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. 2009 Jun;59(6):471-481.
doi: 10.1525/bio.2009.59.6.5.

Molecular Data are Transforming Hypotheses on the Origin and Diversification of Eukaryotes

Yonas I Tekle  1 , Laura Wegener Parfrey, Laura A Katz
Affiliations

Molecular Data are Transforming Hypotheses on the Origin and Diversification of Eukaryotes

Yonas I Tekle et al. Bioscience. 2009 Jun.

Abstract

The explosion of molecular data has transformed hypotheses on both the origin of eukaryotes and the structure of the eukaryotic tree of life. Early ideas about the evolution of eukaryotes arose through analyses of morphology by light microscopy and later electron microscopy. Though such studies have proven powerful at resolving more recent events, theories on origins and diversification of eukaryotic life have been substantially revised in light of analyses of molecular data including gene and, increasingly, whole genome sequences. By combining these approaches, progress has been made in elucidating both the origin and diversification of eukaryotes. Yet many aspects of the evolution of eukaryotic life remain to be illuminated.

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Figures

Figure 1
Figure 1
Representative eukaryotic lineages from the six putative supergroups. (a – c) ‘Plantae’. (a) Eremosphaera viridis, a green alga. (b) Cyanidium sp., red algae. (c) Cyanophora sp., a glaucophyte. (d – i) ‘Chromalveolata’. (d) Chroomonas sp., a cryptomonad. (e) Emiliania huxleyi, a haptophyte. (f) Akashiwo sanguinea, a dinoflagellate. (g) Trithigmostoma cucullulus, a ciliate. (h) Colpodella perforans, an apicomplexan. (i) Thalassionema sp., colonial diatom (Stramenopile). (j – m) ‘Rhizaria’. (j) Chlorarachnion reptans, an autotrophic amoeba (Cercozoa). (k) Acantharea sp., a radiolarian. (l) Ammonia beccarii, a calcareous foraminifera. (m) Corallomyxa tenera, a reticulate amoeba. (n – p) ‘Excavata’. (n) Jakoba sp., a jakobid with two flagella. (o) Chilomastix cuspidata, a flagellate retortamonad. (p) Euglena sanguinea an autotrophic Euglenozoa. (q – s) ‘Amoebozoa’. (q) Trichosphaerium sp., a naked stage (lacking surface spicules) of an unusual amoeba with alternation of generations, one naked and one with spicules. (r) Stemonitis axifera, an acellular slime mold. (s) Arcella hemisphaerica, a testate amoeba. (t – w) Opisthokonta. (t) Larus occidentalis, a bird. (u) Campyloacantha sp., a choanoflagellate. (v) Amanita flavoconia, a basidiomycete fungus. (w) Chytriomyces sp., a chytrid. All scale bars = 10 µm, except b and l = 100 µm and r = 5 mm. All images are provided by micro*scope (http://starcentral.mbl.edu/microscope/portal.php) except v, which is provided by James Parfrey.
Figure 2
Figure 2
The chimeric eukaryotic genome is consistent with a fusion of an archaeon and bacterium at the time of the origin of eukaryotes coupled with subsequent aberrant lateral transfers of genes from food items. (a) An archaeon and proteobacterium that are potential symbiotic partners in origin of eukaryotes. (b) Eukaryogenesis – the origin of the nucleus, cytoskeleton, and mitochondria through unknown mechanisms and events. (c) Mitochondrial genes are transferred to the host nucleus (purple portions of chromosome). (d) Eukaryote engulfs blue food item and incorporates blue genes into host nucleus (in e). (e–h) repeated engulfment of food and incorporation of genes into the host nucleus (hot colors = more recent events). (i) Modern eukaryote whose chimeric genome is the product of (a–h). (j) figure modified from Dagan and Martin (2006) depicts the mixed ancestry of eukaryotic genes as elucidated from BLAST similarity searches (NCBI). The 5,833 genes from the human genome (rows) were compared to 24 archaeal (columns in first block) and 200 bacterial genomes (columns second block). Colors indicate the level of similarity between eukaryotic and bacterial and archaeal homologs. Warmer colors represented higher BLAST scores, and therefore a higher degree of similarity. Inset used with permission (being requested)from BioMed Central Ltd.
Figure 3
Figure 3
A synthesis of the eukaryotic tree of life that depicts the current classification into supergroups plus other emerging hypotheses. The unresolved backbone of the tree indicates the uncertainties and lack of support at deeper nodes. Groups that are generally recovered are indicated with solid lines. Dashed lines and single quotes are used to denote groups that receive inconsistent support and hypothesized groups whose support is still being evaluated.
Figure 4
Figure 4
An example of a multigene tree of the major eukaryotic groups inferred from analyses of SSU-rDNA and amino acid sequences of actin, alpha- and beta-tubulin in MrBayes. Solid black dots indicate Bayesian posterior support values greater than 95%. All branches are drawn to scale. Tree modified from Tekle et al. 2008 and used with permission (being requested) from Elsevier Inc..
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References

    1. Adl SM, et al. The new higher level classification of eukaryotes with emphasis on the taxonomy of protists. Journal of Eukaryotic Microbiology. 2005;52:399–451. - PubMed
    1. Archibald JM. Endosymbiosis: double-take on plastid origins. Current Biology. 2006;16:R690–R692. - PubMed
    1. Baldauf SL, Roger AJ, Wenk-Siefert I, Doolittle WF. A kingdom-level phylogeny of eukaryotes based on combined protein data. Science. 2000;290:972–977. - PubMed
    1. Bhattacharya D, Yoon HS, Hackett JD. Photosynthetic eukaryotes unite: endosymbiosis connects the dots. Bioessays. 2004;26:50–60. - PubMed
    1. Bodyl A. Do plastid-related characters support the chromalveolate hypothesis? Journal of Phycology. 2005;41:712–719.