Issue 8.8

Issue 8.10 is now online!

The October issue of Methods is now online!

This double-sized issue contains three Applications articles and two Open Access articles. These five papers are freely available to everyone, no subscription required.

 Phylogenetic TreesThe fields of phylogenetic tree and network inference have advanced independently, with only a few attempts to bridge them. Schliep et al. provide a framework, implemented in R, to transfer information between trees and networks.

 Emon: Studies, surveys and monitoring are often costly, so small investments in preliminary data collection and systematic planning of these activities can help to make best use of resources. To meet recognised needs for accessible tools to plan some aspects of studies, surveys and monitoring, Barry et al. developed the R package emon, which includes routines for study design through power analysis and feature detection.

 Haplostrips: A tool to visualise polymorphisms of a given region of the genome in the form of independently clustered and sorted haplotypes. Haplostrips is a command-line tool written in Python and R, that uses variant call format files as input and generates a heatmap view.

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Imperfect Pathogen Detection: What to Do When Sampling and Diagnostic Tests Produce Inaccurate Results

Post Provided by Graziella DiRenzo

A salamander having its skin swabbed to test for Bsal infection.

A salamander having its skin swabbed to test for Bsal infection.

Imagine you’re at the doctor’s office. You’re waiting to hear back on a critical test result. With recent emerging infectious diseases in human populations, you are worried you may be infected after a sampling trip to a remote field site. The doctor walks in. You sit nervously, sensing a slight tremble in your left leg. The doctor confidently declares, “Well, your tests results came back negative.” In that moment, you let out a sigh of relief, the kind you feel throughout your body. Then, thoughts start flooding your mind. You wonder– what are the rates of false negatives associated with the test? How sensitive is the diagnostic test to low levels of infection? The doctor didn’t sample all of your blood, so how can they be sure I’m not infected? Is the doctor’s conclusion right?

 Now, let’s say I’m the doctor and my patient is an amphibian. I don’t have an office where the amphibian can come in and listen to me explain the diagnosis or the progression of disease − BUT I do regularly test amphibians in the wild for a fatal fungal pathogen, known as Batrachochytrium dendrobatidis (commonly known as Bd). Diseases like Bd are among the leading causes of the approximately one-third of amphibian species that are threatened, near threatened, or vulnerable to extinction. To test for Bd, and the recently emerged sister taxon Batrachochytrium salamandrivorans (hereafter referred to as: Bsal), disease ecologists rely on non-invasive skin swabs. Continue reading

Multi-State Species Distribution Models: What to do When Species Need Multiple Habitats

Post provided by Jan Engler, Veronica Frans and Amélie Augé

The north, south, east, and west boundaries of a species’ range tell us very little about what is happening inside…

― Robert H. MacArthur (1972, p. 149)

When You Enter the Matrix, Things Become Difficult!

New Zealand sea lion mother and pup. © Amélie Augé

New Zealand sea lion mother and pup. © Amélie Augé

Protecting wildlife calls for a profound understanding of species’ habitat demands to guide concrete conservation actions. Quantifying the relationships between species and their environment using species distribution models (SDMs) has attracted tremendous attention over the past two decades. Usually these species-environment relationships are estimated on coarse spatial scales, using globally-interpolated long-term climate data sets. While they’re useful for studies on large-scale species distributions, these environmental predictors have limited applications for conservation management.

Climatic data were the first environmental information available with global coverage, but a wide range of Earth observation techniques have increased the availability of much finer environmental information. This allows us to quantify species-environment relationships in unprecedented detail. We can now shift the scale that SDMs operate at, resulting in more useful applications in conservation – SDMs now enter the matrix.

This shift in scale brings new challenges, especially for species using multiple distinct habitat types to survive. The landscape matrix, which has been negligible at the broad (global) scale, is hugely important at the fine (local) scale. It is not only that we need to quantify certain habitat types but also need to consider their arrangement in the landscape, which is basically what the landscape matrix is about. But as we enter the matrix, things become difficult. Continue reading

Protecting Habitat Connectivity for Endangered Vultures: Identifying Priorities with Network Analysis

Post provided by Juliana Pereira, Santiago Saura and Ferenc Jordán

The endangered Egyptian vulture. ©Carlos Delgado

The endangered Egyptian vulture. ©Carlos Delgado

One of the main causes behind biodiversity loss is the reduction and fragmentation of natural habitats. The conversion of natural areas into agricultural, urban or other human-modified landscapes often leaves wild species confined to small and isolated areas of habitat, which can only support small local populations. The problem with small, isolated populations is that they are highly vulnerable to extinction caused by chance events (such as an epidemic or a natural disaster in the area), or by genetic erosion (dramatic loss of genetic diversity that weakens species and takes away their ability to adapt to new conditions).

On top of that, we now have the added concern of climate change, which is altering environmental conditions and shifting habitats to different latitudes and altitudes. To survive in the face of these changes, many species need to modify their geographical distribution and reach new areas with suitable conditions. The combination of mobility (a biological property of species) and the possibility of spatial movement (a physical property of the landscape) is critically important for this. Continue reading

Mark-Recapture and Metapopulation Structure: Using Study Design to Minimize Heterogeneity

Post provided by Delphine Chabanne

Pod of bottlenose dolphins observed in Cockburn Sound, Perth, Western Australia.

Pod of bottlenose dolphins observed in Cockburn Sound, Perth, Western Australia.

Wildlife isn’t usually uniformly or randomly distributed across land- or sea-scapes. It’s typically distributed across a series of subpopulations (or communities). The subpopulations combined constitute a metapopulation. Identifying the size, demography and connectivity between the subpopulations gives us information that is vital to local-species conservation efforts.

What is a Metapopulation?

Richard Levins developed the concept of a metapopulation to describe “a population of populations”. More specifically, the term metapopulation has been used to describe a spatially structured population that persists over time as a set of local populations (or subpopulations; or communities).  Emigration and immigration between subpopulations can happen permanently (through additions or subtractions) or temporarily (through the short-term presence or absence of individuals).

How individuals could distribute themselves within an area.

How individuals could distribute themselves within an area.

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Reptile DNA Sexing: Easier Than You Ever Thought

Post provided by Lukáš Kratochvíl and Michail Rovatsos

The sand lizard (Lacerta agilis).

The sand lizard (Lacerta agilis).

Many researchers, breeders and hobbyists need to know sex of their animals. Sometimes it’s easy – in sexually dimorphic species you only have to look. In other species or juveniles it’s often not so straightforward though. And it’s often impossible – but sometimes essential – in embryos or in tissue samples. Determining sex from DNA is the most practical option, or sometimes even the only possibility, in these cases.

Molecular sexing is routinely used in mammals and birds, but until now it has only been available for a handful of reptile species. Many people didn’t believe that this situation would improve considerably any time soon. But why? Continue reading

Listen Up! Using Passive Acoustic Monitoring to Help Forest Elephant Conservation

Post provided by Peter H. Wrege

Forest elephant in Gabon

Forest elephant in Gabon

Heard but not seen, populations of forest elephants (Loxodonta cyclotis) are rapidly declining due to ivory poaching. As one of the largest land mammals in the world, this species is surprisingly difficult to observe in the dense forests of Central Africa, but their low frequency rumbles can be recorded. With the autonomous recording afforded by passive acoustic monitoring (PAM) though, we have a window onto forest elephant ecology and behaviour that’s providing data critical to their conservation and survival.

The diverse ways that PAM can contribute to conservation outcomes is growing and while still underappreciated, the availability of relatively inexpensive recorders, increased power efficiency, and powerful techniques to automate the detection of signals have led to an explosion in use. In 2007 there were only about 20 published papers using PAM techniques, but since then over 400 papers have appeared in peer-reviewed journals.

Spectrogram of two forest elephant rumbles. Horizontal line shows the limit of human hearing.

Spectrogram of two forest elephant rumbles. Horizontal line shows the limit of human hearing.

Essentially, PAM is the automatic recording of sounds in a given environment, often for long periods. The trick, and often greatest challenge, is to find the signals of interest (bird calls, elephant rumbles, gunshots) within the recordings. With these signals we can quantify abundance, occupancy and spatial or temporal patterns of activity. Particularly in landscapes or ecosystems where visual observation is difficult (e.g. oceans, rainforests, nocturnal environments) PAM may be uniquely capable of delivering informative and unbiased data. Because PAM is a relatively new method but of considerable interest across the disciplines of ecology, behaviour and conservation, there is huge interest in refining the sampling and statistical methods needed to deal with the peculiarities of acoustic data. 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

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

Issue 8.5

Issue 8.5 is now online!

The May issue of Methods is now online!

This issue contains three Applications articles and two Open Access articles. These five papers are freely available to everyone, no subscription required.

MatlabHTK: A software interface to a popular speech recognition system making it possible for non-experts to implement hidden Markov models for bioacoustic signal processing.

 PrimerMiner: The R package PrimerMiner batch downloads DNA barcode gene sequences from BOLD and NCBI databases for specified target taxonomic groups and then applies sequence clustering into operational taxonomic units to reduce biases introduced by the different number of available sequences per species.

 BarcodingR: An integrated software package that provides a comprehensive implementation of species identification methods, including artificial intelligence, fuzzy-set, Bayesian and kmer-based methods, that are not readily available in other packages.

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