Cladistics Cladistics 28 (2012) 317–329 10.1111/j.1096-0031.2011.00385.x Detecting areas of endemism with a taxonomically diverse data set: plants, mammals, reptiles, amphibians, birds, and insects from Argentina Claudia Szumika,*, Lone Aagesenb, Dolores Casagrandaa, Vanesa Arzamendiac, Diego Baldod, Lucı´a E. Clapsa, Fabiana Cuezzoa, Juan M. Dı´az Go´meze, Adria´n Di Giacomof, Alejandro Giraudoc, Pablo Goloboffa, Cecilia Gramajog, Cecilia Kopuchianh, Sonia Kretzschmard, Mercedes Lizarraldea, Alejandra Molinaa, Marcos Mollerachi, Fernando Navarroa, Soledad Nomdedeub, Adela Panizzab, Vero´nica V. Pereyraa, Marı´a Sandovali, Gustavo Scrocchid and Fernando O. Zuloagab aInstituto Superior de Entomologı´a (INSUE-CONICET), Miguel Lillo 205, 4000 Tucuma´n, Argentina; bInstituto de Bota´nica Darwinion (CONICET-ANCEFN), Labarden 200, CC22, San Isidro, B1642HYD Buenos Aires, Argentina; cInstituto Nacional de Limnologı´a (CONICET-UNL), Ciudad Universitaria, El Pozo s ⁄ n, 3016 Santa Fe, Argentina; dInstituto de Herpetologı´a (FML), Miguel Lillo 251, 4000 Tucuma´n, Argentina; eInstituto de Bio y Geociencias (IBIGEO), Facultad de Ciencias Naturales, Mendoza 2, 4400 Salta, Argentina; fLaboratorio de Ecologı´a y Comportamiento Animal (FCEN-UBA), Ciudad Universitaria, C1428EHA Buenos Aires, Argentina; gDivisio´n Entomologı´a (FML), Miguel Lillo 251, 4000 Tucuma´n, Argentina; hDivisio´n Ornitologı´a (MACN), Av. Angel Gallardo 470, C1405DJR Buenos Aires, Argentina; iPrograma de investigaciones en Biodiversidad Argentina (PIDBA-FCN), Miguel Lillo 205, 4000 Tucuma´n, Argentina Accepted 16 October 2011 Abstract The idea of an area of endemism implies that different groups of plants and animals should have largely coincident distributions. This paper analyses an area of 1152 000 km2, between parallels 21 and 32°S and meridians 70 and 53°W to examine whether a large and taxonomically diverse data set actually displays areas supported by different groups. The data set includes the distribution of 805 species of plants (45 families), mammals (25 families), reptiles (six families), amphibians (five families), birds (18 families), and insects (30 families), and is analysed with the optimality criterion (based on the notion of endemism) implemented in the program NDM ⁄VNDM. Almost 50% of the areas obtained are supported by three or more major groups; areas supported by fewer major groups generally contain species from different genera, families, or orders. Ó The Willi Hennig Society 2011. The present study aims to evaluate the distributional cover a wide array of diverse taxa is to have studies in concordance among a diverse group of taxa, by using an which numerous authors, with different specialties, optimality criterion specifically designed for detecting collaborate. areas of endemism. In other words, this is one of the first In the past two decades, a considerable number of approximations to analyse total evidence in a biogeo- empirical studies to define and quantify areas of graphical context. Studies of endemicity for taxonom- endemism have been published. Part of that production ically wide samples are difficult because specialists in a can be related to the development of different methods given group seldom have access to first-hand informa- of analysis, starting with parsimony analysis of ende- tion on the distribution of other groups; the only way to mism (PAE; Morrone, 1994), which highlighted the need to formalize and assess the identification of areas of *Corresponding author: endemism with clear and accessible protocols. Several E-mail address: [email protected] alternative methods followed PAE (e.g. Geraads, 1998; Ó The Willi Hennig Society 2011 318 C. Szumik et al. / Cladistics 28 (2012) 317–329 Linder, 2001; Garcı´a-Barros et al., 2002; Hausdorf and Hennig, 2003), trying to improve on the original idea. Szumik et al. (2002) and Szumik and Goloboff (2004) proposed a method that takes into account the spatial component of endemism (ignored by the other methods) and allows for non-hierarchical results (required by most other methods). It is clear that the notion of endemism includes a spatial concept by definition but Szumik et al. (2002, p. 806) are the first to point out that the spatial component has been previously ignored: ‘‘A method used to identify areas of endemism must consider the taxa occurring in a given area and their position in space. This spatial component has not been included in pre-existing clustering methods, and thus those methods (designed only to recover hierarchy) cannot be adopted for identification of areas of endemism.’’ Method of analysis aside, most of these local and global empirical studies were focused on a particular group of taxa (genus, family, order, or class), analysed with a single cell size (e.g. 1 · 1°,2· 2°). Nevertheless, the concept of an area of endemism implies distribu- tional concordance among different groups, not within a single group: ‘‘An endemic taxon is restricted to a region and is found nowhere else. The range of distribution of a taxon is determined by both historical and current factors. Whatever the factors are, Fig. 1. Biogeographical divisions for the study region according to if they affect (or have affected) in a similar way different Cabrera and Willink (1973). taxonomic groups, there will be congruence in the patterns of endemicity in different groups. Thus, areas that have many different groups found there and nowhere else can be defined as set contains almost 14 500 records. In many cases areas of endemism.’’ (Szumik et al., 2002, p. 806) (especially birds and mammals) the records were insuf- This paper represents the first attempt to bring ficient to assess the real distribution of the taxa; in those together a set of high-quality data provided by a large cases, the presumed distribution was estimated by the number of specialists for diverse groups of plants, respective specialist (see Fig. 2 for a map of species mammals, reptiles, amphibians, birds, and insects. diversity). Additionally, a comparison between the results and The present data set is unique among biogeographical some of the previous hypotheses, focusing in particular studies not only for the number and diversity of plant on Cabrera and WillinkÕs biogeographical division, is and animal taxa, but also because it was compiled, presented (Fig. 1). edited, and corroborated by 25 practising taxonomists, whose work specializes in the study region. Thus, it differs substantially from data sets constructed by downloading data from biodiversity websites. Materials and methods The study region is a rectangular area between 21° and 32°Sand70° and 53°W in Argentina, comprising The 805 species analysed represent 53 orders, 129 more than 1152 000 km2 of the Neotropical region, families and 463 genera (Table 1; see also Appendix 1 equivalent to the area of South Africa (as analysed by for a list of number of species per order and family). The Linder, 2001), or twice that of Spain and Portugal (as species were chosen because either (i) they were previ- analysed by Garcı´a-Barros et al., 2002). The high ously used as typical of some biogeographical area, or biogeographical diversity of this zone is well known (ii) they have narrow distributions in the study region. (e.g. Cabrera and Willink, 1973; Fig. 1). Other studies Almost all the records used are connected to actual by Vervoorst (1979), Dinerstein et al. (1995), and specimens in one of the major collections in Argentina Morrone (2001, 2006) are also important. Some of these (the only exception being birds, for which sighting is studies (Cabrera and Willink, 1973; Vervoorst, 1979) did widely considered as acceptable for identification). not use the term ‘‘endemic’’ or ‘‘endemism’’ but simply Many of these vouchers are the result of years of listed plants and a few animals characterizing each of collection and taxonomic study by the authors. The data the biogeographical ‘‘divisions’’ proposed. Because of C. Szumik et al. / Cladistics 28 (2012) 317–329 319 the complexity of the region, there is substantial arguments that were misdirected against phylogenetic disagreement among the proposals. It is also clear that analyses in the past, when criticizing it for dealing with many of these biogeographical divisions continue out- possibly incomplete monophyletic groups (Sokal, 1975, side the study region (e.g. extending into Bolivia); p. 258; see rebuttal by Farris, 1979, p. 486). The tree moreover, some of the taxa included here are absent resulting from a cladistic analysis for a specific set of outside of the study region, while others are present. It taxa makes a statement only about the relationships of should therefore be noted that whenever we report an the included taxa; those taxa not included in the analysis area of endemism defined by species that are distributed could land—in future analyses—on any branch of the outside the study region as well, what we present may be tree. The present analysis, likewise, specifies—for each only a patch of the area. It remains to be seen whether cell in the grid—the membership, or lack thereof, to a such areas persist in future studies as an area of given area; nothing is stated or implied about cells that endemism defined by the same species. However, a would occupy an extended grid. compilation of distributions such as the present one The data set was analysed with the heuristic algo- offers an opportunity to provide first-step testable rithms of NDM-VNDM ver. 2.7 (Goloboff, 2007), hypotheses of areas of endemism for future analyses of which apply the methodology of Szumik and Goloboff neighbouring regions or analyses at more inclusive (2004). The method, which is grid-dependent, basically scales. One could be tempted to criticize the present evaluates spatial concordance among two or more taxa study by claiming that the study region is inadequate or for a given set of cells (area of endemism): assigning a not natural, or that the taxa present outside of this score of endemicity for a given taxon, according to how region must be ignored or eliminated from the analysis.