Phylogenetic relationships in the Lejeuneaceae (Hepaticae) inferred using ITS sequences of nuclear ribosomal DNA

Sequences of the ITS1–5.8S–ITS2 region of nuclear ribosomal DNA were generated for 12 species from 9 genera of Lejeuneaceae and a single species of Jubulaceae (outgroup). The taxon sampling of Lejeuneaceae included representatives of the two widely recognized subfamilies, Lejeuneoideae and Ptychanthoideae. The molecular dataset was analysed independently and in combination with a morphological dataset. The nrITS dataset and the combined dataset resulted in identical topologies. The genus Bryopteris, sometimes treated as a separate family Bryopteridaceae, is nested within the Lejeuneaceae subfamily Ptychanthoideae. Lejeuneaceae subfamily Lejeuneoideae proved to be paraphyletic with the tribe Lejeuneeae sister to Ptychanthoideae, albeit without significant bootstrap support. The tribes Brachiolejeuneeae and Cheilolejeuneeae of Lejeuneoideae, established recently based on morphological evidence, are well supported in bootstrap analyses both of the ITS and the combined molecular–morphological datasets. The results support classifications of Lejeuneaceae based on morphological data and demonstrate the usefulness of the ITS region for phylogenetic studies within or among closely related genera of Lejeuneaceae.     

Phylogenetic relationships of Microdontinae (Diptera: Syrphidae) based on molecular and morphological characters

The intrasubfamilial classification of Microdontinae Rondani (Diptera: Syrphidae) has been a challenge: until recently more than 300 out of more than 400 valid species names were classified in Microdon Meigen. We present phylogenetic analyses of molecular and morphological characters (both separate and combined) of Microdontinae. The morphological dataset contains 174 characters, scored for 189 taxa (9 outgroup), representing all 43 presently recognized genera and several subgenera and species groups. The molecular dataset, representing 90 ingroup species of 28 genera, comprises sequences of five partitions in total from the mitochondrial gene COI and the nuclear ribosomal genes 18S and 28S. We test the sister‐group relationship of Spheginobaccha with the other Microdontinae, attempt to elucidate phylogenetic relationships within the Microdontinae and discuss uncertainties in the classification of Microdontinae. Trees based on molecular characters alone are poorly resolved, but combined data are better resolved. Support for many deeper nodes is low, and placement of such nodes differs between parsimony and Bayesian analyses. However, Spheginobaccha is recovered as highly supported sister group in both. Both analyses agree on the early branching of Mixogaster, Schizoceratomyia, Afromicrodon and Paramicrodon. The taxonomical rank in relation to the other Syrphidae is discussed briefly. An additional analysis based on morphological characters only, including all 189 taxa, used implied weighting. A range of weighting strengths (k‐values) is applied, chosen such that values of character fit of the resulting trees are divided into regular intervals. Results of this analysis are used for discussing the phylogenetic relationships of genera unrepresented in the molecular dataset.     

A review of long-branch attraction

The history of long‐branch attraction, and in particular methods suggested to detect and avoid the artifact to date, is reviewed. Methods suggested to avoid LBA‐artifacts include excluding long‐branch taxa, excluding faster evolving third codon positions, using inference methods less sensitive to LBA such as likelihood, the Aguinaldo et al. approach, sampling more taxa to break up long branches and sampling more characters especially of another kind, and the pros and cons of these are discussed. Methods suggested to detect LBA are numerous and include methodological disconcordance, RASA, separate partition analyses, parametric simulation, random outgroup sequences, long‐branch extraction, split decomposition and spectral analysis. Less than 10 years ago it was doubted if LBA occurred in real datasets. Today, examples are numerous in the literature and it is argued that the development of methods to deal with the problem is warranted. A 16 kbp dataset of placental mammals and a morphological and molecular combined dataset of gall waSPS are used to illustrate the particularly common problem of LBA of problematic ingroup taxa to outgroups. The preferred methods of separate partition analysis, methodological disconcordance, and long branch extraction are used to demonstrate detection methods. It is argued that since outgroup taxa almost always represent long branches and are as such a hazard towards misplacing long branched ingroup taxa, phylogenetic analyses should always be run with and without the outgroups included. This will detect whether only the outgroup roots the ingroup or if it simultaneously alters the ingroup topology, in which case previous studies have shown that the latter is most often the worse. Apart from that LBA to outgroups is the major and most common problem; scanning the literature also detected the ill advised comfort of high support values from thousands of characters, but very few taxa, in the age of genomics. Taxon sampling is crucial for an accurate phylogenetic estimate and trust cannot be put on whole mitochondrial or chloroplast genome studies with only a few taxa, despite their high support values. The placental mammal example demonstrates that parsimony analysis will be prone to LBA by the attraction of the tenrec to the distant marsupial outgroups. In addition, the murid rodents, creating the classic “the guinea‐pig is not a rodent” hypothesis in 1996, are also shown to be attracted to the outgroup by nuclear genes, although including the morphological evidence for rodents and Glires overcomes the artifact. The gall wasp example illustrates that Bayesian analyses with a partition‐specific GTR + Γ + I model give a conflicting resolution of clades, with a posterior probability of 1.0 when comparing ingroup alone versus outgroup rooted topologies, and this is due to long‐branch attraction to the outgroup. © The Willi Hennig Society 2005.     

A New Orchid Genus,Danxiaorchis, and Phylogenetic Analysis of the Tribe Calypsoeae

Background

Orchids have numerous species, and their speciation rates are presumed to be exceptionally high, suggesting that orchids are continuously and actively evolving. The wide diversity of orchids has attracted the interest of evolutionary biologists. In this study, a new orchid was discovered on Danxia Mountain in Guangdong, China. However, the phylogenetic clarification of this new orchid requires further molecular, morphological, and phytogeographic analyses.

Methodology/Principal Findings

A new orchid possesses a labellum with a large Y-shaped callus and two sacs at the base, and cylindrical, fleshy seeds, which make it distinct from all known orchid genera. Phylogenetic methods were applied to a matrix of morphological and molecular characters based on the fragments of the nuclear internal transcribed spacer, chloroplast matK, and rbcL genes of Orchidaceae (74 genera) and Calypsoeae (13 genera). The strict consensus Bayesian inference phylogram strongly supports the division of the Calypsoeae alliance (not including Dactylostalix and Ephippianthus) into seven clades with 11 genera. The sequence data of each species and the morphological characters of each genus were combined into a single dataset. The inferred Bayesian phylogram supports the division of the 13 genera of Calypsoeae into four clades with 13 subclades (genera). Based on the results of our phylogenetic analyses, Calypsoeae, under which the new orchid is classified, represents an independent lineage in the Epidendroideae subfamily.

Conclusions

Analyses of the combined datasets using Bayesian methods revealed strong evidence that Calypsoeae is a monophyletic tribe consisting of eight well-supported clades with 13 subclades (genera), which are all in agreement with the phytogeography of Calypsoeae. The Danxia orchid represents an independent lineage under the tribe Calypsoeae of the subfamily Epidendroideae. This lineage should be treated as a new genus, which we have named Danxiaorchis, that is parallel to Yoania. Both genera are placed under the subtribe Yoaniinae.     

Phylogenetic analysis of phenotypic characters of Tunicata supports basal Appendicularia and monophyletic Ascidiacea

With approximately 3000 marine species, Tunicata represents the most disparate subtaxon of Chordata. Molecular phylogenetic studies support Tunicata as sister taxon to Craniota, rendering it pivotal to understanding craniate evolution. Although successively more molecular data have become available to resolve internal tunicate phylogenetic relationships, phenotypic data have not been utilized consistently. Herein these shortcomings are addressed by cladistically analyzing 117 phenotypic characters for 49 tunicate species comprising all higher tunicate taxa, and five craniate and cephalochordate outgroup species. In addition, a combined analysis of the phenotypic characters with 18S rDNA-sequence data is performed in 32 OTUs. The analysis of the combined data is congruent with published molecular analyses. Successively up-weighting phenotypic characters indicates that phenotypic data contribute disproportionally more to the resulting phylogenetic hypothesis. The strict consensus tree from the analysis of the phenotypic characters as well as the single most parsimonious tree found in the analysis of the combined dataset recover monophyletic Appendicularia as sister taxon to the remaining tunicate taxa. Thus, both datasets support the hypothesis that the last common ancestor of Tunicata was free-living and that ascidian sessility is a derived trait within Tunicata. “Thaliacea” is found to be paraphyletic with Pyrosomatida as sister taxon to monophyletic Ascidiacea and the relationship between Doliolida and Salpida is unresolved in the analysis of morphological characters; however, the analysis of the combined data reconstructs Thaliacea as monophyletic nested within paraphyletic “Ascidiacea”. Therefore, both datasets differ in the interpretation of the evolution of the complex holoplanktonic life history of thaliacean taxa. According to the phenotypic data, this evolution occurred in the plankton, whereas from the combined dataset a secondary transition into the plankton from a sessile ascidian is inferred. Besides these major differences, both analyses are in accord on many phylogenetic groupings, although both phylogenetic reconstructions invoke a high degree of homoplasy. In conclusion, this study represents the first serious attempt to utilize the potential phylogenetic information present in phenotypic characters to elucidate the inter-relationships of this diverse marine taxon in a consistent cladistic framework.     

Is morphology telling the truth about the evolution of the species rich genus Peperomia (Piperaceae)?

Peperomia is with approximately 1,600 species one of the species rich angiosperm genera. Several characters on which current infrageneric classifications are based are influenced by parallel evolution. A well-resolved molecular backbone phylogeny of the genus is needed to address evolutionary questions about morphological traits. Based on separate and combined analyses of a morphological data set and three molecular data sets, phylogenetic relationships within Peperomia are investigated with respect to character evolution. The resulting trees from different datasets are highly congruent. Morphological characters are mapped on a combined molecular tree, visualizing the contrast between previously used homoplastic characters and some newly observed characters, that can be used to delimit monophyletic groups. Length mutational events of the chloroplast dataset are coded and plotted on the respective tree, to test if indels support alternative hypothesis of relationships found in the nuclear datasets as well as the overall performance of indels compared with substitutional mutations. Our findings indicate that length distribution of indels is highest among five and six bp events. Autapomorphic and synapomorphic length mutations are most frequent in both insertions and deletions and are also more frequent independent of the length of the mutation. Concluding, independent of the length, mutations are of phylogenetic importance and should not be disregarded. None of the homoplastic indels turn into synapomorphic indels, supporting the different topology of the nrDNA tree but indicate areas of molecular evolution in favour of length mutations resulting in independent events.     

Molecular resolution of the systematics of a problematic group of fishes (Teleostei: Osmeridae) and evidence for morphological homoplasy

Relationships among the species of Northern Hemisphere smelts (family Osmeridae) have long been debated in the fish systematics literature. Eight independent studies based on morphological characters failed to reach any consensus on osmerid interrelationships. We reconstruct the osmerid phylogeny based on DNA sequence data from three mitochondrial (cytb, 16S, 12S) and three nuclear (ITS2, S71, RAG1) gene regions from multiple individuals of the 14 species in 6 genera, using the Japanese ayu (Plecoglossus altivelis) as the outgroup. Analyses with different combinations of nuclear and mitochondrial datasets yielded a generally well-resolved phylogeny of the genera that conflicts with previous hypotheses of osmerid interrelationships, and Shimodaira–Hasegawa tests suggest our topology with the current molecular dataset is significantly better than earlier reconstructions. In addition, mapping 114 morphological characters used in previous studies onto our phylogeny shows widespread homoplasy, which is likely the source of the systematic disagreement produced in earlier works.     

Combined phylogenetic analysis of the subclass Marchantiidae (Marchantiophyta): towards a robustly diagnosed classification

The most extensive combined phylogenetic analyses of the subclass Marchantiidae yet undertaken was conducted on the basis of morphological and molecular data. The morphological data comprised 126 characters and 56 species. Taxonomic sampling included 35 ingroup species with all genera and orders of Marchantiidae sampled, and 21 outgroup species with two genera of Blasiidae (Marchantiopsida), 15 species of Jungermanniopsida (the three subclasses represented) and the three genera of Haplomitriopsida. Takakia ceratophylla (Bryophyta) was employed to root the trees. Character sampling involved 92 gametophytic and 34 sporophytic traits, supplemented with ten continuous characters. Molecular data included 11 molecular markers: one nuclear ribosomal (26S), three mitochondrial genes (nad1, nad5, rps3) and seven chloroplast regions (atpB, psbT‐psbH, rbcL, ITS, rpoC1, rps4, psbA). Searches were performed under extended implied weighting, weighting the character blocks against the average homoplasy. Clade stability was assessed across three additional weighting schemes (implied weighting corrected for missing entries, standard implied weighting and equal weighting) in three datasets (molecular, morphological and combined). The contribution from different biological phases regarding node recovery and diagnosis was evaluated. Our results agree with many of the previous studies but cast doubt on some relationships, mainly at the family and interfamily level. The combined analyses underlined the fact that, by combining data, taxonomic enhancements could be achieved regarding taxon delimitation and quality of diagnosis. Support values for many clades of previous molecular studies were improved by the addition of morphological data. The long‐held assumption that morphology may render spurious or low‐quality results in this taxonomic group is challenged. The morphological trends previously proposed are re‐evaluated in light of the new phylogenetic scheme.     

Adapting generalized frequency coding to use colour spectra in the determination of phylogenetic relationships: an example with hummingbirds

We introduce a methodology to perform phylogenetic analyses on bird taxa using parsimony based on plumage colour characters obtained as spectra. The generalized frequency coding method was adapted to transform continuous colour spectral data into discrete variables. As an example of the application of the methodology, we analysed two species of the hummingbird genus Campylopterus and all species of the genera Anthracothorax and Eulampis , which occur in South and Central America and the Caribbean islands. The genus Topaza was used as an outgroup because of its basal position within the hummingbirds. The results were mostly in accordance with both traditional morphological as well as molecular analyses indicating that there is phylogenetic information in plumage colours measured in an integral and objective way and that the new method is appropriate for phylogenetic analyses at this lower taxonomic level.     

Phylogeny of the neotropical moth tribe Josiini (Notodontidae: Dioptinae): comparing and combining evidence from DNA sequences and morphology

DNA sequences were gathered from mitochondrial COII and nuclear ribosomal 18S and 28S genes for 21 moth species in the tribe Josiini (Notodontidae: Dioptinae) and two outgroup genera. These data complement a previously published morphological character set for the same taxa. We examine whether relationships in the Josiini are best reflected by a single phylogenetic analysis of all the data, or by a consensus of separate trees generated from DNA and morphology. Even in cases where analyses of partitioned data produce incongruent cladograms, the underlying disagreement between partitions is relatively small. While both molecular and morphological data provide useful character information by themselves, we conclude that the best supported phylogenetic hypothesis is the one derived from combined analysis.     

Molecular systematics of South American dolphins Sotalia: sister taxa determination and phylogenetic relationships, with insights into a multi-locus phylogeny of the Delphinidae

The evolutionary relationships among members of the cetacean family Delphinidae, the dolphins, pilot whales and killer whales, are still not well understood. The genus Sotalia (coastal and riverine South American dolphins) is currently considered a member of the Stenoninae subfamily, along with the genera Steno (rough toothed dolphin) and Sousa (humpbacked dolphin). In recent years, a revision of this classification was proposed based on phylogenetic analysis of the mitochondrial gene cytochrome b, wherein Sousa was included in the Delphininae subfamily, keeping only Steno and Sotalia as members of the Stenoninae subfamily. Here we investigate the phylogenetic placement of Sotalia using two mitochondrial genes, six autosomal introns and four Y chromosome introns, providing a total of 5,196 base pairs (bp) for each taxon in the combined dataset. Sequences from these genomic regions were obtained for 17 delphinid species, including at least one species from each of five or six currently recognized subfamilies plus five odontocete outgroup species. Maximum Parsimony, Maximum Likelihood and Bayesian phylogenetic analysis of independent (each fragment) and combined datasets (mtDNA, nuDNA or mtDNA+nuDNA) showed that Sotalia and Sousa fall within a clade containing other members of Delphininae, exclusive of Steno. Sousa was resolved as the sister taxon to Sotalia according to analysis of the nuDNA dataset but not analysis of the mtDNA or combined mtDNA+nuDNA datasets. Based on the results from our multi-locus analysis, we offer several novel changes to the classification of Delphinidae, some of which are supported by previous morphological and molecular studies.     

Understanding phylogenetic incongruence: lessons from phyllostomid bats

All characters and trait systems in an organism share a common evolutionary history that can be estimated using phylogenetic methods. However, differential rates of change and the evolutionary mechanisms driving those rates result in pervasive phylogenetic conflict. These drivers need to be uncovered because mismatches between evolutionary processes and phylogenetic models can lead to high confidence in incorrect hypotheses. Incongruence between phylogenies derived from morphological versus molecular analyses, and between trees based on different subsets of molecular sequences has become pervasive as datasets have expanded rapidly in both characters and species. For more than a decade, evolutionary relationships among members of the New World bat family Phyllostomidae inferred from morphological and molecular data have been in conflict. Here, we develop and apply methods to minimize systematic biases, uncover the biological mechanisms underlying phylogenetic conflict, and outline data requirements for future phylogenomic and morphological data collection. We introduce new morphological data for phyllostomids and outgroups and expand previous molecular analyses to eliminate methodological sources of phylogenetic conflict such as taxonomic sampling, sparse character sampling, or use of different algorithms to estimate the phylogeny. We also evaluate the impact of biological sources of conflict: saturation in morphological changes and molecular substitutions, and other processes that result in incongruent trees, including convergent morphological and molecular evolution. Methodological sources of incongruence play some role in generating phylogenetic conflict, and are relatively easy to eliminate by matching taxa, collecting more characters, and applying the same algorithms to optimize phylogeny. The evolutionary patterns uncovered are consistent with multiple biological sources of conflict, including saturation in morphological and molecular changes, adaptive morphological convergence among nectar‐feeding lineages, and incongruent gene trees. Applying methods to account for nucleotide sequence saturation reduces, but does not completely eliminate, phylogenetic conflict. We ruled out paralogy, lateral gene transfer, and poor taxon sampling and outgroup choices among the processes leading to incongruent gene trees in phyllostomid bats. Uncovering and countering the possible effects of introgression and lineage sorting of ancestral polymorphism on gene trees will require great leaps in genomic and allelic sequencing in this species‐rich mammalian family. We also found evidence for adaptive molecular evolution leading to convergence in mitochondrial proteins among nectar‐feeding lineages. In conclusion, the biological processes that generate phylogenetic conflict are ubiquitous, and overcoming incongruence requires better models and more data than have been collected even in well‐studied organisms such as phyllostomid bats.     

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.     

An Expanded Combined Evidence Approach to the Gavialis Problem Using Geometric Morphometric Data from Crocodylian Braincases and Eustachian Systems

The phylogenetic position of the Indian gharial (Gavialis gangeticus) is disputed - morphological characters place Gavialis as the sister to all other extant crocodylians, whereas molecular and combined analyses find Gavialis and the false gharial (Tomistoma schlegelii) to be sister taxa. Geometric morphometric techniques have only begun to be applied to this issue, but most of these studies have focused on the exterior of the skull. The braincase has provided useful phylogenetic information for basal crurotarsans, but has not been explored for the crown group. The Eustachian system is thought to vary phylogenetically in Crocodylia, but has not been analytically tested. To determine if gross morphology of the crocodylian braincase proves informative to the relationships of Gavialis and Tomistoma, we used two- and three-dimensional geometric morphometric approaches. Internal braincase images were obtained using high-resolution computerized tomography scans. A principal components analysis identified that the first component axis was primarily associated with size and did not show groupings that divide the specimens by phylogenetic affinity. Sliding semi-landmarks and a relative warp analysis indicate that a unique Eustachian morphology separates Gavialis from other extant members of Crocodylia. Ontogenetic expansion of the braincase results in a more dorsoventrally elongate median Eustachian canal. Changes in the shape of the Eustachian system do provide phylogenetic distinctions between major crocodylian clades. Each morphometric dataset, consisting of continuous morphological characters, was added independently to a combined cladistic analysis of discrete morphological and molecular characters. The braincase data alone produced a clade that included crocodylids and Gavialis, whereas the Eustachian data resulted in Gavialis being considered a basally divergent lineage. When each morphometric dataset was used in a combined analysis with discrete morphological and molecular characters, it generated a tree that matched the topology of the molecular phylogeny of Crocodylia.     

New insights into Trimezieae (Iridaceae) phylogeny: what do molecular data tell us?

Background and Aims

The Neotropical tribe Trimezieae are taxonomically difficult. They are generally characterized by the absence of the features used to delimit their sister group Tigridieae. Delimiting the four genera that make up Trimezieae is also problematic. Previous family-level phylogenetic analyses have not examined the monophyly of the tribe or relationships within it. Reconstructing the phylogeny of Trimezieae will allow us to evaluate the status of the tribe and genera and to examine the suitability of characters traditionally used in their taxonomy.

Methods

Maximum parsimony and Bayesian phylogenetic analyses are presented for 37 species representing all four genera of Trimezieae. Analyses were based on nrITS sequences and a combined plastid dataset. Ancestral character state reconstructions were used to investigate the evolution of ten morphological characters previously considered taxonomically useful.

Key Results

Analyses of nrITS and plastid datasets strongly support the monophyly of Trimezieae and recover four principal clades with varying levels of support; these clades do not correspond to the currently recognized genera. Relationships within the four clades are not consistently resolved, although the conflicting resolutions are not strongly supported in individual analyses. Ancestral character state reconstructions suggest considerable homoplasy, especially in the floral characters used to delimit Pseudotrimezia.

Conclusions

The results strongly support recognition of Trimezieae as a tribe but suggest that both generic- and species-level taxonomy need revision. Further molecular analyses, with increased sampling of taxa and markers, are needed to support any revision. Such analyses will help determine the causes of discordance between the plastid and nuclear data and provide a framework for identifying potential morphological synapomorphies for infra-tribal groups. The results also suggest Trimezieae provide a promising model for evolutionary research.     

First phylogenetic analysis of the tribe Phyllotini (Rodentia: Sigmodontinae) combining morphological and molecular data

Previous phylogenetic analyses of the tribe Phyllotini, one of the largest components of the subfamily Sigmodontinae, have been based on a single source of evidence. In particular, morphological analyses were largely based on craniodental data, almost neglecting the potential phylogenetic information present in the postcranium. Despite the significant advances made in relation to the knowledge of phyllotine phylogeny in recent times, there are several unsolved issues that highlight the importance of a phylogenetic analysis that integrates multiple sources of evidence, including previously considered sources as well as new sources of data. We present here the first combined phylogenetic analysis (morphological and molecular) of phyllotines, which includes the widest taxon and character sampling to date. Our dataset includes 164 morphological characters, of which 83 are postcranial characters, plus 3561 molecular characters, scored for 52 species from 34 genera of Oryzomyalia. In this study 75 postcranial characters not previously considered in this group are thoroughly described, and their utility for solving the relationships within Phyllotini is evaluated by means of different complementary analyses. Phyllotini was retrieved as a monophyletic clade in the combined analysis, with a composition that matches that obtained in most other recent analyses. All genera of phyllotines were monophyletic and show high support values. Abrotrichini, Akodontini and Oryzomyini were also monophyletic. The inclusion of postcranial data appears to be of limited utility to solve the phylogenetic relationships within Phyllotini.     

Mitochondrial DNA,morphology, and the phylogenetic relationships of Antarctic icefishes (Notothenioidei: Channichthyidae)

The Channichthyidae is a lineage of 16 species in the Notothenioidei, a clade of fishes that dominate Antarctic near-shore marine ecosystems with respect to both diversity and biomass. Among four published studies investigating channichthyid phylogeny, no two have produced the same tree topology, and no published study has investigated the degree of phylogenetic incongruence between existing molecular and morphological datasets. In this investigation we present an analysis of channichthyid phylogeny using complete gene sequences from two mitochondrial genes (ND2 and 16S) sampled from all recognized species in the clade. In addition, we have scored all 58 unique morphological characters used in three previous analyses of channichthyid phylogenetic relationships. Data partitions were analyzed separately to assess the amount of phylogenetic resolution provided by each dataset, and phylogenetic incongruence among data partitions was investigated using incongruence length difference (ILD) tests. We utilized a parsimony-based version of the Shimodaira-Hasegawa test to determine if alternative tree topologies are significantly different from trees resulting from maximum parsimony analysis of the combined partition dataset. Our results demonstrate that the greatest phylogenetic resolution is achieved when all molecular and morphological data partitions are combined into a single maximum parsimony analysis. Also, marginal to insignificant incongruence was detected among data partitions using the ILD. Maximum parsimony analysis of all data partitions combined results in a single tree, and is a unique hypothesis of phylogenetic relationships in the Channichthyidae. In particular, this hypothesis resolves the phylogenetic relationships of at least two species (Channichthys rhinoceratus and Chaenocephalus aceratus), for which there was no consensus among the previous phylogenetic hypotheses. The combined data partition dataset provides substantial statistical power to discriminate among alternative hypotheses of channichthyid relationships. These findings suggest the optimal strategy for investigating the phylogenetic relationships of channichthyids is one that uses all available phylogenetic data in analyses of combined data partitions.     

Molecular systematics and biological diversification of Boletales

Historical patterns of morphological evolution and ecology in the Boletales are largely unresolved but appear to involve extensive convergence. We studied phylogenetic relationships of Boletales based on two datasets. The nuc-lsu dataset is broadly sampled and includes roughly 30% of the described species of Boletales and 51 outgroup taxa across the Hymenomycetes. The multigene dataset (nuc-ssu, nuc-lsu, 5.8S, mt-lsu, atp6) sampled 42 key species of Boletales in a framework of 14 representative Hymenomycetes. The Boletales are strongly supported as monophyletic in our analyses on both datasets with parsimony, maximum likelihood and Bayesian approaches. Six major lineages of Boletales that currently are recognized on subordinal level, Boletineae, Paxillineae, Sclerodermatineae, Suillineae, Tapinellineae, Coniophorineae, received varied support. The backbone of the Boletales was moderately resolved in the analyses with the nuc-lsu dataset, but support was strong for most major groups. Nevertheless, most brown-rot producing forms were placed as a paraphyletic grade at the base of the Boletales. Analyses on the multigene dataset confirm sister group relationships among Boletales, Agaricales and Atheliales. Boletineae and Suillineae received the highest support values; Paxillineae and Sclerodermatineae were not consistently resolved as monophyletic groups. The Coniophorineae were not monophyletic in any analyses. The Tapinellineae consisting of morphologically diverse brown-rotting fungi forms the basal group in the Boletales. We performed ancestral state reconstruction with BayesMultiState, which suggested that the ancestor of the Boletales was a resupinate or polyporoid saprotrophic fungus, producing a brown-rot.