Polytypic Species Concept Research Articles

A revision of Neusticomys peruviensis (Rodentia: Cricetidae) with the description of a new subspecies

Abstract Neusticomys peruviensis is a poorly known sigmodontine rodent of the tribe Ichthyomyini, represented in collections by only five specimens collected in five localities from lowland forests of central and southern Peru. Recent expeditions in Llanchama, in northern Peru, north of the Río Amazonas, and near Allpahuayo Mishana Natural Reserve (Loreto, Peru), were successful in obtaining three specimens of Neusticomys. Based on morphological and meristic data, we found the population at Llanchama is distinct from the allopatric populations of N. peruviensis, and other species of Neusticomys. A species distribution model also shows the population at Llanchama is not highly predicted by the set of variables of the known localities of N. peruviensis. However, sequence data from the mitochondrial cytochrome-b gene indicate that genetic distinctiveness is low. Because intraspecific variability is important to understand evolutionary and biogeographic processes, and in concordance with the polytypic species concept, we interpret the population at Llanchama to represent a new subspecies of N. peruviensis that we describe in this paper.

On the shoulders of giants: Reginald Innes Pocock and integrative mammal research in museums and zoos

Abstract Seventy years after his death, Reginald Innes Pocock’s prominence in mammalogy is demonstrated by the continuing amount of citations in recent works and the final acceptance of some of his systematic proposals at generic and suprageneric levels. Pocock’s ability to synthesize and integrate classical taxonomy with the then dominant polytypic species concept, utilizing both skull and external characters, of zoo and museum animals as unique opportunities for the advancement of mammal comparative biology – including the study of several extinct taxa – are an enduring legacy for mammalogy that deserves to be better appreciated especially among European zoologists.

Impacts of taxonomic inertia for the conservation of African ungulate diversity: an overview.

We review the state of African ungulate taxonomy over the last 120 years, with an emphasis on the introduction of the polytypic species concept and the discipline's general neglect since the middle of the 20th century. We single out negative consequences of 'orthodox' taxonomy, highlighting numerous cases of neglect of threatened lineages, unsound translocations that led to lineage introgression, and cases of maladaptation to local conditions including parasitic infections. Additionally, several captive breeding programmes have been hampered by chromosome rearrangements caused by involuntary lineage mixing. We advocate that specimen-based taxonomy should regain its keystone role in mammal research and conservation biology, with its scientific values augmented with genomic evidence. While integration with molecular biology, ecology and behaviour is needed for a full understanding of ungulate alpha diversity, we stress that morphological diversity has been neglected despite its tremendous practical importance for some groups of 'utilizers' such as trophy hunters, wildlife tourists and conservationists. We conclude that there is no evidence that purported 'taxonomic inflation' has adverse effects on ungulate conservation: rather, it is taxonomic inertia that has such adverse effects. We stress that sound science, founded on robust taxonomy, should underpin effective sustainable management (hunting, ranching, captive breeding and reintroduction programmes) of this unique African natural resource.

Primate Taxonomy: Inflation or Real?

This article reviews changes in primate taxonomy, especially those pertaining to the meaning of the term species, since its inception two and a half centuries ago. Despite continuing discoveries and the involvement of competent practitioners, the adoption of the polytypic species concept, especially underpinned by the biological species concept, ensured that primate taxonomy was in a sorry state by the middle of the twentieth century. In the latter half of the twentieth century, a gradual rethinking of the nature of species took place, and many different species concepts were proposed. The phylogenetic species concept has been widely adopted over the past ∼20 years, sustained by a gradual realization that species are evolutionary lineages. This review provides examples of how the old way of thinking about species hampered our understanding of primate biodiversity and of how the phylogenetic species concept (or the diagnosability criterion under the general lineage concept) has clarified matters, opening them up for discussion. The adoption of this evolutionary view of species has implications for conservation, particularly because it increases recognition of biodiversity.

Species taxonomy of birds: Which null hypothesis?

The polytypic species concept unites populations that theoretically could and would interbreed were the opportunity to arise. This concept places the burden of proof of reproductive incapability and species status on those claiming species or higher rank. Advances in our understanding of the nature of reproductive isolation, the genetics of speciation, the limited role of gene flow, the power of directional selection, and the dynamics of hybridization support a different null hypothesis for taxonomic decisions, one that places the burden of proof on ‘lumping' rather than on ‘splitting' taxa at the species level. Switching the burden of proof provides an improved conceptual basis for the recognition of many allopatric island taxa and subspecies groups that merit species status. Taxonomic revisions based on these advances predictably confirm that distinct sister populations once lumped as polytypic species are independent evolutionary lineages that exhibit essential reproductive isolation. Release from the concerns about hybridization also positions proposed species for timely taxonomic decisions. The stage is set to proactively redefine polytypic species to separate component species for the 21st century. The improved species classification will better reflect phylogeny and evolutionary status, characterize biodiversity more accurately, guide improved sampling patterns of bird populations for systematic studies, and enable informed conservation decisions.

Mammal taxonomy without taxonomists: a reply to Zachos and Lovari

Keywords: Rhinocerotidae subspecies conservation polytypic species concept Abstract Ontological and epistemological properties of the Phylogenetic Species Concept (PSC) as applied in recent mammalian taxonomic works are redefined and defended against criticisms raised by Zachos and Lovari (2013), which we find inapplicable to taxonomy because they relate more to the field of population biology. We summarize the negative impacts of the polytypic species concept for conservation and evolutionary biology, with emphasis on Rhinocerotidae. The priority need to embrace and strengthen museum-based taxonomic research is emphasized.

Simultaneous delimitation of species and quantification of interspecific hybridization in Amazonian peacock cichlids (genus cichla) using multi-locus data

BackgroundIntrogression likely plays a significant role in evolution, but understanding the extent and consequences of this process requires a clear identification of species boundaries in each focal group. The delimitation of species, however, is a contentious endeavor. This is true not only because of the inadequacy of current tools to identify species lineages, but also because of the inherent ambiguity between natural populations and species paradigms. The result has been a debate about the supremacy of various species concepts and criteria. Here, we utilized multiple separate sources of molecular data, mtDNA, nuclear sequences, and microsatellites, to delimit species under a polytypic species concept (PTSC) and estimate the frequency and genomic extent of introgression in a Neotropical genus of cichlid fishes (Cichla). We compared our inferences of species boundaries and introgression under this paradigm to those when species are identified under a diagnostic species concept (DSC).ResultsWe find that, based on extensive molecular data and an inclusive species concept, 8 separate biological entities should be recognized rather than the 15 described species of Cichla. Under the PTSC, fewer individuals are expected to exhibit hybrid ancestry than under the DSC (~2% vs. ~12%), but a similar number of the species exhibit introgression from at least one other species (75% vs. 60%). Under either species concept, the phylogenetic breadth of introgression in this group is notable, with both sister species and species from different major mtDNA clades exhibiting introgression.ConclusionsIntrogression was observed to be a widespread phenomenon for delimited species in this group. While several instances of introgressive hybridization were observed in anthropogenically altered habitats, most were found in undisturbed natural habitats, suggesting that introgression is a natural but ephemeral part of the evolution of many tropical species. Nevertheless, even transient introgression may facilitate an increase in genetic diversity or transfer of adaptive mutations that have important consequences in the evolution of tropical biodiversity.

Speciation mirrors geomorphology and palaeoclimatic history in African laminate-toothed rats (Muridae: Otomyini) of the Otomys denti and Otomys lacustris species-complexes in the ‘Montane Circle’ of East Africa

We adopted an integrated systematic approach to delimit evolutionary species and describe phylogeographic, morphometric and ecological relationships in Otomys denti (from the Albertine Rift, Southern Rift in Malawi and the northern Eastern Arc Mountains) and Otomys lacustris (from the Southern Rift in Tanzania and Zambia, and the southern Eastern Arc Mountains). Molecular [cytochrome (cyt) b sequences, 1143 bp, N = 18], craniometric (classical, N = 100 and geometric, N = 60) and ecological (Partial Least Squares regression of shape and ecogeographic variables) approaches show a profound, parallel disjunction between two groups: (1) Eastern Arc and Southern Rift (including the Malawi Rift) (O. lacustris and Otomys denti sungae) and (2) Albertine Rift (Otomys denti denti and Otomys denti kempi) taxa. Within both groups, cyt b sequences or craniometric analysis provided evidence for the differentiation of both southern and northern Eastern Arc from Southern Rift lineages (across the so-called Makambako Gap). Within the Albertine Rift (denti–kempi) lineage, populations from individual mountain ranges differed significantly in skull shape (but not size), but were similar genetically. Over-reliance in the past on very few morphological characters (e.g. number of molar laminae) and a polytypic species concept has obscured phylogenetic relationships and species discrimination in this group. We recognize at least three species in this group, and distinct lineages within two of these species. Each species or lineage was endemic to one of three regions: the Albertine Rift, the Malawi Rift or the Eastern Arc. Our result echo conclusions of recent studies of other mammalian and bird taxa and reflect the geomorphology and palaeoclimatic history of the region. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 913–941.

Refining the polytypic species concept of mangrove monitors (Squamata: Varanus indicus group): a new cryptic species from the Talaud Islands, Indonesia, reveals the underestimated diversity of Indo-Australian monitor lizards

The description of a new cryptic member of the mangrove monitor (Varanus indicus) (Daudin, 1802) group from Indonesia presents a refinement of the systematic concept for a polytypic complex of closely related species. The new species is recognised on the basis of morphological and molecular evidence. It is so far known only from the type locality, the remote Talaud Islands, located between Sulawesi, Halmahera and Mindanao at the outer boundary of the Wallacea transition zone between the Oriental and Australian faunal regions. While the descriptions of several sibling and mostly sympatric species within the last 15 years have not affected the range of V. indicus, here, we demonstrate that morphologically distinct island populations represent independent evolutionary lineages and warrant specific recognition as distinct species within an evolving superspecies complex. In addition, some basic natural history information is provided for the new species based on observations at the type locality. These systematic and zoogeographic investigations reveal shortcomings in the current knowledge concerning the diversity and endemism of Indo-Australian monitor lizards, particularly within the Wallacean region.

HYBRIDIZATION BETWEEN SPECIES OF THE RANA PIPIENS COMPLEX IN CENTRAL TEXAS.

Widespread acceptance and application of the polytypic species concept in the 1930s and 1940s resulted in the taxonomic lumping of many allopatric nominal species on the basis of the assumption of conspecificity. Consequently, for many groups of organisms one can cite cases of what Vaurie (1955) called pseudo-subspecies-good species taxonomically confused as subspecies. The example provided by leopard frogs of the Rana pipiens complex is particularly important because of the prominent place they have had in relation to theories of intraspecific variation and the evolution of isolating mechanisms. Analysis of patterns of geographic variation in morphology and the ability of individuals from some widely separated areas to produce viable offspring in laboratory crosses led Moore (1944) to regard many forms of the Rana pipiens complex as members of one polytypic species. Moore's (1946a, 1946b, 1949a, 1949b, 1950) extensive and influential work on the effects of temperature on embryonic and larval development and on genetic compatibility between frogs from different areas was interpreted within the framework of intraspecific variation. His demonstration that degree of abnormality in embryonic development is related to latitudinal distance (and, to a lesser degree, longitudinal distance) between parental populations provided a model of the manner in which differences accumulate between conspecific populations along environmental gradients. As Moore's interpretation gained wide acceptance, Rana pipiens became a standard textbook

The Systematics ofTimulla oculata(Fabricius) (Hymenoptera, Mutillidae)

AbstractTimulla oculata(Fabr.) is redescribed and ten nominal species of OrientalTimullaare placed in synonymy with it. Fourteen subspecies, including two new ones(T. oculata rosemariaesubsp.n. andT. oculata timorensissubsp.n.), are recognised and keys to the subspecies are given. Geographic variation and the application of the polytypic species concept are discussed. The structure of the male genitalia ofTimullais related to dispersal strategies. The distribution and subspeciation ofT. oculatais discussed in relation to the geological history of South East Asia and the Malay Archipelago.

POLYTYPIC CONCEPT OF THE SPECIES AND ITS APPLICATION TO THE STUDY OF MESOZOIC BRACHIOPODS

A philosophical discussion of the polytypic species concept, stressing the importance of the use and recognition of a number of different intraspecific categories including subspecies, forms, ecomorphs, and abberations. Definitions, genetic, occurrence, and environmental significance are discussed and examples given.--R. S. Boardman.

STUDIES ON THE GENUS KALICEPHALUS (NEMATODA: DIAPHANOCEPHALIDAE): II. A TAXONOMIC REVISION OF THE GENUS KALICEPHALUS MOLIN, 1861

According to some recent authors, the genus Kalicephalus, constituted of approximately 50 species, is characterized by marked intraspecific variation, but the sources of this variation were not identified. Marked morphological variability is herein confirmed for some species, but this is often geographical or host-determined. The latter is difficult to prove without experimental cross-infection studies, but host-determined variation occurring in nature is provisionally identified by a method described. Application of a polytypic species concept permits a simplified classification and a revision of the genus with the following major results. The number of species is reduced from 50 to 23, including five new species, viz. Kalicephalus giganteus from Liasis papuanus, K. truncatus from Python curtus, K. longispicularis from Python reticulatus, (all from snakes dying in zoos), K. posterovulvus from several oriental snakes, and K. megacephalus from Varanus indicus in the Solomon Islands. K. variabilis is a new name for K. gongylophis of Hsü (not Maplestone). K. parvus, K. micrurus, and K. indicus are considered subspecies of K. costatus; K. macrovulvus and K. coronellae as subspecies of K. inermis; and K. chungkingensis and K. obliquus as subspecies of K. viperae. K. rectiphilus neorectiphilus subsp. n. is described from the Neotropical colubrids Herpetodryas carinatus and Eudryas bifossatus. The genera Occipitodontus Ortlepp and Kalicephaloides Yeh are not accepted. Nine forms are listed as species inquirendae. A host–parasite catalogue is appended.

A Synopsis of the Cave Beetles of the Genus Pseudanophthalmus of the Mitchell Plain in Southern Indiana (Coleoptera, Carabidae)

Thirteen species and subspecies of cave beetles of the genus Pseudanophthalmus Jeannel have been reported from the Mitchell Plain of southern Indiana. Horn (1871, 1883), Jeannel (1931, 1949), and Krekeler (1958) have described and illustrated the majority of these forms in considerable detail. The present paper is intended to be used in conjunction with the papers of Jeannel (1949) and Krekeler (1958), and no attempt has been made to repeat descriptions of forms which have been adequately treated by these authors. The discovery of a lost species in Wyandotte Cave and a nearby cavern necessitates a new combination and the changing of several trinomials. A new species, from Lawrence County, is described. For reasons stated in an earlier paper (Barr, 1959) the writer has applied the polytypic species concept to the systematics of Pseudanophthalmus and other genera of troglobious carabids. An alternative taxonomic approach was offered by Krekeler (1958), who regarded each morphologically distinct cave population (or group of similar populations in closely associated caves) as genetically isolated. The specimens upon which the present paper is based were collected in Crawford, Harrison, Lawrence, Monroe, Orange, Owen, and Washington Counties, Indiana, during the summer of 1957 and the fall of 1958. Dr. Carl H. Krekeler, Valparaiso University, whose recent (1958) paper is the most important single contribution to our knowledge of Indiana anophthalmids, provided a topotype P. morrisoni and a paratype P. youngi donaldsoni for examination. One P. morrisoni and six P. youngi donaldsoni were collected for the writer by Mr. Thomas L. Poulson. Deep appreciation is expressed to Mr. Lewis D. Lamon, Corydon, Indiana, and to Miss Leona Hert, Springville, Indiana, for assistance in collecting the material discussed below. Mr. Robert Louden, manager of Wyandotte Cave, was most courteous and helpful. Dr. Harold J. Grant, Academy of Natural Sciences of Philadelphia, kindly compared the writer's topotypes with Horn's types of Anophthalmus eremita and A. tenuis. Five species groups and six species are recognized in the present study, four of the groups being monotypic. The species may be separated by the following key.

The Analysis of Variation in a Natural Population of Lady Beetles

Biometric and taxonomic studies of quantitative characters in natural populations have led to the discovery of cases of continuous geographic variation, or lines, and of subpopulations displaying various degrees of reproductive and morphological intergradation. Because of the empirical fact that two or more natural entities may bear any degree of relationship along the spectrum of reproductive isolation, from complete intersterility to complete interfertility, regardless of their absolute or partial geographic coexistence, only an arbitrary point can be established on that spectrum for the taxonomic convenience of division of such entities into subgroups. The polytypic species concept (lVayr, 1942, Chap. 6) is a function of great subjectivity when applied to geographically separated, and especially morphologically similar, populations. The danger lies in the necessity of classifying microevolutionary units for ease of handling and in the implicit assumption by many taxonomists that such classifications reflect the true biological order of nature. Many authors have vainly sought a species definition for lack of realization of this latter point (see discussion by Gilmour, 1951). One of the most objective methods for investigating the systematic relationships between evolutionary units is that of Womble (1951), even though some subjectivity may enter the picture in the weighting of various characters. Fisher (1936) has dealt with such weightings by the use of discriminant functions. In order to apply Womble's differential systematics, a good deal of information first must be accumulated on the distribution of points on the geno-, pheno-, or ecocline. The genocline iq the most fundamental of the three and much work