Tag: Ecology

Journal updates, Methods papers

Issue 6.12

Issue 6.12 is now online!

The December issue of Methods is now online! 

Our final issue of 2015 contains one Applications article and two Open Access articles, all of which are freely available.

– stagePOP: A tool for predicting the deterministic dynamics and interactions of stage-structured populations (i.e. where the life cycle consists of distinct stages, for example eggs, juveniles and reproductive adults). The continuous-time formulation enables stagePop to easily simulate time-varying stage durations, overlapping generations and density-dependent vital rates.

Julia Cherry et al. provide one of this month’s Open Access articles. In ‘Testing sea-level rise impacts in tidal wetlands: a novel in situ approach‘ the authors describe the use of experimental weirs that manipulate water levels to test sea-level rise impacts in situ and at larger spatial scales. This new method can provide more robust estimates of sea-level rise impacts on tidal wetland processes. This article was accompanied by a press release when it was published in Early View. You can read more about this article here.

Our September issue also features articles on Biodiversity, Demography, Predator-Prey Interactions, Animal Communication and much more. Continue reading “Issue 6.12”

Unknown's avatarIndia Stephenson4 Comments
Methods 5th, Publishing Tips & Tricks

A Quickstart Guide for Building Your First R Package

Post Provided By DR IAIN STOTT

Iain is a Postdoctoral Researcher at the Max Planck Institute for Demographic Research and the MaxO Center at the University of Southern Denmark. He is currently working as a part of MaxNetAging, a Research Network on Aging. Iain was one of the presenters at the UK half of the Methods in Ecology and Evolution 5th Anniversary Symposium in April. You can watch his talk, ‘Methods Put to Good Use: Advances in population ecology through studies of transient demography’ here.

If you’re anything like me, you might experience a minor existential crisis weekly. As scientists we question the world around us and, for me, this questioning turns all-too-often inwards to my career. I don’t think that’s unusual: ask any scientist about their ‘Plan B’, and the extent to which it’s thought through is often astonishing (if a café-cum-cocktail bar ever opens in Glasgow’s West End, which specialises in drinks that employ spice blends from around the world and are named after old spice trade routes and trading vessels, then you know I’ve jumped the science ship).

Contributing open-source software is something which has made my work feel a bit more relevant and helped me feel a bit less of an imposter. I’ll explain why that is, give some tips to beginners for building a first R package, and hopefully persuade other (especially early-career) researchers to do the same. Continue reading “A Quickstart Guide for Building Your First R Package”

Unknown's avatarIndia Stephenson4 Comments
Meetings, Statistical methods, Uncategorized

There’s Madness in our Methods: Improving inference in ecology and evolution

Post provided by JARROD HADFIELD

Last week the Center for Open Science held a meeting with the aim of improving inference in ecology and evolution. The organisers (Tim Parker, Jessica Gurevitch & Shinichi Nakagawa) brought together the Editors-in-chief of many journals to try to build a consensus on how improvements could be made. I was brought in due to my interest in statistics and type I errors – be warned, my summary of the meeting is unlikely to be 100% objective.

True Positives and False Positives

The majority of findings in psychology and cancer biology cannot be replicated in repeat experiments. As evolutionary ecologists we might be tempted to dismiss this because psychology is often seen as a “soft science” that lacks rigour and cancer biologists are competitive and unscrupulous. Luckily, we as evolutionary biologists and ecologists have that perfect blend of intellect and integrity. This argument is wrong for an obvious reason and a not so obvious reason.

We tend to concentrate on significant findings, and with good reason: a true positive is usually more informative than a true negative. However, of all the published positives what fraction are true positives rather than false positives? The knee-jerk response to this question is 95%. However, the probability of a false positive (the significance threshold, alpha) is usually set to 0.05, and the probability of a true positive (the power, beta) in ecological studies is generally less than 0.5 for moderate sized effects. The probability that a published positive is true is therefore 0.5/(0.5+0.05) =91%. Not so bad. But, this assumes that the hypotheses and the null hypothesis are equally likely. If that were true, rejecting the null would give us very little information about the world (a single bit actually) and is unlikely to be published in a widely read journal. A hypothesis that had a plausibility of 1 in 25 prior to testing would, if true, be more informative, but then the true positive rate would be down to (1/25)*0.5/((1/25)*0.5+(24/25)*0.05) =29%. So we can see that high false positive rates aren’t always the result of sloppiness or misplaced ambition, but an inevitable consequence of doing interesting science with a rather lenient significance threshold. Continue reading “There’s Madness in our Methods: Improving inference in ecology and evolution”

Unknown's avatarIndia Stephenson5 Comments
Methods papers, Practical Tools

Why Accurate Stable Isotope Discrimination Factors are so Important: A cautionary tale (involving kea)

Post provided by AMANDA GREER

Stable isotopes as a tool for ecologists

Our research into the foraging ecology of this cheeky parrot (kea: Nestor notabilis) prompted us to develop a simple method to establish discrimination factors © Andruis Pašukonis
Our research into the foraging ecology of this cheeky parrot (kea: Nestor notabilis) prompted us to develop a simple method to establish discrimination factors © Andruis Pašukonis

Isotopes are atoms that have the same number of protons and electrons but differ in their number of neutrons; they are lighter and heavier forms of the same element. Unlike radioactive isotopes, stable isotopes do not decay over time.

The ratio of heavy to light stable carbon (δ13C) and nitrogen (δ15N) isotopes in an animal’s tissues depend on its diet, although offset by a certain amount. This integration of δ13C and δ15N from an animal’s diet into its tissues allows ecologists to use stable isotope analysis to investigate a species’ present and historical diets, food-web structures, niche shifts,  migration patterns and more.   Continue reading “Why Accurate Stable Isotope Discrimination Factors are so Important: A cautionary tale (involving kea)”

Unknown's avatarIndia Stephenson2 Comments
Journal updates

Issue 6.11

Issue 6.11 is now online!

The November issue of Methods is now online!

This month’s issue contains two Applications articles and one Open Access article, all of which are freely available.

– mvMORPH: A package of multivariate phylogenetic comparative methods for the R statistical environment which allows fitting a range of multivariate evolutionary models under a maximum-likelihood criterion. Its use can be extended to any biological data set with one or multiple covarying continuous traits.

– Low-cost soil CO2 efflux and point concentration sensing systems: The authors use commercially available, low-cost and low-power non-dispersive infrared (NDIR) CO2 sensors to develop a soil CO2 efflux system and a point CO2 concentration system. Their methods enable terrestrial ecologists to substantially improve the characterization of CO2 fluxes and concentrations in heterogeneous environments.

This month’s Open Access article comes from Jolyon Troscianko and Martin Stevens. In ‘Image calibration and analysis toolbox – a free software suite for objectively measuring reflectance, colour and pattern‘ they introduce a toolbox that can convert images to correspond to the visual system (cone-catch values) of a wide range of animals, enabling human and non-human visual systems to be modelled. The toolbox is freely available as an addition to the open source ImageJ software and will considerably enhance the appropriate use of digital cameras across multiple areas of biology. In particular, researchers aiming to quantify animal and plant visual signals will find this useful. This article received some media attention upon Early View publication over the summer. You can read the Press Release about it here.

Our November issue also features articles on Population Genetics, Macroevolution, Modelling species turnover, Abundance modelling, Measuring stress and much more. Continue reading “Issue 6.11”

Unknown's avatarIndia StephensonLeave a comment
Conservation and management, Methods papers, Practical Tools, Virtual Issues

High-Res Camera Surveys of Wildlife Colonies: The advantages over traditional approaches

Post provided by ALISTAIR HOBDAY (senior principal research scientist, CSIRO Australia), Tim Lynch (senior research scientist, CSIRO, Australia) and Rachael Alderman (wildlife biologist, Tasmanian Department of Primary Industry, Parks, Water and Environment, Australia).

Cameras and wildlife monitoring

A Gigapan camera setup to record images of an albatross colony. ©Alistair Hobday
A Gigapan camera setup to record images of an albatross colony. ©Alistair Hobday

Behavioural and ecological research and monitoring of wildlife populations are based on collection of field data. Demographic data, such as breeding frequency, birth rates and juvenile survival, have been critical in understanding population trends for a wide range of species.

Photography has been extensively used by field biologists and ecologists to gather these data and they have been quick to take up improvements in this technology. Many field programmes today use photography either for primary data collection or the communication of results. Advances in digital photography, image storage and transmission, image processing software and web-based dissemination of images have been extremely rapid in recent years, offering ecologists and biologists a range of powerful tools.

Digital imagery has been captured from a wide range of platforms, each of which has various advantages and limitations for biological study. The most remote images are captured from satellite-based sensors, which have been used to assess population abundance of large animals, such as elephant seals, or locate colonies of emperor penguins. Cameras mounted on aircraft can also provide large-scale perspectives but both of these platforms suffer from high cost, operational limitations due to weather, and limited temporal replication. Recent use of drones, while cheaper, still requires a person to be close to the survey location and can only be used in short bursts, typically lasting less than 20 minutes.

Land-based cameras – or those fixed onto animals – can track behaviour closely, but have low sample size as data tends to be collected at the scale of individual or small groups. To improve replication, fleets of remote cameras can be used or multiple images stitched together post hoc to form a montage. However, this increases cost, either for hardware or labour to manually construct panoramas. To date all these camera systems have had limits to their spatial and/or temporal resolution and, therefore, to the number of individuals covered. This restricts biological study at the population level. Continue reading “High-Res Camera Surveys of Wildlife Colonies: The advantages over traditional approaches”

Unknown's avatarIndia Stephenson1 Comment
Conservation and management, Methods papers, Practical Tools, Virtual Issues

Making the Most of Volunteer Data: Counting the birds and more…

Post provided by Rob Robinson

It’s 6am on a warm spring morning and I’m about to visit the second of my Breeding Bird Survey1 sites. Like 2,500 other volunteers in the UK, twice a year I get up early to record all the birds I see or hear on the two transects in my randomly selected 1km square. Each year I look forward to these mornings almost as much for the comparisons as the actual sightings. Will there be more or fewer sightings of our summer migrants this year? How will numbers in this rolling Norfolk farmland stack up against those I see in urban, central Norwich?

Dawn bird survey in arable farmland. © Rob Robinson/BTO
Dawn bird survey in arable farmland. © Rob Robinson/British Trust for Ornithology (BTO)

The importance of demography

But simply recording these changes is not enough; we need to understand why they occur if action is to be taken. This requires us to quantify the demographic rates (survival, productivity and movements) that underlie them, which in turn requires samples of marked individuals. Simply counting individuals is not enough. Continue reading “Making the Most of Volunteer Data: Counting the birds and more…”

Unknown's avatarIndia Stephenson2 Comments
Journal updates, Methods papers

Issue 6.10

Issue 6.10 is now online!

The October issue of Methods is now online!

This month’s issue contains two Applications articles and one Open Access article, all of which are freely available.

– letsR: A package for the R statistical computing environment, designed to handle and analyse macroecological data such as species’ geographic distributions and environmental variables. It also includes functions to obtain data on species’ habitat use, description year and current as well as temporal trends in conservation status.

– Cleaning Oil from Seabirds: The authors assess the efficacy of sea water as an alternative to fresh water for cleaning oil from seabirds’ feathers. Results indicate that for oiled feathers, a sea water wash/rinse produced clean, low BAI/unclumped feathers with minimal particulate residue.

Stefano Canessa et al. provide this month’s only Open Access article. In ‘When do we need more data? A primer on calculating the value of information for applied ecologists‘ the authors guide readers through the calculation of Value of Information (VoI) using two case studies and illustrate the use of Bayesian updating to incorporate new information. Collecting information can require significant investments of resources; VoI analysis assists managers in deciding whether these investments are justified. The authors also wrote a blog post on VoI which you can find here.

Our October issue also features articles on Niche Modelling, Population Ecology, Spatial Ecology, Conservation, Monitoring and much more. Continue reading “Issue 6.10”

Unknown's avatarIndia StephensonLeave a comment
Journal updates, Methods papers

Issue 6.9

Issue 6.9 is now online!

The September issue of Methods is now online!

This month’s issue contains one Applications article and two Open Access articles, all of which are freely available.

– POPART: An integrated software package that provides a comprehensive implementation of haplotype network methods, phylogeographic visualisation tools and standard statistical tests, together with publication-ready figure production. The package also provides a platform for the implementation and distribution of new network-based methods.

Michalis Vardakis et al. provide this month’s first Open Access article. In ‘Discrete choice modelling of natal dispersal: ‘Choosing’ where to breed from a finite set of available areas‘ the authors show how the dispersal discrete choice model can be used for analysing natal dispersal data in patchy environments given that the natal and the breeding area of the disperser are observed. This model can be used for any species or system that uses some form of discrete breeding location or a certain degree of discretization can be applied.

Our September issue also features articles on Animal Movement, Population Dynamics, Statistical Ecology, Biodiversity, Conservation Biology and much more. Continue reading “Issue 6.9”

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Journal updates, Methods papers

A new tool based on microbial interactions to analyze bipartite networks

Below is a press release about the Methods paper ‘BiMat: a MATLAB package to facilitate the analysis of bipartite networks‘ taken from the Pompeu Fabra University.

The Georgia Institute of Technology has created, together with the Pompeu Fabra University and the University of Canterbury, a new open-access and open-source tool for the study of bipartite networks

The team led by Joshua S. Weitz, Associate Professor at the School of Biology from the Georgia Institute of Technology, has developed BiMat: an open source MATLAB® package for the study of the structure of bipartite ecological networks inspired by real problems in microbiology and with broader applications. Cesar O. Flores, researcher at the School of Physics of the same institute, describes this new tool in an article published in the journal Methods in Ecology and Evolution. Sergi Valverde, Visiting Professor at the Complex Systems Lab from the Pompeu Fabra University, and Timothée Poisot, from the School of Biological Sciences of the University of Canterbury, are involved in the project. Continue reading “A new tool based on microbial interactions to analyze bipartite networks”

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