CORRESPONDENCE. Forum on historical biogeography: what is cladistic biogeography?

Transcription

1 Journal of Biogeography (J. Biogeogr.) (2005) 32, CORRESPONDENCE Forum on historical biogeography: what is cladistic biogeography? J. J. Morrone: Several papers published recently in this journal have revised and discussed some current different approaches of historical biogeography. In my opinion, some of their conclusions referring to the objectives and methods of cladistic biogeography were incorrect and may lead to some confusion. I would like to begin our exchange of opinions by discussing the question, What is cladistic biogeography?. Among these contributions, I was particularly surprised when I read van Veller et al. (2003). These authors proposed that the available cladistic biogeographical methods have been developed to implement two different research programmes. A priori methods, which allow modification of the taxon area cladograms to deal with dispersal, extinction or duplicated lineages, in order to obtain resolved area cladograms and provide the maximum fit to a general area cladogram, are intended to implement cladistic biogeography. A posteriori methods, which deal with dispersal, extinction or duplicated lineages after the parsimony analysis of a data matrix based on unmodified taxon area cladograms, are intended to implement phylogenetic biogeography. The outcome means that cladistic biogeography, as most biogeographers usually conceive of it, is restricted by van Veller et al. (2003) to include only component analysis, reconciled tree analysis, three area statements analysis, and paralogy-free subtrees analysis, whereas other methods, namely Brooks Parsimony Analysis (BPA) (Wiley, 1987) and component compatibility, really belong to phylogenetic biogeography. In addition to finding this terminology confusing, because phylogenetic biogeography has been used for decades to refer to Hennig s (1966) and Brundin s (1966) cladistic implementation of the dispersalist approach, I am unconvinced about the existence of two different research programmes. It seems that Ebach et al. (2003) also support the distinction between cladistic and phylogenetic biogeography. But is this view justified? M. C. Ebach: I find the distinction between cladistic and phylogenetic biogeography interesting as it does delimit a theoretical rather than a methodological division in historical biogeography. As has been pointed out, the phylogenetic biogeography of Lars Brundin was the beginning of interpreting trees and cladograms from a biogeographical perspective. The taxon area cladogram, a result of Brundin s work, was interpreted as two separate things, on one hand as the phylogenetic diversification of geographically and ecologically associated clades coincide[d] (Brooks, 1990; p. 16), and on the other as historical connections, that is, relationships between biotas in time (Platnick & Nelson, 1978). The two interpretations of taxon area cladograms can be stated as thus: 1. The geographical distribution of taxa on a phylogenetic tree. 2. The distribution of areas based on the relationships of taxa on a cladogram or an areagram. Taxon area cladograms tell us of the evolutionary history of lineages. Areagrams provide a classification of area relationships. Taxon area cladograms still retain nodes, that is, information about individual taxa and areagrams replace nodes with components that contain information about the terminal branches. Taxon area cladograms and areagrams tell us different things and the methods that use them have different functions and therefore provide biogeographers with different aims. The differences between taxon area cladograms and areagrams are theoretical and not methodological. The argument used by van Veller et al. to erect a new biogeographical programme based on comparing the validity of methods, rather than on aims or intentions, is confusing. If we wish to classify historical biogeography into groups or research programmes, as has been attempted previously by Spellerberg & Sawyer (1999) and Crisci (2001), surely we need to clarify the theory first? Can we compare different methods if they are applied from opposing or different theoretical intentions? One example of this is in your own work where you use the Parsimony Analysis of Endemicity (PAE) (Rosen, 1984) to conduct panbiogeography (Croizat, 1958; Craw et al., 1999). Can we compare the use of the same method under two different theories, such as the implementation of PAE in BPA to score the absence and presence of areas on a taxon area cladogram (see Ebach & Humphries, 2003) and the use of BPA in phylogenetic and comparative phylogeography (Riddle & Hafner, 2004)? JJM: I agree that the distinction among research programmes should be based on theoretical rather than methodological bases, so I will try first to state as clearly as possible the research programmes I identify within historical biogeography (Morrone, 2004, 2005): 1. Dispersalism. The approach initiated by Linnaeus and followed later by Darwin and Wallace in the 19th century seeks to locate centres of origin or ancestral areas and then uses dispersal from them to reconstruct biogeographical histories of particular taxa. It does not matter if cladograms are used, e.g. phylogenetic biogeography (Brundin, 1966; Hennig, 1966), ancestral area analysis, and intraspecific phylogeography. All these methods explain distributions looking for ancestral areas and dispersal explanations. 2. Panbiogeography. The approach developed by Croizat (1958) (see also Craw et al., 1999) seeks to reconstruct ancestral biotic distributions by drawing individual tracks on maps (connecting localities of taxa by lines approximating to minimum spanning trees) and looking for coincidence among unrelated taxa (generalized tracks). PAE is considered as a quantitative panbiogeographic technique (Smith, 1992; Craw et al., 1999; Luna Vega et al., 2000). Panbiogeography intends to identify primary biogeographical homology (Morrone, 2001, 2004), which represents a conjecture on a common biogeographical history. ª 2005 The Author. Journal compilation ª 2005 Blackwell Publishing Ltd

2 3. Cladistic biogeography. The approach that combines the panbiogeographic approach and phylogenetic systematics (Nelson & Platnick, 1981; see also Humphries & Parenti, 1999) assumes a correspondence between the phylogenetic relationships of the studied taxa and the relationships among the areas that they inhabit. A cladistic biogeographical analysis constructs taxon area cladograms from taxon cladograms, by replacing their terminal taxa by the areas of endemism that they inhabit, converts them into resolved area cladograms (if necessary), and derives general area cladogram(s). Cladistic biogeography deals with secondary biogeographical homology (Morrone, 2001, 2004), which represents the cladistic test of the primary biogeographical homology formerly recognized. Panbiogeography and cladistic biogeography can be combined under the common denominator of vicariance biogeography, with biogeographical homology as its primary objective. The cladistics of these programmes is: (dispersalism, (panbiogeography, cladistic biogeography)). Your distinction between taxon area cladograms and areagrams is very interesting, reminding me of the discussions about the difference between phylogenetic trees and cladograms of some decades ago, but I cannot imagine its consequences for the practicing biogeographer. If taxon area cladograms are shared by the phylogenetic approaches to dispersalism and some cladistic biogeographical methods (van Veller et al. s phylogenetic biogeography), whereas areagrams are restricted to some methods of cladistic biogeography (van Veller et al. s cladistic biogeography), the implied cladistics of the programmes would be: (dispersalism, van Veller et al. s phylogenetic biogeography), (panbiogeography, van Veller et al. s cladistic biogeography). I would argue, instead, that the use of taxon area cladograms is plesiomorphic and areagrams are autapomorphic (a posteriori transformation of the former), so the cladistics of the research programmes would be: (dispersalism, (panbiogeography, (van Veller et al. s phylogenetic biogeography, van Veller et al. s cladistic biogeography))). If this is correct, van Veller et al. s phylogenetic biogeography may represent a variant of cladistic biogeography, and the distinction between both kinds of approaches by van Veller et al. and you may be valid, although within cladistic biogeography. MCE: Your approach to classifying the research programmes of cladistic biogeography is interesting and is analogous to the division that I feel is occurring in biogeography. I understand that methodologically there is no division within cladistic biogeography. The concept of a phylogenetic biogeography sensu van Veller et al. (2003) is a methodological division based on some highly questionable theory, namely about the a priori and a posteriori arguments. I do think that van Veller et al. have stumbled on a philosophical division, not based on their argument, but based on the aim of their research programme. van Veller s cladistic and phylogenetic biogeography are philosophically different the former uses areagrams and the latter uses taxon area cladograms. The aim of dispersalism, island biogeography, phylogeography, BPA and the event based method DIVA (Ronquist, 1997) is to explain the evolutionary mechanisms that caused diversification. These research programmes aim to tell the geographical story of the taxon. Taxon area cladograms also tell a story, the story of the taxa, their characters, their distribution and the mechanisms that have caused these distributions (dispersal, jump dispersal, founder dispersal, sympatry, parapatry, etc.). This is why one can never compare two taxon area cladograms because they are unique and can never form a general pattern. Areagrams do form a general pattern because they represent the classification of the areas, that is, the biota. Explaining the distribution with a mechanism is of secondary importance, be it vicariance or dispersal. If Patagonia is more closely related to southern New Zealand than to south-western Australia based on areagrams derived from many monophyletic groups, it is because Patagonia and southern New Zealand share the same area homologies (sensu Humphries & Ebach, 2004) or tracks. The general areagram is a classification of the biota, just as Australasia or Pacific are. One may ask, is Australasia monophyletic, that is, a realm that includes biota more closely related to each other than are to another area within another realm? We need to compare the methods, theories and research programmes in biogeography based on their aims. Phylogeography, comparative phylogeography, BPA etc., are about telling us the geographical history of a particular group, in the same way as a phylogenetic tree tells us about the evolutionary mechanisms within a group. Area cladistics (sensu Ebach & Humphries, 2003) and to an extent panbiogeography are about determining a biogeographical classification just as cladograms tell us about the classification of groups. I believe that we do not have two different research programmes but two different biogeographies one that is about classification (sensu Sclater, 1858) and another that is about retracing the evolutionary geography of taxa (sensu Darwin, 1859; Darlington, 1965). With this in mind, would it be possible to unite biogeography as Riddle (2005) and many others have suggested? JJM: I agree that the aims of the research programmes should be taken into consideration when comparing them. I do not, however, fully agree with you that the aim of dispersalism, island biogeography, phylogeography, BPA and DIVA is the same, e.g., to explain the evolutionary mechanisms that caused the diversification, and the aim of cladistic biogeography and panbiogeography is to determine a biogeographical classification. Personally, I do not even find these aims contradictory. I apply panbiogeographic and cladistic biogeographical methods in order to classify areas, to provide a natural regionalization, and then try to explain the historical mechanisms that may have caused their biotic diversification, their evolution in space time. Historical biogeography represents an integral component of evolutionary biology, where detecting biogeographical patterns is as important as attempting to elucidate the processes that caused them. I believe that without an evolutionary framework, it will be rather boring to do biogeography. I find the recently proposed integrative historical biogeography (Donoghue & Moore, 2003) very promising for a more synthetical approach. With prospects of a synthesis or integration in historical biogeography, I find Riddle s (2005) call to unite historical and ecological biogeography the next logical step. If both genealogical and ecological entities exhibit spatial patterns (Lieberman, 2003), I believe that it does not make much sense to have two separate perspectives, historical and ecological biogeography. I would like to cite Riddle (2005; p. 186): the dichotomy between an ecological vs. historical biogeography does not track the many patterns and processes considered relevant and worthy of our attention. If evolutionary biologists, ecologists, geographers and others agree to develop a single biogeography, deconstructing both ecological and historical biogeography, we need a common language. Unrooted (panbiogeography) or rooted (cladistic biogeography) 2180 Journal of Biogeography 32,

3 area cladograms seem good prospects to integrate this common language. What is your opinion about having one biogeography? MCE: Until recently, I did not know why we lacked a unifying language. I wondered if this unity or integration that Donoghue & Moore (2003), Lieberman (2003) and Riddle (2005) refer to will manifest itself as a unifying theory, method or even technique? Each author seemed to think that a unifying synthesis would incorporate their own approach. I think a synthesis is not an answer. Biogeographers, as I see it, have two choices. We can unite biogeography under one aim, one theory or one method. Riddle & Hafner (2004), for instance, suggested that comparative phylogeography (using BPA) would be a unifying synthesis for historical biogeography. Alternatively, we can accept that biogeography, as a whole, is a unity of many ideas, methods and procedures that have various intentions and aims. Accept the first and we create a biogeographical synthesis. Accept the second and we leave the question of the purpose of biogeography alive to interpretation and debate. I think we should stick to the second. Biogeography is a field that cannot communicate with one language or one voice because there is a multitude of conflicting ideas and aims. In your last exchange for instance, you said that there is little difference between forming a classification and explaining the mechanisms that caused it the latter making biogeography more exciting. If we were to accept that there is no difference between classifications and explaining the processes behind them, then in systematics there would be no difference between the Phylocode and Linnaean taxonomy (as practiced by cladists) or monophyly and paraphyly. I feel that biogeography, like systematics, is about the classification of biotic areas. Attempts to explain the hidden processes are speculative as well as being unnecessary and unimportant to understanding a biotic area. Those that tried to explain distribution, such as Ernst Haeckel, William D. Matthew and Philip J. Darlington, were instead practicing evolutionary biology. In my view biogeography is separate, not integral to evolutionary biology. Considering our own conflicting views in this exchange, we can say that there are two biogeographies one about classification of biotic areas and the other about explaining evolutionary mechanisms and events. The dichotomy is obvious when we look at the conflicting methods and ideas in cladistic biogeography. Some focus on explanations and others focus on classification. Try to unite cladistic biogeography under one synthesis and you will start a war at the level of methodology, one that can never be resolved. We will understand more about ourselves and the biota that we study if we accept that cladistic biogeography, or biogeography in general, is a unification of many different ideas, methods and techniques. I know that these two different ways of thinking in cladistic biogeography represent two different kinds of biogeography. If biogeography, as a whole, were to manifest itself in cladistic biogeography, then what is cladistic biogeography? JJM: I believe that an integrative biogeography does not need necessarily to be attached to a single unifying theory, method or technique. My ecumenical approach would be to accept that different biogeographical research programmes have different aims regarding the spatial patterns exhibited by ecological and genealogical entities. Depending on these aims, we choose the most appropriate methods or techniques. Given some time of working together, we may eventually discover that our theories can be articulated as parts of a more inclusive theory, or maybe not. But, if we do not communicate through a common language, how will we discover this? In relation to the previous exchange, there is something that I would like to clarify. I did not state that there is little difference between forming a classification and explaining the mechanisms that caused it. Quite the contrary, I distinguished between both activities, stating that first I classify the areas, by means of panbiogeographic and cladistic biogeographical methods, and then try to explain the mechanisms. First you discover a pattern and then (if possible) you elucidate the processes behind it. Analogies with Phylocode/Linnean taxonomy and monophyletic/paraphyletic groups are inappropriate, to say the least. I find Phylocode to be useless and non-sensical. Ancestors (artefacts due to paraphyletic groups) and centres of origin (artefacts due to geographical paralogy) are the vestiges of old ways to do systematics and biogeography, respectively, which I have never endorsed (Morrone, 2002). Whether biogeography and systematics are integral to or separate from evolutionary biology is a sensitive issue. Two decades ago, as part of the rise of phylogenetic systematics, discussions concerning pattern cladistics or the transformed cladistics gave an incredible impetus to the field; it seemed that comparative biology would emerge as a separate field. Nowadays, again from the viewpoint of a practicing biogeographer and systematist, I find this prospect not very appealing. Instead, I believe that systematics and biogeography should be reintegrated into evolutionary biology, to the place they both had when the first evolutionary biology, as Bowler (1996) called it, emerged, and help continue developing our evolutionary perspective of life. Cladistic biogeography may have a key role in this ecumenical biogeography, providing both robust biotic classifications and setting the framework for other biogeographical studies. Area cladograms can be natural bridges between biogeography and geology (¼ geological area cladograms), between molecular systematics and biogeography (¼ comparative phylogeography), between biogeography and ecology (¼ phylogenetic structure of communities), etc. Thus the general relevance of cladistic biogeography and why it seems to me so important to define it and determine which are its most appropriate methods. How do you think we could do this? MCE: In order to define cladistic biogeography we need to know what biogeography and systematics aim to fulfill. Cladistic biogeography is either one of two things: a field that is united under one paradigm, be it one solid goal, one theory, method or implementation that attempts to answer and explain a series of questions or; a field that classifies the natural world in which the natural world itself is the explanation. The latter is more holistic whereas the former is mechanical. The former, which I would term mechanistic, attempts to explain the natural world in terms of laws, mechanisms and transformations of forms. The latter, which I would term comparative or systematic, attempts to describe and classify. In your ecumenical biogeography you state that finding ancestors and centres of origin are the vestiges of old ways to do systematics and biogeography. Ironically, this is what the majority of methods and theories in biogeography still do. Centres of origin and ancestors go hand-in-hand with dispersal, vicariance and transformation. They are explanatory devices that are independent. You cannot say that taxon A has dispersed to area B without there being a centre or origin. You cannot say that A or 0 has transformed in G or 1 respectively without there being a transformation. Journal of Biogeography 32,

4 Classification and explanation are separate things, just as comparative biology and evolutionary biology are separate fields. Pattern (or transformed ) cladism was not a reaction against phenetics and phylogenetic systematics, but a reaction against cladistics, heralding a return to the original way of doing comparative biology (Adolf Naef, Danielle Rosa, Joseph Kaelin, etc.), prior and separate vestiges of the old way of doing biogeography and systematics, namely the Modern Synthesis (sensu William D. Matthew, George G. Simpson, Ernst Mayr, Willi Hennig, etc.). By integrating biogeography and systematics into evolutionary biology we immediately apply mechanistic laws, procedures and theories under one unifying model, namely natural selection. Orthogenesis, phenomenology and other non-darwinian ways of doing comparative biology cannot co-exist. I do not mean to turn this into an argument for or against Darwinian evolution, but rather to point out that there are other evolutionary ideas in comparative biology. Evolutionary biology is dominated by one way of thinking. In order to embrace the diversity within biogeography and systematics we should refrain from unifying it. A multiplicity, a variation of methods, ideas and ways of thinking will enrich and further our knowledge of the natural world. Thereby, cladistic biogeography can be defined as two different things: comparative (classifying biotic areas) or mechanical (explaining how taxa got to where they are today). Each has a different aim with a different set of theories and methods. The former investigates the relationships between biota and forms a classification whereas the other generates a historical scenario of events (centres of origin, ancestors, etc.) and mechanisms (sympatry, dispersal, extinction, etc.) of a lineage. I think we have two cladistic biogeographies just as we have two biogeographies. One falls under comparative biology and the other under evolutionary biology. Confuse the two and the vestiges of old ways to do systematics and biogeography return. JJM: At this moment of our exchange, I feel we may identify our points of agreement and disagreement. Let me try to state them briefly. We agree about the distinction between three current research programmes in historical biogeography: dispersalism, panbiogeography and cladistic biogeography. We also agree that within the latter there may be a basic methodological division, using the a priori and a posteriori arguments. We disagree in that you would maintain a posteriori methods (van Veller et al. s phylogenetic biogeography ) outside cladistic biogeography, whereas I would prefer to keep them inside. We agree about the distinction between the ways we interpret areagrams and taxonarea cladograms, the former with a comparative aim (to classify biogeographical areas) and the latter with a mechanistic aim (to explain evolutionary history). You consider these aims contradictory, whereas I do not, because I classify areas through a cladistic approach (discovery of the pattern) and then try to explain the historical mechanisms that may have caused their evolution (elucidation of the process). I consider historical biogeography and systematics to be integral to evolutionary biology. You consider them as separate, postulating the existence of two cladistic biogeographies, one that falls under comparative biology and the other under evolutionary biology. You consider that evolutionary biology is dominated by the Modern Synthesis, with the prominent role given to natural selection. I have instead a more pluralistic, I would say Darwinian, perspective of evolutionary biology. We agree that the multiple methods and ideas enrich our biogeographical perspective. You are skeptical about the possibility of unifying or integrating historical and ecological biogeography. I prefer an ecumenical approach, accepting different research programmes with their own aims regarding the biogeographical patterns, and giving them time eventually to discover a more inclusive theory to articulate them. MCE: The methods and techniques in historical biogeography can be classified into the three methodological categories of dispersalism, panbiogeography and cladistic biogeography. On a philosophical level, cladistic biogeography, like biogeography as a whole, is split into two modes of thought, namely mechanistic and contextual thinking. van Veller et al. s phylogenetic biogeography is not relevant to this as this argument represents a mechanical distinction within cladistic biogeography. The split that I indicate above is one between what I herein term evolutionary and systematic biogeography. Evolutionary biogeography or chorology (Wallace, 1876; Haeckel, 1925) (D. M. Williams, pers comm., 2005), terms I will use interchangeably, is about generating mechanisms such as dispersal, sympatry, extinction, etc., in order to explain geographical distribution, that is, the theory of the local distribution of organisms over the surface of the earth (Haeckel, 1925; p. 364). Systematic biogeography, however, attempts to form a classification of biotic areas without recourse to explanatory evolutionary mechanisms. Instead it can discover processes, such as continental drift and evolution. What is interesting about cladistic biogeography is that it falls into both evolutionary and systematic biogeography. When we return to van Veller et al. s argument we see that the methods are evaluated mechanistically. Since systematic biogeography is not mechanistic, methods such as area cladistics (Humphries & Ebach, 2004; Ebach et al., 2005) will appear to be a priori. From the view of a comparative biogeographer, no method is a priori or a posterori, rather some methods assume a mechanism to have occurred whereas others find the relationships between areas without reaching for an explanatory mechanism. In this sense, van Veller et al. s favoured method, BPA, fails to uncover relationships. Instead it generates a scenario based on a mechanism or process. I do not believe that evolutionary and systematic biogeography can ever be integrated. As a systematic biogeographer I do not see a need for mechanistic explanations because the biotic areas are in themselves the explanation. Biogeography, in my view, is about understanding the biotic area, knowing it via observation and experience. Biogeography is not about giving things, such as areas, any greater explanation. Evolutionary biogeography (chorology) is united by the search for meaning and explanation. Biogeographers will not know their taxon or biotic area any better if a model is proposed and a result generated. The taxon or area will always be same thing no matter what explanation we assign it. I believe that our discussion has shown us that the divisions within cladistic biogeography are the same ones that divide biogeography as a whole, between those that want to classify and those that want to explain their classifications or distributions. Systematic biogeography and evolutionary biogeography (chorology) can happily co-exist, but as different approaches to different questions. Malte C. Ebach 1 *andjuanj. Morrone 2 1 Laboratoire Informatique et Systématique (LIS), Université Pierre et Marie Curie (UMR 5143), Paléodiversité Equipe Systématique, 2182 Journal of Biogeography 32,

5 Recherche informatique et Structuration des Cladogrammes, Paris, France and 2 Museo de Zoología Alfonso L. Herrera, Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), Mexico DF, Mexico. jjm@hp.fciencias.unam.mx *Correspondence: Malte C. Ebach, Laboratoire Informatique et Systématique (LIS),Université Pierre et Marie Curie (UMR 5143), Paléodiversité Equipe Systématique, Recherche informatique et Structuration des Cladogrammes, 12 rue Cuvier, Paris, France. mcebach@yahoo.co.uk REFERENCES Bowler, P.J. (1996) Life s splendid drama: evolutionary biology and the reconstruction of life s ancestry The University of Chicago Press, Chicago and London. Brooks, D.R. (1990) Parsimony analysis in historical biogeography and coevolution: methodological and theoretical update. Systematic Zoology, 39, Brundin, L. (1966) Transantarctic relationships and their significance as evidenced by midges. 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Heaney), pp Sinauer Associates, Sunderland, MA. Ronquist, F. (1997) Dispersal vicariance analysis: a new approach to the quantification of historical biogeography. Systematic Biology, 46, Rosen, B.R. (1984) Reef coral biogeography and climate through the late Cainozoic: just islands in the sun or a critical pattern of islands? Fossils and climate (ed. by P.J. Brenchley). Geological Journal Special Issue, 11, Sclater, P.L. (1858) On the general geographical distribution of the members of the class Aves. Journal of the Linnean Society of London, Zoology, 2, Smith, A.B. (1992) Echinoid distribution in the Cenomanian: an analytical study in biogeography. Palaeogeography, Palaeoclimatology, Palaeoecology, 92, Spellerberg, I.F. & Sawyer, J.W.D. (1999) An introduction to applied biogeography. Cambridge University Press, Cambridge. van Veller, M.G.P., van Brooks, D.R. & Zandee, M. (2003) Cladistic and phylogenetic biogeography: the art and the science of discovery. Journal of Biogeography, 30, Wallace, A.R. (1876) The geographical distribution of animals, 2 vols. Macmillan, London. Wiley, E.O. (1987) Methods in vicariance biogeography. Systematics and evolution: a matter of diversity (ed. by P. Hovenkamp), pp University of Utrecht, Utrecht. BIOSKETCHES Malte C. Ebach is a researcher and author in the history and philosophy of comparative biology, Goethe s way of science, trilobite taxonomy and systematics at the Laboratoire Informatique et Systématique (LIS), Université Pierre et Marie Curie. Juan J. Morrone is Professor of Biogeography, Systematics and Comparative Biology at the Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM). His main interests are in phylogenetic systematics and biogeography. Editors: Brett Riddle and Chris Humphries doi: /j x Falklands: facts and fiction A reply to McDowall, R.M. (2005) Falkland Islands biogeography: converging trajectories in the South Atlantic Ocean. Journal of Biogeography, 32, A recent contribution (McDowall, 2005) analysed the biogeography of the Falkland Islands, an archipelago situated in the south-western Atlantic, known in Spanish as Islas Malvinas. After reviewing the Journal of Biogeography 32, ª 2005 The Authors. Journal compilation ª Blackwell Publishing Ltd