“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.”
“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.”
BACIPS (Before-After Control-Impact Paired Series) is probably the best-known and most powerful approach to detect and quantify human interventions on ecosystems. In BACIPS designs, Impact and Control sites are sampled simultaneously (or nearly so) multiple times Before and After an intervention. For each sampling survey conducted Before or After, the difference in the sampled response variable (e.g. density) is calculated. Before and After differences are then compared to provide a measure of the effect of the intervention, assuming that the magnitude of the induced change is constant through time. However, many interventions may not cause immediate, constant changes to a system.
We developed a new statistical approach – called Progressive-Change BACIPS (Before-After Control-Impact Paired-Series) – that extends and generalises the scope of BACIPS analyses to time-dependent effects. After quantifying the statistical power and accuracy of the method with simulated data sets, we used marine and terrestrial case studies to illustrate and validate their approach. We found that the Progressive-Change BACIPS works pretty well to estimate the effects of environmental impacts and the time-scales over which they operate.
The following images show the diversity of contexts in which this approach can be undertaken.
Moorea is an island located in French Polynesia. It’s known for its extraordinary marine biodiversity, but also for the great, natural spatial and temporal variability due to recurrent external forces. This place, and the statistical challenges it represents, has provided us with a wealth of inspiration in formulating our Progressive-Change BACIPS approach to environmental impact assessment.
Unlike classic experimental studies like this one, environmental impacts are not (and often should not) be replicated.
Recurrent disturbances such as Crown-of-Thorns Starfish (Acanthaster planci) outbreaks are important drivers of declines and recoveries in coral reef ecosystems. How can we reliably estimate the effect of local human interventions (for example marine protected areas, MPAs) amid such noise?
The challenge faced by ecologists when conducting impact assessments is to compare the state of the ecosystem in the presence of the intervention with the state of the system that would have existed if the intervention never occurred. This requires scientists to collect data before the intervention.
Here, a scientist is counting fish where a MPA will be implemented using a Diver-Operated Video system. Repeated assessments before enforcement provide an estimate of the spatial variability between the Control and Impact sites in the absence of an effect of the MPA.
A change in the difference in density between the Control and Impact sites after the establishment of the MPA provides an estimate of the local effect of the MPA. This is the BACIPS design.
Progressive-Change BACIPS uses these data to inform the form of the final model. Many models can be tested such as step-change, linear, asymptotic or logistic models – whatever that seems appropriate. This coral reef application was just one of the many possibilities to measure environmental impacts that our tool can reveal when applied to BACIPS data.
We have also applied it to other study contexts – such as the effect of highway construction on the abundance of birds. Here is an Andean condor (Vultur gryphus) flying away after the passage of a car.
This method is also well suited to forest ecosystems, for example to study the effect of increasing tourist visitation on this ancient Araucaria (Araucaria araucana) forest in Chile.
As long as data collected before and after, inside and outside the impacted area, exist Progressive-Change BACIPS is an excellent statistical approach to estimate the effects of environmental impacts.
This issue contains two Applications articles and one Open Access article. These three papers are freely available to everyone, no subscription required.
–Solo: Solo audio recorders are inexpensive, easy to construct and record audible sound continuously for around 40 days. The paper also has a video tutorial explaining how to assemble the required hardware and comes with a companion website with more information.
–The third dimension: A novel design to obtain three-dimensional data on the movements of aquatic organisms at depths of up to 140m. The set-up consists of two synchronised high-speed cameras fixed to two articulated arms and can be used for any underwater applications that require synchronized video recordings of medium- to large-sized animals.
Evelyn Chrystalla ‘E.C.’ Pielou (February 20, 1924 – July 16, 2016) – a towering figure in ecology – was a key pioneer in the incorporation of statistical rigor into biogeography and ecology. She devised many important statistical hypotheses tests for spatial arrangements and patterns ranging in scale from individual plants in a field through to elevational zonation of vegetation to ranges of groups of species distributed over regional through to continental-scale ranges. Her research has provided the impetus for biogeographical analyses for generations.
She published ten books, including several long after her formal retirement in 1988. Her book Biogeography (1979) is a masterpiece. It covers historical biogeography (including inferences from cladograms, which were just beginning to be a hot topic at that time) and ecological biogeography with keen insight and treats topics like long-distance dispersal (that had largely been the subject of just-so stories) with her characteristic statistical rigor. Her books on mathematical ecology have a strong emphasis on models of spatial pattern and ways to estimate biodiversity, and her methods – including the famous Pielou‘s evenness index – are still widely used.Continue reading →
Movement ecology is a cross-disciplinary field. Its main aim is to quantitatively describe and understand how movement relates to individual and population-level processes for resource acquisition and, ultimately, survival. Today the study of movement ecology hinges on two 21st century advances:
Animal-borne devices/tags (biologging science, Hooker et al., 2007) and/or remote sensing technology to quantify movement and collect data from remote or otherwise challenging environments
Computational power sufficient to manipulate, process and analyse substantial volumes of data
Although datasets often involve small numbers of individuals, each individual can have thousands – sometimes even millions – of data points associated with it. Study species have tended to be large birds and mammals, due to the ease of tag attachment. However, the trend for miniaturisation of tags and the development of remote detection technologies (such as radar, e.g. Capaldi et al., 2000), have allowed researchers to track and study ever smaller animals. Continue reading →
Women in academia are special. This isn’t because of their abundance and diversity (or lack of it in some circles) but rather because of the challenges faced by women. As an early career woman researcher, I have had the privilege of knowing and learning from some incredibly inspirational women scientists. In this post – peppered with the lyrics of Joan Baez – we will meet three of these exceptional scientists working in three different realms (terrestrial, estuarine and marine). I hope that their strengths will be as inspirational to others – as they have been to me – and that in the years to come, we, as women, shall overcome the glass cliffs and glass ceilings of academia.
We’ll Walk Hand in Hand, Some Day #Equality
In the terrestrial realm of tropical forests, researchers often have to work with government officials (for instance, the forest department). Challenges of gender equality can be particularly stark in these workplaces. A key challenge for women in such a setting is not being considered a professional. Female researchers are far too often underestimated: lecturers assumed to be trainees, post-doctoral researchers mistaken for students. Continue reading →
Rachel Carson (1940) Fish & Wildlife Service employee photo.
I can’t think of a more inspirational and influential ecologist than Rachel Carson. Nearly fifty years ago she released a book called Silent Spring, which argued that pesticides such as DDT were cascading up through food chains causing the death or sterilisation of birds and other animals. The publication of her book provoked public debate, likely in part because it was serialised in The New Yorker, and led to a paradigm shift in US and (arguably) global pest control policy.
With the full support of the scientific community to verify her facts and arguments, she was able to defeat the chemical industry’s backlash and galvanise public opinion in her favour. The 2005 Stockholm Convention, in which DDT was banned from agricultural use, would likely have never happened if it were not for her work.
“In a post-truth world where trust in the scientific process is being eroded almost daily, Rachel Carson is a perfect example of how we can speak out and be heard while still being scientists.”
Ecological networks represent interactions between different biotic units in an ecosystem and are becoming an increasingly popular tool for describing and illustrating a range of different types of ecological interactions. Food webs – which provide a way to track and quantify the flow of energy and resources in ecosystems – are among the most studied type of ecological networks. These networks usually represent species (nodes) which are connected by pairwise interactions (links) and they play a central role in improving our understanding of ecological and evolutionary dynamics.
Historically, food webs described antagonistic relationships (e.g. plant-herbivore or host-parasitoid networks) but the approach has been developed in recent years to include mutualistic networks (e.g. plant-pollinator networks, phorophyte-epiphyte networks). The development of network ecology, including ever more sophisticated methods to analyse ecological communities, has been driven forward by an enthusiastic community of ecologists, theoreticians and modellers working together to enhance our understanding of how communities interact.
In this blog post, we’ll describe the important role played by female scientists in the development of network ecology, focusing on the contributions by two ground-breaking ecologists and also highlighting contributions from a range of other scientists working in this field. Continue reading →
Around the world there are concerns over the impacts of land use change and the developments (such as wind farms). These concerns have led to the implementation of tracking studies to better understand movement patterns of animals. Such studies have provided a wealth of high-resolution data and opportunities to explore sophisticated statistical methods for analysis of animal behaviour.
We use accelerometer data from aerial (Verreaux’s eagle in South Africa) and marine (blacktip reef shark in Hawai’i) systems to demonstrate the use of hidden Markov models (HMMs) in providing quantitative measures of behaviour. HMMs work really well for analysing animal accelerometer data because they account for serial autocorrelation in data. They allow for inferences to be made about relative activity and behaviour when animals cannot be directly observed too, which is very important.
In addition to this, HMMs provide data-driven estimates of the underlying distributions of the acceleration metrics – and the probability of switching between states – possibly as a function of covariates. The framework that we provide in ‘Analysis of animal accelerometer data using hidden Markov models‘ can be applied to a wide range of activity data. It opens up exciting opportunities for understanding drivers of individual animal behaviour.
Verreaux’s eagles lay one to two eggs but only raise one chick. These are normally hatch during mid-winter and stay on the nest for around 90 days. The parents provision the chick during this time, delivering prey to the nest. Rock hyrax is a frequent item on the menu, as seen here. Having concurred data from accelerometers and nest cameras for the same bird could allow for activity level to be linked to successful prey acquisition or prey type. (Photo taken by a nest camera installed as part of the Black Eagle Project, Megan Murgatroyd)