This paper aims to offer a new argument in defence bacterial species pluralism. To do so, I shall first present the particular issues derived from the conflict between the non-theoretical understanding of species as units of classification and the theoretical comprehension of them as units of evolution. Secondly, I shall justify the necessity of the concept of species for the bacterial world, and show how medicine and endosymbiotic evolutionary theory make use of different concepts of bacterial species due to their (...) distinctive purposes. Finally, I shall show how my argument provides a new source of defence for bacterial pluralism. (shrink)

Species are generally considered to be the basic units of evolution, and hence to constitute spatio-temporally bounded entities. In addition, it has been argued that species also instantiate a natural kind. Evolution is fundamentally about change. The question then is how species can remain the same through evolutionary change. Proponents of the species qua individuals thesis individuate species through their unique evolutionary origin. Individuals, or spatio-temporally located particulars in general, can be bodies, objects, events, or processes, or a combination of (...) these. It is here argued that species are best understood as open or closed, causally integrated processual systems that also instantiate an historically conditioned homeostatic property cluster natural kind. (shrink)

In the life of any species, extinction is the final evolutionary process. It is a common one at present, as the world is entering a major extinction crisis. The pattern of extinction and threat is very non-random, with some taxa being more vulnerable than others. Explaining why some taxa are affected and some escape is a major goal of conservation biology. More ambitiously, a predictive model could, in principle, be built by integrating comparable studies of past and present extinctions. We (...) review progress towards both explanatory and predictive frameworks, comparing correlates of extinction in different groups at different times. Progress towards explanatory models for the current crisis is promising, at least in some well-studied taxa, but the development of a truly predictive model is hampered by the formidable difficulties of integrating studies of present and past extinctions. BioEssays 22:1123–1133, 2000. © 2000 John Wiley & Sons, Inc. (shrink)

The so-called ‘‘species problem’’ has plagued evolution- ary biology since before Darwin’s publication of the aptly titled Origin of Species. Many biologists think the problem is just a matter of semantics; others complain that it will not be solved until we have more empirical data. Yet, we don’t seem to be able to escape discussing it and teaching seminars about it. In this paper, I briefly examine the main themes of the biological and philosophical liter- atures on the species problem, (...) focusing on identifying common threads as well as relevant differences. I then argue two fundamental points. First, the species problem is not primarily an empirical one, but it is rather fraught with philosophical questions that require—but cannot be settled by—empirical evidence. Second, the (dis-)solution lies in explicitly adopting Wittgenstein’s idea of ‘‘family resemblance’’ or cluster concepts, and to consider spe- cies as an example of such concepts. This solution has several attractive features, including bringing together apparently diverging themes of discussion among bio- logists and philosophers. The current proposal is con- ceptually independent (though not incompatible) with the pluralist approach to the species problem advocated by Mishler, Donoghue, Kitcher and Dupre ́, which implies that distinct aspects of the species question need to be emphasized depending on the goals of the researcher. From the biological literature, the concept of species that most closely matches the philosophical discussion pre- sented here is Templeton’s cohesion idea. (shrink)

Biodiversity has become one of the most important conservation values that drive our ecological management and directly inform our environmental policy. This paper highlights the dangers of strategically appropriating concepts from ecological sciences and also of uncritically inserting them into conservation debates as unqualified normative landmarks. Here, I marshal evidence from a cutting-edge research program in microbial ecology, which shows that if species richness is our major normative target, then we are faced with extraordinary ethical implications. This example challenges our (...) well-received beliefs about biodiversity and it invites us to critically rethink the nature of this concept so that a more robust understanding of biodiversity and of its role in conservation policy could emerge. (shrink)

We argue that the logical outcome of the cladistics revolution in biological systematics, and the move towards rankless phylogenetic classification of nested monophyletic groups as formalized in the PhyloCode, is to eliminate the species rank along with all the others and simply name clades. We propose that the lowest level of formally named clade be the SNaRC, the Smallest Named and Registered Clade. The SNaRC is an epistemic level in the classification, not an ontic one. Naming stops at that level (...) because there is no currently acceptable evidence for clades within it, not because no smaller clades exist. Later, included clades may be named. They would then become the SNaRCs, while the original SNaRC would keep its original name. We argue that all theoretical tasks of biology, in evolution and ecology, as well as practical tasks such as conservation assessment, are better approached using this rankless phylogenetic approach. (shrink)

Defining and measuring biodiversity is an important research area in biology, with very interesting theoretical and applied aspects. Numerous definitions have been proposed, and these definitions of biodiversity influence how it is measured. From the still commonly used measure of species diversity, through higher taxon diversity, molecular measures, ecological measures and indicator taxa, these measures have as their fundamental shortcoming the lack of an explicit consideration of the evolutionary context represented by phylogenies. Attempts have been made to incorporate phylogenetic considerations (...) into measuring biodiversity, but more hypothesis‐driven research needs to be done. A specific case study is presented of how this added emphasis on phylogeny‐based biodiversity measurement can influence the way in which research is directed and hypotheses are generated. The elucidation of the relationship of biodiversity to ecosystem functioning is a very timely concern with the unarguable loss of biodiversity this planet is experiencing, whichever way biodiversity is measured. (shrink)

Academia is subdivided into separate disciplines, most of which are quite discrete. In this review I trace the interactions between two of these disciplines: biology and philosophy of biology. I concentrate on those topics that have the most extensive biological content: function, species, systematics, selection, reduction and development. In the final section of this paper I touch briefly on those issues that biologists and philosophers have addressed that do not have much in the way of biological content.

Biodiversity is a term easily applied in different and differing contexts. At first glance it seems to be a biological concept, defined and used in the realm of biological theory, serving for the description of particular aspects of the human and non-human environment. In this sense biodiversity even found its way into the texts of international conventions: “Biological diversity means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic systems and the ecological complexes (...) of which they are part; this includes diversity within species, between species and of ecosystem.” [Harper and Hawksworth (1995)] But despite this clear and distinct definition, the intension of the term BD seems to be ambiguous. This is true for the single aspects of the definition itself, for example, the discussion over “what is a species?” took place in biology during the last 200 years and it is far from being finished [Claridge et al. (1997) Species]. This discussion asks not only for the “correct” biological definition of the term, but at the same time the methodological status of this term is in question. The result of this situation can be seen in the existence of at least 10–20 different definitions, considering biological as well as methodological aspects [Bachmann (1998) Theor Biosci 117:213–230]. Setting aside the fundamental scientific problems even the application of the term, its parametrisation and finally its relevance for biological theory-building is subject matter of controversies. The same is true for further particles of the definition, e.g. the term “ecosystem”, “complexity”, “gen”, “organisms”, etc. The intensity of the debate contrasts in a peculiar way to the reaction of (non-evolutionary) biologists, insofar as the biological research seems to be untouched by the irritating results of the debate itself. Referring to this strange situation, the aim of our article is a reconsideration of the term “biodiversity”. From an epistemological point of view it can be shown that a definition of biodiversity is possible which does not refer to biological knowledge and know-how—at least in its very first steps. Biodiversity then turns out to be a metaphor for specific aspects of societal organisation, the structuration and reproduction of nature-society relations within societies, and not for biological facts at all. (shrink)

Sociologists have challenged the discipline to account for and incorporate biological factors in their analyses. Heeding this call, this article asks how chimeras, a particularly puzzling biological organism, are being officially classified in the interrelated sites of endangered species preservation and the zoo. Based on a qualitative study of endeavors to clone endangered animals, I contend that biology alone cannot determine the classification of these interspecies organisms. Rather, categorizing chimeras requires metaphoric, schematic references to more familiar entities. Here culture and (...) biology are tools for classification, which has consequences for preservation practices and the materiality of endangered wildlife. Drawing on the sociology of culture, I show that positions on classification represent an intermediary space for interpreting the relationship between meaning and action in discourse elaboration. Building on the sociology of science and technology, I show the epistemological limitations of understanding the biological as an a priori factor. (shrink)

The recognition of species proceeds by two fairly distinct phases: (1) the sorting of individuals into groups or basic taxa (‘discovery’) (2) the checking of those taxa as candidates for species-hood (‘justification’). The target here is a rational reconstruction of phase 1, beginning with a discussion of key terms. The transmission of ‘meaning’ is regarded as bimodal: definition states the intension of the term, and diagnosis provides a disjunction of criteria for recognition of its extension. The two are connected by (...) a spectrum, with purely theoretical definition at one pole and purely ‘operational’ diagnosis at the other, with the more operational elements explained by the more theoretical. The current plethora of species concepts provides a good example. Accepting the Ghiselin–Hull thesis, that a species is an individual, a basic taxon is therefore also an individual with organisms as its parts. In a generalised synchronic individual its parts are conceptually integrated by an integrating principle (IP), which consists of a relation applying within a plan or rule. Fully developed, such an IP ensures the maximisation of the information content of the individual. A diachronic individual is then the set of its component synchronic parts, and its IP is provided by near-identity in an appropriate space-time (not necessarily physical). The integration of parts of an individual is illuminated by Gasking's concept of a proper group (in this case a chain-group), whose members are related by the relation serially fitting together with, the IP completed by an appropriate plan or rule. Gasking also applied the term cluster to a proper group persisting over a substantial period of time, individuated by any member acting as focus. A basic taxon is therefore a cluster of individuals, integrated by the relation significantly taxonomically similar and the rule in character-space-time. The nature of those concepts is discussed and defended. A species will inherit certain of the attributes of the preceding basic taxon (taxa). In at least the synchronic version its parts (individuals) will resemble each other significantly, providing the intuitive applicability of ‘members of’ and ‘instances of’ a species. Also, the notion that a species’ name is given by pure ostension, via a name-bearer (holotype) is empirically incoherent: the name cannot be applied in practice without an appropriate set of diagnostic traits. (shrink)

The new millennium has opened with a perfectly splendid decade of scholarship relating to the ‘Species Problem’. So, at least we now have a clear idea of what this is, but still no clear solution that will suit both biologists and philosophers. Richards has recently attempted to capture this story and to fill the void with two projects in one book. The first project is a descriptive and analytical history of the problem, which provides links to other recent works and (...) thereby allows one to fully reconstruct the literature. The second is prescriptive and presents Richards’s solution via a ‘division of labour in a conceptual framework’ followed by recapitulation and conclusions. It is my assessment as presented here that the first project will appeal more to biologists and the second one to philosophers. There is much of value in Richards approach including an excellent evaluation of the essentialism story in the descriptive project and clear exposition of several key issues such as the ‘species-as-individuals’ versus ‘species-as-categories’ debate which are covered in the second project. Interesting and informative as these arguments undoubtedly are, something still seems to be missing here. In this essay I suggest that this perception arises from Richards’ failure to embrace ideas about the importance of relativity and contingency in species definitions and further that his new conceptual framework lacks one hierarchical level to link overarching lineage concepts of species as evolutionary units with practical definitions for their recognition. In my view, the missing link is reproductive isolation and I conclude my review by presenting a prescriptive project for biologists to balance the one that Richards has delivered to philosophers. (shrink)

The variation and selection form of explanationcan be prescinded from the evolutionary biologyhome ground in which it was discovered and forwhich it has been most developed. When this isdone, variation and selection explanations arefound to have potential application to a widerange of phenomena, far beyond the classicalbiological ground and the contemporaryextensions into epistemological domains. Itappears as the form of explanation most suitedto phenomena of fit. It is also found toparticipate in multiple interestingrelationships with other forms of explanation. We proceed with (...) an examination of multiplekinds of phenomena, interrelationships withother members of the family of forms ofexplanation, and some novel applications evenwithin the home ground of evolutionary biology. (shrink)

The circumscription of taxa and classification of organisms are fundamental tasks in the systematization of biological diversity. Their success depends on a unified idea concerning the species concept, evolution, and taxonomy; paradoxically, however, it requires a complete distinction between taxa and evolutionary units. To justify this view, I discuss these three topics of systematics. Species concepts are examined, and I propose a redefinition for the Taxonomic Species Concept based on nomenclatural properties, in which species are classes conventionally represented by a (...) binomial. Speciation is subsequently discussed, to demonstrate that concepts on the evolutionary process are damaged when species are considered as evolutionary units. Speciation should be considered a transition among patterns of a population and, consequently, always a sympatric process. This view contrasts with the majority of speciation models, which analyze cladogeneses and classify speciation geographically, usually considering allopatry the essential condition for the differentiation process. Finally, taxonomy is considered, to show that the equivalence between evolutionary and taxonomic units may also damage the practice of biological systematization. Principles and rules of nomenclature and classification should offer freedom to accommodate divergent opinions about systematics and to incorporate the evolution of knowledge; therefore, they should remain independent of biological theories. (shrink)

This afterword to Species and Beyond provides some reflections on species, with special attention to what I think the most significant developments have been in the thinking of biologists and philosophers working on species over the past 25 years, as well as some bad jokes.

Is it possible to know anything about life we have not yet encountered? We know of only one example of life: our own. Given this, many scientists are inclined to doubt that any principles of Earth’s biology will generalize to other worlds in which life might exist. Let’s call this the “N = 1 problem.” By comparison, we expect the principles of geometry, mechanics, and chemistry would generalize. Interestingly, each of these has predictable consequences when applied to biology. The surface-to-volume (...) property of geometry, for example, limits the size of unassisted cells in a given medium. This effect is real, precise, universal, and predictive. Furthermore, there are basic problems all life must solve if it is to persist, such as resistance to radiation, faithful inheritance, and energy regulation. If these universal problems have a limited set of possible solutions, some common outcomes must consistently emerge. In this chapter, I discuss the N = 1 problem, its implications, and my response (Mariscal 2014). I hold that our current knowledge of biology can justify believing certain generalizations as holding for life anywhere. Life on Earth may be our only example of life, but this is only a reason to be cautious in our approach to life in the universe, not a reason to give up altogether. In my account, a candidate biological generalization is assessed by the assumptions it makes. A claim is accepted only if its justification includes principles of evolution, but no contingent facts of life on Earth. (shrink)

The goal of this thesis is to create a distinctively Aristotelian-Thomistic ethical schema. I shall do this in four stages. First, in chapter one, I am going to present a summary of Aristotelian metaphysics. I will present a slightly Thomistic take on Aristotelian metaphysics specifically when it comes to the distinction between accidental and substantial form. However, I will present a more classically Aristotelian account when it comes to the source of teleology. Along the way I will explore whether science (...) can disprove any aspects of Aristotelian metaphysics. In particular, I will examine whether science can show that there are no final causes, and whether evolution poses problems for the Aristotelian concept of form and essence in biology. Second, in chapter two, I shall explain the nature of goodness within this metaphysical schema. I will also engage with competing accounts of the nature of goodness and will argue that my Aristotelian account is superior. Third, in chapter three, I will list and defend my account of the basic goods. I will also explain why certain things, such as pleasure and freedom, are not included in my list of the basic goods. I will then explain how and why they do fit into my schema. Finally, in chapter four, I will move onto duties. I will show how we can derive a list of pro tanto duties from the Aristotelian ethical schema. Along the way I will also briefly sketch out an account of human rights. My ethical theory will differ from many contemporary neo-Aristotelians in that it will place emphasis on, and smoothly follow from, Aristotelian metaphysics. At the same time, my ethical theory will differ from more traditional neo-Aristotelians and the medieval neo-Aristotelians in the way that it reconciles an Aristotelian ethical schema with a non-natural account of goodness and a reasons-based account of obligation. (shrink)

This paper outlines an alternative perspective on species that avoids some of the underlying assumptions held by the BSC and other gene-centred species concepts. It begins with a characterisation of the species problem and some of the assumptions underpinning conceptions of species. In particular, the underlying bias of some conceptions (such as the BSC) to focus exclusively on the adult stage of the life cycle in articulating what a species is.