Dr. Alastair G.B. Simpson

ASSOCIATE PROFESSOR
BSc (Sydney, 1994)
PhD (Sydney, 2000)


  • Teaching & Research
  • Publications
  • Links   
  • Teaching & Research
    origin and early evolution of eukaryotes, Protistan biodiversity, phylogenetics and systematics, Protistan ultrastructure, and molecular evolution

    Dwas born, raised and educated in Sydney, Australia. I finished a PhD in Biology at the University of Sydney in 2000, having also spent several months at the Marine Biology Laboratory at Woods Hole (USA). I came to Dalhousie University in 2000 as a postdoctoral fellow in the Biochemistry Department, and joined the Biology Faculty in July 2003.

    Classes in which Alastair currently teaches:

    I am a Scholar of the Canadian Institute for Advanced Research, Program in Evolutionary Biology.

    My research examines the origin and evolutionary history of eukaryotic cells. I work with 'protists', that is, all those eukaryotes that are NOT animals, plants or fungi. Most protists are inconspicuous single cells, but they comprise the vast bulk of eukaryote biodiversity. They are therefore key to understanding the course of eukaryotic evolution and are of huge ecological importance. However, most protists are very poorly studied. I examine the evolutionary history and diversity of several major protist groups (think 'phyla' and 'kingdoms'), using molecular phlyogenetics / phylogenomics and sub-cellular morphology. See the lab website for more details.

    My particular interests are:
    1) Protists that have been considered especially primitive eukaryotic cells. Such organisms include the mitochondrion-lacking parasites Giardia and Trichomonas, and 'jakobids' - obscure cells with unusually bacterial-like mitochondrial genomes. We have proposed that these organisms are actually all closely related to each other, falling in a novel 'supra-kingdom-level' group called Excavata. Our recent work mostly concerns free-living relatives of Giardia and its ilk, such as Carpediemonas and Hicanonectes.

    2) Small protists of so-far mysterious affinities. How many major groups of eukaryotes are there in the world? How diverse are they? Some of our recent studies focus in particular on Apusomonads and Ancyromonas (=Planomonas)

    3) The diversity and evolution of heterotrophic protists living in extremely high salt environments (i.e. halophiles and extreme halophiles).

    4) The evolutionary history of the large protistan group Euglenozoa. Euglenozoa includes the trypanosomatids: agents of sleeping sickness, Chagas' disease and kala azar, as well as the laboratory alga Euglena, and a very wide diversity of ecologically important forms.

    I am also interested in eukaryote (protist) genome evolution, including lateral gener transfer, in species concepts and autecology in protists, and in alternative taxomonic and systematic nomenclature.


    Selected Publications

    Hampl, V., Hug, L., Leigh, J., Dacks, J.B., Lang, B.F., Simpson, A.G.B. & Roger, A.J. 2009. Phylogenomic analyses support the monophyly of Excavata and robustly resolve relationships among eukaryotic “supergroups”.  Proceedings of the National Academy of Sciences USA, 106, 3859-64.

    Roger, A.J. & Simpson, A.G.B. 2009. Evolution: Revisiting the Root of the Eukaryote Tree. Current Biology, 19, R165-167.

    Park, J.S., Kolisko, M., Heiss, A.A. & Simpson, A.G.B. 2009. Light microscopic observations, ultrastructure, and molecular phylogeny of Hicanonectes teleskopos n. gen., n. sp., a deep-branching relative of diplomonads.  Journal of Eukaryotic Microbiology, 56, 373-384 .

    Park, J.S., Simpson, A.G.B., Brown, S. & Cho B.C. 2009. Ultrastructure and molecular phylogeny of two heterolobosean amoebae, Euplaesiobystra hypersalinica gen. et sp. nov. and Tulamoeba peronaphora gen. et sp. nov., isolated from an extremely hypersaline habitat.  Protist, 160, 265-283.

    Kolisko, M., Cepicka, I., Hampl, V., Leigh, J., Roger, A.J., Kulda, J., Simpson, A.G.B & Flegr, J. 2008. Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, a-tubulin and HSP90 genes: implications for the evolutionary history of the double karyomastigont of diplomonads. BMC Evolutionary Biology, 8, art.205.

    Simpson, A.G.B., Perley,T. & Lara, E. (2008) Lateral transfer of the gene for a widely used marker, alpha tubulin, indicated by a multi-protein study of the phylogenetic position of Andalucia (Excavata). Molecular Phylogenetics and Evolution, 47, 366-377.

    Park, J.S., Simpson, A.G.B., Lee, W.J. & Cho, B.C. 2007. Ultrastructure and phylogenetic placement within Heterolobosea of the previously unclassified, extremely halophilic heterotrophic flagellate Pleurostomum flabellatum (Ruinen 1938).  Protist, 158, 397-413.

    Kim, E., Simpson, A.G.B. & Graham, L.E. 2006. Evolutionary relationships of apusomonads inferred from taxon-rich analyses of six nuclear-encoded genes. Molecular Biology and Evolution, 23, 2455-2466.

    Park J.S., Cho B.C., and Simpson, A.G.B. 2006. Halocafeteria seosinensis gen et sp. nov. (Bicosoecida), a halophilic bacterivorous nanoflagellate isolated from a solar saltern. Extremophiles, 10, 493-504.

    Simpson, A.G.B., Stevens, J.R. & Lukes J. 2006. The evolution and diversity of kinetoplastid flagellates. Trends in Parasitology, 22, 168-174.

    Simpson, A.G.B., Inagaki, Y. & Roger, A.J. 2006. Comprehensive multi-gene phylogenies of excavate protists reveal the evolutionary positions of 'primitive' eukaryotes. Molecular Biology and Evolution, 23, 615-625.

    Lara, E., Chatzinotas, A. & Simpson, A.G.B. 2006. Andalucia (gen. nov,): a new taxon for the deepest branch within jakobids (Jakobida; Excavata), based on morphological and molecular study of a new flagellate from soil. Journal of Eukaryotic Microbiology, 53, 112-120.

    Adl, S.M., Simpson, A.G.B., Farmer, M., & 25 others 2005.The new higher-level classification of eukaryotes with emphasis on the taxonomy of protists. Journal of Eukaryotic Microbiology, 52, 399-451.

    Miao, W., Simpson, A.G.B., Fu, C. & Lobban C.S. 2005. The giant zooxanthellae-bearing ciliate Maristentor dinoferus (Heterotrichea) is closely related to folliculinidae. Journal of Eukaryotic Microbiology 52, 11-16.

    Simpson A.G.B., Gill E.E., Callahan H.A., Litaker R.W. & Roger A.J. 2004. Early evolution within kinetoplastids (Euglenozoa), and the late emergence of trypanosomatids. Protist 155, 407-422.

    Simpson, A.G.B. & Roger, A.J. 2004.The real 'kingdoms' of eukaryotes. Current Biology 14, R693-696.

    Inagaki, Y, Simpson A.G.B., Dacks J.B. & Roger A.J. 2004. Phylogenetic artifact can be caused by leucine, serine and arginine codon usage heterogeneity: dinoflagellate plastid origins as a case study. Systematic Biology 53: 582-593.

    Simpson A.G.B. & Roger A.J. 2004. Excavata and the origin of amitochondriate eukaryotes. in Hirt, R.P. & Horner, D.S. Organelles, Genomes, and Eukaroyote Phylogeny: An Evolutionary Synthesis in the Age of Genomics. CRC Press.

    Brugerolle G. & Simpson A.G.B. 2004. The flagellar apparatus of Heterolobosea. Journal of Eukaryotic Microbiology, 51: 966-107.

    Simpson A.G.B. & Roger A.J. 2004. Protein phylogenies robustly resolve the deep-level relationships within Euglenozoa. Molecular Phylogenetics and Evolution, 30: 201-212.

    Simpson A.G.B. 2003. Cytoskeletal organisation, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota). International Journal of Systematic and Evolutionary Microbiology, 53: 1759-1777.

    Simpson A.G.B., Lukes J. & Roger A.J. 2002.Evolutionary history of kinetoplastids, and their kinetoplasts. Molecular Biology and Evolution 19: 2071-2083.

    Simpson A.G.B., and Roger A.J. 2002. Eukaryotic evolution: Getting to the root of the problem. Current Biology, 12: 691-693.

    Simpson A.G.B., MacQuarrie E.K., & Roger A.J. 2002. Early evolution of canonical introns. Nature 419: 270.

    Simpson A.G.B., Roger A.J., Silberman J.D., Leipe, D.D., Edgcomb V.P., Jermiin, L.S., Patterson, D.J. & Sogin M.L. 2002. Evolutionary history of 'early diverging' eukaryotes: The excavate taxon Carpediemonas is a close relative of Giardia. Molecular Biology and Evolution 19: 1782-1791.

    Simpson A.G.B., Radek R., Dacks J.B. & O'Kelly, C.J. 2002. How oxymonads lost their groove: An ultrastructural comparison of Monocercomonoides and excavate taxa. Journal of Eukaryotic Microbiology. 49: 239-248.

    Edgcomb V.P., Simpson A.G.B., Amaral Zettler L., Nerad T.A., Patterson D.J., Holder M.E. & Sogin M.L. 2002. Pelobionts are degenerate protists: insights from molecules and morphology. Molecular Biology and Evolution. 19: 978-982.

    Silberman J.D., Simpson A.G.B., Kulda J., Cepicka I., Hampl V., Johnson P.J. & Roger A.J. 2002. Retortamonad flagellates are closely related to diplomonads: implications for the history of mitochondrial function in eukaryote evolution. Molecular Biology and Evolution 19: 777-786.

    Lobban C.S. Schefter M., Simpson A.G.B., Pochon X., Pawlowski J. & Foissner W. 2002. Maristentor dinoferus nov. gen., nov. spec., a giant heterotrich ciliate (Protozoa, Ciliophora) with zooxanthellae, from Pacific coral reefs. Marine Biology, 140: 411-423.

    Simpson A.G.B. & Patterson D.J. 2001. On core jakobids and excavate taxa: The ultrastructure of Jakoba incarcerata. Journal of Eukaryotic Microbiology 48: 480-492.

    Dacks J.B., Silberman J.D., Simpson A.G.B., Moriya S., Kudo T., Ohkuma M. & Redfield R.J. 2001. Oxymonads are closely related to the excavate taxon Trimastix. Molecular Biology and Evolution 18: 1034-1044.

    Edgcomb V.P., Roger A.J., Simpson A.G.B., Kysela D.T., & Sogin M.L. 2001. Evolutionary relationships among "jakobid" flagellates as indicated by alpha- and beta- tubulin phylogenies. Molecular Biology and Evolution 18: 514-522.

    Walker G., Simpson A.G.B., Edgcomb, V.P., Sogin M.L. & Patterson D.J. 2001. Ultrastructural identities of Mastigamoeba punctachora, Mastigamoeba simplex and Mastigella commutans and assessment of hypotheses of relatedness of the pelobionts (Protista). European Journal of Protistology 37: 25-49.

    Simpson A.G.B., Bernard C. & Patterson D.J. 2000. The ultrastructure of Trimastix marina Kent, 1880 (Eukaryota), an excavate flagellate. European Journal of Protistology 36: 229-252.

    Bernard C., Simpson A.G.B. & Patterson D.J. 2000. Some free-living flagellates from anoxic sediments. Ophelia 52: 113-142.

    Simpson A.G.B. & Patterson, D.J. 1999. The ultrastructure of Carpediemonas membranifera: (Eukaryota), with reference to the 'excavate hypothesis'. European Journal of Protistology 35: 353-370.

    Weerakoon N.D., Harper J.D.I., Simpson A.G.B. & Patterson D.J. 1999. Centrin in the groove: Immunolocalisation of centrin and microtubules in the putatively primitive protist, Chilomastix cuspidata (Retortamonadida). Protoplasma 210: 75-84.

    Edgcomb V.P., Viscogliosi E., Simpson A.G.B., Delgado-Viscogliosi P., Roger A.J. & Sogin M.L. 1998. New insights into the phylogeny of trichomonads inferred from small subunit rRNA sequences. Protist 149: 359-366.

    Simpson A.G.B. 1997. The identity and composition of the Euglenozoa. Archiv für Protistenkunde 148: 318-328.

    Simpson A.G.B., van den Hoff J., Bernard C., Burton H. & Patterson D.J. 1997. The ultrastructure and systematic position of the Euglenozoon Postgaardi mariagerensis, Fenchel et al. Archiv für Protistenkunde 147: 213-225.

    Simpson A.G.B., Bernard C., Fenchel T. & Patterson D.J. 1997. The organisation of Mastigamoeba schizophrenia n. sp.: More evidence of ultrastructural idiosyncrasy and simplicity in pelobiont protists. European Journal of Protistology 33: 87-98.

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