TY - JOUR A1 - Voss, Henning A1 - Meyer, Jeannette A1 - Schwonbeck, Susanne A1 - Fritsche, Immo A1 - Hartmann, Bernhard A1 - Wegwarth, Odette A1 - Friedrich, Anke A1 - Buchheister-Knappe, Stefanie A1 - Marwan, Norbert A1 - Bandau, Anja A1 - Bullinger, Hans-Jörg A1 - Weith, Thomas T1 - Portal alumni T2 - Das Ehemaligen-Magazin der Universität Potsdam N2 - Liebe Leserin, lieber Leser, erforschen, was die Welt im Innersten zusammenhält- das ist für viele Studierende ein Traum. Doch welche Opfer muss man bringen, um ihn zu verwirklichen? Welche Bemfsperspektive hat der Bemf Forscher heute noch? Auch viele Absolventen der Universität Potsdam müssen sich diese Fragen beantworten. Zu welchen Antworten einige dabei gekommen sind und welche Probleme sie zu bewältigen haben, vom Spaß am Forschen und von Zukunftsängsten berichten sie in der Rubrik "Forscherkarrieren". Gelder für die Forschung fließen in Deutschland zu spärlich, verglichen mit anderen führenden Industrienationen. So sind die Bedingungen für Forscher hierzulande nicht die besten. Manchen jungen Wissenschaftler zieht es- mitunter notgedrungen- ins Ausland. Wie Deutschland dadurch seine ZukunftsHihigkeit riskiert, thematisiert der Präsident der Fraunhofer-Gesellschaft, Prof. Dr. Hans-Jörg Bullinger, in der Rubrik "wissenstransfer". Auch die Universität ist kein Garant für eine gesicherte Zukunft in der Forschung. Wer sechs Jahre nach der Promotion den Sprung zur Professur nicht geschafft hat, geht einer ungewissen Zukunft als Privatdozent entgegen. Seit einigen Jahren gibt es neben der Habilitation noch einen zweiten Weg zur Professur- die Juniorprofessur. Auch an der Universität Potsdam gibt es seit 2002 Juniorprofessoren, von denen die ersten jetzt evaluiert wurden. Näheres dazu finden Sie ebenfalls in der Rubrik "wissenstransfer". Wer noch nach einer Finanzierungsmöglichkeit für seine Promotion sucht, findet Tipps in der Rubrik "wegweiser". Die Redaktion wünscht Ihnen viel Vergnügen beim Lesen von Portal alumni und freut sich auf zahlreiche Leserbriefe. N2 - Dear readers, many students dream of researching the world's inner and outermost secrets. Still, what sacrifice must one bring in order to achieve this goa/, and what are the professional perspectives being offered to researchers today? Many University of Potsdom alumni have to find answers to these questions as weil. in the section "forscher/eben", a number of alumni discuss their answers, the problems that they have encountered along the way, the enJoyment that they have received through their research and their worries for the future. In Germany, the funding of research on part ofboth the state and the corporate world is sparsein comparison to other leading industrial countries, and the current opportunities for researchers are clearly not the best. in the section ,.wissenstransfer", the president of the Frauenhofer-Gesellschaft, Prof Dr. Hans-jörg Bullinger, discusses how Germany is losing its future potential in the process. Indeed, the university is no guarantee for a secure profossianal future in the research field. A few years ago, the Junior professorship was created as a second path to a Juli professorship, next to the traditional postdoctoral qualification (Habilitation). in 2002, the University of Potsdom began to establish Junior professorships. The first of these are currently being evaluated. More information on this process can be found in the section "wissenstransfer". In addition, suggestions and tips can be found in the section "wegweiser" for those who are seekingfunding opportunities for their dissertation work. T3 - Portal alumni : das Ehemaligen-Magazin der Universität Potsdam - 3/2005 Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-481608 VL - 2005 IS - 3 EP - 58 ER - TY - GEN A1 - Hartmann, Stefanie A1 - Vision, Todd J. T1 - Using ESTs for phylogenomics BT - can one accurately infer a phylogenetic tree from a gappy alignment? T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - Background While full genome sequences are still only available for a handful of taxa, large collections of partial gene sequences are available for many more. The alignment of partial gene sequences results in a multiple sequence alignment containing large gaps that are arranged in a staggered pattern. The consequences of this pattern of missing data on the accuracy of phylogenetic analysis are not well understood. We conducted a simulation study to determine the accuracy of phylogenetic trees obtained from gappy alignments using three commonly used phylogenetic reconstruction methods (Neighbor Joining, Maximum Parsimony, and Maximum Likelihood) and studied ways to improve the accuracy of trees obtained from such datasets. Results We found that the pattern of gappiness in multiple sequence alignments derived from partial gene sequences substantially compromised phylogenetic accuracy even in the absence of alignment error. The decline in accuracy was beyond what would be expected based on the amount of missing data. The decline was particularly dramatic for Neighbor Joining and Maximum Parsimony, where the majority of gappy alignments contained 25% to 40% incorrect quartets. To improve the accuracy of the trees obtained from a gappy multiple sequence alignment, we examined two approaches. In the first approach, alignment masking, potentially problematic columns and input sequences are excluded from from the dataset. Even in the absence of alignment error, masking improved phylogenetic accuracy up to 100-fold. However, masking retained, on average, only 83% of the input sequences. In the second approach, alignment subdivision, the missing data is statistically modelled in order to retain as many sequences as possible in the phylogenetic analysis. Subdivision resulted in more modest improvements to alignment accuracy, but succeeded in including almost all of the input sequences. Conclusion These results demonstrate that partial gene sequences and gappy multiple sequence alignments can pose a major problem for phylogenetic analysis. The concern will be greatest for high-throughput phylogenomic analyses, in which Neighbor Joining is often the preferred method due to its computational efficiency. Both approaches can be used to increase the accuracy of phylogenetic inference from a gappy alignment. The choice between the two approaches will depend upon how robust the application is to the loss of sequences from the input set, with alignment masking generally giving a much greater improvement in accuracy but at the cost of discarding a larger number of the input sequences. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 889 KW - Maximum Parsimony KW - pairwise distance KW - phylogenetic inference KW - alignment error KW - Maximum Parsimony tree Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-436670 SN - 1866-8372 IS - 889 ER - TY - JOUR A1 - Cheng, Fuxia A1 - Hartmann, Stefanie A1 - Gupta, Mayetri A1 - Ibrahim, Joseph G. A1 - Vision, Todd J. T1 - A hierarchical model for incomplete alignments in phylogenetic inference N2 - Motivation: Full-length DNA and protein sequences that span the entire length of a gene are ideally used for multiple sequence alignments (MSAs) and the subsequent inference of their relationships. Frequently, however, MSAs contain a substantial amount of missing data. For example, expressed sequence tags (ESTs), which are partial sequences of expressed genes, are the predominant source of sequence data for many organisms. The patterns of missing data typical for EST-derived alignments greatly compromise the accuracy of estimated phylogenies. Results: We present a statistical method for inferring phylogenetic trees from EST-based incomplete MSA data. We propose a class of hierarchical models for modeling pairwise distances between the sequences, and develop a fully Bayesian approach for estimation of the model parameters. Once the distance matrix is estimated, the phylogenetic tree may be constructed by applying neighbor-joining (or any other algorithm of choice). We also show that maximizing the marginal likelihood from the Bayesian approach yields similar results to a pro. le likelihood estimation. The proposed methods are illustrated using simulated protein families, for which the true phylogeny is known, and one real protein family. Y1 - 2009 UR - http://bioinformatics.oxfordjournals.org/ U6 - https://doi.org/10.1093/bioinformatics/btp015 SN - 1367-4803 ER - TY - GEN A1 - Bleidorn, Christoph A1 - Podsiadlowski, Lars A1 - Zhong, Min A1 - Eeckhaut, Igor A1 - Hartmann, Stefanie A1 - Halanych, Kenneth M. A1 - Tiedemann, Ralph T1 - On the phylogenetic position of Myzostomida : can 77 genes get it wrong? N2 - Background: Phylogenomic analyses recently became popular to address questions about deep metazoan phylogeny. Ribosomal proteins (RP) dominate many of these analyses or are, in some cases, the only genes included. Despite initial hopes, hylogenomic analyses including tens to hundreds of genes still fail to robustly place many bilaterian taxa. Results: Using the phylogenetic position of myzostomids as an example, we show that phylogenies derived from RP genes and mitochondrial genes produce incongruent results. Whereas the former support a position within a clade of platyzoan taxa, mitochondrial data recovers an annelid affinity, which is strongly supported by the gene order data and is congruent with morphology. Using hypothesis testing, our RP data significantly rejects the annelids affinity, whereas a platyzoan relationship is significantly rejected by the mitochondrial data. Conclusion: We conclude (i) that reliance of a set of markers belonging to a single class of macromolecular complexes might bias the analysis, and (ii) that concatenation of all available data might introduce conflicting signal into phylogenetic analyses. We therefore strongly recommend testing for data incongruence in phylogenomic analyses. Furthermore, judging all available data, we consider the annelid affinity hypothesis more plausible than a possible platyzoan affinity for myzostomids, and suspect long branch attraction is influencing the RP data. However, this hypothesis needs further confirmation by future analyses. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 123 KW - Cirriferum myzostomida KW - Mitochondrial genomes KW - Transfer-rna KW - Data sets KW - Sequence Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44893 ER - TY - JOUR A1 - Schröder, Christiane A1 - Bleidorn, Christoph A1 - Hartmann, Stefanie A1 - Tiedemann, Ralph T1 - Occurrence of Can-SINEs and intron sequence evolution supports robust phylogeny of pinniped carnivores and their terrestrial relatives N2 - Investigating the dog genome we found 178965 introns with a moderate length of 200-1000 bp. A screening of these sequences against 23 different repeat libraries to find insertions of short interspersed elements (SINEs) detected 45276 SINEs. Virtually all of these SINEs (98%) belong to the tRNA-derived Can-SINE family. Can-SINEs arose about 55 million years ago before Carnivora split into two basal groups, the Caniformia (doglike carnivores) and the Feliformia (cat-like carnivores). Genome comparisons of dog and cat recovered 506 putatively informative SINE loci for caniformian phylogeny. In this study we show how to use such genome information of model organisms to research the phylogeny of related non-model species of interest. Investigating a dataset including representatives of all major caniformian lineages, we analysed 24 randomly chosen loci for 22 taxa. All loci were amplifiable and revealed 17 parsimony- informative SINE insertions. The screening for informative SINE insertions yields a large amount of sequence information, in particular of introns, which contain reliable phylogenetic information as well. A phylogenetic analysis of intron- and SINE sequence data provided a statistically robust phylogeny which is congruent with the absence/presence pattern of our SINE markers. This phylogeny strongly supports a sistergroup relationship of Musteloidea and Pinnipedia. Within Pinnipedia, we see strong support from bootstrapping and the presence of a SINE insertion for a sistergroup relationship of the walrus with the Otariidae. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/03781119 U6 - https://doi.org/10.1016/j.gene.2009.06.012 SN - 0378-1119 ER - TY - BOOK A1 - Hartmann, Stefanie A1 - Selbig, Joachim T1 - Introductory Bioinformatics Y1 - 2009 SN - 978-3-8370-5189-6 PB - Books on Demand CY - Norderstedt ER - TY - JOUR A1 - Struck, Torsten H. A1 - Paul, Christiane A1 - Hill, Natascha A1 - Hartmann, Stefanie A1 - Hoesel, Christoph A1 - Kube, Michael A1 - Lieb, Bernhard A1 - Meyer, Achim A1 - Tiedemann, Ralph A1 - Purschke, Guenter A1 - Bleidorn, Christoph T1 - Phylogenomic analyses unravel annelid evolution JF - Nature : the international weekly journal of science N2 - Annelida, the ringed worms, is a highly diverse animal phylum that includes more than 15,000 described species and constitutes the dominant benthic macrofauna from the intertidal zone down to the deep sea. A robust annelid phylogeny would shape our understanding of animal body-plan evolution and shed light on the bilaterian ground pattern. Traditionally, Annelida has been split into two major groups: Clitellata (earthworms and leeches) and polychaetes (bristle worms), but recent evidence suggests that other taxa that were once considered to be separate phyla (Sipuncula, Echiura and Siboglinidae (also known as Pogonophora)) should be included in Annelida(1-4). However, the deep-level evolutionary relationships of Annelida are still poorly understood, and a robust reconstruction of annelid evolutionary history is needed. Here we show that phylogenomic analyses of 34 annelid taxa, using 47,953 amino acid positions, recovered a well-supported phylogeny with strong support for major splits. Our results recover chaetopterids, myzostomids and sipunculids in the basal part of the tree, although the position of Myzostomida remains uncertain owing to its long branch. The remaining taxa are split into two clades: Errantia (which includes the model annelid Platynereis), and Sedentaria (which includes Clitellata). Ancestral character trait reconstructions indicate that these clades show adaptation to either an errant or a sedentary lifestyle, with alteration of accompanying morphological traits such as peristaltic movement, parapodia and sensory perception. Finally, life history characters in Annelida seem to be phylogenetically informative. Y1 - 2011 U6 - https://doi.org/10.1038/nature09864 SN - 0028-0836 VL - 471 IS - 7336 SP - 95 EP - U113 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Burleigh, J. Gordon A1 - Bansal, Mukul S. A1 - Eulenstein, Oliver A1 - Hartmann, Stefanie A1 - Wehe, Andre A1 - Vision, Todd J. T1 - Genome-Scale Phylogenetics inferring the plant tree of life from 18,896 gene trees JF - Systematic biology N2 - Phylogenetic analyses using genome-scale data sets must confront incongruence among gene trees, which in plants is exacerbated by frequent gene duplications and losses. Gene tree parsimony (GTP) is a phylogenetic optimization criterion in which a species tree that minimizes the number of gene duplications induced among a set of gene trees is selected. The run time performance of previous implementations has limited its use on large-scale data sets. We used new software that incorporates recent algorithmic advances to examine the performance of GTP on a plant data set consisting of 18,896 gene trees containing 510,922 protein sequences from 136 plant taxa (giving a combined alignment length of >2.9 million characters). The relationships inferred from the GTP analysis were largely consistent with previous large-scale studies of backbone plant phylogeny and resolved some controversial nodes. The placement of taxa that were present in few gene trees generally varied the most among GTP bootstrap replicates. Excluding these taxa either before or after the GTP analysis revealed high levels of phylogenetic support across plants. The analyses supported magnoliids sister to a eudicot + monocot clade and did not support the eurosid I and II clades. This study presents a nuclear genomic perspective on the broad-scale phylogenic relationships among plants, and it demonstrates that nuclear genes with a history of duplication and loss can be phylogenetically informative for resolving the plant tree of life. KW - Gene tree-species tree reconciliation KW - gene tree parsimony KW - plant phylogeny KW - phylogenomics Y1 - 2011 U6 - https://doi.org/10.1093/sysbio/syq072 SN - 1063-5157 VL - 60 IS - 2 SP - 117 EP - 125 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Bonizzoni, Mariangela A1 - Bourjea, Jerome A1 - Chen, Bin A1 - Crain, B. J. A1 - Cui, Liwang A1 - Fiorentino, V. A1 - Hartmann, Stefanie A1 - Hendricks, S. A1 - Ketmaier, Valerio A1 - Ma, Xiaoguang A1 - Muths, Delphine A1 - Pavesi, Laura A1 - Pfautsch, Simone A1 - Rieger, M. A. A1 - Santonastaso, T. A1 - Sattabongkot, Jetsumon A1 - Taron, C. H. A1 - Taron, D. J. A1 - Tiedemann, Ralph A1 - Yan, Guiyun A1 - Zheng, Bin A1 - Zhong, Daibin T1 - Permanent genetic resources added to molecular ecology resources database 1 April 2011-31 May 2011 JF - Molecular ecology resources N2 - This article documents the addition of 92 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Anopheles minimus, An. sinensis, An. dirus, Calephelis mutica, Lutjanus kasmira, Murella muralis and Orchestia montagui. These loci were cross-tested on the following species: Calephelis arizonensi, Calephelis borealis, Calephelis nemesis, Calephelis virginiensis and Lutjanus bengalensis. Y1 - 2011 U6 - https://doi.org/10.1111/j.1755-0998.2011.03046.x SN - 1755-098X VL - 11 IS - 5 SP - 935 EP - 936 PB - Wiley-Blackwell CY - Malden ER - TY - THES A1 - Hartmann, Stefanie T1 - Phylogenomics: comparative genome analysis ursing large-scale gene family data Y1 - 2011 CY - Potsdam ER -