The repeatability of avian egg ejection behaviors across different temporal scales,breeding stages,female ages and experiences

An evolutionarily fundamental, yet rarely examined, aspect of host–parasite arms races is the repeatability of individual host responses to parasitism. We examined the repeatability of egg ejection, and the latency to eject, across a time-scale of days (within one breeding attempt), weeks and months (between breeding attempts within one breeding season), and years (across different breeding seasons). The ejection of non-mimetic model eggs by European blackbirds, Turdus merula, showed overall high repeatability (r?~?0.70) and, similar to empirical patterns on most other behavioral traits already studied, showed decreasing repeatability with time. In contrast, latency to ejection showed negligible repeatability overall (r ~0.20) and did not change with time. Ejection rates, latencies to ejection and the repeatability of egg ejection did not differ between young and old females. Previous experience with experimentation (number of model eggs the female received before the focal trial) marginally non-significantly covaried with egg ejection (positively) and with latency to egg ejection (negatively). Repeatability estimates for both egg ejection and latency to egg ejection at the within one breeding attempt time-scale did not statistically differ from those reported in a previous study of a different blackbird population (introduced population in New Zealand). To our knowledge, this is the first comparison of behavioral repeatability between a native vs. introduced population of any animal species.     

Does temporal and spatial segregation explain the complex population structure of humpback whales on the coast of West Africa?

Humpback whales (Megaptera novaeangliae) in the Southeastern Atlantic Ocean (International Whaling Commission ‘Breeding Stock B’—BSB) are distributed from the Gulf of Guinea to Western South Africa. Genetic data suggest that this stock may be sub-structured, but it remains unknown if this is due to reproductive segregation. This paper evaluates the spatial and temporal population structure of BSB humpback whales using a combination of maternally and bi-parentally inherited markers. The genetic differentiation that we identify in this study could be due to a combination of (1) spatial and/or temporal segregation on breeding grounds in the greater Gulf of Guinea, (2) the possibility of maternally inherited site fidelity to specific feeding grounds and (3) the use of two generalized but exclusive migratory routes (coastal and offshore) between feeding and breeding areas. Further, photo-identification and genetic sampling efforts in other areas of the Sub-Saharan Western Africa winter range and targeted deployment of satellite tags would help to clarify some of the apparent complexity in the population structure of animals biopsied in this region.     

A split flow chamber with artificial sediment to examine the below-ground microenvironment of aquatic macrophytes

We present a new experimental set-up enabling fine-scale examination of how changing environmental conditions affect the below-ground biogeochemical microenvironment of aquatic macrophytes. By means of microsensor and planar optode technology, the influence of plant-mediated radial O₂ release on the below-ground chemical microenvironment of Zostera muelleri and Halophila ovalis was determined in high spatio-temporal resolution. The seagrass specimens were cultured in a new split flow chamber with artificial sediment made of a deoxygenated seawater–agar solution with added sulphide. Microelectrode measurements revealed radial O₂ release from the root–shoot junction of both Z. muelleri and H. ovalis during both light stimulation and darkness, resulting in a rapid decrease in H₂S concentration, and a significant drop in pH was observed within the plant-derived oxic microzone of Z. muelleri. No radial O₂ release was detectable from the below-ground tissue of Z. muelleri during conditions of combined water-column hypoxia and darkness, leaving the plants more susceptible to sulphide invasion. The spatial O₂ heterogeneity within the immediate rhizosphere of Z. muelleri was furthermore determined in two dimensions by means of planar optodes. O₂ images revealed a decrease in the spatial extent of the plant-derived oxic microzone surrounding the below-ground tissue during darkness, supporting the microelectrode measurements. This new experimental approach can be applied to all rooted aquatic plants, as it allows for direct visual assessment of the below-ground tissue surface during microprofiling, while enabling modification of the above-ground environmental conditions.     

Maturation shifts in a temperate marine fish population cannot be explained by simulated changes in temperature-dependent growth and maturity

To disentangle genetic and environmental influences on phenotypic traits that influence maturation of fish, it would be useful to predict the expected change due to environment alone to compare with observations. This requires a realistically scaled, species-specific life history model of environmentally determined variation in individual growth and maturation. In this study, inter-annual variability in the proportion of mature haddock in the west North Sea was predicted using a stochastic, individual-based simulation model incorporating a temperature-dependent maturation threshold. This species and region are particularly relevant to the debate about the relative importance of genetic and climate change because North Sea haddock have experienced both high fishing mortality and substantial warming in recent decades. Using observed temperatures in combination with temperature-dependent models for growth and maturation, the simulation model predicted year-to-year variation in length and maturity at age expected for cohorts produced from 1979 to 2006. The simulated proportions mature at age 2 were then compared to the observed proportions in an annual bottom trawl survey. Although the model explained much of the high-frequency variation in maturation, the simulated time trend under-represented the rate of increase in the observed trend in proportions mature. This inability of the temperature-dependent life history model to predict the magnitude of change appears consistent with a long-term decline in the maturation threshold. This result provides indirect support for a genetic change in a key life history trait.     

Quantifying the effect of wind on internal wave resonance in Lake Villarrica,Chile

Lake Villarrica, located in south central Chile, has a maximum depth of 167 m and a maximum fetch of about 20 km. The lake is monomictic, with a seasonal thermocline located at a depth of approximately 20 m. Field data show the presence of basin-scale internal waves that are forced by daily winds and affected by Coriolis acceleration. A modal linear and non-linear analysis of internal waves has been used, assuming a two-layer system. The numerical simulations show good agreement with the internal wave field observations. The obtained modes were used to study the energy dissipation within the system, which is necessary to control the amplitude growth. Field data and numerical simulations identify (1) the occurrence of a horizontal mode 1 Kelvin wave, with a period of about a day that coincides with the frequency of daily winds, suggesting that this mode of the Kelvin waves is in a resonant state (subject to damping and controlled by frictional effects in the field) and (2) the presence of higher-frequency internal waves, which are excited by non-linear interactions between basin-scale internal waves. The non-linear simulation indicates that only 10 % of the dissipation rate of the Kelvin wave is because of bottom friction, while the rest 90 % represents the energy that is radiated from the Kelvin wave to other modes. Also, this study shows that modes with periods between 5 and 8 h are excited by non-linear interactions between the fundamental Kelvin wave and horizontal Poincaré-type waves. A laboratory study of the resonant interaction between a periodic forcing and the internal wave field response has also been performed, confirming the resonance for the horizontal mode 1 Kelvin wave.     

Utilisation of a coastal grassland by geese after managed re-alignment

In this study we evaluate the effect of coastal re-alignment on the utilisation of coastal grasslands by staging geese. We assessed vegetation change and utilisation by geese using repeated mapping and regular dropping counts in both the restored marsh and adjacent reference sites. All measurements were started well before the actual re-alignment. In addition, we studied the effects of livestock grazing on vegetation and geese, using exclosures. The vegetation transformed from fresh grassland into salt-marsh vegetation. A relatively large proportion of the de-embanked area became covered with secondary pioneer vegetation, and the overall cover of potential food plants for geese declined. Goose utilisation had initially dropped to low levels, both in autumn and in spring, but it recovered to a level comparable to the reference marsh after ten years. Exclosure experiments revealed that livestock grazing prevented the establishment of closed swards of grass in the poorly drained lower area of the restored marsh, and thereby negatively affected goose utilisation of these areas during spring staging. Goose grazing in the restored marsh during spring showed a positive numerical response to grass cover found during the preceding growing season. (1) The value of restored salt marsh as foraging habitat for geese initially decreased after managed re-alignment but recovered after ten years. (2) Our findings support the idea that the value of foraging habitats depends largely on the cover of forage plants and that this can be manipulated by adjusting both grazing and drainage.     

Tracking managerial conflict adaptivity: Introducing a dynamic measure of adaptive conflict management in organizations

Since Darwin, adaptation to change has been associated with survival and fit. Yet, despite this, leaders and managers often get stuck in dominating approaches to conflict, and few scholars have examined the role of adaptation in managing conflicts effectively over time and across changing situations. The goal of this paper is threefold. First, we develop a new measure for assessing conflict adaptivity of managers [the Managerial Conflict Adaptivity Assessment (MCAA)], based on a situated model of conflict in social relations. We define conflict adaptivity as the capacity to respond to different conflict situations in accordance with the demands specified by the situation. The measure consists of 15 distinct work‐conflict scenarios and provides five behavioral response options, which represent five primary strategies employed in conflict. Individuals who tend to respond to the conflicts in a manner consistent with the situations provided are considered to be more adaptive. Second, we test and find that managerial conflict adaptivity is related to higher levels of satisfaction with conflict processes at work as well as higher levels of well‐being at work. Third, we test the MCAA's construct validity and provide evidence that the MCAA is positively related to behavioral flexibility and self‐efficacy. Copyright © 2014 John Wiley & Sons, Ltd.     

Model reactions of chromium compounds with mammalian and bacterial cells†

Chromate uptake, reduction, cytotoxicity and mutagenicity were studied with human red blood cells, Chinese hamster ovary (CHO) cells and/or Salmonella typhimurium mutant cells. All cell types rapidly took up chromates whereas chromium(III) salts were excluded under the experimental conditions. Red blood cells reduced and accumulated chromium from chromate. At concentrations above 0.1 mM, chromate inactivated the red cell chromate carrier. Chromate above 0.01 mM inhibited CHO cell proliferation irrespective of the cations present. Chromate and two chromium(III) complexes were mutagenic with Salmonella mutants in the Ames’ assay. A model for chromate metabolism and genotoxicity is proposed.     

Risk vs. reward: how predators and prey respond to aging olfactory cues

Many animals use olfaction to find food and avoid predators, and must negotiate environments containing odors of varying compositions, strengths, and ages to distinguish useful cues from background noise. Temporal variation in odor cues (i.e., “freshness”) seems an obvious way that animals could distinguish cues, yet there is little experimental evidence for this phenomenon. Fresh cues provide a more reliable indicator of donor presence than aged cues, but we hypothesize that the benefits of responding to aged cues depend on whether the cue indicates the proximity of a predator or a potential meal. As prey cannot remain eternally risk averse in response to predator odor, we predict that antipredator responses should diminish as predator cues age. In contrast, animals searching for food should investigate aged prey cues if investigation costs are sufficiently low and the potential benefit (a meal) sufficiently high; thus, we predict that predators will maintain interest in aged prey cues. We tested these ideas using free-ranging rats (Rattus spp.) in two separate experiments; firstly assessing giving-up densities in the presence of predator odor, and secondly examining investigation rates of prey odors. As predicted, giving-up densities dropped once predator odor had aged, but investigation rates remained similar for aged and fresh prey odor. Thus, rats used temporal variation in odor cues to evaluate the cost–benefit relationship of responding to predator and prey odors. We suggest that the ecological significance of variable cue age needs more research and should be considered when interpreting behavioral responses to olfactory information.     

Effects of feeding and light intensity on the response of the coral Porites rus to ocean acidification

Recently, it has been suggested that there are conditions under which some coral species appear to be resistant to the effects of ocean acidification. To test if such resistance can be explained by environmental factors such as light and food availability, the present study investigated the effect of 3 feeding regimes crossed with 2 light levels on the response of the coral Porites rus to 2 levels of pCO₂ at 28 °C. After 1, 2, and 3 weeks of incubation under experimental conditions, none of the factors—including pCO₂—significantly affected area-normalized calcification and biomass-normalized calcification. Biomass also was unaffected during the first 2 weeks, but after 3 weeks, corals that were fed had more biomass per unit area than starved corals. These results suggest that P. rus is resistant to short-term exposure to high pCO₂, regardless of food availability and light intensity. P. rus might therefore represent a model system for exploring the genetic basis of tolerance to OA.