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The three-taxon approach to phylogenetic analysis separates the universe of cladograms into a larger number of classes of solutions showing decreasing degrees of fit to data than does conventional Farris optimization. The three-taxon approach applies to character analysis Nelson and Platnick's interpretation 2 of multiple branching in cladograms.

ispartof: Cladistics vol:11 issue:2 pages:211-218 ispartof: location:United States status: published

Aim Areas of endemism are the fundamental units of cladistic biogeographical analysis but there is no consensus on the most appropriate method for their delimitation. In this paper, the relative performance of a number of algorithmic approaches for the delimitation of areas of endemism is investigated within the context of the Canary Islands flora, and areas of endemism within the Canary Islands archipelago are defined. Location The Canary Islands. Methods A data matrix comprising the distributions of 609 endemic spermatophyte taxa (c. 90% of the endemic flora) scored on a 10 × 10 km UTM grid was analysed using: (1) UPGMA (unweighted pair group method with arithmetic mean) clustering of Jaccard and Kulczynski similarity coefficient matrices, (2) parsimony analysis of endemicity (PAE), and (3) the program ndm (eNDeMism). The performance of each method was then determined by the extent to which the resulting areas of endemism met three criteria: (1) possession of two or more strict endemic taxa, (2) diagnosability, and (3) geographical contiguity. Results Each of the four methods resulted in substantially different sets of areas. ndm analysis resolved 17 areas of endemism consistent with all three criteria, and collectively these accounted for 59% of all cells. In the hierarchical analyses none of the methods recovered more than eight areas of endemism, and the total coverage of cells ranged from 13% to 33% when the results were confined to intra-island areas of endemism. Main conclusions ndm outperforms hierarchical clustering methods in terms of both the number of intra-island areas of endemism delimited that meet the three evaluation criteria and the total coverage of those areas. ndm may also be considered preferable because it is non-hierarchical, incorporates spatial information into the delimitation of areas, and permits overlap between areas of endemism where there is evidence to support it. The results support the use of ndm as the most appropriate method currently available for the delimitation of areas of endemism. The areas of endemism identified by the ndm analysis are discussed.

The endemic vascular flora of the Canary Islands comprises over 680, taxa collectively accounting for more than 50% of the total native flora. To investigate geographical patterns of diversity within the endemic flora, distribution data from published sources together with other field observation and herbarium data were used to compile a data matrix comprising the distributions of ca. 90% of endemic taxa scored on a 10 × 10km UTM grid. WORLDMAP was then used to investigate patterns of endemic diversity, range size rarity (a measure of endemicity), phylogenetic diversity and threatened taxon richness. Endemic taxon richness was found to be highly heterogeneous across the archipelago, with cells containing between one and 139 taxa each (0.05-22.82% of endemic diversity). Patterns of variation in range size rarity and phylogenetic diversity were found to be largely congruent with endemic diversity, although some cells exhibited markedly higher range size rarity scores than would be predicted by their endemic diversity scores. In contrast, the pattern of endangered taxon richness across the archipelago differed markedly from endemic taxon richness. Many cells in Lanzarote, Fuerteventura and Gran Canaria exhibit higher endangered taxon richness scores than would be predicted from their endemic richness scores whereas in Tenerife, El Hierro, La Palma and La Gomera, the converse is generally true. The implications of the results both for understanding the evolution of Canary Island endemic diversity and for the conservation of the region’s unique and vulnerable flora are considered.La flora vascular endémica de las Islas Canarias comprende unos 680 táxones, lo que viene a representar más del 50% de la flora nativa. Con objeto de investigar patrones geográficos de diversidad en la flora endémica, se recopilaron los datos publicados que, junto con otras observaciones de campo y datos de herbario, sirvieron para completar una matriz de datos que abarca la distribución de cerca del 90% de los táxones endémicos usando cuadrículas UTM de10 × 10 km. A continuación, se utilizó el programa WORLDMAP para investigar los patrones de diversidad de los endemismos, el rango del grado de rareza (una medida de endemicidad), la diversidad filogenética y la riqueza en táxones amenazados. Se observó que la riqueza en endemismos es muy heterogénea a lo largo del archipiélago, con unos valores por cuadrícula que oscilan entre 1 y 139 táxones (0,05-22,82% de la diversidad de táxones endémicos). Los patrones de variación del rango del grado de la rareza y la diversidad filogenética resultaron ser en gran parte congruentes con la diversidad en endemismos, aunque algunas cuadrículas mostraron valores mucho más altos de rareza de los que podían ser predichos dada su diversidad de endemismos. En contraste, los patrones de riqueza en especies amenazadas en el archipiélago difirieron marcadamente de la riqueza en táxones endémicos. Muchas cuadrículas de Lanzarote, Fuerteventura y Gran Canaria mostraron valores más altos de riqueza en especies amenazadas que las que pudieran ser predichas sobre la base de su riqueza en táxones endémicos, mientras que en Tenerife, El Hierro y La Gomera la regla fue generalmente lo contrario. Se consideran las implicaciones que estos resultados suponen para la comprensión de la evolución de la diversidad de endemismos canaria y para la conservación de su singular y vulnerable flora.

Marcelo R. de Carvalho AE Flavio A. Bockmann AE Dalton S. Amorim AE Carlos Roberto F. Brandao AE Mario de Vivo AE Jose L. de Figueiredo AE Heraldo A. Britski AE Mario C. C. de Pinna AE Naercio A. Menezes AE Fernando P. L. Marques AE Nelson Papavero AE Eliana M. Cancello AE Jorge V. Crisci AE John D. McEachran AE Robert C. Schelly AE John G. Lundberg AE Anthony C. Gill AE Ralf Britz AE Quentin D. Wheeler AE Melanie L. J. Stiassny AE Lynne R. Parenti AE Larry M. Page AE Ward C. Wheeler AE Julian Faivovich AE Richard P. Vari AE Lance Grande AE Chris J. Humphries AE Rob DeSalle AE Malte C. Ebach AE Gareth J. Nelson

Aim To discover the pattern of relationships of areas of endemism for Australian genera in the plant family Rhamnaceae tribe Pomaderreae for comparison with other taxa and interpretation of biogeographical history. Location Australian mainland, Tasmania and New Zealand. Methods A molecular phylogeny and geographic distribution of species within four clades of Pomaderreae are used as a basis for recognition of areas of endemism and analysis of area relationships using paralogy-free subtrees. The taxon phylogeny is the strict consensus tree from a parsimony analysis of 54 taxa, in four clades, and sequence data for the internal transcribed spacer regions of ribosomal DNA (ITS1-5.8S-ITS2) and the plastid DNA region trnL-F. Results The biogeographical analysis identified five subtrees, which, after parsimony analysis, resulted in a minimal tree with 100% consistency and seven resolved nodes. Three sets of area relationships were identified: the areas of Arnhem and Kimberley in tropical north Australia are related based on the phylogeny of taxa within Cryptandra; the moister South-west of Western Australia, its sister area the coastal Geraldton Sandplains, the semi-arid Interzone region and arid Western Desert are related, based on taxa within Cryptandra, Spyridium, Trymalium and Pomaderris; and the eastern regions of Queensland, McPherson-Macleay, south-eastern New South Wales (NSW), Victoria, southern Australia, Tasmania and New Zealand are related based on Cryptandra, Pomaderris and Spyridium. Tasmania and NSW are related based entirely on Cryptandra, but the position of New Zealand relative to the other south-eastern Australian regions is unresolved. Main conclusions The method of paralogy-free subtrees identified a general pattern of geographic area relationships based on Australian Pomaderreae. The widespread distribution of clades, the high level of endemicity and the age of fossils for the family, suggest that the Pomaderreae are an old group among the Australian flora. Their biogeographical history may date to the early Palaeogene with subsequent changes through to the Pleistocene.

Aim The aim of this paper was to revise the historical biogeographical method for resolving complicated distribution patterns through a technique that has come to be called assumption 2. Assumption 2 was used to resolve multiple areas on a single terminal branch (masts) as well as paralogous and missing areas in two or more areagrams. Recent examples, however, have shown that assumption 2 may be using rather than resolving paralogy. The paper attempts to resolve this problem by formulating a separate procedure to avoid using paralogous (redundant) area data in area cladistic analyses. Method The revision results in a new derivative method, the transparent method, to replace assumptions 1 and 2. It separates the procedures for resolving paralogy and for solving distribution patterns that occur in more than one area (masts). Results Several hypothetical examples show how the transparent method reduces paralogy and masts. The results show that paralogy can be reduced if the paralogy subtree method is applied after uncovering all possible relationships as single components on the terminals of areagrams. Conclusion The transparent method is a significant step forward in cladistic biogeography as it utilizes area relationships rather than generating general areagrams based on paralogous data.

Aims Cladistic biogeography is about discovering geographical congruence. The agreement of several taxon-area cladograms (TACs) rarely yields a perfect result. Areas may overlap, taxa may not be evenly distributed, and thus, ambiguity may be prevalent in the data. Ambiguity is incongruence and may be resolved by reducing paralogy and resolving potential information. Recently, several new approaches in cladistic biogeography [i.e. Brooks parsimony analysis (BPA), Assumption 0] interpret ambiguity as congruence. These methods are problematic, as they are generational. Methods constructed under the generation paradigm are flawed concepts that are immunized from falsifying evidence. A critique of modified BPA reveals that taking an evolutionary stance in biogeography leads to flaws in implementation. Methods Area cladistics is a new development in cladistic biogeography. Area cladistics adopts paralogy-free subtree analysis using Assumption 2, to discover the relative positions of continents through time. Results Geographical congruence is the result of allopatric (geographical) speciation. Vicariance, dispersal and combinations of both, are recognized causes for allopatric speciation. Area cladistics highlights the concept that all these events occur in response to geological changes (e.g. continental drift) either directly, by geographical boundaries, or indirectly, at the level of ocean currents. Samples of chosen examples all respond to the geological process. The examples include Ordovician–Silurian and Lower Devonian trilobites to yield a general areagram which is a representational branching diagram that depicts the relationships of areas. Main conclusion Finding one common biogeographical pattern from several unrelated groups is a qualitative approach to interpret the positions of continental margins through time. Area cladistics is not a substitute for palaeomaps that are derived from palaeomagnetic data, but general areagrams adding to the body of knowledge that yields more precise interpretations of the earth's past.

The ever-larger data matrices resulting from continuing improvements in DNA sequencing techniques require faster and more efficient methods of phylogenetic analysis. Here we explore a promising new method, parsimony jackknifing, by analyzing a matrix comprising 2538 sequences of the chloroplast generbcL. The sequences included cover a broad taxonomic range, from cyanobacteria to flowering plants. Several parsimony jackknife analyses were performed, both with and without branch-swapping and multiple random addition sequences: 1) including all positions; 2) including only first and second codon positions; 3) including only third positions; and 4) using only transversions. The best resolution was obtained using all positions. Removal of third positions or transitions led to massive loss of resolution, although using only transversions somewhat improved basal resolution. While branch-swapping improved both resolution and the support found for several groups, most of the groups could be recovered by faster simple analyses. Designed to eliminate groups poorly supported by the data, parsimony jackknifing recognizes 1400 groups on the basis of allrbcL positions. These include major taxa such as green plants, land plants, flowering plants, monocots and eudicots. We include appendices of supported angiosperm families, as well as larger groups.

Patricia Williams made a number of claims concerning the methods and practise of cladistic analysis and classification. Her argument rests upon the distinction of two kinds of hierarchy: a ‘divisional hierarchy’ depicting ‘evolutionary’ descent and the Linnean hierarchy describing taxonomic groups in a classification. Williams goes on to outline five problems with cladistics that lead her to the conclusion that systematists should “eliminate cladism as a school of biological taxonomy and to replace it either with something that is philosophically coherent or to replace it with ‘pure’ methodology, untainted by theory” (Williams 1992, 151). Williams makes a number of points which she feels collectively add up to insurmountable problems for cladistics. We examine Williams' views concerning the ‘two hierarchies’ and consider what cladists currently understand about the status of ancestors. We will demonstrate that Williams has seriously misunderstood many modern commentators on this subject and all of her “five persistent problems” are derivable from this misunderstanding. “Some persons believe and argue, on grounds approaching faith it seems to me, that phylogeny comes from our knowledge of evolution. Others have found to their surprise, and sometimes dismay, that phylogeny comes from our knowledge of systematics”. Nelson (1989, 67).

The diversity of the Iberian vascular flora has been investigated using WORLDMAP versions 3·08 and 3·18. Two data sets scoring plant distributions as presences within the Iberian Peninsula were compiled; one for 2133 species at 50 × 50 km grid and the other for 801 species at 10 × 10 km map grids. Patterns of biodiversity were determined using the diversity measures of species richness, range-size rarity and character richness diversity. Using the diversity measures, combined with an area selection method, maps of priority areas were calculated using iterative procedures. Near minimum sets (NMSs) for both scales were calculated. Comparison of the NMS for the 10 × 10 km grid with the near minimum set for existing reserves (NMSER) showed that at least 2% more of the land surface would be required above and beyond the existing protected area network, currently comprising 6% of the area, to ensure representation of all species at least once as listed within the present data-base. It is demonstrated that reserve systems selected on a variety of different criteria are suboptimal when compared to particular groups of target organisms with a definite goal of representation for conservation. Calculating efficiency of existing reserve systems and accounting for all taxa identifies precisely the extra required areas for the protected area system to satisfy particular goals of representation.

Biodiversity conservation requires efficient methods for choosing priority areas for in situ conservation management. We compared three quantitative methods for choosing 5% (an arbitrary figure) of all the 10 × 10 km grid cells in Britain to represent the diversity of breeding birds: (1) hotspots of richness, which selects the areas richest in species; (2) hotspots of range-size rarity (narrow endemism), which selects areas richest in those species with the most restricted ranges; and (3) sets of complementary areas, which selects areas with the greatest combined species richness. Our results show that richness hotspots contained the highest number of species-in-grid-cell records (with many representations of the more widespread species), whereas the method of complementary areas obtained the lowest number. However, whereas richness hotspots included representation of 89% of British species of breeding birds, and rarity hotspots included 98%, the areas chosen using complementarity represented all the species, where possible, at least six times over. The method of complementary areas was also well suited to supplementing the existing conservation network. For example, starting with grid cells with over 50% area cover by existing “Sites of Special Scientific Interest,” we searched for a set of areas that could complete the representation of all the most threatened birds in Britain, the Red Data species. The method of complementary areas distinguishes between irreplaceable and flexible areas, which helps planners by providing alternatives for negotiation. This method can also show which particular species justify the choice of each area. Yet the complementary areas method will not be fully able to select the best areas for conservation management until we achieve integration of some of the more important factors affecting viability, threat, and cost.

Quantitative information on large scale spatial patterns of biodiversity remains poor. This is arguably a consequence of the disproportionate emphasis given to species as units of diversity. In this paper the regional biodiversity of terrestrial and freshwater seed plants, beetles, amphibians, reptiles and mammals is mapped worldwide at the family level. The `hotspots' of family richness are located in southeast Asia for one group, in the New World for two groups, in Africa for one group, and the fifth group has tied values in southeast Asia and the New World. Seed plants, amphibians, reptiles and mammals show classic latitudinal gradients in family richness; beetle family richness essentially lacks a strong latitudinal gradient. A very high proportion of the families of each of the five taxonomic groups can be embraced within a small number of regions.

The primary aims of taxonomy are to name, circumscribe, describe and classify species. The first goal is convention but the remainder are science. The International Codes of Nomenclature are legislative instruments and nomenclature is simply a mechanism to ensure that a species name is legitimately attached to a type specimen, regardless of scientific status. The type of a species does not serve, as Tautz et al. ([1xDNA points the way ahead in taxonomy. Tautz, D. et al. Nature. 2002; 418: 479CrossRef | PubMedSee all References, 2xA plea for DNA taxonomy. Tautz, D. et al. Trends Ecol. Evol. 2003; 18Abstract | Full Text | Full Text PDF | Scopus (441)See all References], but see [3xThe status of taxonomic literature. Minelli, A. Trends Ecol. Evol. 2003; 18Abstract | Full Text | Full Text PDF | Scopus (22)See all References][3]) assert, as ‘the central reference for comparisons’. The crucial link between names and scientific investigation is species circumscription followed by description. The Codes require Linnaean binomials: a genus name and a species epithet. The rules are totally silent about what constitutes a species; rather this is a key goal of biological investigation. Circumscriptions of genera and species evolve as science progresses.The Linnaean binomial system is not ‘inherently unstable’ but is used to interpret the underlying science. The problem that ‘a name that has been used for a long time thus can suddenly disappear’ (or reappear, for that matter) is a nuisance for everyone. However, if name changes are considered a serious problem, then the conservation and rejection criteria available in the Codes can be invoked.Neither the Botanical nor the Zoological Code has a fixed authoritarian supervisory body; rather, they have committees chosen by a democratic process that oversee changes. The Codes work by consensus and are designed to be open and universally applicable [4xTaxonomy needs evolution, not revolution. Knapp, S. et al. Nature. 2002; 419: 559CrossRef | PubMedSee all References][4]. Tautz et al. ([2xA plea for DNA taxonomy. Tautz, D. et al. Trends Ecol. Evol. 2003; 18Abstract | Full Text | Full Text PDF | Scopus (441)See all References][2], and see [3xThe status of taxonomic literature. Minelli, A. Trends Ecol. Evol. 2003; 18Abstract | Full Text | Full Text PDF | Scopus (22)See all References][3]) advocate universal, centralized, apparently obligatory registration, a concept emphatically rejected by the International Botanical Congress in 1999. Taxonomists from developing nations led the move against centralization, fearful that the wealthier nations were attempting to monopolize information. In our view, registration would eventually strangle systematics, as debate will be discouraged.Most current taxonomy is pursued using low-cost technology. Mandatory introduction of DNA sequences into taxonomy seems to us a retrograde step. In most instances, a quick survey of morphology will serve the same purpose and, although morphology has its problems, DNA has as many pitfalls. A sufficiently different sequence might warrant the description of a new species, as will a sufficiently different morphology. An expensive and centralized DNA-based taxonomy would only add to the North–South divide in taxonomy, and might exclude the many taxonomists who have limited access to sequencing technology.Acknowledging that there need not (or cannot) be universal agreement about which region of the genome to sequence, Tautz et al. suggest using house-keeping genes, especially the ribosomal genes (at least in animals). Although abundant, ribosomal sequences might be an inappropriate choice in the long run, because they have profound alignment problems and are subject to different degrees of concerted evolution.Matching existing Linnaean names with DNA sequences is fraught with hazards. Although it is tempting to create a new starting date for priority for the Botanical and Zoological Codes [5xChallenges for taxonomy. Godfray, H.C.J. Nature. 2002; 417: 17–19CrossRef | PubMed | Scopus (246)See all References][5], it seems futile to replace existing types (from which DNA in some cases cannot be extracted) with neotypes. As indicated by the authors [1xDNA points the way ahead in taxonomy. Tautz, D. et al. Nature. 2002; 418: 479CrossRef | PubMedSee all References][1], expert taxonomists are in short supply and many important groups are neglected. It takes little imagination to envisage the problems broad-scale designation of neotypes would cause.Tautz et al. argue that existing DNA data bases represent bad taxonomy, as ‘there is no guarantee that the correct species names were assigned by the submitter of the sequence, because there are no established taxonomic standards under which such submissions have to be done’. The circumscription of a species is an opinion [6xSee all References][6]. One might ask therefore who is going to decide on ‘taxonomic standards’. Circumscription changes with increasing knowledge; that's the science. Many sequences are deposited in DNA data bases, but, if a specimen has been misidentified, only inspection of the voucher can solve this problem. It is naïve to think that ‘phylogenetic analysis of query sequences, will readily place any sequences from new species’, as if the problems of homoplasy, alignment, and even phylogenetic methods would not add to the unreliability of information in existing data bases.The role of collections in systematics is vital. Collections represent a comparative model of diversity, and therefore, as the authors [1xDNA points the way ahead in taxonomy. Tautz, D. et al. Nature. 2002; 418: 479CrossRef | PubMedSee all References][1] point out, specimens should be retained as intact as possible. Destructive sampling of type specimens for any characters has always been a severe problem and such procedures are accepted only as a last resort. To destroy a sample to extract its DNA might be inadvisable in the light of future needs.With regard to taxonomic and phylogenetic studies, current practise attempts to create higher level classifications that do not conflict directly with cladograms [7xSee all References][7]. Today, phylogenetic methods applied to DNA data are a strong focus of systematics research, and it is difficult to believe that the pendulum might swing in another direction. However, methods do change and the fixed opinions of today might seem redundant in the future.So what is the upshot? Indeed, what has the molecular revolution really achieved for taxonomy? The main advance is that it has provided access to copious data for cladistic analysis and, in our view, has provided new data sets and a new class of characters that can be extremely useful in broad-scale comparisons of everything from bacteria to mammals and plants. Often one is forced to use one, or a few, carefully selected specimens as representatives of a taxon, but experience has repeatedly shown that this can be a major mistake. Deliberately using a single specimen as a representative of the taxon will only create havoc in taxonomy, a fact long realized by taxonomists working with other types of data. Individual bases and DNA sequences are simply characters, tiny fragments of the lifecycle. It seems perverse to us to advocate using a DNA sequence as a mandatory identification tag for a species, even as a first approximation. Therefore, this plea for a DNA-based taxonomy is little more than a cri de coeur for bioinformatics and increased reliance on sequence data. We agree that there is a very strong need for efficient, although perhaps not centralized, repositories for DNA samples. How and where such samples should be curated, and how the curators should be funded, is an open question. We also agree that it would be a good idea to include DNA sequences in the diagnoses of taxa. However, we feel that a DNA-based taxonomy along the suggested lines would catastrophically retard taxonomic activity, and it would certainly not relieve the need for many more taxonomists, especially in the tropics, for the good of taxonomy's many dependent user groups.

The intention and practice of conservation reserve selection are different. A major reason for systems of reserves is to sustain biological diversity. This involves protecting examples of as many natural features, e.g. species, communities or environments, as possible. In reality, however, new reserves have rarely been dedicated for their representation of features. Furthermore, the opportunism that has characterized the development of reserve systems can actually jeopardize the representation of all features in reserves through the inefficient allocation of limited resources. More systematic approaches are essential if reserves are to play their role in protecting biodiversity. Some basic principles for conservation planning are emerging from recent systematic procedures for reserve selection. These principles will help to link intention and practice.

Phylogenies based on molecular sequence data and on morphology are surveyed and compared within animals (concentrating on vertebrates, mammals, and hominids in particular) and within plants (concentrating on Asterales, angiosperms, seed plants, and major groups of "green plants"). The theoretical problem of assessing congruence between trees generated from different data sets is still unsolved. However, in practice, we find that incongruence between molecular trees (generated from different data sets or by different analytical methods) is as striking or pervasive as is incongruence between trees generated by morphologists in the long history of their discipline. Morphologists achieved much during that time, and none of their well-supported phylogenies is overthrown by molecular data. So far, molecular sequences have contributed most significantly in areas where morphological data are inconclusive, deficient, nonexistent, or poorly analyzed. The interrelationships of extant hominines (Gorilla, Homo, Pan), where morphology is inconclusive, are exemplary. The pattern [Gorilla [Homo, Pan]] is significantly favored by nucleotide sequence data, but the effort necessary to achieve resolution in that simple case (ca. 30 kb of aligned sequences, sampling all four extant species) may foreshadow the workload that lies ahead.

Politicians and scientists alike non, agree that a priority list of global centres for preservation of biological diversity is required. Diversity has generally been measured only in terms of species richness, or in the form of indices combining richness with abundance. Such measures are considered inadequate for the task in hand. A novel index, based on the information content of cladistic classifications and giving a measure of taxonomic distinctness, is introduced. This taxic diversity measure, when coupled with detailed knowledge of distribution, can be used in modified analyses of the type previously developed as 'critical faunas analysis' or 'network analysis'. Central to all such analyses is the concept of complementarity of floras or .faunas. By employing complementarity, step-wise procedures can identify optimally efficient, single-site sequences of priority areas for a group, taking existing reserves into account or not, as required. For practical planning it is concluded that two basic rounds of analysis are required:first, recognition of global priority areas by taxic diversity techniques; secondly, within any such area, analysis without taxic weighting (as being developed by Margules and his co-workers) to identify a network of reserves to contain all local taxa and ecosystems. The paper concludes with a brief discussion of some immediate prospects.for development of a systematic approach to global conservation

Prior to Linnaeus, the father of modern taxonomy, the origin of systematics dates back to the Greeks, but it was the development of the Greek model by Linnaeus in the middle of the eighteenth century that is recognized as the starting point of systematics. The changes in method that have come about since that time are largely due to different appreciations as to what constitutes homology, hierarchy and the relationship between systematics and evolution. Keywords: systematics; taxonomy; phenetics; cladistics; computer algorithms; parsimony

Upper Triassic of east-central New Mexico. N.M. Mus. Nat. Hist. Sci. Bull. 21:221–234. SMALL, B. J. 1989. Aetosaurs from the Upper Triassic Dockum Formation, Post Quarry, West Texas. Pages 301–308 in Dawn of the age of dinosaurs in the American southwest (S. G. Lucas and A. P. Hunt, eds.). New Mexico Museum of Natural History, Albuquerque. SMALL, B. J. 1998. The occurrence of Aetosaurus in the Chinle Formation (Late Triassic, U.S.A.) and its biochronological significance. Neues Jahrb. Geol. Palaontol. Monatsh. 1998:285–296.

We strongly support initiatives to produce clear, efficient and practical goals for conservation to guide biodiversity planners and decision-makers in governments, agencies, conventions and non-governmental organizations (NGOs). However, as things stand there is only limited consensus on global conservation priorities at international level. We believe that the time is now right for scientists and practitioners to work together to develop a commonly adopted blueprint for action.

Maps of large-scale biodiversity are urgently needed to guide conservation, and yet complete enumeration of organisms is impractical at present. One indirect approach is to measure richness at higher taxonomic ranks, such as families. The difficulty is how to combine information from different groups on numbers of higher taxa, when these taxa may in effect have been defined in different ways, particularly for more distantly related major groups. In this paper, the regional family richness of terrestrial and freshwater seed plants, amphibians, reptiles and mammals is mapped worldwide by combining: (i) absolute family richness; (ii) proportional family richness; and (iii) proportional family richness weighted for the total species richness in each major group. The assumptions of the three methods and their effects on the results are discussed, although for these data the broad pattern is surprisingly robust with respect to the method of combination. Scores from each of the methods of combining families are used to rank the top five richness hotspots and complementary areas, and hotspots of endemism are mapped by unweighted combination of range-size rarity scores.

The complete sequence of a small ribosomal RNA gene of Schistosoma mansoni contained within plasmids pSM389 and pSM889 is presented. It was found to be 1992 bp in length, larger than that of most eukaryotes. Extra nucleotides occur in regions known to be variable (V4 and V7). The predicted secondary structure of the nucleotides 660–853 revealed additional helices which have been designated E21-1A and E21-1B. The other region to differ from higher eukaryotes lies between nucleotides 1457 and 1569. Secondary structure prediction demonstrated that a single extended helix may be formed from this part of the schistosome small subunit rRNA sequence. Nucleotides that could be unambiguously aligned with those of 12 other eukaryotes were used to estimate phylogenetic relationships. The consensus tree obtained by Maximum Parsimony analysis showed the schistosome as a sister taxon to the flatworm Dugesia tigrina .

A preliminary study of eastern Monocalyptus suggested that the peppermint eucalypts, informal subseries Amygdalininae, form a monophyletic group whose sister taxon is series Pilulares. Subseries Amygdalininae was then analysed using four cladistic methods: transformed cladistic method, Wagner trees, a branch and bound method (all three being parsimony methods) and character compatibility analysis. The branch and bound method produced the shortest trees, four in all. They suggested that, within the Amygdalininae, Eucalyptus pulchella is the sister species to E. amygdalina, which in turn is the sister species to all other taxa. The remaining species from Tasmania form a monophyletic group characterized by, for example, protruding oil glands on seedling and juvenile-leaf margins. The Victorian taxa form a monophyletic group characterized by high oil gland densities and lack of anthocyanin pigment on the lamina of juvenile leaves at node 7. Tasmanian and mainland forms attributed to E. nitida were treated as separate terminal taxa and it was shown that they are not sister taxa. Tasmanian populations are typical E. nitida Hook. f. and a new species, E. willisii, is here erected for the mainland populations. A revised classification of subseries Amygdalininae and a formal description of E. willisii sp. nov. are appended. A vicariance-biogeographic analysis is also included.

The stringybark eucalypts form a monophyletic group characterised in Monocalyptus by hispid juvenile leaves. They have been analysed using a phenetic method, additive similarity trees and a cladistic parsimony method (Wagner trees). The shortest Wagner trees indicated that Eucalyptus muelleriana is the sister species to all other stringybarks. E. olsenii and a taxon from the Carnarvon Range (Queensland) are the next most plesiomorphic taxa in the phyletic sequence. The remaining taxa form a trichotomy: E. tindaliae, species with fruits > 8 mm in diameter and with the disc ascending, and species with fruits < 8 mm and with the disc level. Subclades are largely characterised by seedling morphology. A revised informal classification is presented, the group being treated as a superseries. A method of cladistic biogeography is explained and applied. The stringybarks are endemic to eastern mainland Australia plus Kangaroo Island, but not Tasmania, and the consensus area-cladogram suggests a sequence of seven historical events subdividing an ancestral area into eight smaller ones. Queensland appears to be the most plesiomorphic area.

The Western Australian species of Eucalyptus informal subgenus Monocalyptus were shown to be a paraphyletic group. A cladistic analysis of a larger sample of taxa, using a Wagner parsimony method, showed that the Queensland species E. rubiginosa is the sister species to all others in Monocalyptus. The Western Australian species E. jacksonii and E. brevistylis were found to be connected to eastern taxa and are probably related to the lineages leading to the 'green ashes' and 'stringybarks' etc. The remaining Western Australian species formed a number of subclades, one of which, including E. marginata and E. staeri, had a separate connection with eastern species, probably all of the 'blue ashes'. A revised informal classification recognising three sections, five subsections, five infrasections, five superseries, five series and two subseries is presented. Biogeographic analyses of each of the major subclades are summarised as one area-consensus tree representing a classification of areas as determined from the taxonomy of the eucalypts. A comparison with the geological and climatological history points to the Tertiary as the likely time of first speciation within Monocalyptus.