The Right Tool for the Job: Using Zeta Diversity to Communicate Uncertainty in Ecological Modelling

Post provided by Mariona Roigé

The Need for Modelling

Green vegetable bug nymph (Nezara viridula). ©John Marris. Lincoln University.

Green vegetable bug nymph (Nezara viridula). ©John Marris. Lincoln University.

Despite how far modelling has taken us in science, the use of models remains controversial. Modelling covers a huge range of common practices, from scaled models of ships to determine the shape that will have the least resistance to water to complex, comprehensive ‘models of everything’. A great example of the latter is the Earth System Model. This model aims to understand the changes in global climate by taking into account the interaction between physical climate, biosphere, the atmosphere and the oceans. Basically, a model of how the Earth works.

The controversy in the use of modelling resides in how accurately the model describes reality and the level of confidence we have in its outputs. The first argument can be a bit counter-intuitive: sometimes, a very simple model can be a great predictor. Actually, the conventional view in ecology is that simple models are more generalisable than complex models, although this view is being challenged. However, the level of confidence, or the level of uncertainty, that we have in the outputs of the model is a crucial point. We need to be able to accurately determine our levels of uncertainty if we want people to trust our models. 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”)

Continue reading

Tiny Grains, Big Data: The Global Pollen Project

Post Provided by Andrew Martin

A drawer from the Oxford Long-Term Ecology Lab (OxLEL) pollen reference collections, which has been digitised into the Global Pollen Project reference set.

A drawer from the Oxford Long-Term Ecology Lab (OxLEL) pollen reference collections, which has been digitised into the Global Pollen Project reference set.

The Global Pollen Project is a new, online, freely available tool developed to help people identify and disseminate palynological resources. Palynology – the study of pollen grains and other spores – is used across many fields of study modern and fossil vegetation dynamics, forensic sciences, pollination, beekeeping, and much more. This platform helps to facilitate cross/multi-disciplinary integration and discussion, outsourcing identifications, expertise and the sharing of knowledge.

Pollen’s Role in Plant Conservation

Successful conservation of rare, threatened, and valuable plants is dependent on an understanding of the threats that they face. Also, conservationists must prioritise species and populations based on their value to humans, which may be cultural, economic, medicinal, etc. The study of fossil pollen (palaeoecology), deposited through time in sediments from lakes and bogs, can help inform the debate over which species to prioritise: which are native, and when did they arrive? How did humans impact species richness? By establishing such biodiversity baselines, policymakers can make more informed value judgements over which habitats and species to conserve, especially where conservation efforts are weighted in favour of native and/or endemic flora. Continue reading

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

Editor Recommendation – HistMapR: Rapid Digitization of Historical Land-Use Maps in R

Post provided by Sarah Goslee

For an ecologist interested in long-term dynamics, one of the most thrilling experiences is discovering a legacy dataset stashed away somewhere.

For an ecologist interested in long-term dynamics, one of the most daunting experiences is figuring how to turn that box full of paper into usable data.

The new tool HistMapR, described in ’HistMapR: Rapid digitization of historical land-use maps in R’ by Alistair Auffret and colleagues, makes one part of that task much easier.

Examples of input (©Lantmäteriet) and output maps from (a–b) the District Economic map and (c–d) the Economic map.

Examples of input (©Lantmäteriet) and output maps from (a–b) the District Economic map and (c–d) the Economic map.

Historical maps with coloured areas denoting different land cover or use are a valuable record, but difficult to analyse. This R package automates much of the time-consuming and tedious process of turning paper maps into classified categorical raster maps.

A map is scanned, imported into R, and the software is trained by clicking in different areas of each category. It then automatically classifies pixels based on which colour they are most similar to. The resulting classification is assessed manually. The process can be repeated with slightly different parameters until a good fit is achieved.

The authors found 80-90% agreement between HistMapR classification and manual digitisation (sources of error included clarity of original maps and scan quality). Using HistMapR reduced the time needed for digitising a series of historical land cover maps from two months to two days. Ecologists interested in long-term dynamics should be cheering!

The HistMapR package is available on GitHub and you can find example scripts on Figshare, so you can get right to work.

HistMapR: Rapid digitization of historical land-use maps in R‘ by Auffret et al. is a freely available Applications article (no subscription required).

Estimating the Size of Animal Populations from Camera Trap Surveys

Below is a press release about the Methods paper ‘Distance sampling with camera traps‘ taken from the Max Planck Society.

A Maxwell's duiker photographed using a camera trap. Marie-Lyne Després-Einspenner

A Maxwell’s duiker photographed using a camera trap. ©Marie-Lyne Després-Einspenner

Camera traps are a useful means for researchers to observe the behaviour of animal populations in the wild or to assess biodiversity levels of remote locations like the tropical rain forest. Researchers from the University of St Andrews, the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) and the German Centre for Integrative Biodiversity Research (iDiv) recently extended distance sampling analytical methods to accommodate data from camera traps. This new development allows abundances of multiple species to be estimated from camera trapping data collected over relatively short time intervals – information critical to effective wildlife management and conservation.

Remote motion-sensitive photography, or camera trapping, is revolutionising surveys of wild animal populations. Camera traps are an efficient means of detecting rare species, conducting species inventories and biodiversity assessments, estimating site occupancy, and observing behaviour. If individual animals can be identified from the images obtained, camera trapping data can also be used to estimate animal density and population size – information critical to effective wildlife management and conservation. Continue reading

Building Universal PCR Primers for Aquatic Ecosystem Assessments

Post provided by Vasco Elbrecht

Many things can negatively affect stream ecosystems – water abstraction, eutrophication and fine sediment influx are just a few. However, only intact freshwater ecosystems can sustainably deliver the ecosystem services – such as particle filtration, food biomass production and the supply of drinking water – that we rely on. Because of this, stream management and restoration has often been in the focus of environmental legislation world-wide. Macrozoobenthic communities are often key biological components of stream ecosystems. As many taxa within these communities are sensitive to negative stressors introduced by humans, they’re ideal for assessing the quality of water.

Unfortunately, most macrozoobenthic taxa – such as stone-, may-, and caddisflies as well as most other invertebrates – are often found in juvenile larval life stages in these ecosystems, so they’re often difficult to identify based on morphology. With the DNA based metabarcoding method though, almost all taxa in a stream can be reliably identified up to species level using a standardised gene fragment. One key component of this strategy is the development of universal markers, which allow detection of the diverse macrozoobenthic groups.

Our new R package PrimerMiner provides a framework for obtaining sequence data from available reference databases and identifying suitable primer binding sites for marker amplification. The package makes this process quicker and easier. In the following pictures, we summarise the key steps of DNA metabarcoding.

To find out more about PrimerMiner, read our Methods in Ecology and Evolution article ‘PrimerMiner: an r package for development and in silico validation of DNA metabarcoding primers’. Like all Applications articles, this paper is freely available to everyone.

What silver fir aDNA can tell us about Neolithic forests

Below is a press release about the Methods paper ‘HyRAD-X, a versatile method combining exome capture and RAD sequencing to extract genomic information from ancient DNA‘ taken from Swiss Federal Institute for Forest, Snow and Landscape Research WSL (this press release is also available in French, German and Italian via the links below).

A new technique makes it possible to cost-effectively analyse genetic material from fossil plants and animals. Researchers from the Swiss Federal Institute for Forest, Snow and Landscape Research WSL and the universities of Lausanne and Bern have used this technique to examine the DNA of silver fir remains found in lake sediment in Ticino. They found clues as to how forests reacted to the emergence of agriculture.

The new process utilises the latest advances in DNA technology to isolate ancient DNA (aDNA) from prehistoric plants and animals. The techniques used to date are, however, expensive. “As population geneticists often need several dozens samples to make reliable statements, many research ideas are not currently financially viable,” says Nadir Alvarez, a professor at the University of Lausanne’s Department of Ecology and Evolution.

The research team led by Alvarez and his colleagues Christoph Sperisen (a population geneticist at the WSL), Willy Tinner (a professor of palaeoecology at the University of Bern) and Sarah Schmid (a biologist from the University of Lausanne) has now developed a cost-effective alternative and demonstrated its potential with subfossil silver fir needles found at Origlio lake in Ticino. The team showcased the results in the research journal Methods in Ecology and Evolution. Continue reading

New Associate Editors

Today we are welcoming four new Associate Editors to Methods in Ecology and Evolution. Graziella Iossa (University of Lincoln) and Theoni Photopoulou (Nelson Mandela Metropolitan University) are joining as regular Associate Editors and Simon Jarman (Unversity of Porto) and Daniele Silvestro (University of Gothenburg) will be working on Applications articles. You can find out more about all of our new Associate Editors below.

Graziella Iossa

“I am an evolutionary ecologist with broad interests in behavioural and population ecology. My research has explored reproductive strategies and the evolution of male and female reproductive traits in mammals and insects and I have used a range of techniques to study the behaviour and welfare of wildlife. I have just started to explore interdisciplinary approaches with the aim to improve our understanding of the value and role of ecosystem services in human health, specifically for antimicrobial resistance.”

Graziella’s most recent paper – Micropyle number is associated with elevated female promiscuity in Lepidoptera – investigates the evolution of the micropyle, a tiny canal which sperm use to fertilise eggs in insects. This is the first study to show that micropylar variation is driven by female promiscuity – the more micropyles her eggs have, the more choice she is likely to have over which male fathers her offspring. Also, Graziella currently holds a NERC Valuing Nature placement which aims to combine perspectives from evolutionary ecology, microbial ecology, epidemiology, ecosystem science and public health to develop a new, holistic way of understanding antimicrobial resistance

Simon Jarman

“Methods employing epigenetics, environmental DNA analysis or bioinformatics for ecological research are improving rapidly and have clear potential for future development. My research focuses on creating new methods in these areas and using them to study population biology and biodiversity. Epigenetic markers for physiological features such as biological age can be used to determine key features of population biology such as age class distribution. Environmental DNA can be used to measure species distributions; biodiversity in environmental samples; and animal diet composition. I am interested in the molecular biology and computational approaches that are required to implement these methods; as well as how they can be used to study specific ecological questions.”

In November 2016, Simon published an Open Access article in Methods in Ecology and Evolution. ‘Optimised scat collection protocols for dietary DNA metabarcoding in vertebrates‘ explains how to collect scat samples to optimise the detection of food DNA in vertebrate scat samples. More recently, Simon was the last author of ‘KrillDB: A de novo transcriptome database for the Antarctic krill (Euphausia superba)‘ – which introduces the most advanced genetic database on Euphausia superba, KrillDB, and includes comprehensive data sets of former and present transcriptome projects.

Theoni Photopoulou

“I am interested in the way biological and ecological phenomena change in space and over time. My special interest is animal movement ecology and the mechanisms behind the patterns of movement we observe. Most of the time I work on ecological questions about how animals use their environment and the resources in it, using data collected remotely with animal-attached instruments. Marine biology was my first love so I will always have a soft spot for marine systems, especially movement of large marine vertebrates, but I work on all sorts of tracking data and also some non-tracking data.”

Theoni has also recently been published in Methods in Ecology and Evolution. Her article ‘Analysis of animal accelerometer data using hidden Markov model‘ appeared in the February issue of the journal (and provided the cover image). In the paper, the authors provide the details necessary to implement and assess a hidden Markov Model in both the supervised and unsupervised learning contexts and discuss the data requirements of each case. Another of Theoni’s articles has just been accepted for publication in Frontiers in Zoology. ‘Evidence for a postreproductive phase in female false killer whales (Pseudorca crassidens)‘ investigates the evidence for postreproductive lifespan (PRLS) in the false killer whale, using a quantitative measure of PRLS and morphological evidence from reproductive tissue.

Daniele Silvestro

“I am a computational biologist and my research focuses on (macro)evolution and the development of new probabilistic models to better understand it. I am interested in the implementation of Bayesian algorithms to model evolutionary processes such as phenotypic trait evolution and species diversification and extinction. I am also interested in historical biogeography and in particular in the estimation of dispersal rates and biotic connectivity between geographic areas. A lot of my work involves developing new models and algorithms and implementing them in computer programs. I have been using both phylogenetic data and fossil occurrences to infer deep time evolutionary dynamics and I am keen to see an improved integration between paleontological and neontological data in evolutionary research.”

In his most recent article – ‘Bayesian estimation of multiple clade competition from fossil data‘ – Daniele and his co-authors explore the properties of the existing Multiple Clade Diversity Dependence implementation, which is based on Bayesian variable selection, and introduce an alternative parameterisation based on the Horseshoe prior. He was also one of the authors of ‘Mammal body size evolution in North America and Europe over 20 Myr: similar trends generated by different processes‘, published in Proceedings of the Royal Society B earlier this year.

We are thrilled to welcome Simon, Graziella, Theoni and Daniele to the Associate Editor Board and we look forward to working with them over the coming years.