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New Phylogenetic Analysis (new + phylogenetic_analysis)
Selected AbstractsNew Phylogenetic Analysis of the Family Elephantidae Based on Cranial-Dental Morphology,THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2010Nancy E. Todd Abstract In 1973, Vincent Maglio published a seminal monograph on the evolution of the Elephantidae, in which he revised and condensed the 100+ species named by Henry Fairfield Osborn in 1931. Michel Beden further revised the African Elephantidae in 1979, but little systematic work has been done on the family since this publication. With addition of new specimens and species and revisions of chronology, a new analysis of the phylogeny and systematics of this family is warranted. A new, descriptive character dataset was generated from studies of modern elephants for use with fossil species. Parallel evolution in cranial and dental characters in all three lineages of elephants creates homoplastic noise in cladistic analysis, but new inferences about evolutionary relationships are possible. In this analysis, early Loxodonta and early African Mammuthus are virtually indistinguishable in dental morphology. The Elephas lineage is not monophyletic, and results from this analysis suggest multiple migration events out of Africa into Eurasia, and possibly back into Africa. New insight into the origin of the three lineages is also proposed, with Stegotetrabelodon leading to the Mammuthus lineage, and Primelephas as the ancestor of Loxodonta and Elephas. These new results suggest a much more complex picture of elephantid origins, evolution, and paleogeography. Anat Rec, 2010. © 2009 Wiley-Liss, Inc. [source] On the phylogenetic position of Gogonasus andrewsae Long 1985, within the TetrapodomorphaACTA ZOOLOGICA, Issue 2009Timothy Holland Abstract Within the Tetrapodomorpha, the Late Devonian Gogonasus andrewsae of the Gogo Formation, Gogo, Western Australia, has occupied an uncertain phylogenetic position. Following the description of several well-preserved three-dimensional skulls and pectoral girdles, the discovery of the first complete specimen (NMV P221807) made Gogonasus one of the best-known tetrapodomorph fish. Recent studies of pectoral fin structure and the spiracular opening of Gogonasus have suggested an unexpected affinity with ,elpistostegalid' fish such as Tiktaalik. Subsequent work has refuted characters linking these taxa, with phylogenetic analysis of the Tetrapodomorpha placing Gogonasus basal to megalichthyids and tristichopterids. In this paper we reanalyse characters linking Gogonasus with ,elpistostegalid' fish and those supporting the placement of Gogonasus crownward of Eusthenopteron. New phylogenetic analyses of the Tetrapodomorpha show a revised phylogenetic position of Gogonasus as being deeply nested within the Tetrapodomorpha, crownward of Osteolepis and Megalichthys, but basal to Eusthenopteron+,elpistostegalids'. Functional consideration of the spiracular structure suggests a position of Gogonasus closer to ,elpistostegalids', although data is lacking from other less-well-preserved taxa to fully test the hypothesis. The humerus of the Late Devonian lungfish Chirodipterus from Gogo, Western Australia is figured for comparative purposes. [source] 15 Phylogeny of the chlorophyta: inferences from 18S and 26S rDNAJOURNAL OF PHYCOLOGY, Issue 2003M. A. Buchheim Recent studies of the Chlorophyceae using 18S and 26S rDNA data in meta-analysis have demonstrated the power of combining these two sets of rDNA data. Furthermore, the 26S rDNA data complement the more conserved 18S gene for many chlorophycean lineages. Consequently, this data approach was pursued in an expanded taxon-sampling scheme for the Chlorophyta, with special reference to the classes Chlorophyceae and Trebouxiophyceae. Results of these new phylogenetic analyses identify Microspora sp. (UTEX LB 472) and Radiofilum transversale (UTEX LB 1252) as sister taxa which, in turn, form a basal clade in the Cylindrocapsa alliance (Treubaria, Trochiscia, Elakatothrix). The relative position of the "Cylindrocapsa" clade within the Chlorophyceae remains uncertain. The enhanced taxon-sampling has not resolved the relative positions of the Oedogoniales, Chaetophorales or Chaetopeltidales. Furthermore, the Sphaeropleaceae are supported as members of the Sphaeropleales in only some analyses, raising concerns about the status of the order. Although based on a limited set of taxa (currently <10), a combined data approach reveals support for a monophyletic Trebouxiophyceae that includes the distinctive organisms, Geminella and Eremosphaera. The goal of a well-resolved phylogeny for the Chlorophyta remains just that, a goal. Achieving that goal obviously will require additional taxon sampling in the Prasinophyceae and Ulvophyceae, as well as, the Trebouxiophyceae. Moreover, it is clear that other genes (e.g., cp-atpB, cp-rbcL, cp-16S, mt-nad5) will be needed to help address problems of resolution based on the rDNA data alone. Supported by NSF DEB 9726588 and DEB 0129030. [source] Conodont affinity and chordate phylogenyBIOLOGICAL REVIEWS, Issue 2 2000PHILIP C. J. DONOGHUE ABSTRACT Current information on the conodonts Clydagnathus windsorensis (Globensky) and Promissum pulchrum Kovács- Endrödy, together with the latest interpretations of conodont hard tissues, are reviewed and it is concluded that sufficient evidence exists to justify interpretation of the conodonts on a chordate model. A new phylogenetic analysis is undertaken, consisting of 17 chordate taxa and 103 morphological, physiological and biochemical characters; conodonts are included as a primary taxon. Various experiments with character coding, taxon deletion and the use of constraint trees are carried out. We conclude that conodonts are cladistically more derived than either hagfishes or lampreys because they possess a mineralised dermal skeleton and that they are the most plesiomorphic member of the total group Gnathostomata. We discuss the evolution of the nervous and sensory systems and the skeleton in the context of our optimal phylogenetic tree. There appears to be no simple evolution of free to canal-enclosed neuromasts; organised neuromasts within canals appear to have arisen at least three times from free neuromasts or neuromasts arranged within grooves. The mineralised vertebrate skeleton first appeared as odontodes of dentine or dentine plus enamel in the paraconodont/euconodont feeding apparatus. Bone appeared later, co-ordinate with the development of a dermal skeleton, and it appears to have been primitively acellular. Atubular dentine is more primitive than tubular dentine. However, the subsequent distribution of the different types of dentine (e.g. mesodentine, orthodentine), suggests that these tissue types are homoplastic. The topology of relationships and known stratigraphic ranges of taxa in our phylogeny predict the existence of myxinoids and petromyzontids in the Cambrian. [source] | ||||||||||