REVIEW: TAXONOMIC ISSUES IN BEARS 33 Int. Zoo Yb. (2010) 44: 33–46 DOI:10.1111/j.1748-1090.2009.00087.x Taxonomic issues in bears: impacts on conservation in zoos and the wild, and gaps in current knowledge A. C. KITCHENER Department of Natural Sciences, National Museums Scotland, Chambers Street, Edinburgh EH1 1JF, United Kingdom, and Institute of Geography, School of Geosciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, United Kingdom E-mail: [email protected] Taxonomy is essential for underpinning conservation actually comprises two or more species, some science and action, and the international and national of which are critically endangered, poor taxo- implementation of protective legislation. However, many of the current scientific species and subspecies names for nomic research may inadvertently compro- bears have a poor scientific basis. Poor understanding of mise the survival of those threatened ursid taxonomy could compromise conservation both in populations. In captivity, hybridization may the wild and in captivity; all eight ursid species are listed occur accidentally between unrecognized on the Convention on International Trade of Endangered subspecies and even species, ultimately wast- Species of Wild Fauna and Flora and 75% are Endan- gered or Vulnerable. Although there has been much ing huge amounts of resources as well as molecular research on ursids in recent years, this has affecting the conservation of the species. mainly focused on phylogenetic relationships, including Conversely, if too many species or subspecies resolution of whether the Giant panda Ailuropoda mela- are recognized, captive populations may suf- noleuca is an ursid. Some phylogeographical studies have provided new insights into geographical variation fer from inbreeding from small founder po- of some bear species, but these studies are often only pulations, when they would benefit from the regional, or lack sufficient samples, or use only mtDNA. mixing of needlessly separated captive gene There is an urgent need for integrated molecular and pools. However, we must remember that morphological studies of geographical variation of all taxonomy and systematics are fluid – they bear species in order to establish a robust taxonomy for the Ursidae for enhanced conservation management and represent, to a greater or lesser extent, a action. consensus based on current evidence, and today’s taxonomies will continue to change Key-words: bears; conservation management; conser- and, hopefully, improve as better evidence vation science; taxonomy. accumulates. In this paper, I examine the taxonomic INTRODUCTION issues that currently affect the Ursidae. Most Although taxonomy is often regarded as species are widespread, occurring in a wide rather dull, it provides the essential under- variety of habitats, and some species, such as pinning of all conservation. If species and the Brown bear Ursus arctos and the Amer- subspecies do not have scientific names, it is ican black bear Ursus americanus, show not possible to provide full legal protection enormous phenotypic variation in size and for them under national or international law coloration that has led to the recognition of (e.g. O’Brien & Mayr, 1991). Therefore, it is very many species and subspecies in the past. fundamental for conservation science and For Brown bears, some 232 modern [of action, as well as the implementation of which 83 were described by C. Hart Merriam national and international protective legisla- in North America (Hall, 1981)] and 39 fossil tion, that the taxonomy of species and sub- species and subspecies have been described species is accurate. If a widespread species (see Erdbrink, 1953), which Kurte´n& Int. Zoo Yb. (2010) 44: 33–46. c 2010 The Authors. Journal compilation c 2010 The Zoological Society of London 34 BEARS AND CANIDS Anderson (1980) considered ‘a waste of and populations. Combining molecular and taxonomic effort, which, as far as we know, geographical data is known as phylogeogra- is unparalleled’. There are many problems phy, and it has developed into a potent tool for that affect our understanding of the taxonomy examining geographical genetic variation and of ursids and many other mammals. Firstly, population subdivision. The analysis of an- the scientific names on which species and cient DNA (aDNA) even allows us to look subspecies are based are poorly founded back in time at the genetics of past populations scientifically. These names date mainly from and even extinct species, providing further the 19th century when none, one or only a insight into how the distribution of genetic handful of specimens were examined to de- variation has arisen today (Leonard et al., termine the diagnostic characteristics and 2000; Loreille et al., 2001; Barnes et al., differences from related species. It should be 2002; Valdiosera et al., 2007; Krause et al., noted that normally there is a requirement for 2008). New morphometric techniques, such as a holotype, which is the specimen that is geometric morphometrics, allow us to examine selected as the voucher on which the scien- subtle differences in the shapes and sizes of tific name is based (Mayr & Ashlock, 1991; skulls, the normal part of a skeleton that is the Groves, 2001), but a wide range of specimens subject of taxonomic research, including re- needs to be examined to determine which moving and/or controlling for the influence of characters are diagnostic (i.e. typical or char- size, which often reflects a phenotypic re- acteristic) for the taxon, and which are the sponse to the available local food resources. result of individual or other kinds of variation In other words, well-fed bears grow bigger! in the population. Therefore, it is not surpris- Sometimes the molecular and morphological ing that these descriptions capture only a approaches are in strong accord, in other cases fraction of the normal range of individual they disagree, often because the old morpho- variation within a species or subspecies. logical taxonomy is poorly based in science. Where variation is clinal (i.e. changes gradu- The best studies involve a combination of ally over a geographical range) it is easy to morphological and molecular techniques, see how the analysis of a small number of without recourse to previous taxonomic ar- samples distant from each other might result rangements, as checks against each approach. in several new species or subspecies being However, whatever the approach, good inadvertently recognized. Over time, this pro- taxonomic research requires statistically sig- cess has led inevitably to a proliferation of nificant samples that cover the entire range of names, for which there is little or no scientific the species. Using current museum collec- basis. tions, this may be very hard to achieve. Normally taxonomic differences are based Inevitably there are collecting biases that on diagnostic morphological characters, such reflect the interest and collecting activities of as coloration, size, shape, presence/absence of individuals, and the accessibility of the geo- characters, and combinations of measure- graphical range of a species. Opportunities to ments, particularly from skulls, but account enhance the number of specimens available must also be taken of sex, age, season, for all kinds of research must be taken in etc. (Pocock, 1941; Erdbrink, 1953). In recent order to provide a better resource base for years, new techniques and technologies have taxonomic and other research. In the mean- been developed which have greatly benefited time other complementary approaches, such taxonomy and systematics. New molecular as dynamic biogeographical modelling, techniques allow us to examine genetic varia- should be considered to provide a framework tion over wide geographical areas regardless of against which we can examine our current sex, age and local phenotypic responses to the knowledge of the geographical variation environment. These molecular studies com- within each ursid species. pare the sequencing of base pairs of mitochon- As is typical for many mammalian fa- drial and nuclear DNA between individuals milies, the bears suffer from numerous Int. Zoo Yb. (2010) 44: 33–46. c 2010 The Authors. Journal compilation c 2010 The Zoological Society of London REVIEW: TAXONOMIC ISSUES IN BEARS 35 taxonomic uncertainties. While the number of size to hold bamboo stems while feeding recognized species has remained stable over (Pocock, 1941; Salesa et al., 2006b). Spec- the last 140 years, our knowledge of the tacled bears also have a small pseudo-thumb geographical variation in bears, given their for grasping, which might suggest a close phenotypic variation, is still very poor, relationship, but basal arctoids, such as Simo- although some recent studies have improved cyon batalleri (an ancestor of the Red panda our understanding for some species or popu- Ailurus fulgens) from near Madrid, Spain, lations. In this article, I review the current also had a well-developed radial sesamoid, taxonomic status of bear genera, species and which was apparently originally adapted for subspecies, highlighting uncertainties and fu- climbing (Salesa et al., 2006a,b). Therefore, ture areas for research. The impact that these the pseudo-thumb is an ancestral feature or uncertainties have on conservation in the wild plesiomorphy, which cannot be used to infer and in captivity will also be examined. that the Giant panda is an ursid. Thenius (1989) argued that while molecular data are good at establishing phylogenies, particularly GENERA