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1.
Tertiary cormorant fossils (Aves: Phalacrocoracidae) from Late Oligocene deposits in Australia are described. They derive from the Late Oligocene – Early Miocene (26–24 Mya) Etadunna and Namba Formations in the Lake Eyre and Lake Frome Basins, South Australia, respectively. A new genus, Nambashag gen. nov. , with two new species ( Nambashag billerooensis sp. nov. , 30 specimens; Nambashag microglaucus sp. nov. , 14 specimens), has been established. Phylogenetic analyses based on 113 morphological and two integumentary characters indicated that Nambashag is the sister taxon to the Early Miocene Nectornis miocaenus of Europe and all extant phalacrocoracids. As Nambashag, Nectornis, and extant phalacrocoracids constitute a strongly supported clade sister to Anhinga species, the fossil taxa have been referred to Phalacrocoracidae. Sulids and Fregata were successive sister taxa to the Phalacrocoracoidea, i.e. phalacrocoracids + Anhinga. As phalacrocoracids lived in both Europe and Australia during the Late Oligocene and no older phalacrocoracid taxa are known, the biogeographical origin of cormorants remains unanswered. The phylogenetic relationships of extant taxa were not wholly resolved, but contrary to previous morphological analyses, considerable concordance was found with relationships recovered by recent molecular analyses. Microcarbo is sister to all other extant phalacrocoracids, and all Leucocarbo species form a well‐supported clade. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 277–314.  相似文献   

2.
Lampridiformes is a peculiar clade of pelagic marine acanthomorph (spiny‐rayed) teleosts. Its phylogenetic position remains ambiguous, and varies depending on the type of data (morphological or molecular) used to infer interrelationships. Because the extreme morphological specializations of lampridiforms may have overwritten the ancestral features of the group with a bearing on its relationships, the inclusion of fossils that exhibit primitive character state combinations for the group as a whole is vital in establishing its phylogenetic position. Therefore, we present an osteological data set of extant (ten taxa) and fossil (14 taxa) acanthomorphs, including early Late Cretaceous taxa for which a close relationship with extant Lampridiformes has been suggested: ?Aipichthyoidea, ?Pharmacichthyidae, and ?Pycnosteroididae. We find that all three taxa plus Lampridiformes form a clade that we call Lampridomorpha. Under this hypothesis, ?Aipichthyoidea is paraphyletic. The inclusion of fossils in the analysis changes the topology, highlighting their critical importance in phylogenetic studies of morphological characters. When fossils are included, Lampridomorpha is sister to Euacanthomorpha (all other extant acanthomorphs), concurring with most previous anatomical studies, but conflicting with most molecular results. Lampridomorpha as a whole was a major component of the earliest acanthomorph faunas, notably in the Cenomanian. © 2014 The Linnean Society of London  相似文献   

3.
The cranial anatomy of Dinilysia patagonica, a terrestrial snake from the Upper Cretaceous of Argentina, is redescribed and illustrated, based on high‐resolution X‐ray computed tomography and better preparations made on previously known specimens, including the holotype. Previously unreported characters reinforce the intriguing mosaic nature of the skull of Dinilysia, with a suite of plesiomorphic and apomorphic characters with respect to extant snakes. Newly recognized plesiomorphies are the absence of the medial vertical flange of the nasal, lateral position of the prefrontal, lizard‐like contact between vomer and palatine, floor of the recessus scalae tympani formed by the basioccipital, posterolateral corners of the basisphenoid strongly ventrolaterally projected, and absence of a medial parietal pillar separating the telencephalon and mesencephalon, amongst others. We also reinterpreted the structures forming the otic region of Dinilysia, confirming the presence of a crista circumfenestralis, which represents an important derived ophidian synapomorphy. Both plesiomorphic and apomorphic traits of Dinilysia are treated in detail and illustrated accordingly. Results of a phylogenetic analysis support a basal position of Dinilysia, as the sister‐taxon to all extant snakes. The fossil taxa Yurlunggur, Haasiophis, Eupodophis, Pachyrhachis, and Wonambi appear as derived snakes nested within the extant clade Alethinophidia, as stem‐taxa to the crown‐clade Macrostomata. The hypothesis of a sister‐group relationship between Dinilysia and Najash rionegrina, as suggested by some authors, is rejected by the results of our analysis. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 194–238.  相似文献   

4.
Several different groups of birds have been proposed as being the oldest or earliest diverging extant lineage within the avian phylogenetic tree, particularly ratites (Struthioniformes), waterfowl (Anseriformes), and shorebirds (Charadriiformes). Difficulty in resolving this issue stems from several factors, including the relatively rapid radiation of primary (ordinal) bird lineages and the lack of characters from an extant outgroup for birds that is closely related to them by measure of time. To help resolve this question, we have sequenced entire mitochondrial genomes for five birds (a rhea, a duck, a falcon, and two perching birds), one crocodilian, and one turtle. Maximum parsimony and maximum likelihood analyses of these new sequences together with published sequences (18 taxa total) yield the same optimal tree topology, in which a perching bird (Passeriformes) is sister to all the other bird taxa. A basal position for waterfowl among the bird study taxa is rejected by maximum likelihood analyses. However, neither the conventional view, in which ratites (including rhea) are basal to other birds, nor tree topologies with falcon or chicken basal among birds could be rejected in the same manner. In likelihood analyses of a subset of seven birds, alligator, and turtle (9 taxa total), we find that increasing the number of parameters in the model shifts the optimal topology from one with a perching bird basal among birds to the conventional view with ratites diverging basally; moreover, likelihood scores for the two trees are not significantly different. Thus, although our largest set of taxa and characters supports a tree with perching birds diverging basally among birds, the position of this earliest divergence among birds appears unstable. Our analyses indicate a sister relationship between a waterfowl/chicken clade and ratites, relative to perching birds and falcon. We find support for a sister relationship between turtles and a bird/crocodilian clade, and for rejecting both the Haemothermia hypothesis (birds and mammals as sister taxa) and the placement of turtles as basal within the phylogenetic tree for amniote animals.  相似文献   

5.
Metatherian petrosal bones were recovered from the early Late Palaeocene Itaboraí, Brazil, and are formally described. A cladistic analysis of the distribution of 56 petrosal and basicranial characters among extant and fossil metatherians was conducted, resulting in seven parsimonious trees. Relationships among metatherian ingroup taxa are congruent with current understanding of metatherian phylogeny. Metatheria is diagnosed by eight petrosal synapomorphies: stapedial artery absent in adults; reduced, intramural prootic canal; extrabullar internal carotid artery; inferior petrosal sinus between petrosal, basisphenoid, and basioccipital; cava supracochleare and epiptericum completely separated; reduction of the lateral flange; reduction of the anterior lamina; separation of the jugular foramen from the opening for the inferior petrosal sinus. The Palaeocene taxa Mayulestes , Pucadelphy s, and Andinodelphys from Tiupampa, and Petrosal Type II from Itaboraí are the sister groups of all other South American and Australian metatherians. This analysis confirms previous results showing the South American 'monito del monte' Dromiciops nested within the Australasian radiation. Within this australidelphian clade, Dromiciops is closely related to the dasyurids. The South American Caenolestes appears more closely related to the Australidelphia than to the South American didelphids. The Petrosal Types I, III, IV and V from Itaboraí are the stem taxa of the clade Australidelphia plus Caenolestes . The significant synapomorphies supporting this relationship are: enlargement of the fossa subarcuata that produces a bulbous ventral aspect of the mastoid and loss of post-temporal canal.  Journal compilation © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 150 , 85–115. No claim to original French government works.  相似文献   

6.
The first scolopocryptopid centipede known from the fossil record is a specimen of the subfamily Scolopocryptopinae in Miocene amber from Chiapas, southern Mexico. It is described here as Scolopocryptops simojovelensis sp. nov. , displaying a distinct combination of morphological characters compared to extant congeners. Anatomical details of the fossil specimen were acquired by non‐invasive 3D synchrotron microtomography using X‐ray phase contrast. The phylogenetic position of the new species is inferred based on a combination of morphological data with sequences for six genes (nuclear 18S and 28S rRNA, nuclear protein‐coding histone H3, and mitochondrial 12S rRNA, 16S rRNA, and protein‐coding cytochrome c oxidase subunit I) for extant Scolopendromorpha. The data set includes eight extant species of Scolopocryptops and Dinocryptops from North America, east Asia, and the Pacific, rooted with novel sequence data for other blind scolopendromorphs. The molecular and combined data sets, analysed in a parsimony/direct optimization framework, identified a stable pattern of two main clades within Scolopocryptopinae. North American and Asian species of Scolopocryptops are united as a clade supported by both morphological and molecular characters. Its sister group is a Neotropical clade in which the type species of Dinocryptops is nested within a paraphyletic assemblage of Scolopocryptops species; Dinocryptops is placed in synonymy with Scolopocryptops. The strength of support for the relationships of extant taxa from the molecular data allow the Chiapas fossil to be assigned with precision, despite ambiguity in the morphological data; the fossil is resolved as sister species to the extant Laurasian clade. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 768–786.  相似文献   

7.
Fishes of the order Alepocephaliformes, slickheads and tubeshoulders, constitute a group of deep‐sea fishes poorly known in respect to most areas of their biology and systematics. Morphological studies have found alepocephaliform fishes to display a mosaic of synapomorphic and symplesiomorphic characters, resulting in great difficulties when attempting to resolve intra‐ and interrelationships. Molecular data recently added to the confusion by removing Alepocephaliformes from the Euteleostei and placed them as incertae sedis within the Otocephala. In the present study we attempt to further clarify relationships of Alepocephaliformes by adding newly determined whole mitogenome sequences from 19 alepocephaliforms in order to address 1) phylogenetic position of Alepocephaliformes within the Otocephala; and 2) intrarelationships of Alepocephaliformes. The present study includes 96 taxa of which 30 are alepocephaliforms and unambiguously aligned sequences were subjected to partitioned maximum likelihood and Bayesian analyses. Results from the present study support Alepocephaliformes as a genetically distinct otocephalan order as sister clade to Ostariophysi (mostly freshwater fishes comprising Gonorynchiformes, Cypriniformes, Characiformes, Siluriformes and Gymnotiformes). The disputed family Bathylaconidae was found to be an artificial assemblage of the two genera Bathylaco and Herwigia, with the former as the sister group of the family Alepocephalidae and the latter nested within Alepocephalidae. Platytroctidae was found to be monophyletic as sister clade to the rest of Alepocephaliformes. Previously unrecognized clades within the family Alepocephalidae are presented and a clade comprising Alepocephalus, Conocara and Leptoderma was recovered as the most derived. As long as the current classification is being followed, the genera Alepocephalus, Bathytroctes, Conocara and Narcetes were all found non‐monophyletic. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 923–936.  相似文献   

8.
This study is undertaken in order to evaluate specific hypotheses of relationship among extant and extinct sloths (Mammalia, Xenarthra, Tardigrada). Questions of particular interest include the relationship among the three traditional family groupings of extinct ground sloths and the monophyletic or diphyletic origin of the two genera of extant tree sloths. A computer‐based cladistic investigation of the phylogenetic relationships among 33 sloth genera is performed based upon 286 osteological characteristics of the skull, lower jaw, dentition and hyoid arch. Characters are polarized via comparisons with the following successive outgroups, all members of the supraordinal grouping Edentata: the Vermilingua, or anteaters; the Cingulata, or armadillos and glyptodonts; the Palaeanodonta; and the Pholidota, or pangolins. The results of the analysis strongly corroborate the diphyly of living tree sloths, with the three‐toed sloth Bradypus positioned as the sister‐taxon to all other sloths, and the two‐toed sloth Choloepus allied with extinct members of the family Megalonychidae. These results imply that the split between the two extant sloth genera is ancient, dating back perhaps as much as 40 Myr, and that the similarities between the two taxa, including their suspensory locomotor habits, present one of the most dramatic examples of convergent evolution known among mammals. The monophyly of the three traditional ground sloth families Megatheriidae, Megalonychidae and Mylodontidae is confirmed in the present study, and the late Miocene–Pleistocene nothrotheres are shown to form a clade. It is suggested that this latter clade merits recognition as a distinct family‐level grouping, the family Nothrotheriidae. The monophyly of the Megatherioidea, a clade including members of the families Megatheriidae, Megalonychidae and Nothrotheriidae, is also supported. Within Megatherioidea, the families Nothrotheriidae and Megatheriidae form a monophyletic group called the Megatheria. The relationships within the families Megatheriidae and Mylodontidae are fully and consistently resolved, although the hypothesized scheme of relationships among the late Miocene to Pleistocene members of the mylodontid subfamily Mylodontinae differ strongly from any proposed by previous authors. Within the family Megalonychidae, Choloepus is allied to a monophyletic grouping of West Indian sloths, although the relationships within this clade are not fully resolved. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140 , 255–305.  相似文献   

9.
Currently, 49 families of scale insects are recognised, 33 of which are extant. Despite more than a decade of DNA sequence‐based phylogenetic studies of scales insects, little is known with confidence about relationships among scale insects families. Multiple lines of evidence support the monophyly of a group of 18 scale insect families informally referred to as the neococcoids. Among neococcoid families, published DNA sequence‐based estimates have supported Eriococcidae paraphyly with respect to Beesoniidae, Dactylopiidae, and Stictococcidae. No other neococcoid interfamily relationship has been strongly supported in a published study that includes exemplars of more than ten families. Likewise, no well‐supported relationships among the 15 extant scale insect families that are not neococcoids (usually referred to as ‘archaeococcoids’) have been published. We use a Bayesian approach to estimate the scale insect phylogeny from 162 adult male morphological characters, scored from 269 extant and 29 fossil species representing 43/49 families. The result is the most taxonomically comprehensive, most resolved and best supported estimate of phylogenetic relationships among scale insect families to date. Notable results include strong support for (i) Ortheziidae sister to Matsucoccidae, (ii) a clade comprising all scale insects except for Margarodidae s.s., Ortheziidae and Matsucoccidae, (iii) Coelostomidiidae paraphyletic with respect to Monophlebidae, (iv) Eriococcidae paraphyletic with respect to Stictococcidae and Beesoniidae, and (v) Aclerdidae sister to Coccidae. We recover strong support for a clade comprising Phenacoleachiidae, Pityococcidae, Putoidae, Steingeliidae and the neococcoids, along with a sister relationship between this clade and Coelostomidiidae + Monophlebidae. In addition, we recover strong support for Pityococcidae + Steingeliidae as sister to the neococcoids. Data from fossils were incomplete, and the inclusion of extinct taxa in the data matrix reduced support and phylogenetic structure. Nonetheless, these fossil data will be invaluable in DNA sequence‐based and total evidence estimates of phylogenetic divergence times.  相似文献   

10.
The superfamilies of Elateriformia have been in a state of flux since their establishment. The recent classifications recognize Dascilloidea, Buprestoidea, Byrrhoidea and Elateroidea. The most problematic part of the elateriform phylogeny is the monophyly of Byrrhoidea and the relationships of its families. To investigate these issues, we merged more than 500 newly produced sequences of 18S rRNA, 28S rRNA, rrnL mtDNA and cox1 mtDNA for 140 elateriform taxa with data from GenBank. We assembled an all‐taxa (488 terminals) and a pruned data set, which included taxa with full fragment representation (251 terminals); both were aligned in various programs and analysed using maximum‐likelihood criterion and Bayesian inference. Most analyses recovered monophyletic superfamilies and broadly similar relationships; however, we obtained limited statistical support for the backbone of trees. Dascilloidea were sister to the remaining Elateriformia, and Elateroidea were sister to the clade of byrrhoid lineages including Buprestoidea. This clade mostly consisted of four major lineages, that is (i) Byrrhidae, (ii) Dryopidae + Lutrochidae, (iii) Buprestoidea (Schizopodidae sister to Buprestidae) and (iv) a clade formed by the remaining byrrhoid families. Buprestoidea and byrrhoid lineages, with the exception of Byrrhidae and Dryopidae + Lutrochidae, were usually merged into a single clade. Most byrrhoid families were recovered as monophyletic. Callirhipidae and Eulichadidae formed independent terminal lineages within the Byrrhoidea–Buprestoidea clade. Paraphyletic Limnichidae were found in a clade with Heteroceridae and often also with Chelonariidae. Psephenidae, represented by Eubriinae and Eubrianacinae, never formed a monophylum. Ptilodactylidae were monophyletic only when Paralichas (Cladotominae) was excluded. Elmidae regularly formed a clade with a bulk of Ptilodactylidae; however, elmid subfamilies (Elminae and Larainae) were not recovered. Despite the densest sampling of Byrrhoidea diversity up to date, the results are not statistically supported and resolved only a limited number of relationships. Furthermore, questions arose which should be considered in the future studies on byrrhoid phylogeny.  相似文献   

11.
12.
13.
在上个世纪最后的 2 0年里 ,系统学家应用形态性状对种子植物进行了大量的分支分析。其结果显示灭绝的五柱木属加上灭绝的本内苏铁目及尚存的买麻藤目是被子植物的姊妹群 ,形成一个强支 ,称之为生花植物支。生花植物假说对探讨被子植物起源有着重要影响 ,它激发人们讨论被子植物起源时间可能要提前到三叠纪甚至石炭纪 ,除了支持原有的真花学说外 ,还提出新恩格勒学说。但是 ,近年来对现存种子植物进行分子系统学研究的结果是 :(1)拒绝接受生花植物概念 ;(2 )买麻藤目并不是被子植物的姊妹群而是松柏目的姊妹群 ,甚至网结于松柏类而成为松科的姊妹群。这些结果并不使人惊讶 ,因为对探讨像包含许多灭绝类群的种子植物系统 ,决不可能是仅仅单独应用现代类群资料所能完成的。假如生花植物支是成立的 ,但其名称以AGPB支代替生花植物支可能较为合理。  相似文献   

14.
Relationships among extant and fossil echimyids (Rodentia: Hystricognathi)   总被引:1,自引:0,他引:1  
The echimyid rodents are the most diverse group of Neotropical hystricognaths, with approximately 40 extant and fossil genera. Craniodental characters are proposed in order to formulate hypotheses of phylogenetic relationships within the Echimyidae. A data matrix of 54 taxa and 50 characters is constructed and submitted to parsimony analyses using PAUP and WinClada programs. Analysis of the complete data set results in 47 448 most parsimonious trees 107 steps long. These trees are summarized in a strict consensus tree, which is taken as the main phylogenetic hypothesis resulting from this study. The monophyly of several currently recognized supraspecific taxa is not corroborated. These are: the subfamilies Eumysopinae, Echimyinae, Myocastorinae and Adelphomyinae; and the genera Proechimys , Echimys and Makalata . Conversely, the monophyly of Dactylomyinae and Trinomys is supported. New associations are proposed: (1) a clade comprising the extant Carterodon , Clyomys and Euryzygomatomys and the fossil Pampamys and Theridomysops placed at the base of the crown-group Echimyidae; (2) a clade uniting Proechimys , Hoplomys and Trinomys , which is the sister-taxon of (3) a clade including Mesomys , Lonchothrix , Myocastor and a clade with extant dactylomyines and echimyines and associated fossil taxa. Based on this phylogenetic hypothesis, patterns of tooth evolution in Echimyidae are discussed, and minimum ages for the divergence events within the family are estimated.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 142 , 445–477.  相似文献   

15.
There has been little agreement on the phylogeny of palaeognathous birds, with major differences amongst and between results from morphological and molecular data. Two recently published phylogenies using nuclear and mitochondrial DNA have substantial agreement in overall topology, with the ostrich as sister group of all other extant palaeognaths and a kiwi‐emu‐cassowary clade. Here I report a morphological phylogeny based mainly on new characters from the tongue apparatus and cranial osteology, with a theoretical ancestor as outgroup. A new interpretation of the evolution of the avian palate is included. This phylogeny is very similar to these recent molecular results; this is the first report of such congruence, and offers a credible basis for understanding the evolution of this clade. This phylogeny is fully consistent with a Gondwana vicariance model of evolution. Dates attributed from known geological events place the first extant radiation (ostrich) in the mid‐Cretaceous, and offer a means of calibration of future molecular clock investigations. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 959–983.  相似文献   

16.
Puffins, auks and their allies in the wing‐propelled diving seabird clade Pan‐Alcidae (Charadriiformes) have been proposed to be key pelagic indicators of faunal shifts in Northern Hemisphere oceans. However, most previous phylogenetic analyses of the clade have focused only on the 23 extant alcid species. Here we undertake a combined phylogenetic analysis of all previously published molecular sequence data (~ 12 kb) and morphological data (n = 353 characters) with dense species level sampling that also includes 28 extinct taxa. We present a new estimate of the patterns of diversification in the clade based on divergence time estimates that include a previously vetted set of twelve fossil calibrations. The resultant time trees are also used in the evaluation of previously hypothesized paleoclimatic drivers of pan‐alcid evolution. Our divergence dating results estimate the split of Alcidae from its sister taxon Stercorariidae during the late Eocene (~ 35 Ma), an evolutionary hypothesis for clade origination that agrees with the fossil record and that does not require the inference of extensive ghost lineages. The extant dovekie Alle alle is identified as the sole extant member of a clade including four extinct Miocene species. Furthermore, whereas an Uria + Alle clade has been previously recovered from molecular analyses, the extinct diversity of closely related Miocepphus species yields morphological support for this clade. Our results suggest that extant alcid diversity is a function of Miocene diversification and differential extinction at the Pliocene–Pleistocene boundary. The relative timing of the Middle Miocene climatic optimum and the Pliocene–Pleistocene climatic transition and major diversification and extinction events in Pan‐Alcidae, respectively, are consistent with a potential link between major paleoclimatic events and pan‐alcid cladogenesis.  相似文献   

17.
Apple snails (Ampullariidae) are a diverse family of pantropical freshwater snails and an important evolutionary link to the common ancestor of the largest group of living gastropods, the Caenogastropoda. A clear understanding of relationships within the Ampullariidae, and identification of their sister taxon, is therefore important for interpreting gastropod evolution in general. Unfortunately, the overall pattern has been clouded by confused systematics within the family and equivocal results regarding the family's sister group relationships. To clarify the relationships among ampullariid genera and to evaluate the influence of including or excluding possible sister taxa, we used data from five genes, three nuclear and two mitochondrial, from representatives of all nine extant ampullariid genera, and species of Viviparidae, Cyclophoridae, and Campanilidae, to reconstruct the phylogeny of apple snails, and determine their affinities to these possible sister groups. The results obtained indicate that the Old and New World ampullariids are reciprocally monophyletic with probable Gondwanan origins. All four Old World genera, Afropomus, Saulea, Pila, and Lanistes, were recovered as monophyletic, but only Asolene, Felipponea, and Pomella were monophyletic among the five New World genera, with Marisa paraphyletic and Pomacea polyphyletic. Estimates of divergence times among New World taxa suggest that diversification began shortly after the separation of Africa and South America and has probably been influenced by hydrogeological events over the last 90 Myr. The sister group of the Ampullariidae remains unresolved, but analyses omitting certain outgroup taxa suggest the need for dense taxonomic sampling to increase phylogenetic accuracy within the ingroup. The results obtained also indicate that defining the sister group of the Ampullariidae and clarifying relationships among basal caenogastropods will require increased taxon sampling within these four families, and synthesis of both morphological and molecular data. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 61–76.  相似文献   

18.
Metalasia is a genus in tribe Gnaphalieae (Asteraceae), endemic to South Africa and with its main distribution in the Cape Floristic Region. The genus comprises 57 species and, with a number of closely related genera, it constitutes the ‘Metalasia clade’. A species‐level phylogenetic analysis is presented, based on DNA sequences from two nuclear (internal and external transcribed spacer: ITS, ETS) and two plastid (psbA‐trnH, trnL‐trnF) regions together with morphological data. Analyses combining molecular and morphological data attempt not only to resolve species interrelationships, but also to detect patterns in character evolution. Phylogenetic analyses corroborate our earlier study and demonstrate that Metalasia is formed of two equally sized, well‐supported sister groups, one of which is characterized by papillose cypselas. The results differ greatly from earlier hypotheses based on morphology alone, as few morphological characters support the phylogenetic patterns obtained. The two clades of Metalasia do, however, appear to differ in distribution, corresponding to the different rainfall regimes of South Africa. Analyses show a few taxa to be problematic; one example is the widely distributed M. densa which appears to be an intricate species complex. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 173–198.  相似文献   

19.
Balaenidae (right whales) are large, critically endangered baleen whales represented by four living species. The evolutionary relationships of balaenids are poorly known, with the number of genera, relationships to fossil taxa, and position within Mysticeti in contention. This study employs a comprehensive set of morphological characters to address aspects of balaenid phylogeny. A sister‐group relationship between neobalaenids and balaenids is strongly supported, although this conflicts with molecular evidence, which may be an artifact of long‐branch attraction (LBA). Monophyly of Balaenidae is supported, and three major clades are recognized: (1) extinct genus Balaenula, (2) extant and extinct species of the genus Eubalaena, and (3) extant and extinct species of the genus Balaena plus the extinct taxon, Balaenella. The relationships of these clades to one another, as well as to the early Miocene stem balaenid, Morenocetus parvus, remain unresolved. Pliocene taxa, Balaenula astensis and Balaenula balaenopsis, form a clade that is the sister group to the Japanese Pliocene Balaenula sp. Eubalaena glacialis and Pliocene Eubalaena belgica, are in an unresolved polytomy with a clade including E. japonica and E. australis. Extant and fossil species of Balaena form a monophyletic group that is sister group to the Dutch Pliocene Balaenella, although phylogenetic relationships within Balaena remain unresolved.  相似文献   

20.
To date, there is little consensus concerning the phylogenetic relationships among neognath orders, which include all extant birds except ratites and tinamous. Different data sets, both molecular and morphologic, have yielded radically different and often unresolved ordinal topologies, especially within the neoaves clade. This lack of resolution and ongoing conflict indicates a need for additional phylogenetic characters to be applied to the question of higher-level avian phylogeny. In this study, sequences of a single-copy nuclear gene, ZENK, were used to reconstruct an ordinal-level phylogeny of neognath birds. Strong support was indicated for the oldest divergence within Neognathae; the chicken- and duck-like birds formed a clade that was sister to all other modern birds. In addition, many families of traditional taxonomic orders clustered together in the ZENK tree, indicating the gene's general phylogenetic reliability. However, within the neoaves clade, there was little support for relationships among orders, which is a result similar to all other recent molecular studies of higher-level avian phylogeny. This similarity among studies suggests the possibility of a rapid radiation of the major neoaves lineages. Despite the ongoing lack of neoaves resolution, ZENK's sequence divergence and base composition patterns indicate its general utility as a new phylogenetic marker for higher-level avian systematics.  相似文献   

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