A review of the ecology, genetics, evolution, and magnetosome –induced behaviours of the magnetotactic bacteria

The discovery of magnetosome and magnetotaxis in its most simple form in the magnetotactic bacteria (MTB) had created the tremendous impetus. MTB, spanning multiple phyla, are distributed worldwide, and they form the organelles called magnetosomes for biomineralization. Eight phylotypes of MTB belong to Alphaproteobacteria and Nitrospirae. MTB show preference for specific redox and oxygen concentration. Magnetosome chains function as the internal compass needle and align the bacterial cells passively along the local geomagnetic field (GMF). The nature of magnetosomes produced by MTB and their phylogeny suggest that bullet-shaped magnetites appeared about 3.2 billion years ago with the first magnetosomes. All MTB contains ten genes in conserved mamAB operon for magnetosome chain synthesis of which nine genes are conserved in greigite-producing MTB. Many candidate genes identify the aero-, redox-, and perhaps phototaxis. Among the prokaryotes, the MTB possess the highest number of O2-binding proteins. Magnetofossils serve as an indicator of oxygen and redox levels of the ancient environments. Most descendants of ancestral MTB lost the magnetosome genes in the course of evolution. Environmental conditions initially favored the evolution of MTB and expansion of magnetosome-formation genes. Subsequent changes in atmospheric oxygen concentration have led to changes in the ecology of MTB, loss of magnetosome genes, and evolution of nonMTB.

First evidence of hunting of a Crested Indian Porcupine by an avian predator: The Eurasian Eagle Owl

Encounters between birds of prey and porcupines are rarely documented, and so far only in North America. At least 39% of such encounters lead to death of the attacker. We present first evidence for similar encounters between The Eurasian Eagle Owl and the Indian Crested Porcupine, suggesting that young porcupines may occasionally serve as potential prey for the owl.

From Citizen Science to Citizen Management: Suggestions for a pervasive fine-grained and operational approach to biodiversity conservation

Citizen Science involves people as part of a scientific enquiry. However, in an age of great environmental changes, citizens are faced with degradation that affects ecosystem structure and function. Their role as drivers of change can be also relevant for biodiversity conservation. As in Citizen Science, where the citizens, properly trained, can initiate a widespread and fine-grained knowledge process, it is also possible to start a Citizen Management process, where citizens, adequately trained in problem solving, can change the state of an environmental system, with positive effects on the latter and on themselves. To prepare citizens for the acquisition of a problem solving and management paradigms, a quick meeting carried out with citizens by a senior manager as facilitator can be an opportunity to explain some basic steps: introducing them to the concept of ‘problem’, the definition of a project team and SMART objectives, the use of creativity during brainstorming, choosing an approach to the decision-making process and defining a strategy (actions, times, roles, resources, monitoring, and adaptation). According to the Hill and Westbrook’s SWOT approach, we suggest a list of strengths, weaknesses, opportunities and threats that characterize the Citizen Management approach.

The effect of drainage height on plant-species composition on a semi-arid green roof system

Green roofs are expected to contribute to higher biodiversity in urban surroundings. Typically, green roofs have been designed with low plant diversity. However, plant diversity can be enhanced by controlling resource availability and creating distinct niches. Here we hypothesize that by using different drainage heights during the short plant-growing season in a semi-arid green roof system we can create distinct niches and plant communities. Our experiment took place at the University of Haifa, north Israel. We tested three different heights of drainage outlet: 10 cm under the surface of the substrate (Low), 1 cm under the surface of the substrate (Medium) and 3 cm above the surface of the substrate (High) on plant species-composition in green-roof gardens. Grasses cover was higher in High and Medium drainages while forbs cover was higher in Low drainage. Species richness was the highest in Low drainage while diversity indices showed the opposite trend. We conclude that by changing the height of the drainage we can create different niches and change species composition in a short time period of one growing season. This way we can create more diverse green roof communities and enhance biodiversity in urban areas, particularly in semi-arid regions.

Experimental size- and sex-specific predation on dung flies by amphibian and arthropod predators

Because predator-prey interactions in nature are multifarious, linking phenomenological predation rates to underlying behavioral or ecological mechanisms is challenging. Size- and sex-specific predation has been implicated as a major selective force keeping animals small, directing the evolution of body size and sexual size dimorphism. We experimentally assessed predation by 4 amphibian and 3 arthropod species (bug, fly, spider) on 3 species of dung flies with similar ecology but contrasting body sizes, sexual size dimorphism, and coloration. Predators were offered a size range of male and/or female individuals of one prey species. As expected based on optimal foraging theory, some anurans (Bufo bufo) preferred larger prey individuals, others (Bombina variagata, Rana esculenta) showed no preference. Small juvenile Rana temporaria metamorphs preferred small prey, as did all arthropod predators, a pattern that may be explained by gape limitation or larger prey escaping better. Presumably more mobile males were not preyed upon more frequently or faster than cryptic females, even when conspicuously colored. Contrary to expectation, predation rates on flies in mixed groups facilitating mating activity were not higher, nor was predation generally sex-specific, hence contributing little to sexual dimorphism. We conclude that the size-selectivity of predators, and hence the viability selection pattern exerted on their prey, depends foremost on the relative body sizes of the two in a continuous fashion, in addition to any specific prey defense mechanisms. Therefore, the mechanistic study of predation requires integration of both the predator and prey perspectives, and phenomenological field studies of predation remain indispensable.

Scale-independence in beetle species diversity-productivity relationship: The importance of heterogeneity arrangement in space

Species diversity-productivity relationship is often, but not always, scale dependent. We hypothesize that the arrangement of environmental heterogeneity along a rainfall gradient, as a surrogate for productivity, determines whether scale dependence of beetle diversity at our sandy sites exists. We chose seven geographically distant landscapes (360 kms from south to north) within a mean annual rainfall range of 30–585 mm, each having six clusters of five uniformly distributed pitfall traps (within a range of 0.24 km2). Vegetation and physical variables were measured within each landscape and its clusters to characterize both spatial and temporal heterogeneity. We used species diversity of each cluster and the accumulative species diversity in a landscape as local and regional diversity, respectively. Between-clusters dissimilarity in diversity reflected the turnover of species within a landscape. We used environmental measures in each cluster and at the entire landscape to indicate local and regional heterogeneity, respectively, and changes between transects to characterize the within-landscape dissimilarity in heterogeneity. Beetle diversity and productivity showed a unimodal pattern at both spatial scales, with a peak at intermediate productivity of ca. 300 mm. Environmental heterogeneity increased with productivity both at the local and at the landscape scales, but within-landscape dissimilarity in heterogeneity did not change with productivity. Between-clusters dissimilarity in diversity was higher at intermediate productivity, explaining the unimodal pattern at the landscape scale. We suggest that the scale independence in our study results from the equal distribution of environmental heterogeneity within a landscape. We propose that the exploration of the diversity-productivity relationship across scales should consider the way heterogeneity is distributed along the productivity gradient.

Does a bacterial infection lead to a nutritional deficiency in foraging Allenby’s gerbils?

Bacterial infections can have both direct (physiological) and indirect (ecological) costs for their hosts. The direct costs of infection may include nutritional deficiencies, which reduce body condition over time, and result in the hosts modifying their foraging behaviour to compensate for any losses. Allenby’s gerbils are commonly infected with the Mycoplasma haemomuris-like bacteria, which may induce choline (essential vitamin) and arginine (amino acid) deficiencies. Gerbils should therefore alter their behaviour to make up for any shortfalls in nutrient production and retention. We tested two predictions. 1) infected gerbils would compensate for nutrient losses by spending more time foraging in patches, including, during riskier periods of owl presence, and in riskier open microhabitats. Furthermore, infected gerbils would preferentially forage from patches supplemented with choline and arginine enriched food over control food. 2) Alternatively, if infection did not create a nutrient deficiency, then infected individuals would display a similar pattern of patch use to uninfected individuals, and harvest similar amounts of food from supplemented and control patches. Our findings supported the second prediction. There was no observed difference in foraging behaviour between infected and uninfected individuals. Moreover, infected gerbils did not selectively forage more intensively from food patches enriched with either choline or arginine seed over the control patches. These results suggest that this bacteria-gerbil interaction does not result in a nutrient deficiency as observed for other Mycoplasma-rodent systems.

Theory of planned behaviour approach to understand pro-environmental behaviour among young green consumers in Malaysia

The depletion of the natural environment and earth-wide natural resources have led to the increasing demand for green products. This has made young consumers carry on the green, and as a result, it affects the organization’s bottom line in building a positive image and goodwill message. This research explored the facet to investigate while applying some constructs from the Ajzen’s existing theory of planned behaviour (TPB) model with additional construct. 250 viable responses were applied and path modelling using SmartPLS 3.0 analyses was used to establish the model proposed. The results indicate that among the TPB constructs, perceived behavioural control (PBC), green perceived attitude (GPA), and other contextual constructs influence pro-environmental behaviour (PEB) positively. Looking at the relative importance of constructs, perceived green culture (PGC) followed by (GPA) had a stronger impact on PEB. The study provides evidence that young green consumers exhibit great concern towards environment, through model supportability and the inclusion of additional constructs which was supported in the TPB providing insight, and holding a sense of responsibility in the consumption pattern for a peaceful future. The obtained results can promote scientific progress in the respective research area and policy implications.

Positive association between experimental cortisol increases and cage-measures of feeding behavior in wild-caught gerbils

Glucocorticoid hormone levels vary within a forager based upon environmental stressors such as illumination and riskier habitats, and a forager’s response to environmental variables depends upon its glucocorticoid levels. Here, we report on a laboratory experiment in which we manipulated cortisol in Allenbyi’s gerbils (Gerbillus andersoni allenbyi) to test the relationship between cortisol and behavior. We then quantified the resulting blood cortisol levels and feeding behavior in gerbils. Thirty gerbils were injected with 21-day slow-release cortisol pellets drawn from 5 different dosages. We quantified the physiological response to pellet implantation in gerbils by measuring cortisol level in blood serum using ELISA (Enzyme Linked Immunosorbent Assay). We fed gerbils daily by mixing millet seeds into the sand inside rodent cages and measured the remaining seeds the following day to quantify feeding efforts. Some evidence supports that subcutaneous supplementation of glucocorticoids (GCs) in the gerbils led to higher blood serum levels. Cortisol levels varied according to time period of measurement. Gerbils that received lower dosages consumed most of the food presented to them when compared to those receiving the highest doses. In this manner, we delineate a pattern on cortisol hormone level variation over time following dosing and consequences in feeding behavior.