The phylogenetic relationships of Berthelot's Pipit Anthus berthelotii illustrated by DNA sequence data, with remarks on the genetic distance between Rock and Water Pipits Anthus spinoletta

The phylogenetic relationships of Berthelot's Pipit Anthus berthelotii , which is endemic to three groups of North Atlantic islands, have puzzled ornithologists for more than a century. A total of 1041 base pair cytochrome b mitochondrial DNA sequences from Berthelot's Pipit are compared with homologous sequences from the Tawny Pipit Anthus campestris , Richard's Pipit Anthus novaeseelandiae , the Meadow Pipit Anthus pratensis , the Red-breasted Pipit Anthus cervinus , the Tree Pipit Anthus trivialis , Rock and Water Pipits Anthus spinoletta and the White Wagtail Motacilla alba. In the resulting phytogeny, the sister taxon of Berthelot's Pipit is unambiguously the Tawny Pipit, with Richard's Pipit forming a deeper branch on the same clade. Sequences of a Danish Rock Pipit and a Swiss Water Pipit support a close relationship between these two species, but more comprehensive studies of intra- and interpopulation variation are required before considering their taxonomic ranking. Some preliminary inferences are made regarding phylogenetic tendencies in the genus Anthus.     

High levels of mitochondrial cytochrome b divergence in annual killifishes of the genus Cynolebias (Cyprinodontiformes, Rivulidae)

Phylogenetic relationships based on 324 base pairs of the mitochondrial cytochrome b gene were examined in 14 species of the genus Cynolebias. The monophyly of the genus relative to three outgroup taxa belonging to the family Rivulidae was supported by the sequence data. Bootstrap values corroborated the existence of intrageneric monophyletic units in both parsimony and Neighbour-joining analyses. These include a Cynolebias bellottii-C. wolterstorffl clade, a C. adloJfi-2, C. duraznensis, C. viarius and C adloffi-1 group, and a C. gymnoventris, C. luteoflammulatus pair and the strongly supported assemblage that includes C. prognalhus and C. cheradophilus clade. Phylogenetic relationships remain poorly supported for C. nigripinnis, C. qffinis and C. alexandri, and unresolved among the previous ingroup clades. Cytochrome b sequences reveal an unexpectedly high level of divergence among species of the genus Cynolebias. Consequently, cytochrome b shows good resolution of recent cladogenetic events but limited phylogenetic information at deeper nodes. High levels of sequence divergence span a broad range within Cynolebias. The highest sequence divergence (c. 28%) occurred among C. antenori and the remaining species of the genus. The minimum divergence value (4.5%) is exhibited by sympatric species C. cheradophilus and C. prognathus.     

A molecular phylogeny of malarial parasites recovered from cytochrome b gene sequences

A phylogeny of haemosporidian parasites (phylum Apicomplexa, family Plasmodiidae) was recovered using mitochondrial cytochrome b gene sequences from 52 species in 4 genera (Plasmodium, Hepatocystis, Haemoproteus, and Leucocytozoon), including parasite species infecting mammals, birds, and reptiles from over a wide geographic range. Leucocytozoon species emerged as an appropriate out-group for the other malarial parasites. Both parsimony and maximum-likelihood analyses produced similar phylogenetic trees. Life-history traits and parasite morphology, traditionally used as taxonomic characters, are largely phylogenetically uninformative. The Plasmodium and Hepatocystis species of mammalian hosts form 1 well-supported clade, and the Plasmodium and Haemoproteus species of birds and lizards form a second. Within this second clade, the relationships between taxa are more complex. Although jackknife support is weak, the Plasmodium of birds may form 1 clade and the Haemoproteus of birds another clade, but the parasites of lizards fall into several clusters, suggesting a more ancient and complex evolutionary history. The parasites currently placed within the genus Haemoproteus may not be monophyletic. Plasmodium falciparum of humans was not derived from an avian malarial ancestor and, except for its close sister species, P. reichenowi, is only distantly related to haemospordian parasites of all other mammals. Plasmodium is paraphyletic with respect to 2 other genera of malarial parasites, Haemoproteus and Hepatocystis. Explicit hypothesis testing supported these conclusions.     

Phylogeny and historical biogeography of African ground squirrels: the role of climate change in the evolution of Xerus

We used phylogenetic and phylogeographical methods to infer relationships among African ground squirrels of the genus Xerus. Using Bayesian, maximum-parsimony, nested clade and coalescent analyses of cytochrome b sequences, we inferred interspecific relationships, evaluated the specific distinctness of Cape (Xerus inauris) and mountain (Xerus princeps) ground squirrels, and tested hypotheses for historical patterns of gene flow within X. inauris. The inferred phylogeny supports the hypothesized existence of an 'arid corridor' from the Horn of Africa to the Cape region. Although doubts have been raised regarding the specific distinctness of X. inauris and X. princeps, our analyses show that each represents a distinct well-supported, monophyletic lineage. Xerus inauris includes three major clades, two of which are geographically restricted. The distributions of X. inauris populations are concordant with divergences within and disjunctions between other taxa, which have been interpreted as results of Plio-Pleistocene climate cycles. Nested clade analysis, coalescent analyses, and analyses of genetic structure support allopatric fragmentation as the cause of the deep divergences within this species.     

Molecular phylogeny and systematic in the genus Brachycaudus (Homoptera: Aphididae): insights from a combined analysis of nuclear and mitochondrial genes

Phylogenetic relationships among members of the Aphid genus Brachycaudus (Homoptera: Aphididae) were inferred from partial sequences of mitochondrial cytochrome B oxidase (CytB), two partial fragments of mitochondrial cytochrome C oxidase subunit I (COI) and the internal transcribed spacer II (ITS2) of ribosomal DNA. Twenty-nine species, with several specimens per species, were included, representing all the historically recognized species-groups and subgenera used in the genus except the monospecific subgenus Mordvilkomemor. Results indicate that the genus Brachycaudus is a well-supported monophyletic group. While our results validate the monophyly of subgenera Thuleaphis , Appelia and Brachycaudus s. str. , they reveal two discrepancies in the classical taxonomy. First, the monotypic subgenus Nevskyaphis does not appear valid. Second, the traditionally defined Acaudus subgenus is not monophyletic. On the other hand, our phylogenetic trees corroborate Andreev's recent definition of Acaudus and Brachycaudina. However, they clearly show that the subgenera Prunaphis , Nevskyaphis and Scrophulaphis as defined by this author do not form monophyletic groups. Our results also highlight a highly supported clade that has not been discussed by previous authors; this clade could form a new subgenus, the subgenus Nevskyaphis . Finally, our study shows that molecular data and morphology meet the same limits in delimiting species groups and species themselves. Species groups in which taxonomic treatment is difficult are polytomous. Furthermore, except for one node clustering Brachycaudus s. str . and Appelia, intersubgeneric relationships remain poorly resolved even when several genes are added to the phylogenetic analysis. These results, together with previous studies in other aphid groups suggest that diversification might have been a rapid process in aphids.     

Molecular phylogeny of north mediterranean freshwater barbs (genus Barbus: cyprinidae) inferred from cytochrome b sequences: biogeographic and systematic implications

We investigated phylogenetic relationships among north Mediterranean species of the genus Barbus using sequences of the cytochrome b gene. Our results indicate that the species belong to two major clades that are consistent with those previously defined from morphological features. The first clade includes species ranging from France to the Black Sea. In this clade, there is a well-supported monophyletic group of large-sized fluvio-lacustrine barbs; however, the monophyly of the small-sized rheophilic species is not clear. The second clade comprises species found in Spain, Greece, and Asia Minor and probably represents the oldest group present in the north Mediterranean rivers. In general, there is good concordance between geography and phylogenetic relationships. These results are compared to those from previous morphological- and allozyme-based studies and demonstrate widespread discordance and polyphyly in the traditional taxonomy of the genus Barbus. This study is one of the first reporting the phylogenetic and biogeographic relationships of a genus that is widely distributed in European rivers and contains species that are a major component of the European ichthyofauna.     

Evolutionary systematics in African gerbilline rodents of the genus Gerbilliscus: inference from mitochondrial genes

Gerbilliscus has recently been proposed as an endemic African rodent genus distinct from the Asian Tatera. A molecular phylogeny of the genus, including nine species from southern, western and eastern Africa, is presented here based on the analysis of the cytochrome b and 16S mitochondrial genes. With an adequate taxonomic sampling over a wide geographic range, we here provide a clear picture of the phylogenetic relationships between species and species groups in this genus. Three distinct clades were resolved, corresponding to major geographical subdivisions: an eastern clade that possibly diverged first, then a southern and a western clades which appeared later. We suggest two possible hypotheses concerning the dispersal of the genus across Africa, considering also the patterns of karyotypic variation. Finally, we discuss the taxonomic status of G. gambianus and the relationships between Gerbillurus and Gerbilliscus, as previous studies have suggested that the former should be included in the latter. Our data seem to support the synonymy of the two taxa and suggest that Gerbillurus and Gerbilliscus lineages diverged from a common ancestor appeared in eastern Africa.     

Molecular phylogeny of short-tailed shrews, Blarina (Insectivora: Soricidae)

Phylogenetic relationships among the three described species of short-tailed shrews (genus Blarina) were inferred based on mitochondrial DNA sequences of 16S rRNA (506 bp) and cytochrome b (1137 bp) from 38 specimens representing B. brevicauda, B. hylophaga, and B. carolinensis, from across their range in North America. Phylogenetic analyses of both data sets combined followed tests showing lack of incongruence between these fragments. Analysis of substitution patterns indicated saturation of transitions at third codon positions in cytochrome b when Blarina sequences were compared to those of Sorex and Cryptotis, used as outgroups. Maximum-likelihood and weighted parsimony supported the monophyly of the genus and placed B. hylophaga as its basal branch, sister to B. brevicauda + B. carolinensis. Phylogeographic analysis revealed a significant partition between eastern and western populations of B. carolinensis and B. brevicauda, on either side of the Mississippi basin. These results are discussed in relation to cytogenetic, morphological, and fossil data.     

Phylogeny of the Neotropical killifish family Rivulidae (Cyprinodontiformes, Aplocheiloidei) inferred from mitochondrial DNA sequences

Phylogenetic relationships of 70 taxa representing 68 species of the Neotropical killifish family Rivulidae were derived from analysis of 1516 nucleotides sampled from four different segments of the mitochondrial genome: 12S rRNA, 16S rRNA, cytochrome oxidase I, and cytochrome b. The basal bifurcation of Cynolebiatinae and Rivulinae (Costa, 1990a,b) is supported; however, Terranatos, Maratecoara, and Plesiolebias are rivulins, not cynolebiatins. These three genera, along with the other recognized annual rivulin genera, form a monophyletic clade. Austrofundulus, Rachovia, Renova, Terranatos, and 3 species of the genus Pterolebias, all from northeastern South America, form a monophyletic clade excluding other species of Pterolebias. Pterolebias as presently understood is clearly polyphyletic. Trigonectes and Moema are supported as sister groups but do not form a monophyletic group with the genera Neofundulus and Renova as previously proposed. The suite of adaptations necessary for an annual life history has clearly been lost several times in the course of rivulid evolution. Also revealed is a considerable increase in substitution rate in most annual lineages relative to the nonannual Rivulus species. The widespread and speciose genus Rivulus is paraphyletic, representing both basal and terminal clades within the Rivulidae. Previous hypotheses regarding the vicariant origin of Greater Antillean Rivulus species are supported. Most rivulid clades show considerable endemism; thus, detailed analysis of rivulid phylogeny and distribution will contribute robust hypotheses to the clarification of Neotropical biogeography.     

Molecular systematics of a speciose, cosmopolitan songbird genus: defining the limits of, and relationships among, the Turdus thrushes

The avian genus Turdus is one of the most speciose and widespread of passerine genera. We investigated phylogenetic relationships within this genus using mitochondrial DNA sequence data from the ND3, ND2 and cytochrome b genes. Our sampling of Turdus included 60 of the 65 extant species currently recognized, as well as all four species from three genera previously shown to fall inside Turdus (Platycichla, Nesocichla, and Cichlherminia). Phylogenetic trees based on maximum likelihood and maximum parsimony algorithms were congruent. Most of the Turdus taxa sampled fall into one of four clades: an African clade, a Central American-Caribbean clade, a largely South American clade, and a Eurasian clade. Still other taxa are placed either at the base of Turdus, or as links between clades. In no instance is any continent reciprocally monophyletic for the species distributed on it. A general lack of nodal support near the base of the phylogeny seems related to a rapid intercontinental establishment of the major clades within Turdus very early in the history of the genus. The monotypic genus Psophocichla is distantly related to, but clearly the sister of, Turdus rather than a constituent member of it.     

Phylogenetic relationships, biogeography and speciation in the avian genus Saxicola

The avian genus Saxicola is distributed throughout Africa, Asia, Europe and various islands across Oceania. Despite the fact that the group has great potential as a model to test evolutionary hypotheses due to the extensive variability in life history patterns recorded between and within species, the phylogenetic relationships among species and subspecies of this genus are poorly understood. We undertook a systematic investigation of the relationships within this genus with three main objectives in mind, (1) to test the monophyly of the genus; (2) to ascertain geographical origin and dispersal sequence; and (3) to test for monophyly within the most morphologically diverse species, S. torquata and S. caprata. We studied sequence data from the mitochondrial cytochrome b gene from 11 of the 12 recognized species and 15 of the 45 described subspecies. Four clades, two exclusively Asian, one Eurasian, and the fourth encompassing Eurasia and Africa, were identified. Based on our analyses, monophyly of the genus Saxicola is not supported and an Asian origin for the genus can be inferred. Results from DIVA analyses, tree topology and nodal age estimates suggest independent colonisation events from Asia to Africa and from Asia to the Western Palearctic, with the Sahara desert acting as a natural barrier for S. torquata. Subspecies and populations of S. torquata are not monophyletic due to S. tectes, S. dacotiae and S. leucura grouping within this complex. Subspecies and populations of S. caprata are monophyletic. Importantly, within S. torquata and S. caprata, slight morphological traits and plumage colour pattern differences used to recognize subspecies are indicative of the greater cryptic diversification that has occurred within this genus.     

Evolutionary history of the genus Rhamdia (Teleostei: Pimelodidae) in Central America

We constructed phylogenetic hypotheses for Mesoamerican Rhamdia, the only genus of primary freshwater fish represented by sympatric species across Central America. Phylogenetic relationships were inferred from analysis of 1990 base pairs (bp) of mitochondrial DNA (mtDNA), represented by the complete nucleotide sequences of the cytochrome b (cyt b) and the ATP synthase 8 and 6 (ATPase 8/6) genes. We sequenced 120 individuals from 53 drainages to provide a comprehensive geographic picture of Central American Rhamdia systematics and phylogeography. Phylogeographic analysis distinguished multiple Rhamdia mtDNA lineages, and the geographic congruence across evolutionarily independent Rhamdia clades indicated that vicariance has played a strong role in the Mesoamerican diversification of this genus. Phylogenetic analyses of species-level relationships provide strong support for the monophyly of a trans-Andean clade of three evolutionarily equivalent Rhamdia taxa: R. guatemalensis, R. laticauda, and R. cinerascens. Application of fish-based mitochondrial DNA clocks ticking at 1.3-1.5% sequence divergence per million years (Ma), suggests that the split between cis- and trans-Andean Rhamdia extends back about 8 Ma, and the three distinct trans-Andean Rhamdia clades split about 6 Ma ago. Thus the mtDNA divergence observed between cis- and trans-Andean Rhamdia species is too low to support an ancient colonization of Central America in the Late Cretaceous or Paleocene as had been hypothesized in one colonization model for Mesoamerican fishes. Rather the mtDNA data indicate that Rhamdia most likely colonized Central America in the late Miocene or Pliocene, promoting a strong role for the Isthmus of Panamá in the Mesoamerican expansion of this genus. Basal polytomies suggest that both the R. laticauda and R. guatemalensis clades spread rapidly across the Central American landscape, but differences in the average mtDNA genetic distances among clades comprising the two species, indicate that the R. laticauda spread and diversified across Mesoamerica about 1 million years before R. guatemalensis.     

Molecular phylogeny of the marmots (Rodentia: Sciuridae): tests of evolutionary and biogeographic hypotheses

There are 14 species of marmots distributed across the Holarctic, and despite extensive systematic study, their phylogenetic relationships remain largely unresolved. In particular, comprehensive studies have been lacking. A well-supported phylogeny is needed to place the numerous ecological and behavioral studies on marmots in an evolutionary context. To address this situation, we obtained complete cytochrome (cyt) b sequences for 13 of the species and a partial sequence for the 14th. We applied a statistical approach to both phylogeny estimation and hypothesis testing, using parsimony and maximum likelihood-based methods. We conducted statistical tests on a suite of previously proposed hypotheses of phylogenetic relationships and biogeographic histories. The cyt b data strongly support the monophyly of Marmota and a western montane clade in the Nearctic. Although some other scenarios cannot be rejected, the results are consistent with an initial diversification in North America, followed by an invasion and subsequent rapid diversification in the Palearctic. These analyses reject the two major competing hypotheses of M. broweri's phylogenetic relationships--namely, that it is the sister species to M. camtschatica of eastern Siberia, and that it is related closely to M. caligata of the Nearctic. The Alaskan distribution of M. broweri is best explained as a reinvasion from the Palearctic, but a Nearctic origin can not be rejected. Several other conventionally recognized species groups can also be rejected. Social evolution has been homoplastic, with large colonial systems evolving in two groups convergently. The cyt b data do not provide unambiguous resolution of several basal nodes in the Palearctic radiation, leaving some aspects of pelage and karyotypic evolution equivocal.     

Phylogenetic relationships of African killifishes in the genera Aphyosemion and Fundulopanchax inferred from mitochondrial DNA sequences

We have analyzed the phylogenetic relationships of 52 species representing all defined species groups (J. J. Scheel, 1990, Atlas of Killifishes of the Old World, 448 pp.) of the African aplocheiloid fish genera Aphyosemion and Fundulopanchax in order to examine their interrelationships and to reveal trends of karyotypic evolution. The data set comprised 785 total nucleotides from the mitochondrial 12S rRNA and cytochrome b genes. The molecular-based topologies analyzed by both maximum parsimony and neighbor-joining support the monophyly of most previously defined species groups within these two killifish genera. The genus Aphyosemion is monophyletic except for the nested position of Fundulopanchax kunzi (batesi group; subgenus Raddaella) within this clade, suggesting that this taxon was improperly assigned to Fundulopanchax. The remaining Fundulopanchax species sampled were supported as being monophyletic in most analyses. Relationships among the species groups in both genera were not as strongly supported, suggesting that further data will be required to resolve these relationships. Additional sampling from the 16S rRNA gene allowed further resolution of relationships within Fundulopanchax, more specifically identifying the nonannual scheeli group as the basal lineage of this otherwise annual genus. Chromosomal evolution within Aphyosemion has been episodic, with the evolution of a reduced n = 9-10 metacentric complement having occurred in multiple, independent lineages. Polarity of chromosomal reductions within the elegans species group appears to support previous hypotheses concerning mechanisms of karyotypic change within the genus Aphyosemion.     

Phylogenetic relationships of Pelobatoidea re-examined using mtDNA

Pelobatoidea is a clade of ancient anurans with obscure relationships to the remaining clades of frogs. We used partial sequences of two mitochondrial genes (cytochrome b and 16S RNA) from all Pelobatoidea subclades, including all species of Pelobatidae and Pelodytidae and four outgroup taxa (Xenopus, Ascaphus, Discoglossus, and Rana), to propose a phylogenetic hypothesis for relationships within Pelobatoidea. Maximum likelihood and Bayesian analyses support the monophyly of Pelobatoidea, but our hypothesis of internal relationships differs substantially from all previous hypotheses. Megophryidae is sister to Pelobates, and this clade is sister to Pelodytes. The most basal clade within Pelobatoidea is formed by Scaphiopus and Spea. The family Pelobatidae, as previously defined is not monophyletic, and it is split into Eurasian spadefoot toads Pelobates which retain the name Pelobatidae and North American spadefoot toads Scaphiopus and Spea which comprise the revived taxon Scaphiopodidae. Our analysis uncovers the existence of morphologically cryptic taxa within previously recognized species of the genus Spea and reveals marked genetic differentiation within Iberian Pelodytes. We discuss biogeographic implications and the evolution of fossoriality in the light of the new phylogenetic hypothesis.     

Molecular systematics and origin of sociality in mongooses (Herpestidae, Carnivora)

The Herpestidae are small terrestrial carnivores comprising 18 African and Asian genera, currently split into two subfamilies, the Herpestinae and the Galidiinae. The aim of this work was to resolve intra-familial relationships and to test the origin of sociality in the group. For this purpose we analysed sequences of the complete cytochrome b gene for 18 species of Herpestidae. The results showed that the mongooses were split into three clades: (1) the Malagasy taxa (Galidiinae and Cryptoprocta), (2) the true social mongooses and (3) the solitary mongooses, each group being also supported by morphological and chromosomal data. Our results suggested unexpected phylogenetic relationships: (1) the genus Cynictis is included in the solitary mongoose clade, (2) the genera Liberiictis and Mungos are sister-group, and (3) the genus Herpestes is polyphyletic. We examined the evolution of the sociality in mongooses by combining behavioural traits with the cytochrome b data. Some of the behavioural traits provided good synapomorphies for characterizing the social species clade, showing the potential benefit of using such characters in phylogeny. The mapping of ecological and behavioural features resulted in hypothesizing solitary behavior and life in forest as the conditions at the base of the mongoose clade.     

A molecular phylogenetic analysis of the "true thrushes" (Aves: Turdinae)

The true thrushes (Passeriformes: Muscicapidae, subfamily Turdinae) are a speciose and widespread avian lineage presumed to be of Old World origin. Phylogenetic relationships within this assemblage were investigated using mitochondrial DNA (mtDNA) sequence data that included the cytochrome b and ND2 genes. Our ingroup sampling included 54 species representing 17 of 20 putative turdine genera. Phylogenetic trees derived via maximum parsimony and maximum likelihood were largely congruent. Most of the Turdine taxa sampled can be placed into one of six well supported clades. Our data indicate a polyphyletic Zoothera which can be divided into at least two (Afro-Asian and Austral-Asian) main clades. The genus Turdus, as presently recognized, is paraphyletic but forms a well supported clade with the addition of three mostly monotypic genera (Platycichla, Nesocichla, and Cichlherminia). We identify an exclusively New World clade that includes a monophyletic Catharus, Hylocichla, Cichlopsis, Entomodestes, Ridgwayia, and Ixoreus. Members of the morphologically and behaviorally distinct genera Sialia, Myadestes, and Neocossyphus unexpectedly form a basal clade. Using multiple outgroup choices, we show that this group is distantly related, but unequivocally the sister group to the remaining Turdines sampled. The Turdinae appear to be a relatively old songbird lineage, originating in the mid to late Miocene. If the Turdinae are indeed Old World in origin, our data indicate a minimum of three separate invasions of the New World.     

Molecular phylogeny of the Cheilodactylidae and Latridae (Perciformes: Cirrhitoidea) with notes on taxonomy and biogeography

Phylogenetic relationships among cheilodactylid and latrid fishes were estimated from cytochrome oxidase I and cytochrome b mitochondrial DNA sequences. Two South African cheilodactylids, Cheilodactylus fasciatus and Cheilodactylus pixi, were divergent from the remaining members of their genus and family, and the monophyly of these groups was rejected based on parametric bootstrap analysis. As C. fasciatus is the nominal species for the genus and family, widespread taxonomic reassignment is implicated for the remaining 12 and 17 members of these groups, respectively. As these 17 cheilodactylids are not genetically or morphologically distinct from the latrids, it is proposed that the Latridae should be expanded to encompass them. The inferred relationships among those Cheilodactylus requiring generic reassignment were largely unresolved, and hence few recommendations can be made regarding their placement. Divergence time estimates indicate that chance oceanic dispersal subsequent to Gondwanan fragmentation best explains the Southern Hemisphere radiation of cheilodactylids.     

Historical biogeography of tamarins,genus Saguinus: the molecular phylogenetic evidence

Hypotheses of the historical biogeography of tamarins (genus Saguinus) based on variation in coat colors and body size are tested using phylogenetic relationships inferred from mitochondrial DNA (mtDNA) sequence data. Samples from all 12 species of Saguinus and several subspecies are included in the analysis. Approximately 1,200 bases of mtDNA sequence from the cytochrome b and D-loop regions are reported for the tamarins and several outgroup taxa. Parsimony analysis of the mtDNA sequence data reveals Saguinus to be a monophyletic taxon composed of two major clades: one, the Small-bodied clade, contains S. nigricollis, S. tripartitus, and S. fuscicollis, and the other, the Large-bodied clade, contains the other nine species. The phylogenetic relationships among tamarins inferred from the mtDNA sequence data reject previous hypotheses for the historical biogeography of tamarins and suggest different dispersal routes for this group of New World monkeys. The molecular data suggest that tamarins dispersed across South America in two major waves from an origin somewhere south of the Amazon. One wave moved in a westerly direction, whereas the other moved in a northeastern direction toward the Amazon delta and then west along the northern portion of the continent into northern Colombia and Panama. Am J Phys Anthropol 108:65–89, 1999. © 1999 Wiley-Liss, Inc.     

The impact of parsimony weighting schemes on inferred relationships among toucans and neotropical barbets (Aves: piciformes)

The development of new schemes for weighting DNA sequence data for phylogenetic analysis continues to outpace the development of consensus on the most appropriate weights. The present study is an exploration of the similarities and differences between results from 22 character weighting schemes when applied to a study of barbet and toucan (traditional avian families Capitonidae and Ramphastidae) phylogenetic relationships. The dataset comprises cytochrome b sequences for representatives of all toucan and Neotropical barbet genera, as well as for several genera of Paleotropical barbets. The 22 weighting schemes produced conflicting patterns of relationship among taxa, often with conflicting patterns each receiving strong bootstrap support. Use of multiple weighting schemes helped to identify the source within the dataset (codon position, transitions, transversions) of the various putative phylogenetic signals. Importantly, some phylogenetic hypotheses were consistently supported despite the wide range of weights employed. The use of phylogenetic frameworks to summarize the results of these multiple analyses proved very informative. Relationships among barbets and toucans inferred from these data support the paraphyly of the traditional Capitonidae. Additionally, these data support paraphyly of Neotropical barbets, but rather than indicating a relationship between Semnornis and toucans, as previously suggested by morphological data, most analyses indicate a basal position of Semnornis within the Neotropical radiation. The cytochrome b data also allow inference of relationships among toucans. Supported hypotheses include Ramphastos as the sister to all other toucans, a close relationship of Baillonius and Pteroglossus with these two genera as the sister group to an (Andigena, Selenidera) clade, and the latter four genera as a sister group to Aulacorhynchus.