do justice to the insights of many different groups of systematists. After arguing that species are sets and not individuals, I proceed to outline briefly some defects of the biological species concept. I draw the general moral that similar shortcomings arise for other popular views of the nature of species. These shortcomings arise because the legitimate interests of biology are diverse, and these diverse interests are reflected (...) in different legitimate approaches to the classification of organisms. In the final section, I show briefly how the pluralistic approach can help to illuminate some areas of biological and philosophical dispute. (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)

The rosy dawn of my title refers to that optimistic time when the logical concept of a natural kind originated in Victorian England. The scholastic twilight refers to the present state of affairs. I devote more space to dawn than twilight, because one basic problem was there from the start, and by now those origins have been forgotten. Philosophers have learned many things about classification from the tradition of natural kinds. But now it is in disarray and is unlikely to (...) be put back together again. My argument is less founded on objections to the numerous theories now in circulation, than on the sheer proliferation of incompatible views. There no longer exists what Bertrand Russell called ‘the doctrine of natural kinds’—one doctrine. Instead we have a slew of distinct analyses directed at unrelated projects. (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.

In recent years, several prominent biologists have pointed to the relatively new field of evolutionary developmental biology (EvoDevo) as evidence of an Extended Synthesis in evolutionary biology. More particularly, these biologists claim that theoretical and empirical EvoDevo research is extending the Modern Synthesis framework of evolutionary theory through investigation of evolutionarily important concepts that are not part of the framework developed during the 20th century. To describe the current changes in evolutionary biology as an Extended Synthesis, however, is incorrect. Through (...) review of Extended Synthesis arguments and analysis of the same biological concepts used to support these arguments, I argue that the foundation of the Modern Synthesis framework, theoretical population genetics, faces significant, perhaps insurmountable challenges from the concepts highlighted by EvoDevo research. As the foundation of the Modern Synthesis framework will require considerable remodeling—if possible—in light of the concepts emphasized by EvoDevo, it is incorrect to describe the ongoing changes in evolutionary biology as an Extended Synthesis. (shrink)

In recent years, several prominent biologists have pointed to the relatively new field of evolutionary developmental biology as evidence of an Extended Synthesis in evolutionary biology. More particularly, these biologists claim that theoretical and empirical EvoDevo research is extending the Modern Synthesis framework of evolutionary theory through investigation of evolutionarily important concepts that are not part of the framework developed during the 20th century. To describe the current changes in evolutionary biology as an Extended Synthesis, however, is incorrect. Through review (...) of Extended Synthesis arguments and analysis of the same biological concepts used to support these arguments, I argue that the foundation of the Modern Synthesis framework, theoretical population genetics, faces significant, perhaps insurmountable challenges from the concepts highlighted by EvoDevo research. As the foundation of the Modern Synthesis framework will require considerable remodeling—if possible—in light of the concepts emphasized by EvoDevo, it is incorrect to describe the ongoing changes in evolutionary biology as an Extended Synthesis. (shrink)

This paper aims to illustrate one of the primary goals of the philosophy of biology⎯namely, the examination of central concepts in biological theory and practice⎯through an analysis of the concepts of population and metapopulation in evolutionary biology and ecology. I will first provide a brief background for my analysis, followed by a characterization of my proposed concepts: the causal interactionist concepts of population and metapopulation. I will then illustrate how the concepts apply to six cases that differ in their population (...) structure; this analysis will also serve to flesh out and defend the concepts a bit more. Finally, I will respond to some possible questions that my analysis may have raised and then conclude briefly. (shrink)

How do fitness and natural selection relate to other evolutionary factors like architectural constraint, mode of reproduction, and drift? In one way of thinking, drawn from Newtonian dynamics, fitness is one force driving evolutionary change and added to other factors. In another, drawn from statistical thermodynamics, it is a statistical trend that manifests itself in natural selection histories. It is argued that the first model is incoherent, the second appropriate; a hierarchical realization model is proposed as a basis for a (...) statistical treatment. It emerges that natural selection does not cause evolution; it just is evolution. The theory incorporates relations of statistical correlation, but not the kind of causation found in fundamental physical processes. (shrink)