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1.
Triploblastic relationships were examined in the light of molecular and morphological evidence. Representatives for all triploblastic "phyla" (except Loricifera) were represented by both sources of phylogenetic data. The 18S ribosomal (rDNA) sequence data for 145 terminal taxa and 276 morphological characters coded for 36 supraspecific taxa were combined in a total evidence regime to determine the most consistent picture of triploblastic relationships for these data. Only triploblastic taxa are used to avoid rooting with distant outgroups, which seems to happen because of the extreme distance that separates diploblastic from triploblastic taxa according to the 18S rDNA data. Multiple phylogenetic analyses performed with variable analysis parameters yield largely inconsistent results for certain groups such as Chaetognatha, Acoela, and Nemertodermatida. A normalized incongruence length metric is used to assay the relative merit of the multiple analyses. The combined analysis having the least character incongruence yields the following scheme of relationships of four main clades: (1) Deuterostomia [((Echinodermata + Enteropneusta) (Cephalochordata (Urochordata + Vertebrata)))]; (2) Ecdysozoa [(((Priapulida + Kinorhyncha) (Nematoda + Nematomorpha)) ((Onychophora + Tardigrada) Arthropoda))]; (3) Trochozoa [((Phoronida + Brachiopoda) (Entoprocta (Nemertea (Sipuncula (Mollusca (Pogonophora (Echiura + Annelida)))))))]; and (4) Platyzoa [((Gnathostomulida (Cycliophora + Syndermata)) (Gastrotricha + Plathelminthes))]. Chaetognatha, Nemertodermatida, and Bryozoa cannot be assigned to any one of these four groups. For the first time, a data analysis recognizes a clade of acoelomates, the Platyzoa (sensu Cavalier-Smith, Biol. Rev. 73:203-266, 1998). Other relationships that corroborate some morphological analyses are the existence of a clade that groups Gnathostomulida + Syndermata (= Gnathifera), which is expanded to include the enigmatic phylum Cycliophora, as sister group to Syndermata.  相似文献   

2.
A remarkable diversity of life history strategies, geographic distributions, and morphological characters provide a rich substrate for investigating the evolutionary relationships of arhynchobdellid leeches. The phylogenetic relationships, using parsimony analysis, of the order Arhynchobdellida were investigated using nuclear 18S and 28S rDNA, mitochondrial 12S rDNA, and cytochrome c oxidase subunit I sequence data, as well as 24 morphological characters. Thirty-nine arhynchobdellid species were selected to represent the seven currently recognized families. Sixteen rhynchobdellid leeches from the families Glossiphoniidae and Piscicolidae were included as outgroup taxa. Analysis of all available data resolved a single most-parsimonious tree. The cladogram conflicted with most of the traditional classification schemes of the Arhynchobdellida. Monophyly of the Erpobdelliformes and Hirudiniformes was supported, whereas the families Haemadipsidae, Haemopidae, and Hirudinidae, as well as the genera Hirudo or Aliolimnatis, were found not to be monophyletic. The results provide insight on the phylogenetic positions for the taxonomically problematic families Americobdellidae and Cylicobdellidae, the genera Semiscolex, Patagoniobdella, and Mesobdella, as well as genera traditionally classified under Hirudinidae. The evolution of dietary and habitat preferences is examined.  相似文献   

3.
Dai YC  Wang Z  Binder M  Hibbett DS 《Mycologia》2006,98(4):584-592
Three nuclear genes, lsu-rDNA (encoding nuclear large subunit rDNA), ITS (encoding the rDNA internal transcribed spacers and 5.8 S rDNA) and rpb2 (encoding the second largest subunit of RNA polymerase II), and the mitochondrial gene atp6 (encoding the sixth subunit of ATP synthase), were sequenced from all recognized Sparassis lineages. Sparassis latifolia sp. nov. from boreal coniferous forests in China is described based on morphological, ecological, geographical and molecular data. The nuclear gene phylogeny strongly supported groups corresponding to morphological differences, geographic distribution and host shifts among species that produce clamp connections, such as S. crispa from Europe, S. radicata from western North America and S. latifolia from Asia. The atp6 phylogeny however showed no divergence among these three species. For clampless Sparassis species, such as S. spathulata from eastern North America, S. brevipes and a new species from Europe, the atp6 phylogeny was congruent with the nuclear gene phylogeny. Sparassis cystidiosa is basal in the nuclear tree but sister to S. brevipes-S. spathulata clade in the ATP6 tree. The differences between the phylogenetic inferences from the atp6 gene and those from nuclear genes within Sparassis species are discussed.  相似文献   

4.
Drosophilidae (Diptera) is a diverse, cosmopolitan family of flies. Here, we present a combined analysis phylogeny of Drosophilinae, one of the two subfamilies of Drosophilidae, based on data from six different data partitions, including both molecular and morphological characters. Although our data show support for the monophyly of the Hawaiian Drosophilidae, and the subgenus Sophophora, neither the genus Drosophila nor the subgenus Drosophila is monophyletic. Partitioned Bremer support (PBS) indicates that morphological data taken from Grimaldi's monograph (Grimaldi, 1990a), as well as sequences from the mitochondrial (mt) 16S rDNA and the nuclear Adh gene, lend much support to our tree's topology. This is particularly interesting in the case of Grimaldi's data, since his published hypothesis conflicts with ours in significant ways. Our combined analysis cladogram phylogeny reflects the catch-all designation that the name Drosophila has become, in that the cladogram does not support the monophyly of either the genus or subgenus Drosophila.  相似文献   

5.
The Zingiberales are a tropical group of monocotyledons that includes bananas, gingers, and their relatives. The phylogenetic relationships among the eight families currently recognized are investigated here by using parsimony and maximum likelihood analyses of four character sets: morphological features (1), and sequence data of the (2) chloroplast rbcL gene, (3) chloroplast atpB gene, and (4) nuclear 18S rDNA gene. Outgroups for the analyses include the closely related Commelinaceae + Philydraceae + Haemodoraceae + Pontederiaceae + Hanguanaceae as well as seven more distantly related monocots and paleoherbs. Only slightly different estimates of evolutionary relationships result from the analysis of each character set. The morphological data yield a single fully resolved most-parsimonious tree. None of the molecular datasets alone completely resolves interfamilial relationships. The analyses of the combined molecular dataset provide more resolution than do those of individual genes, and the addition of the morphological data provides a well-supported estimate of phylogenetic relationships: (Musaceae ((Strelitziaceae, Lowiaceae) (Heliconiaceae ((Zingiberaceae, Costaceae) (Cannaceae, Marantaceae))))). Evidence from branch lengths in the parsimony analyses and from the fossil record suggests that the Zingiberales originated in the Early Cretaceous and underwent a rapid radiation in the mid-Cretaceous, by which time most extant family lineages had diverged.  相似文献   

6.
The main goals of this study were to provide a robust phylogeny for the families of the superfamily Curculionoidea, to discover relationships and major natural groups within the family Curculionidae, and to clarify the evolution of larval habits and host-plant associations in weevils to analyze their role in weevil diversification. Phylogenetic relationships among the weevils (Curculionoidea) were inferred from analysis of nucleotide sequences of 18S ribosomal DNA (rDNA; approximately 2,000 bases) and 115 morphological characters of larval and adult stages. A worldwide sample of 100 species was compiled to maximize representation of weevil morphological and ecological diversity. All families and the main subfamilies of Curculionoidea were represented. The family Curculionidae sensu lato was represented by about 80 species in 30 "subfamilies" of traditional classifications. Phylogenetic reconstruction was accomplished by parsimony analysis of separate and combined molecular and morphological data matrices and Bayesian analysis of the molecular data; tree topology support was evaluated. Results of the combined analysis of 18S rDNA and morphological data indicate that monophyly of and relationships among each of the weevil families are well supported with the topology ((Nemonychidae, Anthribidae) (Belidae (Attelabidae (Caridae (Brentidae, Curculionidae))))). Within the clade Curculionidae sensu lato, the basal positions are occupied by mostly monocot-associated taxa with the primitive type of male genitalia followed by the Curculionidae sensu stricto, which is made up of groups with the derived type of male genitalia. High support values were found for the monophyly of some distinct curculionid groups such as Dryophthorinae (several tribes represented) and Platypodinae (Tesserocerini plus Platypodini), among others. However, the subfamilial relationships in Curculionidae are unresolved or weakly supported. The phylogeny estimate based on combined 18S rDNA and morphological data suggests that diversification in weevils was accompanied by niche shifts in host-plant associations and larval habits. Pronounced conservatism is evident in larval feeding habits, particularly in the host tissue consumed. Multiple shifts to use of angiosperms in Curculionoidea were identified, each time associated with increases in weevil diversity and subsequent shifts back to gymnosperms, particularly in the Curculionidae.  相似文献   

7.
8.
The phylogeny of the gall-midge subtribe Baldratiina (Diptera: Cecidomyiidae) was reconstructed from molecular (partial sequence of the mitochondrial 12S rDNA), morphological and ecological data sets, using 16 representative species of most of the genera. The morphological and ecological data were combined in a single character matrix and analyzed separately from the molecular data, resulting in an eco-morphological cladogram and a molecular cladogram. Attributes of galls and host associations were superimposed on the molecular cladogram in order to detect possible trends in the evolution of these traits. The cladograms resulting from the two independent analyses were statistically incongruent, although both provide evidence for the monophyly of the genera Baldratia and Careopalpis and the paraphyly of the genera Stefaniola and Izeniola. The results suggest a minor impact of the morphological characters traditionally used in the classification of the Baldratiina, whereas ecological data had a major impact on the phylogenetic inference. Mapping of gall and host attributes on the molecular cladogram suggests that multi-chambered stem galls constitute the ancestral state in the subtribe, with several subsequent shifts to leaf galls. It is concluded that in contrast to other studied groups of gall insects, related baldratiine species induce different types of galls, attesting to speciation driven by gall-type shifts at least as often as host shifts.  相似文献   

9.
Abstract. Phylogenetic relationships among species groups of Trichadenotecnum were inferred based on morphology and the partial sequences of five gene regions (mitochondrial 12S rDNA, 16S rDNA, cytochrome oxidase I, NADH dehydrogenase subunit 5 and nuclear 18S rDNA). All analyses supported the monophyly of Trichadenotecnum and all previously proposed species groups, except that T. circularoides was excluded from the spiniserrulum group. To examine the phylogenetic usefulness of morphological data, the morphological characters used in the construction of an earlier taxonomic system for Trichadenotecnum were mapped parsimoniously on the molecular tree. As a result: (1) commonly used forewing marking features (sparsely or extensively spotted) are considered to be very homoplastic and less informative of higher‐level phylogenetic relationships; (2) a broadly expanded epiproct lobe is considered to be independently evolved at least two or three times, and a detailed morphological re‐examination allows recognition of these convergent structures; (3) the short ventral valve of gonapophyses independently evolved at least three or four times, although this character was used initially to diagnose the spiniserrulum group.  相似文献   

10.
Aligned 18S and insect phylogeny   总被引:20,自引:0,他引:20  
Kjer KM 《Systematic biology》2004,53(3):506-514
The nuclear small subunit rRNA (18S) has played a dominant role in the estimation of relationships among insect orders from molecular data. In previous studies, 18S sequences have been aligned by unadjusted automated approaches (computer alignments that are not manually readjusted), most recently with direct optimization (simultaneous alignment and tree building using a program called "POY"). Parsimony has been the principal optimality criterion. Given the problems associated with the alignment of rRNA, and the recent availability of the doublet model for the analysis of covarying sites using Bayesian MCMC analysis, a different approach is called for in the analysis of these data. In this paper, nucleotide sequence data from the 18S small subunit rRNA gene of insects are aligned manually with reference to secondary structure, and analyzed under Bayesian phylogenetic methods with both GTR+I+G and doublet models in MrBayes. A credible phylogeny of Insecta is recovered that is independent of the morphological data and (unlike many other analyses of 18S in insects) not contradictory to traditional ideas of insect ordinal relationships based on morphology. Hexapoda, including Collembola, are monophyletic. Paraneoptera are the sister taxon to a monophyletic Holometabola but weakly supported. Ephemeroptera are supported as the sister taxon of Neoptera, and this result is interpreted with respect to the evolution of direct sperm transfer and the evolution of flight. Many other relationships are well-supported but several taxa remain problematic, e.g., there is virtually no support for relationships among orthopteroid orders. A website is made available that provides aligned 18S data in formats that include structural symbols and Nexus formats.  相似文献   

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