Overcoming the Challenges of Studying Soil Nematodes: A New Approach with Implications for All (Soil) Organisms

Post provided by Stefan Geisen

(Soil) Nematodes

“…if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes…” (Cobb 1914)

He may have said it more than a century ago but we now, more than ever, realise that Nathan Augustus Cobb was right. Nematodes are by far the most abundant animals soil, freshwater and marine ecosystems. These tiny worms are barely visible to the human eye (if they’re visible at all), hundreds can inhabit a single gram of soil . Their similar shape might lead you to think that they’re all alike, but that’s not the case. More than 25,000 species have been identified and estimates put their entire species diversity in the 100,000s.

Some common nematode species found in most soils. a) Plectus sp; b) Aphelenchus sp; c) Helicotylenchus sp; d) Thonus sp; e) Mononchus sp; © Wageningen University, Laboratory of Nematology, NL; Hanny van Megen

Some common nematode species found in most soils. a) Plectus sp, b) Aphelenchus sp, c) Helicotylenchus sp, d) Thonus sp, e) Mononchus sp. © Wageningen University, Laboratory of Nematology, NL; Hanny van Megen

This taxonomic and functional diversity has boosted nematodes to become useful bioindicators for soil quality. Nematodes perform many different functions in both terrestrial and aquatic ecosystems. These are mainly defined by what they eat:

  • Bacteria/Fungi: Many nematode groups eat bacteria and fungi. They control the population of these organisms and keep them active.
  • Plants: Plant feeders are the unwanted guests in agricultural systems as well as in our gardens. They can destroy entire harvests by piercing into or infiltrating roots.
  • Omnivores/Predators: Many nematode species prey on other smaller organisms including smaller nematodes and control their abundances.
  • Parasites: These species inhabit other larger organisms and can act as biocontrol agents.

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Editor Recommendation: Assessing Strengths and Weaknesses of DNA Metabarcoding-Based Macroinvertebrate Identification for Routine Stream Monitoring

Post provided by Andrew R. Mahon

The use of molecular methods for monitoring and surveillance of organisms in aquatic and marine systems has become more and more common. We’ve since expanded this technology this through using both captured whole organisms and collecting/filtering environmental DNA (eDNA).  These methods naturally migrated from single species, active surveillance methods towards using high throughput sequencing as a method of passive surveillance via metabarcoding.

In this virtual issue, the article “Assessing strengths and weaknesses of DNA metabarcoding-based macroinvertebrate identification for routine stream monitoring” by Vasco Elbrecht et al. provides an excellent overview to the field. It also helps to clarify the work being done to provide interested groups, including management agencies, with the best practices for utilising these new methods for monitoring and surveillance.  This work will help the field, particularly for those searching for rare species of organisms in aquatic systems.

I’d recommend this paper to all researchers and management groups interested in applying metabarcoding techniques to answer both experimental and applied questions. The design of this article will provide both experienced researchers and those new to the field with important information to further this rapidly expanding field.

To find out more about, read the full Methods in Ecology and Evolution article ‘Assessing strengths and weaknesses of DNA metabarcoding-based macroinvertebrate identification for routine stream monitoring

 This article is part of ‘Practical Tools: A Field Methods Virtual Issue’. All articles in this Virtual Issue will be available for a limited time.

Practical Tools: A New Article Type and a Virtual Issue

Today, we’re pleased to announce that we’re launching a new article type for Methods in Ecology and Evolution: Practical Tools. Like our Applications articles, Practical Tools will be short papers (up to 3000 words). They’ll focus on new field techniques, equipment or lab protocols. From this point forward, our Applications papers will solely focus on software and code.

Practical tools need to clearly demonstrate how tools designed for specific systems or problems can be adapted for more general use. Online supporting information can include specific instructions, especially for building equipment. You can find some examples of Applications that would now fit into this article type here and here.

To help launch our new article type, we asked four of our Associate Editors – Pierre Durand, Graziella Iossa, Nicolas Lecomte and Andrew Mahon – to put together a Virtual Issue of papers about Field Methods that have previously been published in the journal. All of the articles in ‘Practical Tools: A Field Methods Virtual Issue‘ will be free to everyone for the next month. You can find out a bit more about each of the four sections of the Virtual Issue below. Continue reading

Microbial Methods Virtual Issue

The BES Microbial Ecology Special Interest Group is running a workshop today (Thursday 2 November) on Novel Tools for Microbial Ecology. To compliment this workshop, Xavier Harrison has edited a Virtual Issue of the best Methods in Ecology and Evolution articles on advances in methods of studying microbial evolution and ecology from the past few years.

Advances in Next-Generation Sequencing (NGS) technology now allow us to study associations between hosts and their microbial communities in unprecedented detail. However, studies investigating host-microbe interactions in the field of ecology and evolution are dominated by 16S and ITS amplicon sequencing. While amplicon sequencing is a useful tool for describing microbial community composition, it is limited in its ability to quantify the function(s) performed by members of those communities. Characterising function is vital to understanding how microbes and their hosts interact, and consequently whether those interactions are adaptive for, or detrimental to, the host. The articles in this Virtual Issue cover a broad suite of approaches that allow us to study host-microbe and microbe-microbe interactions in novel ways.

All of the articles in the Microbial Methods Virtual Issue will be freely available for the next two months. You can find out a little more about each one below. Continue reading

Assessment of Stream Health with DNA Metabarcoding

Following on from last week’s press release ‘How Clean are Finnish Rivers?’, Vasco Elbrecht et al. have produced a video to explain the methods in ‘Assessing strengths and weaknesses of DNA metabarcoding-based macroinvertebrate identification for routine stream monitoring‘.

In this video, the authors explore the potential of DNA metabarcoding to access stream health using macroinvertebrates. They compared DNA and morphology-based identification of bulk monitoring samples from 18 Finnish stream ecosystems. DNA-based methods show higher taxonomic resolution and similar assessment results as currently used morphology-based methods. Their study shows that the tested DNA-based methods integrate well with current approaches, but further optimisation and validation of DNA metabarcoding methods is encouraged.

This video is based on the article ‘Assessing strengths and weaknesses of DNA metabarcoding-based macroinvertebrate identification for routine stream monitoring‘ by Elbrecht et al.

 

Fast-Moving Biodiversity Assessment: Are We Already in the Future?

Post provided by Carola Gómez-Rodríguez & Alfried P. Vogler

Time flies… in the blink of an eye! And even more so in science. The molecular lab work we were used to two decades ago seems like ancient history to today’s PhD students. The speed of change in sequencing technology is so overwhelming that imagination usually fails to foresee how our daily work will be in 10 years’ time. But in the field of biodiversity assessment, we have very good clues. Next Generation Sequencing is quickly becoming our workhorse for ambitious projects of species and genetic inventories.

One by One Approach to Studying Biodiversity

For decades, most initiatives measured biodiversity in the same way: collect a sample of many individuals in the field, sort the specimens, identify them to a Linnaean species one at a time (if there was a good taxonomist in the group which, unfortunately, it is kind of lucky these days!), and count them. Or, if identification was based on molecular data, the specimen was subject to DNA extraction, to sequence one (or several) short DNA markers. This involved countless hours of work that could be saved if, instead of inventorying biodiversity specimen-by-specimen, we followed a sample-by-sample approach. To do this now, we just have to make a “biodiversity soup”.

Biodiversity assessment based on morphological identification and/or Sanger sequencing (“The one-by-one approach”)

Biodiversity assessment based on morphological identification and/or Sanger sequencing (“The one-by-one approach”)

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How Clean are Finnish Rivers?

Below is a press release about the Methods paper ‘Assessing strengths and weaknesses of DNA metabarcoding-based macroinvertebrate identification for routine stream monitoring‘ taken from the University of Duisburg-Essen.

©Shanthanu Bhardwaj

©Shanthanu Bhardwaj

Dragonflies, mayflies and water beetles have one thing in common: They indicate how clean the streams are in which they live. Scientists from the University of Duisburg-Essen and the Finnish Environment Institute (SYKE) have developed a DNA-based method, which allows to assess the stream water quality with unprecedented speed and accuracy. The article – ‘Assessing strengths and weaknesses of DNA metabarcoding-based macroinvertebrate identification for routine stream monitoring‘ – was just released in the esteemed peer-reviewed journal Methods in Ecology and Evolution.

Traditional stream assessment using visual identification of indicator species is time-consuming, expensive and procedures are seldom standardised. Especially small organisms may look similar and misidentifications happen frequently. Using a genetic method to identify the species these concerns are not an issue, as even small organisms can be securely identified using a DNA marker. Continue reading

Issue 8.4: Technological Advances at the Interface of Ecology and Statistics

Issue 8.4 is now online!

The April issue of Methods, which includes our latest Special Feature – “Technological Advances at the Interface of Ecology and Statistics” – is now online!

This new Special Feature is a collection of five articles (plus an Editorial from Guest Editor David Warton) inspired by the December 2015 Eco-Stats conference at the University of New South Wales in Australia. It shows how interdisciplinary collaboration help to solve problems around estimating biodiversity and how it changes over space and time.

The five articles are based on joint talks given at the conference. They focus on:

As David Warton states in his Editorial, “interdisciplinary collaboration and the opportunities offered by recent technological advances have potential to lead to interesting and sometimes surprising findings, and will continue to be fertile ground for scientists in the foreseeable future”. Meetings like Eco-Stats 15 and Special Features like this one will, hopefully, help to encourage these sorts of collaborative research projects.

All of the articles in the ‘Technological Advances at the Interface of Ecology and Statistics‘ Special Feature will be freely available for a limited time.
Continue reading

New Associate Editors

Today we are welcoming two new people to the Methods in Ecology and Evolution Associate Editor Board. Pierre Durand is joining us from the University of the Witwatersrand (South Africa) and Andrew Mahon joins from Central Michigan University (USA). You can find out more about Pierre and Andrew below.

Pierre Durand

Pierre Durand

“My research is broadly focussed on the evolution of complexity. Many of my projects are related to the evolutionary ecology of programmed cell death (PCD) in unicellular organisms; how PCD impacts microbial communities; and how the philosophy of levels of selection informs our understanding of PCD evolution. I have also examined other aspects of complexity evolution such as the origin of life and group formation in unicellular chlorophytes in response to predation. The model organisms I typically use are phytoplankton. With specific reference to submissions to Methods in Ecology and Evolution, I have used a range of methods in my research, including general cell and molecular biology tools, biochemical assays, microscopy, flow cytometry, bioinformatics and computational algorithms.”

The most current projects in Pierre’s laboratory concern: programmed cell death evolution and complexity in microbial communities; changes in phytoplankton abundance and diversity in harmful algal blooms, led by PhD candidate Andrew Ndhlovu (“A red tide forming dinoflagellate Prorocentrum triestinum: identification, phylogeny and impacts on St Helena Bay, South Africa” in review in Phycologia); and the genomics of the four-celled chlorophyte Tetrabaena socialis, led by PhD candidate Jonathan Featherson.

Andrew Mahon

Andrew Mahon

“I’m a molecular ecologist who uses genetic and genomic tools to ask questions ranging from surveillance and monitoring to biodiversity and phylogeography.  My work includes development of novel molecular detection tools and metabarcoding applications for aquatic invasive species.  I’m also interested in applying molecular tools to ask questions related to the evolution and biodiversity of benthic marine invertebrates in Antarctica.”

Andrew has recently been published in the journal Research Ideas and Outcomes (‘DNAqua-Net: Developing new genetic tools for bioassessment and monitoring of aquatic ecosystems in Europe‘) and in Environmental Science and Technology (‘Influence of Stream Bottom Substrate on Retention and Transport of Vertebrate Environmental DNA‘). He also has a manuscript in press with Ecology and Evolution (‘Geographic structure in the Southern Ocean circumpolar brittle star Ophionotus victoriae (Ophiuridae) revealed from mtDNA and single-nucleotide polymorphism data‘).

We are thrilled to welcome Pierre and Andrew to the Associate Editor Board and we look forward to working with them over the coming years.

The Field Guide to Sequence-Based Identification of Biodiversity: An Interview with Simon Creer

In a new Methods in Ecology and Evolution podcast, Georgina Brennan (Bangor University) interviews Simon Creer (Bangor University) about his article ‘The ecologist’s field guide to sequence-based identification of biodiversity‘. They talk about about where the idea for the paper came from, what it’s aim are and who will benefit from it. We hear how new sequences can improve and enhance current biomonitoring programmes (and make them quicker and cheaper).

To find out more about Sequence-based Identification of Biodiversity, read the Open Access Methods in Ecology and Evolution article ‘The ecologist’s field guide to sequence-based identification of biodiversity‘.