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Showing papers in "Ornithological Monographs in 2010"


Journal ArticleDOI
TL;DR: The history of the subspecies concept and the major debates and issues surrounding its use are summarized, with an emphasis on ornithology, in which the concept originated.
Abstract: in this review i summarize the history of the subspecies concept and the major debates and issues surrounding its use, with an emphasis on ornithology, in which the concept originated. The study of subspecific variation in birds has been an important driving force in the development of evolutionary biology. Subspecific study has also been essential in the description and preservation of biodiversity. Although controversy has surrounded the concept of subspecies since its inception, it continues to play an important role in both basic and applied science. i cover 10 relevant issues that have been largely resolved during this 150-year controversy, although not all are widely appreciated or universally accepted. These include nomenclature, sampling theory, evolutionary biology, and the heterogeneity of named subspecies. i also address three big unresolved questions and some of the philosophy of science related to them: What are subspecies, how do we diagnose them, and what does subspecific variation mean? discordance between genotypic and phenotypic data at these shallow evolutionary levels should be expected. The process of diagnosing states that exist along a continuum of differentiation can be difficult and contentious and necessarily has some arbitrariness; professional standards can be developed so that such diagnoses are objective. Taxonomies will change as standards do and as more data accrue. Given present evidence, our null hypothesis should be that subspecific variation probably reflects local adaptation. in looking forward, it seems assured that geographically partitioned variation— and the convenient label "subspecies"—will continue to play an integral role in zoology.

97 citations


Journal ArticleDOI
TL;DR: The traditional subspecies concept, as originally construed, identifies minimum diagnosable units as terminal taxa, and it is suggested that it is thus essentially synonymous with the phylogenetic species concept.
Abstract: Dissatisfaction with the subspecies unit of classification is, in part, a consequence of the failure of many of those who have described subspecies to follow the conceptual definition of the subspecies, namely that it should represent diagnosable units. The antiquity of the descriptions of most subspecies (median year of description of currently recognized subspecies estimated to be 1908–1909) means that the majority predated any statistical tools for assessing diagnosability. The traditional subspecies concept, as originally construed, identifies minimum diagnosable units as terminal taxa, and I suggest that it is thus essentially synonymous with the phylogenetic species concept. Therefore, both must deal with the fundamental difficulties inherent in using diagnosability as a criterion. Application of monophyly as a criterion for taxon rank at the population level has inherent difficulties. An advantage of the biological species concept is that it incorporates, in its classification of taxa, ass...

81 citations


Journal ArticleDOI
TL;DR: Until a sound and defensible null expectation is developed for genetic differentiation of subspecies, genetic approaches will be fraught with problems and long-standing charges of subjectivity in the naming and diagnosis of sub species must be addressed.
Abstract: The utility of subspecies in studies of evolution and migration and in conservation planning has been debated hotly for a half-century. Inconsistent and sometimes sloppy application of the subspecies concept has led some to deem it a failure, but recent quantitative definitions of subspecies have put the concept on more rigorous footing. Nonetheless, the molecular revolution has added fuel to the fire as researchers attempt to test subspecies by genetic means. Until a sound and defensible null expectation is developed for genetic differentiation of subspecies, genetic approaches will be fraught with problems. A test for monophyly is insufficient, because parapatric subspecies interbreed by definition. Moreover, because much geographic variation may arise via natural selection, tests restricted to selectively neutral genetic data are likewise problematic. Moreover, long-standing charges of subjectivity in the naming and diagnosis of subspecies must be addressed if subspecies are to continue to be ...

62 citations


Journal ArticleDOI
TL;DR: The genetic homogeneity within this clade suggests a late Pleistocene range expansion at a time when today's montane forest types existed at lower elevati...
Abstract: The Slate-throated Redstart (Myioborus miniatus) is a common warbler of montane forests from northern Mexico to Argentina. We examined phylogenetic structure and plumage pattern in relation to subspecific taxonomy across the broad geographic range of this species. Phylogenetic analysis of two complete mitochondrial protein-coding genes (subunits 2 and 3 of NADH dehydrogenase) from 36 individuals, representing 10 of the 12 subspecies, revealed four clades, three of which showed general concordance with subspecific classification. However, in a Central American clade, four subspecies (hellmayri, connectens, comptus, and aurantiacus) could not be resolved by the molecular phylogenetic analysis, even though populations of hellmayri and connectens are currently geographically isolated from those of comptus and aurantiacus by the Nicaraguan lowlands. The genetic homogeneity within this clade suggests a late Pleistocene range expansion at a time when today's montane forest types existed at lower elevati...

36 citations


Journal ArticleDOI
TL;DR: Examination of genetic and morphological characteristics of the Song Sparrows of northwestern North America showed little information about these subspecies, with no reciprocal monophyly evident; however, differences in body mass and microsatellite allele frequencies supported continued recognition of subspecific units for taxonomy and conservation.
Abstract: w e examined genetic and morphological characteristics of the Song Sparrows (Melospiza melodia) of northwestern North America, which have a relatively large number of phe- notypically described subspecies (n = 6 in this region). mitochondrial DNA (mtDNA) sequences showed little information about these subspecies, with no reciprocal monophyly evident. however, differences in body mass and microsatellite allele frequencies supported continued recognition of subspecific units for taxonomy and conservation. Song Sparrow subspecies in this region are probably representative of many recently diverged populations that have not been isolated long enough for complete lineage sorting using mtDNA markers, yet which have evolved differences that are likely to be genetically based. we emphasize the importance of using multiple lines of evidence, genetic and morphological, in assessing subspecific status, lest we overlook important biological diversity that has accrued below the level of full species.

35 citations


Journal ArticleDOI
TL;DR: It is suggested that genuine consensus about subspecies is an impossible goal, because trinomial epithets will inevitably be applied to a heterogeneous mix of evolutionary phenomena, thereby precluding genuine standardization of the concept.
Abstract: The century-long debate over the meaning and utility of the subspecies concept has produced spirited print but only superficial consensus. I suggest that genuine consensus about subspecies is an impossible goal, because trinomial epithets will inevitably be applied to a heterogeneous mix of evolutionary phenomena, thereby precluding genuine standardization of the concept. Populations that have intermediate levels of phenotypic differentiation and geographic isolation from one another often fall into a region I refer to as the "zone of art," where even skilled experts can disagree about the validity of any one subspecific treatment. The trinomial system cannot accurately represent the kind of information now available about genetic and character variation across space. Instead, ever more accurate tools are being perfected for quantitative, standardized descriptions of variation. These analyses—not subspecies classifications—will keep providing new scientific insights into geographic variation. Eve...

32 citations


Journal ArticleDOI
TL;DR: Here, it is described how subspecies designations are evaluated under the Endangered Species Act, tradeoffs between maintaining the biological species conce...
Abstract: Scientific debate over identification of taxa below the species level has persisted for centuries. This issue can be especially problematic for avian species, because dispersal is often orders of magnitude greater than in other vertebrates, leaving genetic differences among groups proportionately smaller. While the debate lingers, management decisions, often with millions of dollars and potential extinctions resting on the outcome, are regularly made by agencies tasked with maintaining lists of threatened and endangered taxa. With outdated taxonomic treatments and no formal policy or guidelines for defining species or subspecies, agencies have no authority to cite in determining limits to species or subspecies ranges. Lack of guidance from professional organizations regarding taxonomic criteria and lists does not benefit these species of concern. Here, we describe how subspecies designations are evaluated under the Endangered Species Act, tradeoffs between maintaining the biological species conce...

29 citations



Journal ArticleDOI
TL;DR: This work reviews avian taxonomic history in the Hawaiian Islands, speciation patterns in Pacific island pigeons and doves, and patterns of variation in the widespread Polynesian Starling to demonstrate that the biological species concept, if applied with consideration of potential isolating mechanisms, vagility, and degree of freedom, could be applied to island birds.
Abstract: Outdated and overly lumped alpha taxonomy among the world's island birds has serious consequences for scientific research and conservation. The underestimation of biodiversity on islands obscures their role as speciation laboratories, distorts sampling in genetic studies, biases research planning, leads to neglect of endangered island species mistakenly classified as subspecies, and reduces potentially valuable information that might be gathered by recreational birders. Suggestions such as abandoning the biological species concept and the subspecies category in favor of the phylogenetic species concept create new problems and disrupt widely understood terminology. I review avian taxonomic history in the Hawaiian Islands, speciation patterns in Pacific island pigeons and doves, and patterns of variation in the widespread Polynesian Starling (Aplonis tabuensis) to demonstrate that the biological species concept, if applied with consideration of potential isolating mechanisms, vagility, and degree o...

26 citations


Journal ArticleDOI
TL;DR: This work compared the North American Tetraoninae—which have been defined using plumage, morphology, and behavior—and considered the effects of redefinition using only neutral molecular genetic data, and failed to recognize the five species whose mating system is highly polygynous, with males displaying on leks.
Abstract: Species and subspecies delineations were traditionally defined by morphological and behavioral traits, as well as by plumage characteristics. Molecular genetic data have more recently been used to assess these classifications and, in many cases, to redefine them. The recent practice of utilizing molecular genetic data to examine taxonomic questions has led some to suggest that molecular genetic methods are more appropriate than traditional methods for addressing taxonomic uncertainty and management units. We compared the North American Tetraoninae—which have been defined using plumage, morphology, and behavior—and considered the effects of redefinition using only neutral molecular genetic data (mitochondrial control region and cytochrome oxidase subunit 1). Using the criterion of reciprocal monophyly, we failed to recognize the five species whose mating system is highly polygynous, with males displaying on leks. In lek-breeding species, sexual selection can act to influence morphological and beha...

23 citations



Journal ArticleDOI
TL;DR: This monograph remedies what had become a significant obstacle to further studies in the country by providing, in Howell's own words, a comprehensive background for subsequent explorations.
Abstract: . Between December 1951 and April 1967, Thomas R. Howell made 13 separate research trips to Nicaragua. The result was a collection of over 2,000 bird skins and at least 16 publications that form the backbone of Nicaraguan ornithology. In the late 1970s, Howell began working on a manuscript that was intended to be his major contribution to the ornithology of the country. The first version of this "Check-list of the Birds of Nicaragua" was not ready until 1983, and many different typewritten versions circulated among a small but growing number of Nicaraguan biologists for the next two decades. Partly because of Howell's passion for detail and completeness, and finally because of his failing health in the late 1990s, the check-list was never published before his death in December 2004. This monograph remedies what had become a significant obstacle to further studies in the country by providing, in Howell's own words, a comprehensive background for subsequent explorations. It documents the 654 species...

Journal ArticleDOI
TL;DR: The evidence that subspecies may capture early stages of the speciation process is reviewed and what is learned about factors that drive subspecies diversification is considered.
Abstract: Avian taxonomists have traditionally used subspecies to describe geographic variation in morphology, plumage, and song. A complementary evolutionary perspective is that subspecies are incipient species, representing the first stages of speciation. Here, I review the evidence that subspecies may capture early stages of the speciation process and consider what we have learned about factors that drive subspecies diversification. I apply variants on the birth–death model to species age and subspecies richness data from 1,100 bird species. Clade-wide estimates of species diversification rates correlate positively with subspecies origination (hereafter "subspeciation") rates but not subspecies richness; thus, the evidence for heritable factors promoting speciation and subspeciation is equivocal. Subspeciation rates are higher among insular than among continental species, although this result is highly sensitive to the definition of insularity. A posteriori simulations based on the maximum-likelihood co...

Journal ArticleDOI
TL;DR: This work sought to assess quantitatively, on the basis of the D-statistic, those subspecies described using mensural characters, to quantify morphological variation, and to examine the influence of ecological correlates in the genus.
Abstract: Many authors have criticized the use of subspecies, but most of this criticism has been directed at the inconsistent treatment of subspecies rather than the inutility of diagnosable populations To assess the validity of a taxon, one must include in the analysis those characters used in the original diagnosis and remember that different character sets may lack geographic concordance We examined morphometric variation using 3,027 specimens representing all five species and 30 subspecies in the woodcreeper genus Dendrocolaptes (Dendrocolaptinae) Most subspecies in the genus differ in plumage patterns and coloration, but a few taxa were described using characters of size and structure We sought to assess quantitatively, on the basis of the D-statistic (Patten and Unitt 2002), those subspecies described using mensural characters, to quantify morphological variation, and to examine the influence of ecological correlates in the genus Males average slightly larger than females but have a less massiv

Journal ArticleDOI
TL;DR: The Cinnamon Teal (Anas cyanoptera) comprises five subspecies that inhabit a variety of habitats along an elevational gradient at temperate and tropical latitudes.
Abstract: The Cinnamon Teal (Anas cyanoptera) comprises five subspecies that inhabit a variety of habitats along an elevational gradient at temperate and tropical latitudes. North American and South American subspecies differ in their migratory behavior, which may have contributed to differences in body size. We measured body size of the five recognized subspecies (A. c. cyanoptera, A. c. orinomus, A. c. borreroi, A. c. tropica, and A. c. septentrionalium) throughout their ranges and evaluated morphometric differentiation in relation to Bergmann's rule. Subspecies and geographic regions differed significantly, with the largest subspecies and the largest individuals found at high elevations in the central Andes (A. c. orinomus) and at high latitudes in southern Patagonia (A. c. cyanoptera). Smaller-bodied individuals (A. c. cyanoptera) were found at the northern and southern limits of the Altiplano, where intermixing between subspecies with different body sizes might occur. However, there is no direct evide...