Taxonomy and systematics: generators of prime biodiversity data

1. Taxonomy and systematics: generators of prime biodiversity data Yves Samyn1 & Hendrik Segers2 1Belgian Focal Point to the Global Taxonomy Initiative 2Belgian Biodiversity Platform Royal Belgian Institute of Natural Sciences Vautierstraat 29, B-1000 Brussels

2. Taxonomy, a multilayered science • < Greek: Taxis = order; nomos = law • => taxinomie (French); taxonomy (English) (concept from A.P. de Candolle, 1813) • Simpson (1961): ‘The theory and practice of delimiting kinds of organisms and of classifying them • Wilson (1992): ‘ Science and art ...’ • ICZN: theory and practice of classifying organisms.

3. Taxonomy, a multilayered science • Steps in taxonomy: Microtaxonomy: the demarcation of species What is a species ? What species concept is best? Pluralism seems to be the key! Link Macrotaxonomy: the classification of species How do we classify organisms ? According to genealogy or to degree of similarity... or both? • Steps in taxonomy...: a-taxonomy: recognition and description of species & first classification -taxonomy: classification of species in hierarchical system -taxonomy: understanding the evolutionary factors Micro- taxonomy Macro- taxonomy

4. Taxonomy, roles and consequences • Roles of taxonomy: Proximate: • Establish universal, unique and unambiguous tags: necessary for interdisciplinary communication • Provide an heuristic information retrieval system (identification, comparative research) Ultimate: • Comprehension of the living world • (ordering; prediction) • Consequences of taxonomy: Scientific names are critical keys that unlock biosystematic information Scientific names also represent hypotheses; they place information in a hierarchical system that allows prediction

5. But how does taxonomy operate? Amalgam of raw biodiversity data Flow-through limitators Ecological diversity Organismal diversity Genetic diversity Detection Temporal, spatial, methodological, infrastructural & financial resources Recognition & description of taxonomic units Variation, incipient and cryptic nature of life Observational phase Working hypothesis (standing taxonomy of taxon under study) Voucher collections, literature (including grey), character recognition Redescription phase Character analysis Phenogram Black box in which taxonomists operate Similarity scrutinizing phase Overall similarity clustering, shared derived character clustering Cladogram Homology scrutinizing phase Genetic diversity Understanding of clock estimators, assembly of physical & biological parameters Organismal diversity Phylogeny Integrative phase Ecological diversity Classification: information storage and retrieval + prediction Nomenclature Product development: taxonomic tools Refined biodiversity data Identification (e.g. keys, bar codes) Communication & information retrieval

6. Biological Classification - what is it? • Classifying has always been a favorite human occupation • Every classification system has two functions: • facillitation of information retrieval (incl. communication) • serve as the basis for comparative research • Biological classification is concerned with the hierarchical ordering of organisms into objective (principled) hierarchical groups • Approach to biological classifications has changed through history (e.g. classifications existed two millenia before evolutionary theory entered the scene)

7. What supplies the principle for hierarchical classification? Two kinds of answers have been offered : • phenetic hierachy based upon similarity of form of the groups being classified - numerical taxonomy • phylogenetic hierarchy based on the pattern of evolutionary descent, that is according to recency of common ancestry - cladism • The result of these 2 approaches may agree or disagree

8. Some examples Agreement between the two if: • rate of evolution is approximately constant • Direction of evolution is divergent • Disagreement between the two if: • differential rate • convergence Deciding on the approach implies agreeing on the principle

9. Phenetics(numerical taxonomy) • Starting point: • Phylogeny is unknown and most probably cannot be known and thus classification according to genealogy is not an option Development of methodologies (basically multivariate cluster analysis) to reveal the differences and similarities between OTU In order to be successful: • Consideration of as many characters as possible (+ 100) • Equal character weighting • Similarity-index expresses relatedness between OTU

10. Pheneticsin practice • Determination of the distance between the units being classified • e.g. trait 1 thorax length: sp. A (6 cm); sp. B (4 cm) => distance =2 units; • trait 2, digit length: sp. A (0.9 cm); sp. B (0.6 cm) => distance 0.3 units • Average distance for both (mean trait distance) (2+0.3)/2 = 1.15 units • cluster statistic forms groups by successively aggregating the units with the shortest distances to each other • classification equals the hierarchical output of the statistic

11. Pheneticsclaims • Thus obtained classifications are: • objective • repeatable • Are these claims justified?

12. No! Thus phenetics successfully removed subjectivity from the choice of traits, but subjectivity re-entered in the choice of cluster statistic (From Ridley 1985)

13. Fylogenetic classification (cladistics)

14. Cladistic analysis • Starting point: • Phylogeny should be retrievable and thus classification according to genealogy is the best option (Hennig) Relationship according to common decent (≈Darwin, Wallace, …, Haeckel,…) Methodology to arrive at cladograms • Characters are • Autapomorph = when unique to a taxon (A & D in species X) • Synapomorph = when derived from the nearest common ancestor (B& C in species x & y) • Symplesiomorph = whenderived from an older common ancestor (a & d in species z & y) • Clades are • Monophyletic = when sharing synapomorphies (X & Y sharing characters B&C) • Non-monophyletic= when sharing symplesiomorphies (Z & Y sharing characeters a & d); when convergent characters determine relationship (E in Z & Y) Determination of condition: outgroup comparison, ontogeny, paleontology

15. Cladistic analysis C C C B B B Out Out Out A A A Characters 1 2 3 4 5 Outgroup 0 0 0 0 0 A 1 0 0 0 1 B 1 1 0 1 0 C 1 0 1 1 0 C B Out A C B Out A 2 2 2 2 3 3 3 4 5 4 1 1 1 1 1 Shared derived characters determine the classification

16. 1 2 3 4 5 6 7 8 9 10 Outgroup 0 0 0 0 0 0 0 0 0 0 Alpha 0 0 0 1 1 1 0 0 0 0 Beta 0 0 0 1 0 1 0 0 0 0 Gamma 0 0 0 0 0 0 1 0 1 0 Delta 1 1 1 0 0 0 1 1 1 0 Epsilon 1 1 1 0 0 0 1 0 1 1 Zeta 1 1 0 0 0 0 1 0 1 1 Theta 1 0 0 0 0 0 1 0 1 1 Zeta Theta Gamma Epsilon Theta Alpha Beta Delta Gamma Epsilon Zeta Alpha Beta Delta 8 5 3 8 5 4 3 -2 4 3 6 2 6 10 1 2 1 7 7 9 9 12 steps Theta Gamma Epsilon Zeta Alpha Beta Delta -10 8 5 4 3 6 2 10 1 7 11 steps 9

17. What cladograms say about relationships • Cladistics is: • only a relativestatement of relationship • hypothesizes on a sister-group hierarchy (sharing of a more recent common ancestor) • expressed as branching diagrams: cladograms • Cladistics does not: • explicitely hypothesize ancestor-descendant relationships

18. Classification & phylogeny Paraphyletic taxon Polyphyletic taxon Monophyletic taxon Species C Species D Species C Species D Species B Species G Paraphyletic taxon Species E Species A Species P Species O Species P Species O Species K Species N Species J

19. Evolutionary taxonomy(eclectic taxonomy) • Same methodology as cladists (search for monophyletic groups) • But classification does not necessarily reflect phylogeny • Weighting of number of synapomorphies in relation to taxonomic rank e.g. Aves merits class of its own due to abundant synapomorphies Valuation of certain paraphyletic taxa

20. Tools to the aid of taxonomic research

21. Taxonomy, an information-rich science For specialists only? • Ultimate difficulties • Complexity • Evolution • Recognition • Identification • Concepts & Language • a, b, g taxonomy • Biogeography • Nomenclature • Characters • Homology - anology • Variation • Ontogeny • Proximate difficulties • Access to information storage system • Literature (original + derived) • Collections (types + other representatives) • Data (geographical, ecological: databases) • Access to information retrieval system • Identification keys • Classifications • Nomenclature • Operability • Infrastructure • Know-how • Funding

23. Traditional tools for the taxonomist • Zoological Record • Nomenclator zoologicus • List of available names in zoology • Index Nominum Genericorum • Approved list of Botanical Names • Other, more general, abstracting services (Biological abstracts; BIOSIS Previews,…) • How to get to the tools?

24. Some traditional entry points • General guides to zoological, biological and botanical literature • Bell, G.H. and Rhodes D.B. 1994. A Guide to the Zoological Literature: The Animal Kingdom. Englewood, Colo., Libraries Unlimited • Sims, R.W. 1980. Animal Identification: A Reference Guide. New York, Wiley. 3 vols • Books and textbooks • Rupert, E.E. and Barnes, R.D. 1994. Invertebrate Zoology, Sixth edition. New York, Saunders College Publishing • Nichols, D. 1969. Echinoderms, Fourth edition.Hutchinson University Library, London. • Field Guides • Hickman, C.P. 1998. A Field Guide to Sea Stars and other Echinoderms of Galapagos. Galapagis Marine Life Series, Sugar Spring Press, Lexington, USA.

25. Some traditional entry points • Specialised literature (revisions, monographs,…) • Rour, E., Ghahlaoui A., Van Goethem, J. 2002. Etat actuel des connaisances de la malacofaune terrestre du Maroc. Bull IRSNB, Biologie 72: 189-198 • Abstract and indexes • Zoological Record: from 1864 onwards, from biodiversity and the environment to taxonomy and veterinary sciences, covers 4,500 serials • Biological Abstracts: braoder than Zoological Records, covers every life sciences discipline, covers some 3,700 serials • …

26. The present-day taxonomist • Has access to digitalised information • On CD ROM • On the internet • Knows where to start his search wisely • Is aware of the pitfalls of non peer-reviewed information

27. The present-day taxonomist • Also has access to digitalised information • On CD ROM • On the internet

28. Some websites that provide data on species distributions (from Graham et al. 2004)

29. The present-day taxonomist • Some noteworthy entry points: • Non-specialist: • Wikipedia; Google scholar; SciDev.Net, Public library of Science • Specialist: • The Natural History Portal of the Natural History Museum in London • Species 2000 • uBio, GBIF, ITIS, GTI, IPNI, Index Fungorum • ICZN, ICBN, E-type initiative • Journals: • Journal of Natural History, Systematics and Biodiversity; Zootaxa;…(previews!) • Zoological Studies • And many more…

32. Thank you for your attention

33. Thank you for your attention