BACKGROUND: The advancement of sequencing technologies results in the rapid release of hundreds of new genome assemblies a year providing unprecedented resources for the study of genome evolution. Within this context, the significance of in-depth analyses of repetitive elements, transposable elements (TEs) in particular, is increasingly recognized in understanding genome evolution. Despite the plethora of available bioinformatic tools for identifying and annotating TEs, the phylogenetic distance of the target species from a curated and classified database of repetitive element sequences constrains any automated annotation effort. Moreover, manual curation of raw repeat libraries is deemed essential due to the frequent incompleteness of automatically generated consensus sequences. RESULTS: Here, we present an example of a crowd-sourcing effort aimed at curating and annotating TE libraries of two non-model species built around a collaborative, peer-reviewed teaching process. Manual curation and classification are time-consuming processes that offer limited short-term academic rewards and are typically confined to a few research groups where methods are taught through hands-on experience. Crowd-sourcing efforts could therefore offer a significant opportunity to bridge the gap between learning the methods of curation effectively and empowering the scientific community with high-quality, reusable repeat libraries. CONCLUSIONS: The collaborative manual curation of TEs from two tardigrade species, for which there were no TE libraries available, resulted in the successful characterization of hundreds of new and diverse TEs in a reasonable time frame. Our crowd-sourcing setting can be used as a teaching reference guide for similar projects: A hidden treasure awaits discovery within non-model organisms.

Anglia Ruskin University East Rd Cambridge CB1 1PT UK

Berlin Center for Genomics in Biodiversity Research 14195 Berlin Germany

Biological and Environmental Science and Engineering Division King Abdullah University of Science and Technology Thuwal Saudi Arabia

Centogene GmbH Am Strande 7 18055 Rostock Germany

Centre for Molecular Biodiversity Research Leibniz Institute for the Analysis of Biodiversity Change Adenauerallee 127 53113 Bonn Germany

Departamento de Biodiversidad y Biología Evolutiva Museo Nacional de Ciencias Naturales José Gutiérrez Abascal 2 Madrid 28006 Spain

Department of Bioinformatics and Genetics Swedish Natural History Museum Stockholm Sweden

Department of Biological and Environmental Science University of Jyväskylä P O Box 35 Jyväskylä 40014 Finland

Department of Biological Geological and Environmental Science University of Bologna Via Selmi 3 Bologna 40126 Italy

Department of Biological Sciences University of Notre Dame Notre Dame IN 46556 USA

Department of Biotechnology National Institute of Technology Durgapur Durgapur India

Department of Botany Jagannath Univerity Dhaka 1100 Bangladesh

Department of Ecology and Evolution The University of Chicago Chicago IL 60637 USA

Department of Ecology and Evolutionary Biology University of California Los Angeles Los Angeles CA United States of America

Department of Ecology and Genetics Uppsala University Uppsala Sweden

Department of Ecology Faculty of Science Charles University Prague Czech Republic

Department of Genetics Environment and Evolution Centre for Biodiversity and Environment Research University College London London UK

Department of Organismal Biology Systematic Biology Evolutionary Biology Centre Uppsala University Uppsala SE 752 36 Sweden

Department of Systematic and Evolutionary Botany University of Zurich Zurich Switzerland

Eurofins Genomics Europe Pharma and Diagnostics Products and Services Sales GmbH Ebersberg Germany

Evolutionary Biology and Ecology University of Freiburg Freiburg Germany

Evolutionary Genetics Department Leibniz Institute for Zoo and Wildlife Research 10315 Berlin Germany

German Cancer Research Center NGS Core Facility DKFZ ZMBH Alliance 69120 Heidelberg Germany

INBIOS Conservation Genetic Lab University of Liege Liege Belgium

Institute of Botany Czech Academy of Sciences Průhonice Czech Republic

Institute of Evolution and Ecology University of Tuebingen Tuebingen Germany

Institute of Evolutionary Biology Faculty of Biology Biological and Chemical Research Centre University of Warsaw Warsaw Poland

Institute of Genetics and Biotechnology Hungarian University of Agriculture and Life Sciences Budapest Hungary

Institute of Hydrobiology Biology Centre of the Czech Academy of Sciences České Budějovice Czech Republic

LOEWE Centre for Translational Biodiversity Genomics Senckenberganlage 25 60325 Frankfurt Germany

Molecular Ecology Group Verbania Italy

Natural History Museum Oslo University Oslo Norway

New York University Abu Dhabi Saadiyat Island United Arab Emirates

Physalia courses 10249 Berlin Germany

Plant Pathology Group Institute of Integrative Biology ETH Zurich Zurich Switzerland

Present address Centre for Molecular Biodiversity Research Leibniz Institute for the Analysis of Biodiversity Change Adenauerallee 160 53113 Bonn Germany

Reed College Portland OR United States of America

Research Unit Comparative Microbiome Analysis Helmholtz Zentrum München Ingolstädter Landstraße 1 D 85764 Neuherberg Germany

Royal Botanic Gardens Kew Richmond Surrey TW9 3AE UK

School of Biological Sciences University of East Anglia Norwich Research Park Norwich NR4 7TU UK

Skolkovo Institute of Science and Technology Moscow Russia

Swiss Ornithological Institute Vogelwarte Sempach CH 6204 Switzerland

The Natural History Museum Cromwell Road London SW6 7SJ UK

Tree of Life Wellcome Sanger Institute Cambridge CB10 1SA UK

University of Arizona Tucson AZ USA

Zell und Molekularbiologie der Pflanzen Technische Universität Dresden Dresden Germany

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