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- 5 July 2017
- 1 January 2017
It is widely assumed that many activities that free-living animals perform, such as migration, must represent ‘hard work’, with individuals differing in their ability to support, or deal with the costs of, high intensity activity (e.g. elevated metabolic rate, increased oxidative stress). But how hard do free-living animals work during more routine activities, especially those that appear less obviously ‘intense’ but which still have important fitness consequences, such as daily foraging, escaping predators (or mates), pursuing prey or engaging in mating displays. What determines how hard individuals will work on specific activities? Is “exercise”, defined as activity that improves or maintains performance, a useful paradigm to apply to routine movement behaviour in free-living animals? Can animals work too hard, such that they pay costs of high levels of activity, and do concepts such as “over-training”, common in the human sports medicine literature, provide a model for costs of high levels of performance in free living animals?
Until recently, much work on “exercise" has been based in the laboratory (e.g. wheel- or treadmill-running in mammals and reptiles, birds flying in wind tunnels) and has been divorced from ecological context. To what extent these systems provide good models for understanding activity in free-living animals (during routine behaviours) remains unclear; do they help us understand the physiology of exercise in free-living animals? However, the rapid pace of recent technological advances (geolocators, GPS, accelerometers, automated tracking systems) are now giving biologists an unprecedented ability to track the behaviour of free-living animals 24/7. This will allow researchers to directly address questions of individual variation in movement behaviour, the specific physiological mechanisms underlying this variation and the fitness consequences of variation in movement.
We have selected a set of papers from Functional Ecology and the Journal of Animal Ecology, published in the last 3 years. These papers cover a wide range of taxa and a wide range of movement behaviours, and include several that illustrate the value of new tracking technologies, or analytical approaches. While the aim for this Virtual Issue is to generate discussions and to provide a sample of research published in this field, we hope the issue encourages future submissions to these Journals that utilise the power of new bio-tracking technologies, integrating behaviour, ecology, physiology and evolutionary biology to tackle broad questions about the ecology of exercise.
- 9 November 2016
The full introduction to this Virtual Issue can be downloaded here.
- 1 August 2016
- 1 May 2016
- 1 March 2016
This virtual issue Demography Behind the Population highlights the interdisciplinary nature of the field as well as providing added context for the publication of our recently published cross-journal Special Feature Demography Beyond the Population showcasing the latest in demography research and linking several disciplines and scales across ecology and evolution. This Special Feature is first time that the BES journals have collaborated in this unique way. You can read the lay summaries for Functional Ecology's contribution to the special feature here.
On Tuesday 1 March at 1pm GMT we are hosting a live webinar in association with the Special Feature. It is free to register for the webinar via the BES website. The webinar will also be available online to watch afterwards as well.
- 1 March 2017
A first theme is defined by papers that focus on characterizing what makes the perfect invasive species (invasiveness). These studies go beyond trait comparisons and explore changes in population dynamics, the role of genetic mixture, and the evolution of adaptations, also presenting new modelling approaches and improved datasets.
A second theme includes studies which address impacts on ecological processes. These papers evaluate the effects of invasives on species interactions (particularly of plants with herbivores, pollinators, and soil mutualistic fungi), explore broad scale ecosystem and community impacts, propose new metrics, and characterize the synergistic consequences of combined impacts like climate change and invasives.
The final theme includes studies that focus on management. These publications present new and more robust decision tools, showcase the application of methods like e-DNA sampling and spatial-explicit models to manage invasives across different stages, particularly establishment and spread, and highlight the importance of considering social costs and benefits and of engaging with practitioners.
- 1 September 2015
Editor, Journal of Animal Ecology
More recently, the utility of network analysis has been embraced with some enthusiasm by ecologists interested in social behaviour, social structure, and the effects of social structure on a wide range of ecological processes. The enthusiasm reflects not only the fact that network analysis provides new, standardised, and rigorously quantitative methods to describe social structure. Using network analysis also provides a theoretical framework to understand some of the key emergent properties of social structure, from the extent to which they result from non-random assortment of different types of individuals, to the effect they have on the transmission of properties, such as disease and information, in natural populations. This increased enthusiasm has been driven in part by technological developments. First, the development of automated observation or logging devices provides access to potentially very much larger quantities of data than could be obtained by observation alone. Second, increased computing power has greatly facilitated the analysis of social networks, for which computer-intensive methods are frequently needed to construct appropriate null models.
Journal of Animal Ecology has been at the forefront of this recent surge of application of social network analysis in animal populations, and this Virtual Issue has been compiled to reflect that and to coincide with the publication of an open access 'How to...' guide to social network analysis by Damien Farine and Hal Whitehead. Farine & Whitehead’s comprehensive guide deals not only with the methods involved, but also emphasises the need to think carefully about the way that data collection and observation constrain the types of social processes that can be studied, and also looks forward to the use of social network analysis as a way to test and quantify many poorly understood processes in animal populations.
Over recent years, empirical papers in Journal of Animal Ecology featured in this Virtual Issue have reflected some of the points that Farine & Whitehead make. Perkins et al. show how the method of observation and construction of a social network matters a lot for its resultant structure, and Lusseau et al. show how the social network of bottle-nosed dolphins results from largely short-term associations between individuals in a classic fisson-fusion society. Tanner and Jackson show that the social network structure of a crab results from the interaction between resource distribution and individual behavioural variability. A common focus of social network studies papers in Journal of Animal Ecology has been their use in understanding pathogen spread, or the potential for pathogen spread, in animal populations. Böhm et al. and Rushmore et al. used observations of badgers and chimpanzees respectively to construct social networks and to model the potential effects of the resultant structures on the transmission of pathogens. Fenner et al. and VanderWaal et al. applied the methods to understand the role of social structure in explaining the distribution of three contrasting pathogens (a nematode, a tick and E. coli). Fenner et al’s analysis suggests that the transmission of different parasites is driven by social interactions of different classes of individuals, with residents and dispersers playing pathogen taxon-dependent roles.
Social network structure can influence many other processes, and papers by Schlicht et al. and McFarland et al. illustrate this nicely. Schlicht et al. use a network-like approach to understand how the occurrence of extra-pair paternity in blue tits depends on the properties of the local network of neighbours. McFarland et al. show how variable thermal stress in primates can be explained in terms of social network position.
Finally, Tur et al. combine an individual-level social network approach with a community network, to ask whether understanding individual variability in associations in an insect-pollinator network provides a more refined picture of a community network; they show that individual specialisation is masked by a species-level analysis and hence that combining these approaches may offer a much more refined understanding of interactions within communities of species.
- 25 October 2015
- 22 March 2015
- 28 March 2017
- 1 June 2016
Journal of Animal Ecology
A key process in understanding patterns of diversity is dispersal. The act of dispersal mixes populations, moves animals, genes, and associated properties through space, and ultimately is a key determinant of colonisation and extinction rates in meta-populations. Understanding dispersal requires both the development of theory to predict how dispersal should evolve, as well as empirical tests of the forces acting on dispersal behaviour. Shaw & Kokko (2014) develop theoretical models to ask how dispersal, on the one hand, and mate-searching, on the other, interact with each other. They show that this interaction depends crucially on the timing of mating with respect to dispersal. Berger-Tal et al. (2016) use experimental studies of social spiders to show that dispersal decisions from natal colonies can be predicted by increased competition, or declining resource availability. Jacob et al. (2015) show - using microcosm experiments with ciliates - how the information carried by immigrants can influence the dispersal decisions in those populations into which immigrants move. Finally, dispersal may have consequences not only for the individuals dispersing, but also for their parasites, and other associated organisms. Knowles et al. (2014) use a long-term bird-malaria study to ask how natal dispersal of hosts interacts with malaria parasitism in wild bird populations, and show that selection on dispersal in the host depends crucially on the parasite distribution in the environment.
A striking aspect of diversity, that has intrigued ecologists since the 19th century, concerns the adaptive nature of colour polymorphisms. Nokelainen et al. (2014) investigate selection on the warning colour polymorphism of the wood tiger moth, and show that the presence of different communities of predatory bird species changes which colour is selected. Gordon et al. (2015) then tested how mating preferences act to maintain the same system and showed that despite positive frequency-dependent mating advantages for male colour, migration between patches with different predation preferences could lead to the maintenance of stable polymorphisms. Sumasgutner et al. (2016) explore the forces acting on another polymorphism: coloration in the black sparrowhawk, breeding in South Africa. They show that the fitness of breeding attempts of this species depend both on the diversity of morphs in the parents (pairs comprising different morphs having higher success) as well as interactions between climatic conditions and parental morph. Finally, Mérot et al. (2016) explore Mullerian mimicry in the textbook Heliconius group, asking what happens to the degree of mimicry as the composition of the butterfly community changes over space. They show that mimics track the local changes in community composition. Taken together, these papers emphasise the way that understanding such classic evolutionary examples as colour polymorphism requires an understanding of ecological variation in space.
The raw material of evolution is variation in fitness, and it is the covariance between fitness and phenotypic traits that defines natural selection. Work on the evolutionary ecology of fitness variation in Journal of Animal Ecology has followed many paths over the years. A growing recent theme has been to understand the way that fitness, and fitness components, change with age, and as long-term population studies mature, such variation has been easier to quantify. Zhang et al. (2015) used a long-term common tern population study to determine which process drives age-related changes in life history traits, showing that in the majority of cases, improvement within individuals is key. Kervinen et al. (2016) used similar data for displaying male black grouse to show that sexual selection on male display traits becomes significantly stronger as males grow older. Finally, while natural selection is relatively easy to quantify, it is much harder to assign causes to variation in natural selection. Bouwhuis et al. (2015) used hierarchical partitioning of trait variation..
- 1 November 2016
- 1 April 2016
Journal of Animal Ecology
Journal of Animal Ecology has, over the years, published many papers that fall under the remit of nutritional ecology. This virtual issue highlights recent papers in Journal of Animal Ecology focused on nutritional ecology, and which span a range of scales and interactions, including the effects of nutrients on foraging behavior, animal life history traits and ecology, host-parasite/pathogen interactions, community ecology and ecosystems. This virtual issue also coincides with an up-coming nutritional homeostasis workshop that will be hosted at the LIMES Institute, at the University of Bonn (May 1-4).
Foraging behavior will always be a central tenet of nutritional ecology, and given the recent attention bee health has received, and the importance of bees as pollinators, there has been a surge in studies exploring how bees forage for pollen. Eckhardt et al. show that a generalist solitary bee practices pollen mixing as a mechanism that allows them to incorporate into their diets, a relatively high amount of pollen that alone would be unsuitable. Dramatic abiotic effects can also alter the nutritional landscape. For herbivores, fire is an important event in grasslands and savannas and is known to modify plant nutrient characteristics. However, fire also reduces vegetation height, which can increase visibility and risks to predation. Eby et al. show that fire increases leaf nitrogen, copper, potassium and magnesium content in leaves, and that smaller herbivores prefer burned areas more strongly than larger herbivores. They suggest that increased herbivore abundance on burned areas is driven by an increase in non-nitrogen nutrients. Body size, as well as ontogeny, and their link to nutrition has been recently investigated by Richman et al. Working with Canada and lesser snow geese, they show that smaller-bodied goslings are more negatively affected by low quality food (defined by protein and fiber content), and suggest that larger body size may provide some flexibility in dealing with low forage quality. Interestingly, nutrients can sometimes modify foraging behavior. Rodriguez-Pena et al. show that when nectar contains only sugar, a specialist nectarivorous bat prefers the most concentrated sugar-only nectar. However, this preference disappears when the nectar contains amino acids. For a generalist nectarivorous bat, supplementing nectar with an amino acid cocktail did not alter preferences.
Life history, and changes in food nutrient content and temperature, can also interact to impact how animals respond to food nutrient content. Providing supplemental food for garden birds is a growing trend, and Plummer et al. have investigated the carry-over effects of winter food supplementation on egg production in wild blue tits. They found that winter provisioning can have negative downstream consequences, but this was dependent on the combination of nutrients provisioned. Supplementing the diet with fat alone resulted in larger eggs with smaller relative yolk mass and reduced carotenoid concentrations. These negative effects were not observed when foods were supplemented with fat plus vitamin E. Animals adapted to short and cold summers also respond to changes in food quality and temperature. Liess et al. found that arctic tadpoles grew and developed faster on high-quality food and that rearing temperature affected their stoichiometric (and life history) responses. They suggest that increased temperature likely alters uptake and incorporation of nutrients, and may modify nutrient requirements and nutrient cycling.
We are now also beginning to better understand how nutritional status mediates an animal’s response to parasites. Cornet et al. infected canaries with Plasmodium parasites and then allocated them to control or supplemented diets. They then transferred parasites from these two environments (employing a factorial design) to new hosts reared on control or supplemented diets. They found that parasites from control hosts performed better in their subsequent hosts, and were more virulent. Using a somewhat similar approach, Lalubin et al. looked at how the nutritional status of mosquitos infected..
- 1 February 2016
More recently there has been an attempt to provide a conceptual unification of the wide and somewhat disparate field of movement studies, under the Movement Ecology framework (or paradigm, see Nathan et al. 2008 PNAS). The underlying idea of the framework is that the geometry of any movement path is given by the combined effect of four main mechanistic components, namely that the decision of when and how to move is determined by the interactions between the individual organism (internal state, individual conditions) and the external environment (abiotic and biotic), conditional on the movement and orientation capacities of the organism. Thus different frameworks, from empirical to methodological to theoretical, can be accommodated under this unifying paradigm. Hence, whilst individual studies may focus on different mechanistic causes of movement, such as the internal state (why move?) or the navigation process (where to move?), the interpretation and generalisation of the inferences obtained is facilitated by the unifying interpretative framework.
Journal of Animal Ecology has been at the forefront of animal movement research, including novel technological and methodological developments which are fuelling the strong developments in the field (see Biotelemetry and Biologging, Virtual Issue 2008), and a growing number of publications specifically focussed on the ‘Movement Ecology’ paradigm. In rapidly growing fields, fuelled by technological and methodological advancements, a divide can form between the developments of new tools and the research questions addressed, with the former taking the centre stage. Accordingly, in the current Issue the Journal has published a Movement Ecology Special Feature, guest edited by Bram van Moorter, Manuela Panzacchi, Francesca Cagnacci and Mark S. Boyce, aimed at addressing this disconnect and provide examples of how to connect ‘tools’ with the research questions (Borger 2016).
This Virtual Issue has been compiled to coincide with the Movement Ecology Special Feature and is aimed at complementing it by reflecting recent exciting developments in the field, covered by papers in the Journal. Among the four mechanistic components of the Movement Ecology paradigm, understanding the effects of the external environment is certainly of paramount importance under current global change scenarios. Movement is one of the first behavioural responses of animals to environmental change and Senner et al. investigated the movement and fitness consequences of an extreme weather event for a long-distance migratory bird. Given that extreme weather events are expected to increase, under current climate change predictions, it is timely to see that such events may not constitute a great challenge for populations with large behavioural plasticity, continued access to food and no strict time constraints, as many populations might in reality be constrained by one of these aspects.
Orben et al. in fact show in another migratory diving seabird species how even an impressive behavioural flexibility in responding to local conditions may not be sufficient to adjust to changing environmental conditions, when constraints on movement capacity (here, expressed through body size) act differently between movement phases (small scale foraging vs. large scale migration), thereby restricting the set of available movement strategies. Diving capacity is a key movement capacity for seabirds, determining the functional relationship between environmental conditions and species distributions, yet studies with data on both prey and predator distributions are rare for seabirds, due to the difficulty of monitoring both; even less with concurrent data on foraging movements of individuals. Boyd et al. present data on the foraging movements of two surface-diving seabirds with different foraging modes (plunge vs. pursuit divers), combined with concurrent data on the abundance and depth distribution of the primary fish prey. Using this unique dataset the authors show that oceanographic processes determining the accessibility (depth distribution) of prey may be more important for surface foragers than those determining the overall abundance, with direct implications for marine reserve design.
- 1 October 2015
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