Does natal habitat preference modulate cereal kernel preferences in the rice weevil?

The influence of larval diet source in Sitophilus oryzae (L.), a primary grain feeder, on the choice of a new cereal host by young adult was investigated through a multiple choice comparative bioassay. For this purpose, virgin male and female adults, which had been reared as immatures in different grain commodities, were monitored according to their food preference in cylindrical arenas containing whole kernels of maize, rice, barley and wheat. The adults showed a clear individual preference for maize kernels, regardless of the previous food experience, sex and also the interval on which the adults are exposed to food. Males were much more mobile than females and visited more vigorously different commodities before the final choice. Female response was found to be related with male response to specific food sources. Hence, our results indicate that there was no natal habitat preference induction, since maize was, in most cases, the final commodity choice.     

Do birds of a feather flock together? Comparing habitat preferences of piscivorous waterbirds in a lowland river catchment

The aim of the present study was to use the analysis of surface water chemistry to understand vegetation succession pathways in terrestrializing polyhumic lakes. We hypothesized that Sphagnum mire development was accompanied by a decrease in the mineral content in water. A total of 111 vegetation plots along 23 transects were analysed in 11 lakes and adjacent peat lands in the Wigry National Park (NE Poland). The vegetation of the lake-mire systems forms distinct zones: (1) nymphaeid-, bladderwort- and bryophyte-dominated aquatic vegetation; (2) sedge-dominated edge of the Sphagnumcarpet; (3) quaking, extremely poor fen with various Cyperaceae; (4) non-quaking, Eriophorum vaginatum-dominated bog-like vegetation and (5) pine woodland. Surface water corrected conductivity (EC_corr.), pH, COD-KMnO₄ and Ca²⁺, Mg²⁺, Fetot. and SiO₂ were measured along the transects. The environmental gradients best explaining the observed pattern were pH (with the highest values in the lake and the lowest in the bog-like vegetation) and COD-KMnO₄ (showing an inverse direction). At least in some Sphagnum-mires conditions were more minerotrophic than in the lakes. The process of humic lake overgrowing by Sphagnum-mires in NE Poland results in pine woodlands on mineralised peat. The climate conditions in NE Poland, combined with evapotranspiration accelerated by encroaching trees, do not seem to support the development of ombrotrophic bogs.     

Providing nest boxes for hole-nesting birds – Does habitat matter?

Nest boxes are a popular management tool to increase nest site availability for hole-nesting birds, but biological consequences of this technique in different habitats are poorly studied. In our study area in southwestern Estonia, nest boxes for small passerines were set up in deciduous and coniferous woods. Great tits Parus major preferred the food-rich deciduous habitat for breeding, as judged by higher nest-box occupation, earlier egg-laying and larger clutches and eggs. However, in coniferous habitat more and heavier young fledged per nest, and the return rate of both fledglings and adults was higher. We propose two mutually non-exclusive explanations, both related to the maladaptive outcome of the provision of nest boxes: (i) in the preferred habitat, nest boxes caused a supra-optimal breeding density leading to an ecological trap; (ii) boxes drastically improved the non-preferred habitat, but birds were unable to exploit the breeding habitat fully. One should be careful in providing large numbers of artificial nest sites in preferred habitats. Sometimes it would be more preferable to improve less favourable habitats by removing critical constraints.     

Use of hunters in wildlife surveys: does hunter and forest grouse habitat selection coincide?

Wildlife monitoring performed by volunteer personnel may suffer from bias with regard to their habitat use. Such errors can lead to erroneous population estimates, evidently influencing both management programmes and research that are based on the monitoring. We used a dataset on hunters’ habitat use in forest while searching for black grouse (Tetrao tetrix) and capercaillie (Tetrao urogallus) to test whether hunters’ utilisation of the habitat was independent of that of grouse or if it corresponded to the grouse habitat preference. Twenty volunteer hunters with dogs registered their tracks and all observations of capercaillie and black grouse in Østfold County, Norway, during August 2003 and 2004. We performed an ecological niche factor analysis (ENFA) and a K-select analysis with respect to hunters’ selection for habitat, described with ecogeographical variables related to forest stand characteristics, as well as the habitat preference of the observed grouse, conditional on the habitat utilisation of the hunters. Individual ENFA on the hunter's tracks revealed large variation in the habitat preferences of the hunters. The K-select indicated few overall patterns in the habitat characteristics of grouse observations, conditional on the hunters selected habitat. Accordingly, the results indicate that hunters’ observation of grouse prior to the hunt may give indicators of changes in grouse density unbiased by habitat preference due to the large between-hunter variation in habitat preference, given that a sufficient number of hunters is used. This suggests that such monitoring programmes can provide information about fluctuations in grouse population sizes valuable for both the management and research of forest grouse species.     

Does rattling deter? The case of domestic dogs

Although the rattling of rattlesnakes (Crotalus and Sistrurus) is widely accepted as being aposematic, the hypothesis that rattling deters approach from the snake's potentially dangerous adversaries has not been well tested. In a controlled study using rattling recorded from captive rattlesnakes (C. oreganus helleri) and a variety of comparison sounds or no-sound controls, domestic dogs (Canis familiaris) showed no hesitation to approach camouflaged speakers projecting the recorded rattles. The dogs were equally likely to approach speakers projecting rattling as they were to approach speakers playing control sounds, or speakers that were silent. Furthermore, the dogs spent no less time in front of the speakers projecting the rattles than they did in front of speakers projecting control sounds or no sound. The dogs' reactions may not be representative of other species with whom rattlesnakes come into contact, but the data suggest a need for some circumspection about the role of rattling in the rattlesnake's defensive repertoire. Our results also suggest that dogs may be vulnerable to envenomation because they fail to react to the sound of rattling with avoidance.     

Does common architecture reveal a viral lineage spanning all three domains of life?

Our discovery that the major coat protein of bacteriophage PRD1 resembles that of human adenovirus raised the unexpected possibility that viruses infecting bacteria could be related by evolution to those infecting animal hosts. We first review the development of this idea. We then describe how we have used structure-based modeling to show that several other viruses with no detectable sequence similarity are likely to have coats constructed from similar proteins-the "double-barrel trimer." There is evidence that the group includes a diversity of viruses infecting very different hosts in all three domains of life: Eukarya; Bacteria; and Archaea that diverged billions of years ago. The current classification of viruses obscures such similarities. We propose that the occurrence of a double-barrel trimer coat protein in an icosahedral dsDNA virus with large facets, irrespective of its host, is a very strong indicator of its membership in a lineage of viruses with a common ancestor.     

Does autonomic blockade reveal a potent contribution of nitric oxide to locomotion-induced vasodilation?

We sought to test the role of nitric oxide (NO) in governing skeletal muscle (iliac) vascular conductance during treadmill locomotion in dogs (n = 6; 3.2 and 6.4 km/h at 0% grade, and 6.4 km/h at 10% grade). As seen previously, the increase in muscle vascular conductance accompanying treadmill locomotion was little influenced by NO synthase inhibition alone with N(omega)-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg iv), but the absolute value of conductance achieved during locomotion was reduced. Such ambiguous results provide an unclear picture regarding the importance of NO during locomotion. However, muscle vasodilation is normally restrained by the sympathetic system during locomotion. Thus a significant contribution by NO to the increase in vascular conductance that accompanies locomotion could be masked by partial withdrawal of the competing influence of sympathetic vasoconstrictor nerve activity secondary to the rise in arterial pressure following systemic L-NAME administration. To test this possibility, we compared the rise in muscle vascular conductance before and after L-NAME treatment while ganglionic transmission was blocked by hexamethonium. Under these conditions, L-NAME significantly reduced both the rise in vascular conductance (by 32%, P < 0.001) and the absolute level of vascular conductance (by 30%, P < 0.001) achieved during locomotion with no effect on blood flow. Thus augmented NO production normally provides a significant drive to relax vascular smooth muscle in active skeletal muscle during locomotion. Potential deficits stemming from the absence of NO following L-NAME treatment are masked by less intense sympathetic restraint when autonomic function is intact.     

Does habitat fragmentation reduce genetic diversity and subpopulation connectivity?

The estimation of levels of genetic variation has received considerable attention because it is generally thought to be indicative of overall species vitality and the potential for evolutionary responses to environmental changes. Here, we use allozymes markers and two distinct collections of Cakile maritima, an annual species from sandy coastal habitats (2000 generation and 2005 generation collected from 9 populations in their natural habitats), to assess the magnitude of expected genetic change. We compared genetic diversity between generations (all populations combined), and then between populations at each generation. Based on 13 loci scored from the eight enzymes examined, a high genetic diversity was detected at both the population and generation level as compared to other herbaceous species. However, allelic richness reduction in the 2005 generation suggested restricted gene flow and a high risk of future genetic bottlenecks, if larger tracts of coastal areas disappear. Most loci showed deviation from Hardy‐Weinberg equilibrium due to excess of heterozygotes in all populations suggesting that this species has an allogamic mode of reproduction. It appears most likely that this species has experienced a recent decrease in population size, and that genetic drift in small populations has resulted in a loss of alleles occurring at low frequency. Despite the deterioration process, maintenance of high genetic diversity suggests that there are some ecological factors determining population structure.     

Conservation of remnant populations of Colchicum autumnale – The relative importance of local habitat quality and habitat fragmentation

Semi-natural habitat is extremely vulnerable to habitat fragmentation and degradation since its socio-economic value has decreased substantially during the last century in most parts of Europe. We evaluated the relative effects of habitat fragmentation and local environmental conditions on population structure and reproductive performance of the long-lived corm geophyte Colchicum autumnale in 17 highly fragmented populations. Habitat isolation did not affect patch occupancy, population structure or plant performance. In contrast, population size and local environment strongly affected population structure and reproductive performance. Densities of all life stages increased with increasing population size. Large populations also showed a higher reproductive performance and a larger proportion of new recruits. Relationships with local growth conditions pointed towards the importance of an open grassland sward for flower and fruit set and the presence of microsites for successful sexual recruitment. These results suggest that the distribution of C. autumnale consists of an assemblage of basically unconnected populations that are remnants of formerly larger populations. This is in accordance with the species' ability to grow clonally, allowing long-term persistence under deteriorating conditions that occurred during a long period of habitat fragmentation. In conclusion, our results indicate that local habitat and population size are more important than habitat fragmentation (i.e. calcareous grassland isolation and surface area) and argue in favour of a management that is primarily focused on local habitat restoration. This is preferentially accomplished by reintroducing grazing practices, complemented by regular setback of spontaneous succession towards forest.     

Does the modern urbanized sleeping habitat pose a breast cancer risk?

Due to its disruptive effects on circadian rhythms and sleep deprivation at night, shiftworking is currently recognized as a risk factor for breast cancer (BC). As revealed by the present analysis based on a comparative case-control study of 1679 women, exposure to light-at-night (LAN) in the "sleeping habitat" is significantly associated with BC risk (odds ratio [OR]?=?1.220, 95% confidence interval [CI]?=?1.118-1.311; p?相似文献   

Does gender influence learning style preferences of first-year medical students?

Students have specific learning style preferences, and these preferences may be different between male and female students. Understanding a student's learning style preference is an important consideration when designing classroom instruction. Therefore, we administered the visual, auditory, reading/writing, kinesthetic (VARK) learning preferences questionnaire to our first-year medical students; 38.8% (97 of 250 students) of the students returned the completed questionnaire. Both male (56.1%) and female (56.7%) students preferred multiple modes of information presentation, and the numbers and types of modality combinations were not significantly different between genders. Although not significantly different, the female student population tended to be more diverse than the male population, encompassing a broader range of sensory modality combinations within their preference profiles. Instructors need to be cognizant of these differences and broaden their range of presentation styles accordingly.     

Our use,misuse, and abandonment of a concept: Whither habitat?

The foundational concept of habitat lies at the very root of the entire science of ecology, but inaccurate use of the term compromises scientific rigor and communication among scientists and nonscientists. In 1997, Hall, Krausman & Morrison showed that ‘habitat’ was used correctly in only 55% of articles. We ask whether use of the term has been more accurate since their plea for standardization and whether use varies across the broader range of journals and taxa in the contemporary literature (1998–2012). We searched contemporary literature for ‘habitat’ and habitat‐related terms, ranking usage as either correct or incorrect, following a simplified version of Hall et al.'s definitions. We used generalized linear models to compare use of the term in contemporary literature with the papers reviewed by Hall et al. and to test the effects of taxa, journal impact in the contemporary articles and effects due to authors that cited Hall et al. Use of the term ‘habitat’ has not improved; it was still only used correctly about 55% of the time in the contemporary data. Proportionately more correct uses occurred in articles that focused on animals compared to ones that included plants, and papers that cited Hall et al. did use the term correctly more often. However, journal impact had no effect. Some habitat terms are more likely to be misused than others, notably ‘habitat type’, usually used to refer to vegetation type, and ‘suitable habitat’ or ‘unsuitable habitat’, which are either redundant or nonsensical by definition. Inaccurate and inconsistent use of the term can lead to (1) misinterpretation of scientific findings; (2) inefficient use of conservation resources; (3) ineffective identification and prioritization of protected areas; (4) limited comparability among studies; and (5) miscommunication of science‐based findings. Correct usage would improve communication with scientists and nonscientists, thereby benefiting conservation efforts, and ecology as a science.     

Does habitat specialization shape the evolutionary potential of wild bird populations?

Because specialist species evolved in more temporally and spatially homogeneous environments than generalist species, they are supposed to experience less fluctuating selection. For this reason, we expect specialists to show lower overall genetic variation as compared to generalists. We also expect populations from specialist species to be smaller and more fragmented, with lower neutral genetic diversity. We tested these hypotheses by investigating patterns of genetic diversity along a habitat specialization gradient in wild birds, based on estimates of heritability, coefficients of variation of additive genetic variance, and heterozygosity available in the literature. We found no significant effect of habitat specialization on any of the quantitative genetic estimators but generalists had higher heterozygosity. This effect was mainly a consequence of the larger population size of generalists. Our results suggest that evolutionary potential does not differ at the population level between generalist and specialist species, but the trend observed in heterozygosity levels and population sizes may explain their difference in susceptibility to extinction.