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1.
While plant–pollinator interactions are a classic model system for evolutionary relationships, the relationship between forager energetics and floral motions remains little explored. In this study, we show that hawkmoths preferentially feed on horizontally oscillating flowers, which have previously been shown to yield higher energy gains during feeding bouts than looming flowers. We also analyze natural flower motions exhibited by four hawkmoth-pollinated species. Our analysis shows these flowers have higher amplitude motions in the horizontal axis than that in the looming axis. This work demonstrates the potential for adaptation between the biomechanical determinates of flower motions and the feeding performance of hawkmoths.  相似文献   

2.
Solitary bees (Halictus sp.) were found to be the effective pollinators ofCephalanthera longifolia. In the same foraging flight the bees also visit flowers ofCistus salviifolius which has a similar colour pattern.Cephalanthera offers no reward to its pollinators, but orange papillae on its labellum successfully imitate pollen ofCistus. AsCephalanthera also attracts pollinators in the absence ofCistus, this is regarded as facultative floral mimicry.  相似文献   

3.
Humans are at risk from exposure to extremes in their environment, yet there is no consistent way to fully quantify and understand the risk when considering more than just meteorological variables. An outdoor ‘bio-comfort’ threshold is defined for Melbourne, Australia using a combination of heat stress, air particulate concentration and grass pollen count, where comfortable conditions imply an ideal range of temperature, humidity and wind speed, acceptable levels of air particulates and a low pollen count. This is a new approach to defining the comfort of human populations. While other works have looked into the separate impacts of different variables, this is the first time that a unified bio-comfort threshold is suggested. Composite maps of surface pressure are used to illustrate the genesis and evolution of the atmospheric structures conducive to an uncomfortable day. When there is an uncomfortable day due to heat stress conditions in Melbourne, there is a high pressure anomaly to the east bringing warm air from the northern interior of Australia. This anomaly is part of a slow moving blocking high originating over the Indian Ocean. Uncomfortable days due to high particulate levels have an approaching cold front. However, for air particulate cases during the cold season there are stable atmospheric conditions enhanced by a blocking high emanating from Australia and linking with the Antarctic continent. Finally, when grass pollen levels are high, there are northerly winds carrying the pollen from rural grass lands to Melbourne, due to a stationary trough of low pressure inland. Analysis into days with multiple types of stress revealed that the atmospheric signals associated with each type of discomfort are present regardless of whether the day is uncomfortable due to one or multiple variables. Therefore, these bio-comfort results are significant because they offer a degree of predictability for future uncomfortable days in Melbourne.  相似文献   

4.
Nuclear DNA content (2C) and pollen vitality and colour are used as new criteria to investigate all species of the genus Agapanthus LHéritier. The species have the same chromosome number (2n=2x=30), with exception of four triploid plants found. The nuclear DNA content of the diploids, as measured by flow cytometry with propidium iodide, is demonstrated to range from 22.1–31.6 pg. This implies that the largest genome contains roughly 1010 more base pairs than the smallest. The species could be divided in two groups based on pollen colour and DNA content: a group with lilac pollen and a DNA content between 22.3 and 24.1 pg containing the species A. campanulatus Leighton, A. caulescens Sprenger and the rarer A. coddii Leighton, and a group with yellow/brownish pollen and a DNA content from 25.2–31.6 pg containing the species A. praecox Willd., A. inapertus Beauv. and A. africanus (L.) Hoffmanns. Four other taxa, recognized by Leighton (1965) are treated as follows: A. comptonii Leighton, has a nuclear DNA content similar to A. praecox and is considered to be a synonym of A. praecox subsp. minimus Leighton. A. walshii L. Bol., has with 31.6 pg the same high amount of DNA as A. africanus from the same area and is therefore renamed as a subspecies (A. africanus subsp. walshii (Leighton) Zonn. & Duncan comb. nov.). The nuclear DNA amounts of A. dyeri Leighton, including the geographically isolated plants from Mozambique, are shown to be identical to A. inapertus. Therefore A. dyeri is considered synonymous with A. inapertus subsp. intermedius Leighton. A. nutans Leighton is identical in DNA content to A. caulescens and is considered to be synonymous with that species. Concluding there are six species: A. campanulatus Leighton, A. caulescens Sprenger, A. coddii Leighton, A. praecox Willd., A. inapertus Beauv. and A. africanus (L.) Hoffmanns. Nuclear DNA content as measured by flow cytometry and pollen colour are shown to be relevant traits to throw light on the relationships between Agapanthus species.  相似文献   

5.
This paper deals with a discrete-time predator-prey system which is subject to an Allee effect on prey.We investigate the existence and uniqueness and find parametric conditions for local asymptotic stability of fixed points of the discrete dynamic system.Moreover,using bifurcation theory,it is shown that the system undergoes Neimark-Sacker bifurcation in a small neighborhood of the unique positive fixed point and an inv aria nt circle will appear.Then the direction of bifurcation is given.Furthermore,numerical analysis is provided to illustrate the theoretical discussions with the help of Matlab packages.Thus,the main theoretical results are supported with numerical simulations.  相似文献   

6.
Members of the euasterid angiosperm family Solanaceae have been characterized as remarkably diverse in terms of flower morphology and pollinator type. In order to test the relative contribution of phylogeny to the pattern of distribution of floral characters related to pollination, flower form and pollinators have been mapped onto a molecular phylogeny of the family. Bilateral flower symmetry (zygomorphy) is prevalent in the basal grades of the family, and more derived clades have flowers that are largely radially symmetric, with some parallel evolution of floral bilateralism. Pollinator types (‘syndromes’) are extremely homoplastic in the family, but members of subfamily Solanoideae are exceptional in being largely bee pollinated. Pollinator relationships in those genera where they have been investigated more fully are not as specific as flower morphology and the classical pollinator syndrome models might suggest, and more detailed studies in some particularly variable genera, such as Iochroma and Nicotiana, are key to understanding the role of pollinators in floral evolution and adaptive radiation in the family. More studies of pollinators in the field are a priority.  相似文献   

7.
Summary Abundance and flower visitation rate of the pollinators of Lavandula latifolia (Labiatae), an insect-pollinated shrub, were studied over a 6-year period. The objective was to elucidate interspecific patterns in the quantity component of the plant-pollinator interaction. A total of 54 insect taxa are considered in the analyses, including hynenopterans, dipterans and lepidopterans. Most pollinators were comparatively scarce, with a few taxa acounting collectively for the majority of individuals. Pollinators differed broadly in flower visitation rate (0.2–30 flowers/min). Most of this variation was explained by differences in flower handling time (HT). Regardless of proboscis length, hymenopterans had intrinsically shorter handling times than lepidopterans. Within each group, HT decreased exponentially with increasing proboscis length. Abundance and visitation rate were uncorrelated across pollinator taxa. The total number of visits that each pollinator contributed to the plant (NFV) was estimated as the product of abundance x visitation rate. NFV values spanned four orders of magnirade. A small, taxonomically diverse group of species (1 moth, 1 butterfly, 4 bees) accounted for most visits and thus could effectively exert some selection on floral features. Nevertheless, the morphological diversity represented in this group of dominant pollinators probably constrains plant specialization, as they will most likely select for different floral features or in opposing directions on the same traits.  相似文献   

8.
Summary This paper reports a rare malformation syndrome which is observed in two sibs (brother and sister) of a family. It consists of nearly symmetric reductive defects of the limbs, flexon contractures of various joints, cleft lip and cleft palate, multiple minor abnormalities including capillary hemangioma of the forehead, hypoplastic cartilages of ears and nose, micrognathia, intrauterine growth retardation, and possibly mental retardation. Chromosomes of both parents and propositi are normal. Genetic data suggest autosomal recessive inheritance.  相似文献   

9.
The aim of this study was to construct a picture of the influence of meteorological conditions on the start and duration of the airborne Betulaceae pollen season and the pollen concentrations in the atmosphere of Zagreb, Croatia. The study during three seasons (2002–2004) used a 7‐day Hirst‐type volumetric pollen and spore trap. Total annual airborne pollen of Alnus, Corylus and Betula greatly varied from year to year. The differences in the dates of onset of airborne pollen presence of Alnus, Corylus and Betula noted in Zagreb in 2002–2004 were controlled by weather conditions, particularly temperature and precipitation. In all years studied, airborne pollen peaks were recorded on days with temperature above 0°C and without or minimal precipitation. The mean number of days with airborne pollen concentrations exceeding levels which provoke symptoms of an allergic reaction was 15, 16 and 29 days for alder, hazel and birch, respectively. The results of the present study may provide useful data for allergologists to reach accurate diagnoses, and timely information on concentrations of airborne pollen types and concentrations for individuals with pollen hypersensitivity.  相似文献   

10.
We describe the environment effects on the amount and quality of resources collected by Melipona rufiventris Lepeletier in the Atlantic Forest at Ubatuba city, S?o Paulo state, Brazil (44o48'W, 23o22'S). Bees carrying pollen and/or nectar were captured at nest entrances during 5 min every hour, from sunrise to sunset, once a month. Pollen loads were counted and saved for acetolysis. Nectar was collected, the volume was determined and the total dissolved solids were determined by refractometer. Air temperature, relative humidity and light intensity were also registered. The number of pollen loads reached its maximum value between 70% and 90% of relative humidity and 18oC and 23oC; for nectar loads this range was broader, 50-90% and 20-30oC. The number of pollen loads increased as relative humidity rose (rs = 0.401; P < 0.01) and high temperatures had a strong negative influence on the number of pollen loads collected (rs = -0.228; P < 0.01). The number of nectar loads positively correlated with temperature (rs = 0.244; P < 0.01) and light intensity (rs = 0.414; P < 0.01). The percentage of total dissolved solids (TDS) on nectar loads positively correlated with temperature and light intensity (rs = 0.361; P < 0.01 and rs = 0.245; P < 0.01), negatively correlated with relative humidity (rs = -0.629; P < 0.01), and it increased along the day. Most nectar loads had TDS between 11% and 30%, with an average of 24.7%. The volume measures did not show any pattern. Important pollen sources were Sapindaceae, Anacardiaceae, Rubiaceae, Arecaceae, Solanaceae and Myrtaceae; nectar sources were Sapindaceae, Fabaceae, Rubiaceae, Arecaceae and Solanaceae.  相似文献   

11.
Predator avoidance of noxious prey, aposematism and defensive mimicry are normally associated with bright, contrasting patterns and colours. However, noxious prey may be unable to evolve conspicuous coloration because of other selective constraints, such as the need to be inconspicuous to their own prey or to specialist predators. Many venomous snakes, particularly most vipers, display patterns that are apparently cryptic, but nevertheless highly characteristic, and appear to be mimicked by other, non-venomous snakes. However, predator avoidance of viper patterns has never been demonstrated experimentally. Here, the analysis of 813 avian attacks on 12,636 Plasticine snake models in the field shows that models bearing the characteristic zigzag band of the adder (Vipera berus) are attacked significantly less frequently than plain models. This suggests that predator avoidance of inconspicuously but characteristically patterned noxious prey is possible. Our findings emphasize the importance of mimicry in the ecological and morphological diversification of advanced snakes.  相似文献   

12.
Many local livestock breeds in developing countries are being replaced by exotic breeds, leading to a loss of genetic resources. In southern Mali, for the past two decades, a trend towards increasing crossbreeding between the trypanotolerant N’Dama cattle and the trypano-susceptible Fulani Zebu cattle has been taking place. A survey with 160 farmers owning a cattle herd was carried out in southern Mali to investigate their production objectives, as well as trait and breed preferences and correlated socio-economic determinants in order to understand farmers’ breeding decisions and to identify comparative advantages of three breed groups (N’Dama, Fulani Zebu and crossbreds) raised in the study area. Data were analyzed using an exploded logit model. The reasons for raising cattle, as well as trait and breed preferences reflected the multiple objectives of the farmers. Draught power and savings were the most important production objectives. Productive traits were ranked highest; farmers reported large body size as the most preferred trait, followed by fertility, draught ability and milk yield. Crossbreds were the favored breed group. Breed preferences were mainly explained by ‘resistance to disease’ for N’Dama cattle and ‘high market price’ for Fulani Zebu and crossbred cattle. Production objectives, trait and breed preferences were mainly influenced by farmer group (local farmers and settled transhumants). Local farmers put comparatively more emphasis on livestock functions linked to crop production such as draught power. They had a higher preference for traction ability as a selection trait and preferred N’Dama over Fulani Zebu cattle. Settled transhumants emphasized milk yield as a selection trait and preferred Fulani Zebu over N’Dama. The results indicate that the trend towards more crossbreeding will continue putting the N’Dama breed under high risk of genetic dilution in southern Mali. The N’Dama cattle remain a valuable breed due to their adaptive traits such as disease and drought tolerance and their good traction ability, fulfilling the diverse objectives of local farmers. Crossbreeding was found to be a promising breeding strategy, which might contribute to the maintenance of the local breed, provided that breeding schemes are thoroughly planned and organized.  相似文献   

13.
Environmental conditions likely affect physiology and behaviour of mice used for life sciences research on Earth or in Space. Here, we analysed the effects of cage confinement on the weightbearing musculoskeletal system, behaviour and stress of wild-type mice (C57BL/6JRj, 30 g b.wt., total n = 24) housed for 25 days in a prototypical ground-based and fully automated life support habitat device called “Mice in Space” (MIS). Compared with control housing (individually ventilated cages) the MIS mice revealed no significant changes in soleus muscle size and myofiber distribution (type I vs. II) and quality of bone (3-D microarchitecture and mineralisation of calvaria, spine and femur) determined by confocal and micro-computed tomography. Corticosterone metabolism measured non-invasively (faeces) monitored elevated adrenocortical activity at only start of the MIS cage confinement (day 1). Behavioural tests (i.e., grip strength, rotarod, L/D box, elevated plus-maze, open field, aggressiveness) performed subsequently revealed only minor changes in motor performance (MIS vs. controls). The MIS habitat will not, on its own, produce major effects that could confound interpretation of data induced by microgravity exposure during spaceflight. Our results may be even more helpful in developing multidisciplinary protocols with adequate scenarios addressing molecular to systems levels using mice of various genetic phenotypes in many laboratories. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

14.

Background

Poor nutrition is harmful to one’s health as it can lead to overweight and obesity and a number of chronic diseases. Understanding consumer perceptions toward diet and nutrition is critical to advancing nutrition-related population health interventions to address such issues. The purpose of this paper was to examine Canadians’ perceived health and diet status, compared to their actual health status, and general concern about their own diet and beliefs about health. Also analyzed were some of the perceived barriers to eating “healthy” foods, with a focus on the availability of “healthy” processed foods.

Methods

Two surveys were administered online to a group of Canadian panelists from all ten provinces during May 2010 to January 2011. Thirty thousand were invited; 6,665 completed the baseline survey and 5,494 completed the second survey. Panelists were selected to be nationally representative of the Canadian adult population by age, sex, province and education level, according to 2006 census data.

Results

Approximately one third of Canadians perceived their health or diet to be very good while very few Canadians perceived their health or diet to be very poor. While the majority of Canadians believed food and nutrition to be very important for improving one’s health, fewer Canadians were concerned about their own diets. The majority of Canadians reported difficulty finding “healthy” processed foods (low in salt and sugar and with sufficient vitamins and minerals). Many also reported difficulty finding healthy foods that are affordable.

Conclusion

Although consumers believe that nutrition is one of the most important factors for maintaining health, there are still a number of attitudinal and perceived environmental barriers to healthy eating.  相似文献   

15.
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16.
Moss polsters, pollen traps and lake surface sediment samples are commonly used as climate calibration data or as modern analogues for reconstructing vegetation from fossil profiles, but the differences in pollen content between these media have received little attention. This study aims to analyse how the three media differ in reflecting individual vegetation types and spatial differences in vegetation. 119 modern samples (64 moss polsters, 37 lake surface sediment samples and 18 pollen traps from which a collection was made annually) were taken from northern Fennoscandia and the Kola Peninsula as a broad transect crossing the northernmost forest limits of Betula pubescens ssp. czerepanovii (mountain birch), Pinus sylvestris (Scots pine) and Picea abies (Norway spruce). The pollen assemblages from these samples were compared with the surrounding vegetation visually and via PCA (principle components analysis) and cluster analysis. Both comparisons allow a correct distinction between pollen assemblages of arctic/alpine heath, mountain birch dominated areas, and boreal coniferous forests. The differences between the vegetation zones are stronger than the differences between the sampling media. Nevertheless, lake sediment samples from the mountain birch woodland zone tend to overestimate pine and underestimate birch. Pollen traps are biased towards lower tree pollen percentages and higher values of shrubs, herbs and Cyperaceae. This bias is especially strong in traps that have missing years in the data. Irrespective of the vegetation zone, pollen traps tend to have lower Pinus pollen percentages than in the adjacent moss polsters.  相似文献   

17.
Heat shock, or stress, proteins (HSPs) are cellular proteins induced in response to conditions that cause protein denaturation, and their induction is essential for survival of such conditions. In the olfactory system we have found intense HSP expression occurs during normal processing of environmental odorants/inhalants as well as following hyperthermia and drug exposure. The HSPs involved include ubiquitin, HSP70, HSC70, and HSP25. Responses are both cell type- and stress-specific, occurring primarily in olfactory supporting cells and to some extent in Bowman’s gland acinar cells. Responses to these stresses are not seen in olfactory sensory neurons. This article reviews those studies and the significance of their findings. It also discusses a distinct subpopulation of rat olfactory sensory neurons (OSNs), the 2A4(+)OSNs, found to be constitutively reactive with HSP70, the predominantly stress-inducible isoform of the 70 kD HSP family. Their high HSP70 expression appears to confer on the 2A4(+)OSNs an enhanced ability to survive damage-induced OSN turnover. New findings are also presented on HSP25-specific changes following olfactory bulbectomy. All data are discussed in the context of the overall olfactory and bioprotective functions of the olfactory mucosa.  相似文献   

18.
19.
Two types of males are present in the Jalapa population of Xiphophorus helleri: Males with a black or dark brownish mid-lateral stripe ("black males") mature earlier and are smaller than males with a red or brownish mid-lateral stripe ("red males"). We tested the hypothesis that the colour patterns of red males may be regarded as ornaments, which evolved as the result of inter- and/or intrasexual selection. As predicted, in choice tests females exhibited a strong preference for red versus black males. Furthermore, in competition experiments red males became dominant over black males with no exception, both when body size was equal and even when red males were 3–5 mm smaller than black males. However, contrary to our prediction, sneak–chase behaviour in black males was not detected, and courtship displays occurred at similar rates in both morphs. Red males are always heterozygous, with one allele for red and another for black colouration. This genetic constraint potentially prevents the extinction of the black morph. Possibly, the colour patterns of red males are functioning as indicators of heterozygosity. According to the "heterozygosity theory of mate choice", the female's preference for red males may be adaptive.  相似文献   

20.
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