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Systematics and the historization of biology

Group leader: Mikael Härlin

 

Group members

Mikael Härlin, Associate Professor, Systematic Zoology

Yann Bertrand, PhD-student, Systematic Zoology

 

Within our group we are interested in both theoretical and practical aspects of viewing biology as a historical science. In particular we are interested in such things as identity over time and what it means to be a historical entity. Our research project is very much interdisciplinary since most of our work get influences from disciplines like philosophy of language, history, and evolutionary biology. Examples of our research concerns the development and understanding of a biological nomenclature that is adapted to tree-thinking. That is, how do we name historical entities?This research will, in combination with an international effort, eventually and hopefully replace the traditional approach to biological nomenclature that has its roots in the writings of Linnaeus. More applied aspects of our research focuses on phylogenetics, systematics, taxonomy, evolution, and biogeography in ribbon worms (Nemertea) and whirligig beetles (Gyrinidae, Coleoptera).

 

Understanding historical entities

Ever since Darwin it has become increasingly clear that biology is a historical science. But it is equally clear that we still are puzzled by what it means to be a historical entity. The debate over species concepts is just one example. Biodiversity is another one. From an evolutionary perspective it is obvious that biodiversity and its components are historical entities. But how do we go about to identify these components? Once we have an understanding of the historical nature of biodiversity, how do we go about to link this knowledge with conservation interests? The latter is clearly an issues that should interest society in general.

 

As biologist interested in things like this which very much are linked to phylogeny, that is history, we have to adopt an interdisciplinary approach. Our main problem is that history cannot be directly observed - we have to rely on indirect evidence from extant and fossil specimens. Consequently we are left with hypotheses of history rather than the "real" history.

 

From this perspective (the process of historical inference) we focus on the role of definitions and concepts like identity and sameness, concepts that have long philosophical traditions. Yet other concepts that play central roles in our research are indviduality and natural kinds. The relationship between individual and natural kind is at present a hot subject in philosophy of biology that has a obvious impact on the development of a new biological nomenclature.

 

  • Härlin M. 1998. Taxonomic names and phylogenetic trees. Zoologica Scripta 27: 381-390.
  • Härlin M. 2003a. Taxon names as paradigms: the structure of nomenclatural revolutions. Cladistics 19: 138-143.
  • Härlin M. 2003b. On the relationship between content, ancestor and ancestry in phylogenetic nomenclature. Cladistics 19: 144-147.

  • Härlin M. 2003c. Classification nomenclature. In McGraw-Hill Yearbook 2004 of Science and Technology, pp. 000-000. McGraw-Hill, Inc., New York.

  • Härlin M. 2003d. Definitions and phylogenetic nomenclature. Submitted manuscript

  • Härlin M, Sundberg P. 1998. Taxonomy and philosophy of names. Biology & Philosophy 13: 233-244.
  • Härlin C, Härlin M. 2003. Towards a historization of aposematism. Evolutionary Ecology 17: 197-212.
  • Härlin M, Thollesson M. 2003. Fundamentals of phylogenetic nomenclature(s): an exchange of views. Submitted manuscript.

Phylogenetic nomenclature

Names play a prominent role both in science and life in general. Without names our ability to communicate is severely hampered. From this perspective biological taxonomy is, perhaps, the most fundamental discipline in biosciences since it is devoted to giving names to biodiversity and thus biasing what biologists in general can talk and think about. The names themselves function as the common currency in biological thinking. Consequently, taxon names has both a high general scientific interest as well as a more specific value for understanding and describing biodiversity.

 

During the last ten years it has become increasingly clear that the traditional system of Linnaean nomenclature is inadequate to communicate information about phylogeny. Giving up 250 years of Linnaean nomenclature is a difficult but stimulating task. So far, a draft version of an alternative phylocode has been posted on the web. However, within our project we study the fundamentals of biological nomenclature. Questions like "what do we mean by the same clade under different hypotheses" and "how should a nomenclatural system be designed in order to capture reference of taxon names throughout changing views about phylogenetic hypotheses" are at the heart of the project. To be able to shed light on these, and similar, issues we try to reconcile philosophy of language with history and evolutionary biology. We have applied new theories of nomenclature on both nemerteans and whirligig beetles. Within this project we are also interested in the relationships between nomenclature, hierarchies, and biodiversity.

 

  • Härlin M. 1998. Taxonomic names and phylogenetic trees. Zoologica Scripta 27: 381-390.
  • Härlin M. 1998. Tree-thinking and nemertean systematics, with a systematization of the Eureptantia. Hydrobiologia 365: 33-46 
  • Härlin M. 1999. Phylogenetic approaches to nomenclature: a comparison based on a nemertean case study. Proceedings of the Royal Society of London, Series B 266: 2201-2207.
  • Härlin M. 1999. The logical priority of the tree over characters and some of its consequences for taxonomy. Biological Journal of the Linnean Society 68: 497-503.
  • Härlin M. 2003a. Taxon names as paradigms: the structure of nomenclatural revolutions. Cladistics 19: 138-143.
  • Härlin M. 2003b. On the relationship between content, ancestor and ancestry in phylogenetic nomenclature. Cladistics 19: 144-147.

  • Härlin M. 2003c. Classification nomenclature. In McGraw-Hill Yearbook 2004 of Science and Technology, pp. 000-000. McGraw-Hill, Inc., New York.

  • Härlin M. 2003d. Definitions and phylogenetic nomenclature. Submitted manuscript.
  • Härlin M, Sundberg P. 1998. Taxonomy and philosophy of names. Biology & Philosophy 13: 233-244. Härlin M, Härlin C. 2001. Phylogeny of the eureptantic nemerteans revisited. Zoologica Scripta 30: 49-58.
  • Pleijel F, Härlin M. 2004. Phylogenetic nomenclature is compatible with diverse philosophical perspectives. Zoologica Scripta (in press)
  • Härlin M, Thollesson M. 2003. Fundamentals of phylogenetic nomenclature(s): an exchange of views. Submitted manuscript.

Kuhn and the development of science

In a broader perspective our research on nomenclature has led to more general studies on how science develops. With biological nomenclature as a model we have contrasted Poppers cumulativism with Kuhns more disruptive view of scientific development. At present we are trying to develop Kuhns views at a low theoretical level - the level of taxa. Could it be that taxa can be treated as low level paradigms? (Härlin 2003a). This project is very much in line with our general aim of understanding historical entities and the process of historical inference.

  • Härlin M. 2003a. Taxon names as paradigms: the structure of nomenclatural revolutions. Cladistics 19: 138-143.

Applied phylogenetic systematics

The nemerteans

Ribbon worms are found in marine habitats around the world. They are characterized by the unique rhynchocoel with its eversible proboscis. Many species are brightly colored and are toxic to predators. Within this project we have focused on Eureptantia, which is one of the major clades of polystiliferous nemerteans. As a result of the phylogenetic analyses we have developed a novel key based on phylogenetic information. With the phylogenetic hyptheses as our foundation we study the historical biogeography of the group and one of our aims is to correlate the phylogeny with the evolution of the islands in the Indonesian archipelago. The Eureptantia has also functioned as a guinea pig for the development of phylogenetic nomenclature. If you want to know more about nemerteans, click here.

 

  • Härlin M. 1996. Biogeographic patterns and the evolution of eureptantic nemerteans. Biological Journal of the Linnean Society 58: 325-342.
  • Härlin M. 1998. Tree-thinking and nemertean systematics, with a systematization of the Eureptantia. Hydrobiologia 365: 33-46.
  • Härlin M, Sundberg P. 1995. Cladistic analysis of the eureptantic nemerteans (Nemertea: Hoplonemertea). Invertebrate Taxonomy 9: 1211-1229.
  • Härlin M, Härlin C. 2001. Phylogeny of the eureptantic nemerteans revisited. Zoologica Scripta 30: 49-58.
  • Sundberg P, Svensson M (=Härlin M). 1994. Homoplasy, character function, and nemertean systematics. Journal of Zoology, London 234: 253-263.
  • Sundberg P, Turbeville JM, Härlin M. 1998. There is no support for Jensen's hypothesis of nemerteans as ancestors to the vertebrates. Hydrobiologia 365: 47-54.

  • Svensson M (= Härlin M). 1993. Morphological variation in the palaeonemertean Tubulanus annulatus (Montagu, 1804). Hydrobiologia 266: 239-246

The whirligigs

The whirligigs (Gyrinidae, Coleoptera) are small aquatic beetles that normally aggregate in large schools on the water surface and are easily recognized by their gyrating or zigzag swimming pattern when threatend. They have a world-wide distribution with some 1000 described species. We are primarily interested in their phylogeny and systematics and have recently finished a phylogenetic study based on morphology. Forthcoming projects include molecular phylogenetics and evolution of behavioral characters.

 

  • Härlin C, Härlin M. 2003. A phylogenetic hypothesis of Gyrinus (Gyrinidae, Coleoptera) inferred by absence/presence coded morphological characters. Submitted manuscript.

Collaborators

We also work in close collaboration with the systematic botany group at Södertörn.

 

Theses within the project

  • Bertrand Y. ongoing. Tentative title: Historical entities, nomenclature, and biodiversity. PhD-thesis.
  • Härlin M. 1996. Tree-thinking and nemertean systematics. PhD-thesis. Department of Zoology (Zoomorphology), Göteborg University, Sweden (ISBN 91-628-1952-6)
  • Härlin C. 2003. Phylogeny and evolution of predator defense in whirligig beetles. PhD-thesis. Department of Zoology (Animal Ecology), Göteborg University, Sweden (ISBN 91-628-5619-7).

Published book reviews

  • Härlin M. 1998. Metaphysics and the origin of species, by Michael T. Ghiselin. Zoologica Scripta 27: 87-88.
  • Härlin M. 2001. Towards a new biological taxonomy - let us give up the Linnaean hierarchy! Zoologica Scripta 30: 337-339.
  • Härlin M, Schander C. 1998. The Darwin multimedia CD-ROM, by Michael T. Ghiselin and Pete Goldie. Zoologica Scripta 27: 271-272.

Some links 

Contact information

mail address: Department of Natural Sciences, Södertörn University College, SE-141 89 Huddinge, Sweden

e-mail: mikael.harlin@sh.se

phone: int 46 8 6084720

fax: int 46 8 6084510

Visting address: Alfred Nobels Allé 7 (room MD469)

 

 

 




Uppdaterat av Mikael Härlin 2004-03-16