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.     

Phylogeny and biogeography of cichlid fishes (Teleostei: Perciformes: Cichlidae)

Family level molecular phylogenetic analyses of cichlid fishes have generally suffered from a limited number of characters and/or poor taxonomic sampling across one or more major geographic assemblage, and therefore have not provided a robust test of early intrafamilial diversification. Herein we use both nuclear and mitochondrial nucleotide characters and direct optimization to reconstruct a phylogeny for cichlid fishes. Representatives of major cichlid lineages across all geographic assemblages are included, as well as nearly twice the number of characters as any prior family‐level study. In a strict consensus of 81 equally most‐parsimonious hypotheses, based on the simultaneous analysis of 2222 aligned nucleotide characters from two mitochondrial and two nuclear genes, four major subfamilial lineages are recovered with strong support. Etroplinae, endemic to Madagascar (Paretroplus) and southern Asia (Etroplus), is recovered as the sister taxon to the remainder of Cichlidae. Although the South Asian cichlids are monophyletic, the Malagasy plus South Asian lineages are not. The remaining Malagasy lineage, Ptychochrominae, is monophyletic and is recovered as the sister group to a clade comprising the African and Neotropical cichlids. The African (Pseudocrenilabrinae) and Neotropical (Cichlinae) lineages are each monophyletic in this reconstruction. The use of multiple molecular markers, from both mitochondrial and nuclear genes, results in a phylogeny that in general exhibits strong support, notably for early diversification events within Cichlidae. Results further indicate that Labroidei is not monophyletic, and that the sister group to Cichlidae may comprise a large and diverse assemblage of percomorph lineages. This hypothesis may at least partly explain why morphological studies that have attempted to place Cichlidae within Percomorpha, or that have tested cichlid monophyly using only “labroid” lineages, have met with only limited success. © The Willi Hennig Society 2004.     

Phylogeny of Ensifera (Hexapoda: Orthoptera) using three ribosomal loci, with implications for the evolution of acoustic communication

Representatives of the Orthopteran suborder Ensifera (crickets, katydids, and related insects) are well known for acoustic signals produced in the contexts of courtship and mate recognition. We present a phylogenetic estimate of Ensifera for a sample of 51 taxonomically diverse exemplars, using sequences from 18S, 28S, and 16S rRNA. The results support a monophyletic Ensifera, monophyly of most ensiferan families, and the superfamily Gryllacridoidea which would include Stenopelmatidae, Anostostomatidae, Gryllacrididae, and Lezina. Schizodactylidae was recovered as the sister lineage to Grylloidea, and both Rhaphidophoridae and Tettigoniidae were found to be more closely related to Grylloidea than has been suggested by prior studies. The ambidextrously stridulating haglid Cyphoderris was found to be basal (or sister) to a clade that contains both Grylloidea and Tettigoniidae. Tree comparison tests with the concatenated molecular data found our phylogeny to be significantly better at explaining our data than three recent phylogenetic hypotheses based on morphological characters. A high degree of conflict exists between the molecular and morphological data, possibly indicating that much homoplasy is present in Ensifera, particularly in acoustic structures. In contrast to prior evolutionary hypotheses based on most parsimonious ancestral state reconstructions, we propose that tegminal stridulation and tibial tympana are ancestral to Ensifera and were lost multiple times, especially within the Gryllidae.     

Using 18S rDNA to resolve diaptomid copepod (Copepoda: Calanoida: Diaptomidae) phylogeny: an example with the North American genera

The phylogenetic relationships among the numerous genera of diaptomid copepods remain elusive due to difficulties in obtaining sufficient numbers of phylogenetically informative morphological characters for cladistic analysis. Molecular phylogenetic techniques offer high potential to resolve phylogenetic relationships in the absence of sufficient morphological characters because of the ease in which many characters can be unambiguously coded. I present the first molecular phylogeny for diaptomid copepod genera using 18S rDNA. Specifically, I test Light’s (1939) hypothesis regarding the interrelationships among the North American diaptomid genera. The 18S phylogeny is remarkably consistent with Light’s hypothesis. The endemic North American genera represent a monophyletic group exclusive of the non-endemic genera. Moreover, his hypothesized basal genus for the North America genera, Hesperodiaptomus, is the basal genus in this analysis. However, his Leptodiaptomus group is not reciprocally monophyletic with his Hesperodiaptomus group, but is rather a derived member of the latter group. Finally, the genus Mastigodiaptomus is found to be more closely allied with the non-endemic genera, as Light suggested. This phylogeny contributes heavily to the understanding of phylogenetic relationships among North American diaptomids and has large implications for the systematics of diaptomids in general. The use of 18S rDNA sequences in phylogenetic analyses of diaptomid copepods can be used to confirm the monophyly of recognized genera, the interrelationships among genera, and subsequent biogeographic interpretation of the family’s diversification. The use of molecular data, such as 18S rDNA sequences, to test phylogenetic hypotheses based on a very limited number of morphological characters will be a particularly useful approach to phylogenetic analysis in this system.     

Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers

Gulls (Aves: Laridae) constitute a recent and cosmopolite family of well-studied seabirds for which a robust phylogeny is needed to perform comparative and biogeographical analyses. The present study, the first molecular phylogeny of all Larids species (N=53), is based on a combined segment of mtDNA (partial cytochrome b and control region). We discuss our phylogenetic tree in the light of previous suggestions based on morphological, behavioral, and plumage characters. Although the phylogeny is not fully resolved, it highlights several robust species groups and confirms or identifies for the first time some sister relationships that had never been suggested before. The Dolphin Gull (Leucophaeus scoresbii) for instance, is identified as the sister species of the Grey Gull (Larus modestus) and the Ross's Gull (Rhodostethia rosea) forms a monophyletic group with the Little Gull (Larus minutus). Our results clearly demonstrate that the genus Larus as currently defined is not monophyletic, since current taxonomy of gulls is based on the use of convergent phenotypic characters. We propose a new systematic arrangement that better reflects their evolutionary history.     

The Phylogeny of the Families Lecanoraceae and Bacidiaceae (Lichenized Ascomycota) Inferred from Nuclear SSU rDNA Sequences

Abstract: The phylogeny of the families Lecanoraceae and Bacidiaceae (Lecanorales, Ascomycota) was investigated using 29 nuclear small subunit ribosomal DNA sequences, 9 of which were newly determined. The data set contained 368 variable characters, 234 of which were parsimony-informative. Phylogenetic estimations were performed with maximum parsimony and maximum likelihood optimality criteria. In the most parsimonious and most likely reconstructions, the Bacidiaceae sensu Hafellner 1988 forms a monophyletic group and the Lecanoraceae sensu Hafellner a paraphyletic group. The genera Tephromela and Scoliciosporum appear to belong outside these families. However, the hypothesis that the Lecanoraceae sensu Hafellner is monophyletic cannot be rejected, as indicated by a Kishino-Hasegawa test. Three hypotheses were rejected by Kishino-Hasegawa tests, viz. (1) that the Lecanoraceae and Bacidiaceae together form a monophyletic group; (2) that both the Lecanoraceae (incl. Scoliciosporum ) and Bacidiaceae (incl. Tephromela ) are monophyletic; and (3) that the ascus apex anatomy reflects phylogeny. The suborder Lecanorineae is paraphyletic unless the Stereocaulaceae and Cladoniaceae are included. One or both of the Bacidia and Lecanora types of ascus have probably evolved at least twice.     

Cladistic analysis of the Sepsidae (Cyclorrhapha: Diptera) based on a comparative scanning electron microscopic study of larvae

The result of a phylogenetic analysis of the Sepsidae based on larval characters is presented. It is shown that cyclorrhaphan larvae can be as rich a source of characters as Nematocera immatures when investigated using an SEM. The cladistic analysis comprised fifty-two species in sixteen genera of the Sepsidae and five outgroup species and used fifty-seven morphological characters. It found seven parsimonious trees which only differed with respect to the arrangement of some species within the genus Themira. The basal dichotomies of the phylogenetic trees are particularly well supported, indicating the conservative nature of larval characters. Orygma is confirmed as the sister group of all the remaining sepsids, the Sepsinae. There is good larval evidence that Ortalischema is the sister group of all remaining Sepsinae and that the Toxopodinae constitute an early radiation within the Sepsidae. According to larval data, some genera are paraphyletic ( Themira, Palaeosepsis ), but adult characters appear to contradict these findings. Among the traditionally recognized higher taxa within the Sepsidae, Hennig's Themira species-group and Steysbal's Sepsini have to be rejected as polyphyletic. However, Hennig's Sepsis species-group is confirmed as monophyletic and will probably constitute one major element of a future phylogenetic system of the Sepsidae. States of the strongly modified fore-legs of some adult sepsid males are mapped onto the phylogenetic tree, largely confirming Šulc's ideas about the evolution of these features. The origin and evolution of male sternites with brushes and a gland on the tibiae of the males ('osmeterium') are discussed. Whereas adult characters point to a sister-group relationship between the Sepsidae and the Ropalomeridae, larval characters appear to indicate a sister-group relationship between the Coelopidae and the Sepsidae. The evidence for both hypotheses is critically evaluated.     

Phylogenetics of barbets (Aves: Piciformes) based on nuclear and mitochondrial DNA sequence data

A combination of nuclear (beta-fibrinogen intron 7; 938 bp) and mitochondrial (cytochrome b; 1045 bp) DNA sequence data analyzed with model-based phylogenetic methods yields a hypothesis of barbet and toucan relationships supported by high Bayesian posterior probabilities and several synapomorphic indels in the nuclear intron data. The basal topology differs from previous morphology and mitochondrial DNA sequence based hypotheses, but is consistent with DNA-DNA hybridization results. The mitochondrial DNA sequence data provide resolution at the tips of the tree, but when analyzed alone, yield a different basal topology than the combined data. However, the basal nodes in the mitochondrial-based tree have little statistical support. Combined data analysis produced strong statistical support at basal nodes and a relatively simple geographic structure. Barbets from each of the three tropical regions are monophyletic, but the Old World barbets are paraphyletic. The African and New World clades are sister taxa, and the Asian clade is basal. This geographic structure indicates that similarities in plumage, voice, and behavior between Gymnobucco and Calorhamphus are convergent. The data are not conclusive, but suggest paraphyly of the New World barbets. Only 4% of the Bayesian posterior distribution unites Semnornis with the other New World barbets.     

Phylogenetic relationships and biogeography of the Ipsiura cuckoo wasps (Hymenoptera: Chrysididae)

Phylogenetic studies addressing relationships among chrysidid wasps have been limited. There are no hypotheses proposed for the Neotropical lineages of Chrysidini other than the classic cladogram published in the 1990s by Kimsey and Bohart. Herein we present a cladistic analysis based on 64 morphological characters coded for 54 species of Chrysidini, 32 of them being Ipsiura and 22 representing Caenochrysis, Chrysis, Exochrysis, Gaullea, Neochrysis, and Pleurochrysis. The species of Ipsiura were recovered as monophyletic and as the sister clade of Neochrysis in all most parsimonious trees. We discuss the high plasticity of some morphological characters as evidenced by their high homoplasy in the phylogenetic results, and we clarify the main morphological changes inferred on the phylogenetic tree for this genus. The effects of the inferred homoplasy were evaluated under an implied weighting cladistic analysis, and from a probabilistic perspective with Bayesian inference. Those alternative strategies did not alter the general conclusions about the monophyly of Ipsiura or the generic relationships in Chrysidini (changes were noticed in the species‐level relationships within certain parts of Ipsiura, where low branch support was common across all approaches). Among the species groups proposed by Linsenmaier (1985), only the marginalis group was recovered as monophyletic. We also evaluated the convoluted biogeographic history of the group. The resulting historical reconstructions indicate a complicated scenario of diversification of these wasps in the Neotropics, and a close association with forested biomes is discussed.     

Phylogenetic Relationships of Extinct Cetartiodactyls: Results of Simultaneous Analyses of Molecular, Morphological, and Stratigraphic Data

Although some recent morphological and molecular studies agree that Cetacea is closely related to Hippopotamidae, there is little consensus on the phylogeny within Cetartiodactyla. We addressed this problem by conducting two analyses: (1) a simultaneous cladistic analysis of intrinsic data (morphology and molecules) and (2) a stratocladistic analysis, which included morphological, molecular, and stratigraphic data. Unlike previous simultaneous analyses, we had the opportunity to include data from the recently described hindlimbs of protocetid and pakicetid cetaceans. Our intrinsic dataset includes 73 taxa scored for 8,229 informative characters, of which 208 are morphological and 8,021 molecular. Both analyses supported the exclusion of Mesonychia from Cetartiodactyla and a close phylogenetic relationship between Hippopotamidae and Cetacea. Many polytomies in the strict consensus of the most parsimonious trees for the intrinsic dataset can be attributed to differing positions for Raoellidae, which in some trees is the sister-group to Cetacea. Pruning Raoellidae and 18 other taxa from all most parsimonious produced a fully resolved agreement subtree, which indicates that the Old World taxa Cebochoerus and Mixtotherium are successive stem taxa to Whippomorpha (i.e., Cetacea + Hippopotamidae). The main result of adding stratigraphic information to the intrinsic dataset was that we found fewer most parsimonious trees, which in most respects were congruent with a subset of the shortest trees for the intrinsic dataset. Our stratocladistic analysis supports species of Diacodexis as the most basal cetartiodactyls, a clade of suiform cetartiodactyls, a monophyletic Tylopoda that includes Protoceratidae, and a monophyletic Carnivora. We were unable to identify any pre-Miocene stem taxa to Hippopotamidae, thus its ghost lineage is still 39 million years long. The relatively low Bremer support for many nodes in our trees indicates that our phylogenetic hypotheses should be subjected to further testing.     

Testing the monophyly of the New Zealand and Australian endemic family Conoesucidae Ross based on combined molecular and morphological data (Insecta: Trichoptera: Sericostomatoidea)

Conoesucidae (Trichoptera, Insecta) are restricted to SE Australia, Tasmania and New Zealand. The family includes 42 described species in 12 genera, and each genus is endemic to either New Zealand or Australia. Although monophyly has been previously assumed, no morphological characters have been proposed to represent synapomorphies for the group. We collected molecular data from two mitochondrial genes (16S and cytochrome oxidase I), one nuclear gene (elongation factor 1-α) (2237–2277 bp in total), and 12 morphological characters to produce the first phylogeny of the family. We combined the molecular and morphological characters and performed both a maximum parsimony analysis and a Bayesian analysis to test the monophyly of the family, and to hypothesize the phylogeny among its genera. The parsimony analysis revealed a single most parsimonious tree with Conoesucidae being a monophyletic taxon and sistergroup to the Calocidae. The Bayesian inference produced a distribution of trees, the consensus of which is supported with posterior probabilities of 100% for 15 out of 22 possible ingroup clades including the most basal branch of the family, indicating strong support for a monophyletic Conoesucidae. The most parsimonious tree and the tree from the Bayesian analysis were identical except that the ingroup genus Pycnocentria changed position by jumping to a neighbouring clade. Based on the assumption that the ancestral conoesucid species was present on both New Zealand and Australia, a biogeographical analysis using the dispersal-vicariance criteria demonstrated that one or two (depending on which of the two phylogenetic reconstructions were applied) sympatric speciation events took place on New Zealand prior to a single, late dispersal from New Zealand to Australia.     

BIOGEOGRAPHY OF NEW WORLD TAIGA-DWELLING MICROTUS (MAMMALIA: ARVICOLIDAE): A HYPOTHESIS TEST THAT ACCOUNTS FOR PHYLOGENETIC UNCERTAINTY

If we adopt a statistical approach to systematics and recognize that phylogenies are estimated with error, then we can begin to explore statistically justified methods for testing a variety of comparative hypotheses, including those concerning the evolution of life-history characters and biogeography. In this paper I examine two biogeographic hypotheses concerning the rodent genus Microtus. Like many comparative hypotheses, these can be phrased so that each predicts the existence of a particular monophyletic group. Neither of the predicted groups appear on the single best phylogeny as determined by both Dollo parsimony and maximum likelihood analysis of restriction site maps of mitochondrial DNA. Simulation studies, however, suggest that often the best phylogeny from a single data set has only a low probability of being exactly correct. We must also examine those trees that, while not the single best-supported tree, are not rejected by the data. If we find the best phylogeny for which a hypothesis is satisfied, then likelihood methods can be used to test whether that phylogeny is significantly worse then the best tree overall. If that tree can be rejected, then so can the hypothesis. Computational constraints limit the use of likelihood methods for searching among topologies, so parsimony is used as a data exploratory tool. One of the predicted groups cannot be rejected, even though the most parsimonious tree which includes that group requires 11 more steps than does the most parsimonious tree.     

Pathways of lysozyme evolution inferred from the sequences of cytochrome b in birds

A reliable phylogeny relating the major groups of Galliformes was sought in order to shed light on an unusual case of coupled amino acid replacements in the lysozymes c of these birds. The New World quail and the African guinea fowl share a unique trio of amino acids at three internal positions but have been separated phylogenetically by the majority of trees based on morphological characters. Alternative hypotheses based on molecular data have suggested an arrangement that would be more parsimonious with regard to the lysozyme data. The entire mitochondrial cytochrome b gene (1,143 bp) was amplified via the polymerase chain reaction (PCR) and sequenced for nine galliforms and a representative anseriform to provide DNA sequence data for a phylogenetic reconstruction. The mode and tempo of change in these sequences were analyzed to determine the characters most appropriate for phylogenetic reconstruction. Our results place the New World quail outside all other representative game birds except the cracids. Although in conflict with various morphological analyses, this finding is consistent with the results of DNA-DNA hybridization studies. A model to account for the coupled replacements in the lysozymes is presented. Our results also suggest a rapid but ancient radiation among the Galliformes such that the majority of cytochrome b sequence differences among taxa have accumulated on the terminal branches of the reconstructed phylogenetic trees.Deceased July 21, 1991 Correspondence to: J.R. Kornegay     

Molecular Phylogeny of Fulgoromorpha (Insecta, Hemiptera, Archaeorrhyncha). The Enigmatic Tettigometridae: Evolutionary Affiliations and Historical Biogeography

Previous morphologically based studies by several taxonomists disagree on whether the Tettigometridae represent a sister group to all other fulgoromorphans or whether they are a relatively derived family within the Fulgoromorpha. In this study, several parsimony-based analyses using data sets composed of nucleotide sequences of 18S rDNAs (genes encoding 18S rRNAs) support a monophyletic Fulgoromorpha. All analyses depict Tettigometridae as a relatively derived lineage in a monophyletic relationship with Tropiduchidae. Unscored and unweighted data sets position the tettigometrid + tropiduchid clade as sister to Flatidae. The tettigometrid + tropiduchid clade is supported by four synapomorphic sites, two deletions and two transversions. Constraining tettigometrids to a basal fulgoromorphan lineage significantly reduces parsimony, with several hundreds to thousand of trees being more parsimonious. An analysis employing the Barriel method for scoring potential phylogenetic information in regions containing deletions also supports a non-basal tettigometrid + tropiduchid clade. However, this method results in three equally most parsimonious trees and a sister relationship of the tettigometrid + tropiduchid clade to Flatidae becomes ambiguous.
The molecular-based results showing a derived Tettigometridae agree with previous morphological interpretations of Bourgoin. The current biogeographical distribution of tettigometrids and morphological features supporting the 18S rDNA-based phylogeny are discussed.     

Inflorescence diversification in the "finger millet clade" (Chloridoideae, Poaceae): a comparison of molecular phylogeny and developmental morphology

Within the Poaceae, inflorescence diversification and its bearing on phylogeny and evolution are exceedingly complex. We used phylogenetic information of the "finger millet clade," a group of grasses with digitate inflorescences, to study the inflorescence diversification. This clade appears monophyletic in the morphological and molecular phylogenetic analyses. Three well-supported clades are shown in our cpDNA-derived phylogeny, with clades I and III consisting of species of Chloris and Microchloa, respectively, and clade II including species of Cynodon, Dactyloctenium, and Eleusine. Variation appears at different times throughout development. Changes involving primordium number and arrangement occur very early, changes involving duration of primordium activity occur much later. Characters derived from the comparison of developmental sequences were optimized onto the most parsimonious tree. The developmental characters were congruent with the molecular phylogeny. Two developmental characters may not be homologous in the Chloris subclade and the Cynodon subclade.     

An investigation into the cladistic relationships and monophyly of therocephalian therapsids (Amniota: Synapsida)

A comprehensive phylogenetic investigation was performed to elucidate the cladistic relationships and possible monophyly of therocephalian therapsids (Amniota: Synapsida). The phylogenetic positions of 30 therapsid taxa were examined under maximum parsimony, including 23 therocephalian genera. The analysis incorporated 110 cranial and postcranial characters in order to assess the interrelationships of basal therocephalians and eutherocephalians and their relationships to Cynodontia, representing the most complete review of therocephalian phylogeny to date. The analysis supports the hypothesis that Therocephalia represents the monophyletic sister taxon to Cynodontia, with as many as 15 morphological synapomorphies, in contrast with other recent analyses of lesser taxon sampling. The results also support the hypothesis that Scylacosauridae is more closely related to Eutherocephalia than to the basal therocephalian family Lycosuchidae, supporting a ‘Scylacosauria’ clade. The taxa suggested here to be neotenic forms (e.g. Ictidosuchoides and Ictidosuchops) are positioned near the base of a monophyletic Baurioidea. Neotenic development of the therocephalian feeding apparatus and evolutionary parallelism with cynodonts are suggested to have been important trends in the early evolution of baurioid therocephalians into the Late Permian and Early Triassic.     

Systematic relationships and biogeography of the tracheophone suboscines (Aves: Passeriformes)

Based on their highly specialized "tracheophone" syrinx, the avian families Furnariidae (ovenbirds), Dendrocolaptidae (woodcreepers), Formicariidae (ground antbirds), Thamnophilidae (typical antbirds), Rhinocryptidae (tapaculos), and Conopophagidae (gnateaters) have long been recognized to constitute a monophyletic group of suboscine passerines. However, the monophyly of these families have been contested and their interrelationships are poorly understood, and this constrains the possibilities for interpreting adaptive tendencies in this very diverse group. In this study we present a higher-level phylogeny and classification for the tracheophone birds based on phylogenetic analyses of sequence data obtained from 32 ingroup taxa. Both mitochondrial (cytochrome b) and nuclear genes (c-myc, RAG-1, and myoglobin) have been sequenced, and more than 3000 bp were subjected to parsimony and maximum-likelihood analyses. The phylogenetic signals in the mitochondrial and nuclear genes were compared and found to be very similar. The results from the analysis of the combined dataset (all genes, but with transitions at third codon positions in the cytochrome b excluded) partly corroborate previous phylogenetic hypotheses, but several novel arrangements were also suggested. Especially interesting is the result that the genus Melanopareia represents a basal branch within the tracheophone group, positioned in the phylogenetic tree well away from the typical tapaculos with which it has been supposed to group. Other novel results include the observation that the ground antbirds are paraphyletic and that Sclerurus is the sister taxon to an ovenbird-woodcreeper clade. Patterns of generic richness within each clade suggest that the early differentiation of feeble-winged forest groups took place south of the Amazon Basin, while the more recent diversification was near the equator and (in tapaculos and ovenbirds) in the south of the continent.     

Skeletal morphology and the phylogeny of skuas (Aves: Charadriiformes,Stercorariidae)

The skuas (Aves: Charadriiformes, Stercorariidae) consist of two assemblages. On the basis of size, plumage, and distributional similarities, each of the two assemblages has long been considered monophyletic, and this traditional hypothesis has commonly been manifested in the recognition of two genera, Stercorarius and Catharacta; conversely, more recently collected molecular and ectoparasite evidence yields an alternative hypothesis, in which one member of Stercorarius, Stercorarius pomarinus, is more closely related to the forms in Catharacta than to the other Stercorarius sp. In this study we used skeletal morphology to test the competing hypotheses of skua phylogeny. Cladistic analysis of 141 osteological characters provided strong support for the molecular/ectoparasite hypothesis. However, those skeletal data did not support a sister‐taxon relationship between S. pomarinus and Catharacta skua, as inferred from mitochondrial DNA sequence data; instead, they resolved pomarinus as the sister of a monophyletic Catharacta. Additionally, our skeletal evidence did not support a sister‐group relationship between skuas and auks, as constraining skua/auk monophyly increased the tree length by nearly 5%. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157 , 612–621.     

Phylogenetic analysis of the Amphitritinae (Polycnaeta: Terebellidae)

The phylogenetic relationships of the Amphitritinae (Polychaeta: Terebellidae) were studied using parsimony analysis of 22 external morphological characters. To choose outgroups to polarize the characters, I carried out a preliminary analysis of the relationships of the four terebellid subfamilies and the Trichobranchidae. The single most parsimonious tree from the analysis supports monophyly of the Terebellidae by the presence of ventral glandular shields. However, this character is homoplasious within the Terebellomorpha, and further evaluation of the Terebellidae is recommended. Artacama and Thelepus were chosen as outgroups for the analysis of amphitritine genera. The generic level analysis yielded seven equally parsimonious trees, which are consistent in their topologies except for the relationships among seven genera in one large clade. In all trees, Artacama is the sister taxon to a large clade within the Amphitritinae; the Artacaminae is therefore synonymized with the Amphitritinae, which is diagnosed by the presence of double rows of uncini. Within the Amphitritinae, the status of several monotypic genera is questioned; plesiomorphic character states indicated by the analysis are discussed. The results presented are offered as working hypotheses of the relationships among amphitritine genera. The large number of homoplasies indicated by the analysis emphasizes the need to further evaluate these hypotheses using additional characters. With a robust phylogenetic hypothesis of amphitritine relationships, a re-classification of the group based on apomorphic character states can be undertaken, and questions regarding the evolution of morphological characters, reproductive modes, or biogeographical patterns can be properly addressed.