GBOL III: Dark Taxa

GBOL III: Dark Taxa

GBOL III: Dark Taxa

Researchers launch new BIOSCAN project that aims to illuminate thousands of new insect species on Germany's doorstep.

A “pixelated” Diptera.

Currently, around 1.4 million species of animals are known. For tropical regions, many species are still unknown, with estimates of global biodiversity ranging from five to 30 or even 100 million species. More recent studies suggest that there are about 10 million species on our planet. In contrast to the tropics, the Central European fauna is considered to be very well studied. However, specialists have mostly concentrated on less diverse and easy-to-study organisms, neglecting the species-rich, often taxonomically difficult groups, like many Diptera and Hymenoptera. This led to a mismatch between high species numbers and a small number of researchers, often referred to as the ‘taxonomic impediment’. This is most prominent for the megadiverse faunas of tropical regions. Less known is that this also applies, to some extent, for countries with a long history of taxonomic research like Germany, covering 200 or more years. For example, for the compilation of the German checklist of Hymenoptera, 32 specialists were available for 247 species of digger wasps (Crabronidae), while for parasitoid wasps of the family Ichneumonidae one specialist had to deal with 3,332 species.

In Germany, about 48,000 species of animals have been documented, including about 33,300 species of insects. In little-studied groups such as insects and arachnids, preliminary results of earlier DNA barcoding initiatives indicate the presence of thousands of species that are still awaiting discovery. Among the groups with a particularly large suspected number of unknown species are the Diptera (flies) and the Hymenoptera (in particular, the parasitoid wasps). With almost 10,000 known species each, these two insect orders account for two-thirds of the German insect fauna, underlining their importance.

Bar Graph depicting availability of taxonomic expertise for major insects orders in Germany.

“Dark taxa” are, as a rule, small-sized and rich in species, and have therefore been largely ignored by taxonomists. This is reflected by the number of undescribed species in these taxa, combined with a low chance to get specimens identified by specialists.

The insight that there are not only a few but many unknown species in Germany is a result of the earlier German Barcode of Life projects GBOL I and II, both supported by the Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, BMBF) and the Bavarian Ministry of Science (project Barcoding Fauna Bavarica). The projects aimed at making all German species reliably, quickly and inexpensively identifiable by DNA barcodes. Since the first project was launched about ten years ago, more than 25,000 animal species have been barcoded, in collaboration with national and international partners. Among them are mostly well-known groups such as butterflies, moths, beetles, grasshoppers, spiders, bees and wasps.

Two scatterplots demonstrating relationship between body size (top) and species richness (bottom) in German Diptera

Relationship between body size (top) and species richness (bottom) in German Diptera1

Despite their popularity, these groups represent only a fraction of the total inventory of German insects. In Germany there are 170 butterfly species, 81 dragonfly and damselfly species, 87 species of grasshoppers, katydids and crickets, and 580 species of ground beetles, all of which are well-studied. Taken together, these 918 species stand for only a small fraction (2.8%) of the German insect fauna. They are morphologically well identifiable, have manageable species numbers, can easily be monitored during daytime and are therefore regarded as relevant in nature conservation and often used for monitoring species diversity. Conversely, however, this means that the vast majority of the native species diversity has been largely ignored in nature conservation and in general and applied research.

Circular tree depicting Nematocera (midges) and Brachycera (flies)
A circular neighbour‐joining tree for the two suborders of flies, Nematocera and Brachycera1. Each line in the tree corresponds to a distinct Barcode Index Number (BIN). Whereas for two of the “big four” insect orders, the Lepidoptera and Coleoptera, the number of German species are very precisely known, the numbers for the Diptera and Hymenoptera must rely on rough estimates. 

This applies in particular to the Diptera (flies). The observation that estimates of the number of species of native Diptera have been far too low was not only a result of the DNA barcoding projects at the ZSM, but became clear in a recent study by Paul Hebert and his team2. In this large-scale study, DNA barcodes of about one million insects were analyzed. Based on this study, Canada’s gall midges alone are estimated to include about 16,000 species, suggesting the existence of at least two million species on earth. That would be more species of gall midges worldwide than all previously described animal species combined.

The little-known or unknown species, referred to as ‘dark taxa’, are the subject of another BMBF-funded DNA barcoding project that is being carried out at the ZSM in collaboration with other German natural history museums and institutions. The project focuses on Diptera and Hymenoptera (in particular, parasitoid wasps), each with a large proportion of ‘dark taxa’. The new project, funded by a grant of 5.3 million Euro, starts July 1st 2020, with 12 PhD students at three major natural history institutions in Bonn (Zoological Research Museum Alexander Koenig), Munich (SNSB – Zoologische Staatssammlung München) and Stuttgart (State Museum of Natural History Stuttgart), to address a range of questions related to the taxonomy of German ‘dark taxa’, targeting selected groups of Diptera and parasitoid Hymenoptera.

Detailed photo of a Eulophidae specimen
Yellow Mymaridae specimen

Small parasitoid wasps of the families Eulophidae (top) and Mymaridae (bottom), both group with possibly hundreds of new species in Germany that still await discovery.

Among the major aims of GBOL III is assessing of the performance of DNA barcoding for species identification of ‘dark taxa’, and assessing the species detection ability of DNA barcodes in mass samples that are obtained from metabarcoding studies. Other aims of the project include the development of a platform for managing OTU-based taxonomic data, developing a pipeline for reliable and fast barcoding of small and poor-quality samples, and training of the next generation of taxonomists.

GBOL III is designed to make an important contribution to the global BIOSCAN initiative of the Centre for Biodiversity Genomics. It helps to lay the foundations for a global biomonitoring system to record the biodiversity of our planet on a large geographical scale in times of rising temperatures, increasing weather extremes and receding ice, and to track its changes as a result of global environmental changes.

References:

1. Morinière J, Balke M, Doczkal D, Geiger MF, Hardulak LA, Haszprunar G, Hausmann A, Hendrich L, Regalado L, Rulik B, Schmidt S, Wägele J, Hebert PDN (2019) A DNA barcode library for 5,200 German flies and midges (Insecta: Diptera) and its implications for metabarcoding‐based biomonitoring. Molecular Ecology Resources 19: 900–928. https://doi.org/10.1111/1755-0998.13022

2. Hebert PDN, Ratnasingham S, Zakharov EV, Telfer AC, Levesque-Beaudin V, Milton MA, Pedersen S, Jannetta P, deWaard JR (2016) Counting animal species with DNA barcodes: Canadian insects. Philosophical Transactions of the Royal Society B: Biological Sciences 371: 20150333. https://doi.org/10.1098/rstb.2015.0333

Written by

Axel Hausmann

Axel Hausmann

SNSB - Zoologische Staatssammlung München, Munich, Germany

Lars Krogmann

Lars Krogmann

State Museum of Natural History Stuttgart, Stuttgart, Germany

Ralph S. Peters

Ralph S. Peters

Zoological Research Museum Alexander Koenig, Bonn, Germany

Vera Rduch

Vera Rduch

Zoological Research Museum Alexander Koenig, Bonn, Germany

Stefan Schmidt

Stefan Schmidt

SNSB - Zoologische Staatssammlung München, Munich, Germany

July 10, 2020

doi: 10.21083/ibol.v10i1.6242

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30 million reasons you will be missed

30 million reasons you will be missed

30 million reasons you will be missed

Pioneer field biologist, entomologist, and mentor, Terry Erwin passes away at age 79
Erwin supervising the trees at work, the Tiputini Research Station, Ecuador, 2013. PHOTO CREDIT: Beulah Garner

The world lost a brilliant mind last week when Terry L. Erwin passed away on May 11, 2020, at the age of 79. Many among us in the scientific community feel this great loss, for you did not need to have personally known, or even have met Erwin to recognize the name or appreciate the significance of his work.

    Erwin not only published prolifically on beetle systematics – describing four tribes, 22 genera, and 439 species of Carabidae – but also tremendously influenced the way many think about biodiversity.

    “He brought alive for many the far-off world and the mysteries therein of the neotropics,” said Beulah Garner, Senior Curator at the Natural History Museum in London, and Erwin’s colleague and friend of nine years. “I think it was the first time anyone, through their scientific exploration, had made a place and a fauna at once seem magical, touchable, and quantifiable.”

    Erwin was serving as a research entomologist and curator of Coleoptera at the Smithsonian Institution’s National Museum of Natural History at the time of his death. He was a pioneer in neotropical conservation biology and canopy research, having developed the study of tree canopy insects into an academic discipline as early as 1974.

    Notably, in his small paper in 1982 that examined canopy beetles and host plant relationships to understand the number of species present in an acre of Panamanian forest, Erwin dramatically expanded our conception of terrestrial insect diversity.

    Graphical abstract of Erwin’s 1982 paper IMAGE CREDIT: Michelle Lynn D’Souza

    As a young graduate student interested in using DNA barcoding to evaluate insect diversity in Central America and to assess global diversity estimates, Erwin’s work was a guidepost for my own research. His 1982 publication was particularly iconic. Ironically, it was in the last ‘throwaway’ paragraph (as he described it) – suggesting the presence of 30 million arthropod species, at the time estimated to be around one-and-a half million – that he sparked a global debate about the number of species on the planet.

    Even years later, he was enduring in his defense of the ‘30 million’ estimate, according to Garner. His holistic approach to field biology, with Carabidae at its core, enabled him to understand the relatedness of species as well as the mechanisms that drive such incredible diversity so clearly. “Even higher [than 30 million] he would say! And, having been in the field with him, with his meticulous observations of the microverse, his pioneering investigations into the forest canopy, I absolutely believe him,” said Garner. “These were not assumptions from a dataset, a modelling outcome, these were from direct in-field observations: a true naturalist.” While his estimate has been debated, refuted, and revised to approximately seven million arthropod species, the discussion remains active today.

    A true naturalist at home in the jungles of Yasuni National Park, Ecuador, 2018.
    PHOTO CREDIT: Beulah Garner

    While always having been interested in DNA-based techniques, it was not until much later in Erwin’s career that he used it in his own work. Heavily involved in the field of systematics, he was among the first of those in the early 1980s that experienced its infusion with the beginnings of gene sequencing. While in its own right revolutionary, sequencing technology was just another tool to study the natural world, one that would eventually be replaced by the tricorder, Erwin explained to Dr. Bilgenur Baloglu, then a Ph.D. student at the National University of Singapore studying chironomid diversity, in an interview during the International Congress of Entomology in Florida in 2016. He was referring to DNA barcoding and the beginnings of Drs. Paul Hebert and Dan Janzen’s tests with Costa Rican moths.

    As noted by Dr. Scott Miller, science committee member of the International Barcode of Life Consortium (iBOL) and deputy undersecretary at the Smithsonian Institution, Erwin was always enthusiastic about collaborations between iBOL and the Smithsonian to barcode insect genera, such as that currently funded by the Global Genome Initiative (GGI). He is the main reason that Carabid beetles were one of the first families covered under the project, contributing substantially to the species barcoded and deposited on the Barcode of Life Data Systems (BOLD), according to Miller. He also collaborated with Dr. Carlos Garcia-Robledo and others at the Smithsonian on a series of papers on insect-host plant relationships, among many others, that used DNA barcoding to identify the gut contents of insect herbivores as well as egg and larval plant associations to reconstruct species interactions in tropical networks.

    Miller first began working with Erwin in 1986 at the Smithsonian Institution as a postdoctoral fellow. Together they had a vision that became the Biodiversity in Latin America Tropics (BIOLAT), a program based around standardized sampling, something that may seem logical now, but was novel in fields like entomology at the time, according to Miller. Since then, a lot of other organizations have tried similar standardized programs but have struggled under the weight of the taxonomic impediment.  “When seen against this background, iBOL initiatives such as the Global Malaise Program or BioAlfa are truly amazing,” said Miller. “It is most unfortunate that DNA barcoding was not available when Terry started canopy fogging!”

    Erwin canopy fogging at 4 a.m. at the Onkone Gare camp, Yasuni National Park, Ecuador, 2018.
    PHOTO CREDIT: Beulah Garner

    From planning BIOLAT, to consulting for Biosphere 2 (the subject of the documentary ‘Spaceship Earth’), to the initial canopy fogging endeavour in Papua New Guinea (PNG) that eventually led to the Binatang Research Center and the PNG insect ecology program, Erwin encouraged, guided, and inspired Miller’s endeavours for years.

    Terry understood the importance of nurturing the next generation of talent, and especially the importance of diversifying the [scientific] pipeline.

    Dr. Scott Miller

    Science committee member of the International Barcode of Life Consortium (iBOL) and deputy undersecretary at the Smithsonian Institution

    “Terry understood the importance of nurturing the next generation of talent, and especially the importance of diversifying the [scientific] pipeline,” says Miller. “Terry was always eager to provide opportunities for young scientists, especially women, and people from developing countries.” While working together at the Smithsonian, Miller recounts how Erwin always hosted interns and fellows, bringing them to meetings and conferences, and trying to connect them to future opportunities.

    Erwin had the greatest spirit of academic generosity, quick to provide advice, a reference from his encyclopedic library, or specimens for one’s own research, according to Garner. Erwin nurtured a passion for discovery in many students and inspired it in even more biologists. As he told Bilgenur back in 2016, you do not become a biologist if you are out for money, but you do it for the joy of being out in the field. “For me, the bottom line is if you like fieldwork, be a biologist. It’s the best place to be,” said Erwin in her interview. “If you are out in the rainforest, every single day, actually maybe every hour, there’s a tremendous discovery. And that’s what’s really rewarding – discovery.”

    Erwin hunting Carabidae near the Tiputini Research Station, Ecuador, 2013.
    PHOTO CREDIT: Beulah Garner

    In the field, Garner recounts, Erwin would wake early, sit by the Tiputini river with black coffee and binoculars, and study the jungle whilst it woke. “Canopy fogging is a race to finish before the dawn and Terry was indefatigable,” said Garner. “It’s 4 a.m. in the primary jungles of South America, you’re setting up your traps, and Terry is right beside you, overseeing operations as if the rainforest were his orchestra and he the conductor.” In the evening after supper with head torch and aspirator, it would be time to go on a Carabidae hunt.

    It’s 4 a.m. in the primary jungles of South America, you’re setting up your traps, and Terry is right beside you, overseeing operations, as if the rainforest were his orchestra and he the conductor.

    Beulah Garner

    Senior Curator at the Natural History Museum, London

    He was fearless, saving Garner from a pack of marauding peccaries in Ecuador, as well as rescuing her from bivouacking army ants as they surrounded their camp in the dead of night. “He was and is the reason I endeavour to be a good field biologist,” said Garner. “His compassion and consideration and genuine every-day awe for the natural world is a method to live and work by.”

    Beulah Garner (left) and Terry Erwin (right) inspecting the flight intercept traps, Tiputini Research Station, Ecuador, 2013. PHOTO CREDIT: Dr. Kelly Swing

    Erwin very much valued the natural world, possessing an astute understanding of it that unfortunately, he takes with him. He feared having species reduced to just a sequence and believed that the rich natural history and the awe that the living world inspires in us needed to be accounted for as well, sentiments that led him to catalyze the Encyclopedia of Life (EOL) in 2004, according to Nana Naisbitt, EOL co-catalyst, founder of Chalkboard, and Erwin’s dear friend of 22 years. The EOL makes knowledge about life on Earth globally accessible and has had a long-standing collaboration with BOLD.

    As Naisbitt explained, Erwin was a profound mentor, one who changed the course of her life and the lives of many others through her work and her connection to him. He effectively snowballed Naisbitt’s career as a science champion, instrumental in her founding the Pinhead Institute, a science education non-profit and Smithsonian Affiliate. He was also key to many community outreach and mentorship programs while she worked as Executive Director of the Telluride Science Research Center, a job she got because of her work as the director of Pinhead. “It’s just impossible to say how many people he impacted,” said Naisbitt. “Terry liked to say that he plants seeds – ideas in students – and watches them grow. He planted countless seeds that grew strong and bright.”

    In Naisbitt’s assessment, Erwin was able to help so many people flourish because he possessed a phenomenal gift in the way he supported them and gave them confidence without being intrusive. “He connected me to the right people, then showed up for and supported me. Most times he would just sit there quietly in meetings and let me do the talking,” said Naisbitt. “His reputation and presence were enough – it conveyed the message, ‘I anoint this person’. In that way, he was so unbelievably respectful.”

    Naisbitt said that she had the impression Erwin believed he stood on the shoulders of giants. She described to me this image she had of him, of someone reaching down and pulling up younger scientists to stand on his shoulders. “And he did that so well. He did it over and over again, with immense generosity and without ego. And that is so rare.”

    His reputation and presence were enough – it conveyed the message, ‘I anoint this person’. In that way, he was so unbelievably respectful.

    Nana Naisbitt

    Founder of Chalkboard

    When Dr. Marlin Rice, back in a 2015 interview, asked Erwin how he would like others to remember him, his answer was simple – by what his students do. The influence a mentor has on their students and them on theirs, he described, is an unbroken chain that keeps connecting generations of thinkers. Erwin told Rice, “There’s this chain all the way from the great old-timers down through George [Ball – his Ph.D. mentor] and his students and what I’d like to do is to keep that chain going.”

    Indeed, Erwin’s brilliance, passion, and dedication for science extended those chains far beyond his students and colleagues, to countless others across space, like me. As the value of his research will certainly endure, those chains will also extend across time. Erwin was undoubtedly one of the rare ones among us whose influence has had, and will continue to have, an extraordinary reach.

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