Do individual Activity Patterns of Brown Trout (Salmo trutta) alter the Exposure to Parasitic Freshwater Pearl Mussel (Margaritifera margaritifera) Larvae?

The hypothesis that interindividual differences in the activity of brown trout alter the exposure to parasitic freshwater pearl mussel glochidia was tested in a Swedish stream. Wild yearling brown trout (N = 103) were caught, individually tagged for identification and scored for open‐field activity during standardized laboratory tests in June. Fifty gravid freshwater pearl mussels were relocated to the stream, where after the trout were released back into the stream. The fish were recaptured in October (N = 35), checked for glochidia encystment (infested individuals: n = 6) and re‐scored for open‐field activity traits. Swimming velocity during the test was higher in fish infected with glochidia, suggesting that high activity could increase their exposure to glochidia. Potentially, as metabolism rate and ventilation rate typically increase with activity, elevated activity may lead to an increased likelihood of glochidia passing over the gills. This novel finding suggests that glochidia infestation is non‐random and that the behaviour of the host fish can influence the likelihood of glochidia infestation.     

Similar recent selection criteria associated with different behavioural effects in two dog breeds

Selection during the last decades has split some established dog breeds into morphologically and behaviourally divergent types. These breed splits are interesting models for behaviour genetics since selection has often been for few and well‐defined behavioural traits. The aim of this study was to explore behavioural differences between selection lines in golden and Labrador retriever, in both of which a split between a common type (pet and conformation) and a field type (hunting) has occurred. We hypothesized that the behavioural profiles of the types would be similar in both breeds. Pedigree data and results from a standardized behavioural test from 902 goldens (698 common and 204 field) and 1672 Labradors (1023 and 649) were analysed. Principal component analysis revealed six behavioural components: curiosity, play interest, chase proneness, social curiosity, social greeting and threat display. Breed and type affected all components, but interestingly there was an interaction between breed and type for most components. For example, in Labradors the common type had higher curiosity than the field type (F_1,1668 = 18.359; P < 0.001), while the opposite was found in goldens (F_1,897 = 65.201; P < 0.001). Heritability estimates showed considerable genetic contributions to the behavioural variations in both breeds, but different heritabilities between the types within breeds was also found, suggesting different selection pressures. In conclusion, in spite of similar genetic origin and similar recent selection criteria, types behave differently in the breeds. This suggests that the genetic architecture related to behaviour differs between the breeds.     

Looking to the future: key points for sustainable management of northern Great Plains grasslands

The grasslands of the northern Great Plains (NGP) region of North America are considered endangered ecosystems and priority conservation areas yet have great ecological and economic importance. Grasslands in the NGP are no longer self‐regulating adaptive systems. The challenges to these grasslands are widespread and serious (e.g. climate change, invasive species, fragmentation, altered disturbance regimes, and anthropogenic chemical loads). Because the challenges facing the region are dynamic, complex, and persistent, a paradigm shift in how we approach restoration and management of the grasslands in the NGP is imperative. The goal of this article is to highlight four key points for land managers and restoration practitioners to consider when planning management or restoration actions. First, we discuss the appropriateness of using historical fidelity as a restoration or management target because of changing climate, widespread pervasiveness of invasive species, the high level of fragmentation, and altered disturbance regimes. Second, we highlight ecosystem resilience and long‐term population persistence as alternative targets. Third, because the NGP is so heavily impacted with anthropogenic chemical loading, we discuss the risks of ecological traps and extinction debt. Finally, we highlight the importance of using adaptive management and having patience during restoration and management. Consideration of these four points will help management and restoration of grasslands move toward a more successful and sustainable future. Although we specifically focus on the NGP of North America, these same issues and considerations apply to grasslands and many other ecosystems globally.     

Life‐history evolution under fluctuating density‐dependent selection and the adaptive alignment of pace‐of‐life syndromes

We present a novel perspective on life‐history evolution that combines recent theoretical advances in fluctuating density‐dependent selection with the notion of pace‐of‐life syndromes (POLSs) in behavioural ecology. These ideas posit phenotypic co‐variation in life‐history, physiological, morphological and behavioural traits as a continuum from the highly fecund, short‐lived, bold, aggressive and highly dispersive ‘fast’ types at one end of the POLS to the less fecund, long‐lived, cautious, shy, plastic and socially responsive ‘slow’ types at the other. We propose that such variation in life histories and the associated individual differences in behaviour can be explained through their eco‐evolutionary dynamics with population density – a single and ubiquitous selective factor that is present in all biological systems. Contrasting regimes of environmental stochasticity are expected to affect population density in time and space and create differing patterns of fluctuating density‐dependent selection, which generates variation in fast versus slow life histories within and among populations. We therefore predict that a major axis of phenotypic co‐variation in life‐history, physiological, morphological and behavioural traits (i.e. the POLS) should align with these stochastic fluctuations in the multivariate fitness landscape created by variation in density‐dependent selection. Phenotypic plasticity and/or genetic (co‐)variation oriented along this major POLS axis are thus expected to facilitate rapid and adaptively integrated changes in various aspects of life histories within and among populations and/or species. The fluctuating density‐dependent selection POLS framework presented here therefore provides a series of clear testable predictions, the investigation of which should further our fundamental understanding of life‐history evolution and thus our ability to predict natural population dynamics.     

Brain size predicts behavioural plasticity in guppies (Poecilia reticulata): An experiment

Understanding how animal personality (consistent between‐individual behavioural differences) arises has become a central topic in behavioural sciences. This endeavour is complicated by the fact that not only the mean behaviour of individuals (behavioural type) but also the strength of their reaction to environmental change (behavioural plasticity) varies consistently. Personality and cognitive abilities are linked, and we suggest that behavioural plasticity could also be explained by differences in brain size (a proxy for cognitive abilities), since accurate decisions are likely essential to make behavioural plasticity beneficial. We test this idea in guppies (Poecilia reticulata), artificially selected for large and small brain size, which show clear cognitive differences between selection lines. To test whether those lines differed in behavioural plasticity, we reared them in groups in structurally enriched environments and then placed adults individually into empty tanks, where we presented them daily with visual predator cues and monitored their behaviour for 20 days with video‐aided motion tracking. We found that individuals differed consistently in activity and risk‐taking, as well as in behavioural plasticity. In activity, only the large‐brained lines demonstrated habituation (increased activity) to the new environment, whereas in risk‐taking, we found sensitization (decreased risk‐taking) in both brain size lines. We conclude that brain size, potentially via increasing cognitive abilities, may increase behavioural plasticity, which in turn can improve habituation to novel environments. However, the effects seem to be behaviour‐specific. Our results suggest that brain size likely explains some of the variation in behavioural plasticity found at the intraspecific level.     

Microbial biofilms: new catalysts for maximizing productivity of long-term biotransformations

The performance of biocatalytic reactions is often hampered by product and/or substrate toxicity and short-term reaction times due to instable biocatalysts. Microbes in biofilms show a remarkable resistance against biocides and form stable communities. In nature, especially in environments characterized by harsh conditions such as heavily contaminated sites, cells grow pre-dominantly in biofilms, which enable them to cope with physiological stress. This robustness was utilized to design a bioprocess concept based on catalytic biofilms for stable long-term transformations of toxic reactants. Sixty-nine bacterial strains have been screened to find organisms suitable for biofilm-based biotransformations. This included host strains important for recombinant enzyme expression and strains isolated from biofilters or contaminated soils. Nearly all organisms with bioremediation potential showed good biofilm forming capacities. Pseudomonas sp. strain VLB120DeltaC was chosen as a model organism due to its excellent biofilm forming capacity and its well-studied capability of catalyzing asymmetric epoxidations. A tubular reactor was used for the biotransformation of styrene to (S)-styrene oxide as a model reaction. The process was stable for at least 55 days at a maximal volumetric productivity of 16 g/(L(aq) day) and a yield of 9 mol%. In situ product extraction prevented product inhibition of the catalyst. Biofilm physiology and dynamics are characterized during the biotransformation and limitations and advantages of this reaction concept are discussed.     

Early queen infection shapes developmental dynamics and induces long-term disease protection in incipient ant colonies

Infections early in life can have enduring effects on an organism's development and immunity. In this study, we show that this equally applies to developing ‘superorganisms’––incipient social insect colonies. When we exposed newly mated Lasius niger ant queens to a low pathogen dose, their colonies grew more slowly than controls before winter, but reached similar sizes afterwards. Independent of exposure, queen hibernation survival improved when the ratio of pupae to workers was small. Queens that reared fewer pupae before worker emergence exhibited lower pathogen levels, indicating that high brood rearing efforts interfere with the ability of the queen's immune system to suppress pathogen proliferation. Early-life queen pathogen exposure also improved the immunocompetence of her worker offspring, as demonstrated by challenging the workers to the same pathogen a year later. Transgenerational transfer of the queen's pathogen experience to her workforce can hence durably reduce the disease susceptibility of the whole superorganism.     

Reproductive success of a marine teleost was correlated with proactive and reactive stress-coping styles

The present study investigated the relationship between reproductive success and stress-coping styles in gilthead seabream Sparus aurata in captivity. To characterise stress-coping styles, a total of 22 breeders were submitted to three different individual-based tests, one group-based test and post-handling glucocorticoid quantification. To assess spawning participation, a microsatellite analysis was performed on a total of 2698 larvae, which allowed each offspring to be assigned unambiguously to a single parental couple. Overall, S. aurata showed defined proactive and reactive behavioural traits. Proactive breeders exhibited higher levels of activity and risk taking and lower glucocorticoid blood levels than reactive breeders. The stress-coping style traits were consistent over time and context (different tests). Breeders that contributed to a higher number of progeny exhibited proactive behaviours, while those showing low progeny contribution exhibited reactive behaviour. Therefore, breeders with a high proportion of progeny (> 20%) had significantly higher activity and risk taking and lower cortisol than breeders with low progeny contribution (< 20%). In addition, males were more proactive than females and males exhibited significantly higher activity, risk taking and lower cortisol than females. This study is the first to establish in S. aurata breeders: (a) a relationship between stress-coping styles and spawning success; (b) a relationship between stress-coping styles and gender; and (c) the existence of proactive and reactive traits at the adult stage.     

The role of intraspecific competition in the dispersal of an invasive fish

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Do alternative reproductive strategies in the Wellington tree weta represent different behavioural types?

In many animal species, variation in reproductive success among individuals has led to the evolution of alternative mating strategies, which in the case of insects can often be correlated with developmental trajectories. In the Wellington tree weta, Hemideina crassidens, males can mature at the 8th, 9th or 10th instar, while females mature at the 10th instar only. A number of morphological attributes including male head and mandible size correlate with final instar number, and as these attributes represent a form of weaponry, they are often used in mate/site guarding and male–male competition. Tenth instar males have larger head/mandible/body sizes and show a conventional (guarder) reproductive strategy, whereas smaller 8th instar males typically show an unconventional (sneaker) strategy. In contrast, 9th instar males are predicted to adopt a “jack‐of‐all‐trades” strategy whereby they can fight or sneak depending context. Here, we tested whether alternative reproductive morphs exhibit strategy‐specific differences in risk‐taking associated with refuge emergence, activity and antipredator behaviour and further, whether these traits correlate to form a behavioural syndrome. We found that tree weta show consistent and repeatable differences in activity and refuge use at the individual level; however, behavioural covariances suggest that only 8th instar males exhibit a behavioural syndrome. That 9th instar males show high plasticity and variance in their gallery‐related behaviours supports the hypothesis that these males are a “jack‐of‐all‐trades.” Contrary to our predictions, antipredator behaviour was not correlated with other traits, and differences in behaviour overall were consistently more pronounced between individuals rather than between male morphs or sexes.