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1.
The yellow pitcher plant, Sarracenia flava, is an insectivorous plant restricted to fire-maintained wetland ecosystems in southeastern Virginia. Only four natural sites remain in the state totaling fewer than 100 clumps. Plants from sites located in Dinwiddie, Greensville, Prince George, Sussex counties, and the city of Suffolk were tested for the effects of self-pollination, intrasite outcrossing, and intersite outcrossing on offspring quantity (total seed number and total seed mass) and offspring quality (avarage seed mass, germination, and growth).Self-pollination resulted in significantly lower offspring quantity and quality. Total seed number and total seed mass for self-pollinated capsules were approximately one-fourth that of outcrossed capsules. Germination, survivorship, and growth over 5 yr were also significantly lower for offspring from self-pollinated capsules. Together, these results suggest strong inbreeding depression in this species.Relative to offspring from intrasite crosses, offspring from intersite crosses were significantly larger after 5 yr of growth. This suggests that restoration efforts for Virginia S. flava will be most successful when plants from multiple sites are used.  相似文献   

2.
The phytotelmata of the North American pitcher plant Sarracenia purpurea are colonised by a great variety of aquatic organisms and, thus, provide an ideal model to study trophic interactions in small freshwater ecosystems. Although algae are discussed as a potential food source for predators, little is known about the structure of algae coenoses in pitchers of S. purpurea. This study aims to elucidate temporal shifts in the algae community structure in pitchers of an allochthonous population of S. purpurea in Saxony, Germany. A total of 78 algae taxa was found in the pitchers. Mean algae abundances in new and old pitchers were similar (2.6 x 10(5) and 2.3 x 10(5) algae ml(-1), respectively). Taxa from the orders Chlamydomonadales, Chlorococcales, and Ochromonadales were the primary colonisers. With increasing age of the pitchers the filamentous green algae from the order Klebsormidiales became more abundant. In contrast, pennate diatoms dominated the algae coenoses in the fen. Algae community structure in vase-shaped 50 ml Greiner tubes was similar to those of natural pitchers. Differences in the temporal patterns of algae coenoses in individual pitchers suggested a colonisation of the pitchers by algae via trapped insects, air and rain water rather than via the surrounding fen. Biomass of algae approximated 0.3 mg C ml(-1), which corresponds to 82.8 % of the living biomass (bacteria, heterotrophic nanoflagellates, algae, protozoans and rotifers). Rotifers were abundant in new pitchers; nematodes and mites were seldom found in all pitchers. A similar qualitative and quantitative composition of the aquatic biocoenoses was observed in pitchers of another allochthonous S. purpurea population growing in Blekinge, Sweden. Biomass of algae represented nearly one quarter of the total organic matter content in the pitchers. Thus, nitrogen and phosphorus compounds present in the algae biomass might be used by the carnivorous S. purpurea plant as additional food source in allochthonous populations in Europe lacking top predators.  相似文献   

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6.
A new form of Habrotrocha rosa Donner 1949 and aspects of its life as an inquiline of the northern pitcher plant, Sarracenia purpurea L. are described.  相似文献   

7.
BACKGROUND AND AIMS: The long-lived and mainly outcrossing species Sarracenia purpurea has been introduced into Switzerland and become invasive. This creates the opportunity to study reactions to founder effect and how a species can circumvent deleterious effects of bottlenecks such as reduced genetic diversity, inbreeding and extinction through mutational meltdown, to emerge as a highly invasive plant. METHODS: A population genetic survey by random amplified polymorphism DNA markers (RAPD) together with historical insights and a field pollination experiment were carried out. KEY RESULTS: At the regional scale, S. purpurea shows low structure (thetast=0.072) due to a recent founder event and important subsequent growth. Nevertheless, multivariate statistical analyses reveal that, because of a bottleneck that shifted allele frequencies, most of the variability is independent among populations. In one population (Tenasses) the species has become invasive and genetic analysis reveals restricted gene flow and family structure (thetast=0.287). Although inbreeding appears to be high (Fis >0.410 from a Bayesian estimation), a field pollination experiment failed to detect significant inbreeding depression upon F1 seed number and seed weight fitness-traits. Furthermore, crosses between unrelated individuals produced F1 seeds with significantly reduced fitness, thus showing local outbreeding depression. CONCLUSIONS: The results suggest that, under restricted gene flow among families, the species may not only have rapidly purged deleterious alleles, but also have undergone some form of selection for inbreeding due to co-adaptation between loci.  相似文献   

8.
Błedzki  Leszek A.  Ellison  Aaron M. 《Hydrobiologia》1998,385(1-3):193-200
The population growth and biomass production of the pitcher-plant (Sarracenia purpurea L.) inquiline, Habrotocha rosa Donner (Rotifera: Bdelloidea), its consumption by other pitcher-plant inqulines, and its excretion of phosphorus (PO4–P) and nitrogen (NO3–N and NH4–N), were investigated in laboratory experiments. Observed population growth and production rate of H. rosa were higher at pH 4 (2.3 rotifers d-1) than at pH 3 (1.3 rotifers d-1), 5 (1.9 rotifers d-1), or 6 (0.8 rotifers d-1). Populations of H. rosa are an abundant and reliable food source for larvae of the dipteran inqulines Wyeomyia smithii (Coq.) and Blaesoxipha fletcheri (Aldrich) that co-occur with H. rosa in S. purpurea pitchers. Abundance of H. rosa within a pitcher is negatively associated with abundance of dipteran larvae, and these larvae consume rotifers in direct proportion to rotifer density (Type I functional response). Habrotrocha rosa may also account for the majority of the plant's supply of N and P. An average population of rotifers in the field (∼400 per pitcher) can excrete ∼5.2 μg NO3-N, ∼3.91 μg NH4-N, and ∼18.4 μg PO4–P per day into a single leaf, and excretion rate is independent of water pH. Over the six-month growing season of pitcher-plants in Massachusetts, U.S.A., we estimate that rotifers could supply 8.8–43 mg of N and 18.2–88 mg of P. These values far exceed the amount of N and P previously estimated to be supplied annually to the plants through insect capture or rainfall. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

9.
    
Genetic variability in the federally endangered pitcher plant Sarracenia rubra ssp. alabamensis was assessed in eight Alabama populations using starch gel electrophoresis. Ten populations of the more widespread Sarracenia rubra ssp. rubra were sampled in the southeastern United States for comparison. Fifteen allozyme loci representing 13 enzyme systems were scored for each species. In contrast to S. oreophila and S. jonesii, two previously analyzed endangered pitcher plants, genetic diversity was high for both S. rubra subspecies. Within ssp. alabamensis the percentage polymorphic loci (Ps) was 80.0, the mean number of alleles per polymorphic locus was (APs) = 2.58, and expected heterozygosity (Hes) was 0.209. Genetic diversity was slightly lower for ssp. rubra (Ps = 73.3, APs = 2.91, and Hes = 0.177). The proportion of total genetic diversity found among populations was fairly low for both species (GST = 0.09 for ssp. alabamensis and 0.14 for ssp. rubra). Little genetic divergence has occurred between the two subspecies as indicated by the lack of diagnostic alleles, the proportion of total genetic diversity between taxa (GST = 0.09), and the genetic identity estimate (I = 0.90). The relatively high genetic diversity found for ssp. alabamensis indicates that the maintenance of its evolutionary potential is possible if population sizes are maintained or increased. Low levels of genetic diversity found within small Georgia ssp. rubra populations indicate that genetic erosion may increase extinction risks for these populations.  相似文献   

10.
Petersen  R. L.  Hanley  L.  Walsh  E.  Hunt  H.  Duffield  R. M. 《Hydrobiologia》1997,354(1-3):63-66
Sarracenia purpurea L. plants were studiedin seven bogsalong the eastern seaboard of the United States fromNew Jersey to Georgia. Water sampled from 225 leaveswas found to contain several invertebrates. A singlebdelliod rotifer, a form of Habrotrocha cf. rosaDonner very similar to that described by Bateman(1987) in S. purpurea in western Newfoundland,was identified in 70% of the leaves. Investigationsare in progress to examine the possibility that thisstrong association indicates H. cf. rosa isspecific to S. purpurea.  相似文献   

11.
Hamilton IV  Robert  Duffield  Richard M. 《Hydrobiologia》2002,482(1-3):191-196
The invertebrate communities in Sarracenia purpurea were characterized by surveying the contents of 474 leaves from six pitcher plant populations in the eastern United States. More than 8200 invertebrate specimens, both living and dead, were recovered. Midge and mosquito larvae comprised 7907 (96%) of the specimens, with a mean of 16.9 dipteran larvae per leaf. Although midge larvae were present at all collection sites, mosquito larvae were absent from two of the sites. In the latter sites, the number of midge larvae per leaf was greater. This report documents for the first time that there is no statistical difference between the average number of Diptera larvae per leaf for sites that contain both midge and mosquito larvae compared to sites that contain only midge larvae. It appears that pitcher plants maintain an average number of larvae per leaf based on a number of interacting factors which we do not fully understand. This investigation documents that in the absence of mosquito larvae, more midge larvae are found per leaf per leaf than would be predicted based on data from sites that contain both larval taxa.  相似文献   

12.
Pitcher plants have been widely used in ecological studies of food webs; however, their bacterial communities are poorly characterized. Pitchers of Sarracenia purpurea contain several distinct sub-habitats, namely the bottom sediment, the liquid, and the internal pitcher wall. We hypothesized that those three sub-habitats within pitcher plants are inhabited by distinct bacterial populations. We used denaturing gradient gel electrophoresis and 16S rRNA gene sequencing to characterize bacterial populations in pitchers from three bogs. DGGE and sequencing revealed that in any given pitcher, the three sub-habitats contain significantly different bacterial populations. However, there was significant variability between bacterial populations inhabiting the same type of habitat in different pitchers, even at the same site. Therefore, no consistent set of bacterial populations was enriched in any of the three sub-habitats. All sub-habitats appeared to be dominated by alpha- and betaproteobacteria in differing proportions. In addition, sequences from the Bacteroidetes and Firmicutes were obtained from all three sub-habitats. We conclude that container aquatic habitats such as the pitchers of S.?purpurea possess a very high bacterial diversity, with many unique bacterial populations enriched in individual pitchers. Within an individual pitcher, populations of certain bacterial families may be enriched in one of the three studied sub-habitats.  相似文献   

13.

Background and Aims Nepenthes

(Nepenthaceae, approx. 120 species) are carnivorous pitcher plants with a centre of diversity comprising the Philippines, Borneo, Sumatra and Sulawesi. Nepenthes pitchers use three main mechanisms for capturing prey: epicuticular waxes inside the pitcher; a wettable peristome (a collar-shaped structure around the opening); and viscoelastic fluid. Previous studies have provided evidence suggesting that the first mechanism may be more suited to seasonal climates, whereas the latter two might be more suited to perhumid environments. In this study, this idea was tested using climate envelope modelling.

Methods

A total of 94 species, comprising 1978 populations, were grouped by prey capture mechanism (large peristome, small peristome, waxy, waxless, viscoelastic, non-viscoelastic, ‘wet’ syndrome and ‘dry’ syndrome). Nineteen bioclimatic variables were used to model habitat suitability at approx. 1 km resolution for each group, using Maxent, a presence-only species distribution modelling program.

Key Results

Prey capture groups putatively associated with perhumid conditions (large peristome, waxless, viscoelastic and ‘wet’ syndrome) had more restricted areas of probable habitat suitability than those associated putatively with less humid conditions (small peristome, waxy, non-viscoelastic and‘dry’ syndrome). Overall, the viscoelastic group showed the most restricted area of modelled suitable habitat.

Conclusions

The current study is the first to demonstrate that the prey capture mechanism in a carnivorous plant is constrained by climate. Nepenthes species employing peristome-based and viscoelastic fluid-based capture are largely restricted to perhumid regions; in contrast, the wax-based mechanism allows successful capture in both perhumid and more seasonal areas. Possible reasons for the maintenance of peristome-based and viscoelastic fluid-based capture mechanisms in Nepenthes are discussed in relation to the costs and benefits associated with a given prey capture strategy.  相似文献   

14.
Carnivorous plants of the genus Sarracenia rely on microorganisms in their pitchers to decompose drowned insects. The environment inside pitchers is considered to be aerobic; however, there might be zones, such as at the bottom of the pitcher, where anaerobic conditions develop. Samples of the sediment at the bottom of Sarracenia purpurea pitchers were analyzed for the presence of archaea, using PCR and sequencing of the 16S rRNA gene. Archaeal DNA was detected in 20% of sampled pitchers. All sequences were closely related to Methanobrevibacter . Therefore, pitchers may contain anoxic zones inhabited by methanogens.  相似文献   

15.
Sarracenia purpurea L., a carnivorous bog plant (also known as the pitcher plant), represents an excellent model of a well-defined, self-contained ecosystem; the individual pitchers of the plant serve as a microhabitat for a variety of micro- and macro-organisms. Previously, fecal indicator bacteria (Escherichia coli and enterococci) were shown as incidental contaminants in pitcher fluid; however, whether their occurrence in pitcher fluid is incidental or common has not been established. The purpose of this study was to investigate the occurrence, distribution, and growth potential of E. coli and enterococci in pitcher plant fluid from a protected bog in northwest Indiana. Escherichia coli and enterococci were recovered in pitcher fluids (n=43 plants), with mean densities (log CFU mL-1) of 1.28+/-0.23 and 1.97+/-0.27, respectively. In vitro experiments showed that E. coli growth in fluid not containing insects or indigenous organisms was directly proportional to the fluid concentration (growth was 10-fold in 24 h in 100% fluid); however, in the presence of other indigenous organisms, E. coli and enterococci were only sustained for 5 days at 26 degrees C. Pulsed-field gel electrophoresis (PFGE) analysis showed that the plant Enterococcus faecalis isolates were genetically distinct from the human isolates; identical PFGE patterns were observed among plant isolates that fell into one of six clonal groups. These findings suggest that (i) E. coli and enterococci occurrence in pitcher plants is rather common in the bog studied, although their originating source is unclear, and (ii) the pitcher fluid contains adequate nutrients, especially carbon and energy sources, to promote the growth of indicator bacteria; however, under natural conditions, the biotic factors (e.g., competition for nutrients) may restrict their growth.  相似文献   

16.
Summary Wyeomyia smithii mosquitoes distribute their eggs across available oviposition sites (water-holding pitcher plant leaves) of varying quality. I experimentally examined responses to three components of site quality: conspecific larval density, larval density of the pitcher plant midge,Metriocnemus knabi, and pitcher size. Responses to larval treatments were complex and apparently suboptimal. Although mosquito larval performance is better in leaves with fewer conspecific and more midge larvae, females did not lay more eggs in such pitchers. Instead, more eggs were laid in experimental pitchers containing either midge or mosquito larvae, but fewer eggs in pitchers with neither or both. More eggs were laid in larger pitchers, which tend to accumulate more resources and dry out less often. Therefore, although the oviposition decisions made were suboptimal, they were better than random.  相似文献   

17.
Mechanisms that improve prey richness in carnivorous plants may involve three crucial phases of trapping:attraction, capture and retention.Nepenthes rafflesiana var. typica is an insectivorous pitcher plant that is widespread in northern Borneo.It exhibits ontogenetic pitcher dimorphism with the upper pitchers trapping more flying prey than the lower pitchers.While this difference in prey composition has been ascribed to differences in attraction,the contribution of capture and retention has been overlooked.This study focused on distinguishing between the prey trapping mechanisms, and assessing their relative contribution to prey diversity.Arthropod richness and diversity of both visitors and prey in the two types of pitchers were analysed to quantify the relative contribution of attraction to prey trapping.Rate of insect visits to the different pitcher parts and the presence or absence of a sweet fragrance was recorded to clarify the origin and mechanism of attraction.The mechanism of retention was studied by insect bioassays and measurements of fluid viscosity. Nepenthes rafflesiana was found to trap a broader prey spectrum than that previously described for any Nepenthes species,with the upper pitchers attracting and trapping a greater quantity and diversity of prey items than the lower pitchers.Capture efficiency was low compared with attraction or retention efficiency.Fragrance of the peristome,or nectar rim,accounted mainly for the observed non-specific, better prey attraction by the upper pitchers, while the retentive properties of the viscous fluid in these upper pitchers arguably explains the species richness of their flying prey.The pitchers of N. rafflesiana are therefore more than simple pitfall traps and the digestive fluid plays an important yet unsuspected role in the ecological success of the species.  相似文献   

18.
The pitchers of the tropical carnivorous plant Nepenthes alata are highly specialized organs for the attraction and capture of insects and absorption of nutrients from them. This study examined the structure and development of these pitchers, with particular focus on the nectaries and digestive glands. Immature pitchers developed at the tips of tendrils and were tightly sealed by a lid structure that opened during the end of pitcher elongation. Opened pitchers exposed a ridged peristome containing large nectaries. Like other members of the genus, a thick coating of epicuticular waxy scales covered the upper one-third of the pitcher. Scattered within this zone were cells resembling a stomatal complex with a protruding ridge. Cross sections showed that this ridge was formed by asymmetric divisions of the epidermal cells and lacked an underlying pore. The basal region of the trap had large multicellular glands that developed from single epidermal cells. These glands were closely associated with underlying vascular traces and provided a mechanism for supplying fluid to closed immature pitchers.  相似文献   

19.
Carnivorous syndrome in Asian pitcher plants of the genus Nepenthes   总被引:1,自引:0,他引:1  
BACKGROUND AND AIMS: Pitcher plants Nepenthes alata and N. mirabilis are carnivorous species with leaves composed of a photosynthetic part (lamina) and a pitcher trap. This characteristic permitted direct physiological and anatomical comparison between these two distinct parts of the leaves to determine those features involved in the 'carnivorous syndrome', which include low net photosynthetic assimilation rate (A(N)) and low photosynthetic nitrogen use efficiency (PNUE). METHODS: Photosynthetic rate (A(N)) and respiration rate (R(d)) were measured gasometrically, chlorophyll concentration was determined spectrophotometrically and nitrogen concentration was determined using a CHN elemental analyser in lamina and trap separately. Anatomy of N. alata was observed using light, fluorescence and transmission electron microscopy. A(N), foliar nitrogen and chlorophyll concentration were also compared with values for other carnivorous plant species (genera Sarracenia, Drosera) that combine both autotrophic and carnivorous functions into the same physical organ. KEY RESULTS: It was found that the A(N) in Nepenthes lamina was low and PNUE was only slightly higher or similar in comparison with other carnivorous plants. It was not observed that the pitcher had a higher R(d) than the lamina, but A(N) in the pitcher was significantly lower than in the lamina. Nepenthes possesses a cluster of characters that could result in reduced photosynthesis in the pitcher and be responsible for carnivorous function of the leaf: replacement of chlorophyll-containing cells with digestive glands, low chlorophyll and nitrogen concentration, compact mesophyll with a small portion of intercellular spaces, absence of palisade parenchyma and low stomatal density. CONCLUSION: Low photosynthetic capacity, nitrogen efficiency, chlorophyll and nitrogen concentration of Nepenthes pitchers was found, together with a set of features that characterized the carnivorous syndrome. Dual use of leaves for photosynthesis and nutrient gain can decrease photosynthetic efficiency in carnivorous plants in general.  相似文献   

20.
As a component of the inquiline community of the purple pitcher plant (Sarracenia purpurea), the pitcher plant midge Metriocneus knabi has been the subject of various ecological studies. However, very little is known about its characteristics beyond the larval stage, in particular the dispersal ability of adults. This study presents new molecular tools developed for testing of evolutionary and ecological questions in natural populations of this species. We describe a set of 12 microsatellite loci specific to M. knabi that are sufficiently polymorphic to provide insight into population genetic structure and dispersal patterns.  相似文献   

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