Consequences of food distribution for optimal searching behavior: an evolutionary model

Resource distribution can vary greatly in space and time. Consequently, animals should adjust their searching tactics to such spatio–temporal patterns in accordance with their innate capabilities, or alternatively, they should use a genetically fixed searching tactic that has been evolved in response to the specific pattern of the food they experience. Using a simulation model and a genetic algorithm, we show how optimal searching tactics change as a function of food spatial pattern. Searching tactics for hidden prey can be approximated using the following three components: (1) Extensive search mode (ESM), the type of movement before encountering a food item; (2) Intensive search mode (ISM), the type of movement after encountering a food item; and (3) ISM duration. Both ESM and ISM are characterized by movement tortuosity. We show that searching behavior adaptively changes as a function of food pattern. When food is distributed in a regular pattern, ISM is more directional than ESM, but under a clumped food pattern, ISM is much more tortuous than ESM. It may suggest that animals with larger spectra of searching tactics should experience greater variance or seasonal changes in their food pattern than animals with narrow spectra of searching tactics. Increased forager attack radius diminishes the differences between ESM and ISM, and thus the use of these three components to model searching in animals with higher attack radii is not appropriate. Increased handling time, which is a surrogate of reducing habitat profitability results in longer patch residency time as expected by optimal foraging theory. To conclude, we suggest that using such a combined approach of simulation models and genetic algorithms may improve our understanding of how extrinsic and intrinsic factors interact to influence searching behavior.     

Genetic Diversity of the Cestode Echinococcus multilocularis in Red Foxes at a Continental Scale in Europe

Background

Alveolar echinococcosis (AE) is a severe helminth disease affecting humans, which is caused by the fox tapeworm Echinococcus multilocularis. AE represents a serious public health issue in larger regions of China, Siberia, and other regions in Asia. In Europe, a significant increase in prevalence since the 1990s is not only affecting the historically documented endemic area north of the Alps but more recently also neighbouring regions previously not known to be endemic. The genetic diversity of the parasite population and respective distribution in Europe have now been investigated in view of generating a fine-tuned map of parasite variants occurring in Europe. This approach may serve as a model to study the parasite at a worldwide level.

Methodology/Principal Findings

The genetic diversity of E. multilocularis was assessed based upon the tandemly repeated microsatellite marker EmsB in association with matching fox host geographical positions. Our study demonstrated a higher genetic diversity in the endemic areas north of the Alps when compared to other areas.

Conclusions/Significance

The study of the spatial distribution of E. multilocularis in Europe, based on 32 genetic clusters, suggests that Europe can be considered as a unique global focus of E. multilocularis, which can be schematically drawn as a central core located in Switzerland and Jura Swabe flanked by neighbouring regions where the parasite exhibits a lower genetic diversity. The transmission of the parasite into peripheral regions is governed by a “mainland–island” system. Moreover, the presence of similar genetic profiles in both zones indicated a founder event.     

Complementary medicine in the primary care setting: Results of a survey of gender and cultural patterns in Israel

Objective: The purpose of this study was to examine the use of complementary and alternative medicine (CAM) in a primary care practice in Israel to determine prevalence and patterns of use.Methods: Trained research assistants invited all patients attending the administrative, medical, pharmaceutical, or nursing services of 7 clinics in urban and rural areas of northern Israel over a 16-month period, from April 1, 2005, through August 1, 2006, to complete a 13-item written questionnaire about CAM use and beliefs about CAM safety and efficacy. CAM was defined as therapies often referred to as alternative, complementary, natural, or folk/traditional medicine, and which are not usually offered as part of the medical treatment in the clinic, including herbal medicine, Chinese medicine (including acupuncture), homeopathy, folk and traditional remedies, dietary/nutritional therapy (including nutritional supplements), chiropractic, movement/manual healing therapies (including massage, reflexology, yoga, and Alexander and Feldenkrais techniques), mind-body techniques (including meditation, guided imagery, and relaxation), energy and healing therapies, and other naturopathic therapies. The Pearson χ² test and multivariate logistic regression were used to assess univariate associations with the odds ratios of CAM use among Arab and Jewish women. A t test was performed to determine whether there were any differences in the continuous variables between the 2 groups.Results: Of 3972 consecutive patients who received the questionnaire, 3447 responded; 2139 respondents (62%) were women. Of the female respondents, 2121 reported their religion (1238 respondents [58%] self-identified as being Arab, and 883 [41.6%] as being Jewish). Compared with men, more women used CAM during the previous year (46.4% vs 39.4%; P < 0.001). Women were more likely to use CAM and to be interested in receiving CAM at primary care clinics. Arab women reported less CAM use than Jewish women but were more interested in experiencing CAM, had a higher degree of confidence in CAM efficacy and safety, and more frequently supported the integration of CAM practitioners in primary care clinics.Conclusions: In this study, women visiting primary care clinics in northern Israel used CAM more often than men did. Arab women reported less use of CAM than did Jewish women but also reported greater confidence in CAM efficacy and safety.     

The involvement of sand disturbance, cannibalism and intra-guild predation in competitive interactions among pit-building antlion larvae

Competition in trap-building predators such as antlion larvae is a complex biotic interaction, potentially involving exploitation competition, sand throwing (i.e., interference competition), cannibalism and intra-guild predation. We investigated the short-term behavioral and developmental responses of the strict sit-and-wait antlion predator Myrmeleon hyalinus to sand disturbance (i.e., quantification of the impact of severe sand throwing), and to con- and hetero-specific competition by a larger sit-and-pursue antlion species Lopezus fedtschenkoi. We found that antlions subjected to sand disturbances reduced their pit construction activity and relocated less often. Furthermore, the reduction in pit construction activity was stronger among antlions subjected to disturbances prior to feeding. Almost no death occurred during the sand disturbance experiment, but as expected, disturbances caused reductions in the relative growth rates of antlions. This negative effect was stronger in the group exposed to sand disturbances prior to feeding. The presence of the sit-and-pursue competitor led to reductions both in pit construction and in relocation activities of M. hyalinus. Although the per-capita food supply was identical in both experiments, only 48% of M. hyalinus larvae survived the competition experiment, and this pattern was consistent between the con- and hetero-specific treatments. However, in the presence of hetero-specific competitors, the relative growth rate of surviving larvae was significantly lower than that measured in the presence of con-specific competitors. Our study demonstrates that investigating the different components of complex biotic interactions can markedly improve our understanding of how these different factors interact to influence the behavior and life history of organisms.     

Taxonomic size structure consistency of the English Channel phytoplankton

Here we report the worldwide first results on long-term variability of marine phytoplankton taxonomic size structure based on traditional taxonomic size spectra (TTSS). The Plymouth Marine Laboratory monitoring database for station L4 was used to build annual TTSS patterns (1992-2005) and estimate their similarity with the help of hierarchical cluster analysis. Almost identical TTSS patterns were observed each year. While the height of the main peaks was slightly variable, their horizontal positions were unchanged. Whereas the above patterns resembled the phytoplankton TTSS established for the subtropical Lake Kinneret, the L4 spectrum size range was much broader and the distance between the main peaks approximately two times greater. The similarity level (Pearson r = 0.872-0.992) in TTSS pairs for station L4 was comparable to the estimates established at several lakes, while being much higher than in the inter-ecosystem (L4 and Kinneret) pairs (r = 0.317-0.578). Thus, the phenomenon of long-term consistency of phytoplankton taxonomic size structure, found previously at freshwater ecosystems, for the first time is confirmed for marine phytoplankton, which speaks in favor of much higher generality of this important structural property of aquatic communities. The TTSS multi-annual consistency can be helpful for long-term monitoring, environment protection and forecasting. The evident and permanent difference in the peak positions between ecosystems opens a way for additional analyses which can be helpful for the development of theoretical models. A set of plausible mechanisms, capable to produce and support the empirically obtained distribution patterns, is discussed.     

The Involvement of IL-17A in the Murine Response to Sub-Lethal Inhalational Infection with Francisella tularensis

Background

Francisella tularensis is an intercellular bacterium often causing fatal disease when inhaled. Previous reports have underlined the role of cell-mediated immunity and IFNγ in the host response to Francisella tularensis infection.

Methodology/Principal Findings

Here we provide evidence for the involvement of IL-17A in host defense to inhalational tularemia, using a mouse model of intranasal infection with the Live Vaccine Strain (LVS). We demonstrate the kinetics of IL-17A production in lavage fluids of infected lungs and identify the IL-17A-producing lymphocytes as pulmonary γδ and Th17 cells. The peak of IL-17A production appears early during sub-lethal infection, it precedes the peak of immune activation and the nadir of the disease, and then subsides subsequently. Exogenous airway administration of IL-17A or of IL-23 had a limited yet consistent effect of delaying the onset of death from a lethal dose of LVS, implying that IL-17A may be involved in restraining the infection. The protective role for IL-17A was directly demonstrated by in vivo neutralization of IL-17A. Administration of anti IL-17A antibodies concomitantly to a sub-lethal airway infection with 0.1×LD₅₀ resulted in a fatal disease.

Conclusion

In summary, these data characterize the involvement and underline the protective key role of the IL-17A axis in the lungs from inhalational tularemia.