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1.
Peter Alpert 《Biological invasions》2006,8(7):1523-1534
Introduced species, those dispersed outside their natural ranges by humans, now cause almost all biological invasions, i.e.,
entry of organisms into habitats with negative effects on organisms already there. Knowing whether introduction tends to give
organisms specific ecological advantages or disadvantages in their new habitats could help understand and control invasions.
Even if no specific species traits are associated with introduction, introduced species might out-compete native ones just
because the pool of introduced species is very large (“global competition hypothesis”). Especially in the case of intentional
introduction, high initial propagule pressure might further increase the chance of establishment, and repeated introductions
from different source populations might increase the fitness of introduced species through hybridization. Intentional introduction
screens species for usefulness to humans and so might select for rapid growth and reproduction or carry species to suitable
habitats, all which could promote invasiveness. However, trade offs between growth and tolerance might make introduced species
vulnerable to extreme climatic events and cause some invasions to be transient (“reckless invader hypothesis”). Unintentional
introduction may screen for species associated with human-disturbed habitats, and human disturbance of their new habitats
may make these species more invasive. Introduction and natural long-distance dispersal both imply that species have neither
undergone adaptation in their new habitats nor been adapted to by other species there. These two characteristics are the basis
for many well-known hypotheses about invasion, including the “biotic resistance”, “enemy release”, “evolution of increased
competitive ability” and “novel weapon” hypotheses, each of which has been shown to help explain some invasions. To the extent
that biotic resistance depends upon local adaption by native species, altering selection pressures could reduce resistance
and promote invasion (“local adaptation hypothesis”), and restoring natural regimes could reverse this effect. 相似文献
2.
Invasive species can alter patterns of biodiversity by displacing closely related native species that occupy similar habitats.
We used multivariate ecological niche modeling to determine the potential spread and displacement of native congeners by the
invasive aquatic plant, variable-leaf milfoil (VLM, Myriophyllum heterophyllum) in New Hampshire, USA. We show that VLM occurs almost exclusively in “higher order” lakes characterized as large, low elevation
systems with relatively high pH, alkalinity and conductivity. In contrast, native milfoils occur across a broad range of lake
orders. The strong association between lake order and VLM invasions suggests that VLM is most likely to displace native milfoils
in higher order lakes. However, the mechanism by which VLM occurs in higher order lakes—higher propagule pressure versus higher
growth and survivorship—is unclear. We therefore caution that native species may ultimately be susceptible to displacement
from lower order lakes if the current distribution of VLM reflects higher propagule pressures. Our model provides a valuable
tool for the prioritization of monitoring efforts. 相似文献
3.
A seaweed with the local name “endong” is a rare eucheumoid variety that has recently been farmed in Tawi-Tawi, southern Philippines.
Local farmers describe it as “eel-like” because of its long, slender and smooth thalli. Being somewhat similar in appearance
to the dominantly farmed seaweed “tambalang” (Kappaphycus alvarezii var. tambalangii), farmers mix their harvests of “endong” with those of “tambalang”. We analyzed the hydrocolloid extract from “endong” using
spectroscopic and chemical techniques. The extract’s infrared and nuclear magnetic resonance (1H and 13C) spectra, and sulfate and 3,6-anhydrogalactose contents revealed carrageenan of the iota-type, similar to extracts from
another farmed species, Eucheuma denticulatum. This result implies that “endong” carrageenan exhibits physico-chemical properties different from those of kappa-carrageenan
of “tambalang”. The findings of this study are of significance to the seaweed industry, as carrageenan quality problems could
potentially arise from a mixed harvest. Seaweed farmers are advised to separate their harvests of “endong” and “tambalang”.
Presented at the 19th International Seaweed Symposium, Kobe, Japan 相似文献
4.
Invasive plants are degrading wildlands around the globe by displacing native species, reducing biodiversity, and altering
ecological functions. The current approach of applying herbicides to invasive plants in wildlands has not been effective at
curtailing their expansion and, in certain circumstances, may do more harm than good. Preventing the spread of invasive species
has been identified as an important strategy to protect wildlands. However, few prevention strategies have actually been tested.
We hypothesized that establishing competitive vegetation next to infestations would increase the biotic resistance of the
plant community to invasion and decrease the invasive species propagule pressure beyond the competitive vegetation. To evaluate
this, we established twelve competitive vegetation barriers in front of invasive annual grass, Taeniatherum caput-medusae (L.) Nevski, infestations. The non-native perennial grass Agropyron desertorum (Fisch. ex Link) Schult. was seeded into plant communities adjacent to the infestations to create the competitive vegetation
barriers. Soil nutrient concentrations and the spread of T. caput-medusae were compared between where A. desertorum was seeded and not seeded (control treatment) 3 years after treatment. Less T. caput-medusae and lower soil ammonium and potassium concentrations in the competitive vegetation barrier than control treatment (P ≤ 0.01) suggest that establishing competitive vegetation increased the biotic resistance of the plant communities to invasion.
Taeniatherum caput-medusae cover and density in the plant communities protected by the competitive vegetation barrier (locales across the barriers from
the infestations) were ~42- and 47-fold less, respectively, than unprotected plant communities (P < 0.01). This suggests that invasive plant propagule pressure was decreased in the plant communities protected by competitive
vegetation barriers. The establishment of competitive vegetation around infestations may be an effective strategy to prevent
or at least reduce the spread of invasive plant species. 相似文献
5.
6.
Flowers emit a large variety of floral signals that play a fundamental role in the communication of plants with their mutualists
and antagonists. We investigated phenotypic selection on floral scent and floral display using the rewarding orchid species
Gymnadenia odoratissima. We found positive directional selection on inflorescence size, as well as positive and negative selection on floral scent
compounds. Structural equation modeling showed that “active” compounds, i.e. those that were shown in earlier investigations
to be detected by pollinator insects, were positively linked to fitness, whereas “non-active” were negatively linked to fitness.
Our results suggest that different patterns of selection impact on different scent compounds, which may relate to the functions
of compounds for attracting/deterring insects. 相似文献
7.
Michael P. Moulton Wendell P. Cropper Jr. Linda E. Moulton Michael L. Avery David Peacock 《Biodiversity and Conservation》2012,21(1):155-174
Introduced species are widely believed to represent a significant threat to conservation of biological diversity. A better
understanding of the ecological factors associated with successful species establishment should lead to improved management
and mitigation of these introductions. The “propagule pressure hypothesis”, implying a greater chance of successful introduction
with greater numbers introduced, has been widely accepted as a principal ecological factor in explaining establishment of
exotic species. The historical record of bird introductions in a few locations, including the state of Victoria in Australia,
has been advanced as the principal quantitative support for the hypothesis. We compiled lists of bird species introductions
into Australia from several sources, and discovered inconsistencies in the records of introductions. In a series of comparisons,
we found that the historical record of passerine introductions to Australia does not support the propagule pressure hypothesis
unless superfluous introductions of already successful species are included. An additional problem with previous analyses
is the inclusion of unsuccessful haphazard cage escapes. 相似文献
8.
Jing Zhang Yan Liu Dan Yu Hongze Song Jingjin Cui Tao Liu 《Journal of applied phycology》2011,23(2):165-171
Hybridization of gametophytes, continuous self-crossing and targeted selection were utilized to breed a new Laminaria variety. After five-generation selection breeding, the new variety “Rongfu” was obtained. Its male parent “Yuanza No.10”
was the high-yield cultivation variety, and its female parent was variety “Fujian” which could tolerate relatively high seawater
temperature. “Yuanza No.10” and “Fujian” were different but complement in their morphological characteristics and biological
habits. Variety “Rongfu” was bred through their hybridization which exhibited high-yield potential and high seawater temperature
tolerance. The results of traits evaluation in consecutive years showed that “Rongfu” attained higher yields by 24–27% compared
to the control (widely used commercial variety) and also contained considerable amounts of iodine, mannitol, and algin. When
seawater temperature was 18–21°C, the blade growth of “Rongfu” was maintained and tissue loss by abrasion was significantly
lower than the control. Since the adoption of variety “Rongfu” in 2001, its cultivation areas have been extended to Shandong,
Fujian and Guangdong province and have reached 14,133 ha currently, i.e., almost one-tenth of the total cultivation areas
of Laminaria in China. The results of Random Amplified Polymorphic DNA analysis showed that the relationship between “Rongfu” and other
cultivation varieties in China was very close. 相似文献
9.
An Assessment of the Impact of Chromium-Amended Sediment on a Marine Nematode Assemblage Using Microcosm Bioassays 总被引:1,自引:0,他引:1
Fehmi Boufahja Amor Hedfi Jalila Amorri Patricia Aïssa Hamouda Beyrem Ezzeddine Mahmoudi 《Biological trace element research》2011,142(2):242-255
Microcosms were used to assess the impact of chromium on free-living marine nematodes. Nematodes were exposed to three chromium
concentrations (500 ppm (dm, dry mass), 800 ppm (dm) and 1,300 ppm (dm)), and effects were examined after 4 weeks. Results
showed significant differences between univariate measures of control nematodes and those from medium- and high-chromium microcosms.
Most, decreased significantly with increasing level of chromium contamination. The medium-chromium treatment seems to be the
minimal concentration that could has a negative effect on nematodes. Results from multivariate analyses demonstrated that
responses of nematode species to chromium treatments were varied: Leptonemella aphanothecae was eliminated at all doses tested and seemed to be intolerant species to chromium; Daptonema normandicum and Sabatieria longisetosa which significantly increased at 500 ppm chromium (dm) appeared to be “opportunistic” species at this dose whereas the two
Bathylaimus species (Bathylaimus capacosus and Bathylaimus tenuicaudatus) which increased at all the doses tested seemed to be “chromium resistant”. As we think such “opportunistic” and “resistant”
species could be used as sensitive indicators of unsafe marine food. The use of microcosms has allowed the effects of the
chromium on nematodes to be assessed individually, which was not possible in the field. 相似文献
10.
Preventing horticultural introductions of invasive plants: potential efficacy of voluntary initiatives 总被引:1,自引:0,他引:1
Jennifer W. Burt Adrianna A. Muir Jonah Piovia-Scott Kari E. Veblen Andy L. Chang Judah D. Grossman Heidi W. Weiskel 《Biological invasions》2007,9(8):909-923
Although prevention is the most cost-effective way to avoid the enormous expenses associated with plant invasions, invasive
plants continue to be imported as trade commodities for horticultural use. With very little government regulation of horticultural
imports of invasive plants, efforts have turned toward fostering voluntary initiatives to encourage self-regulation by the
horticulture trade. Our study takes the first step toward evaluating the potential success of these voluntary initiatives.
We conducted a survey of nursery professionals to gauge their perceptions of invasive species, the role of the horticulture
trade in invasive plant introductions, and their participation—potential and actual—in preventive measures outlined in the
St Louis Voluntary Codes of Conduct for nursery professionals. We found nursery professionals to be highly aware of invasive
plants and to accept responsibility as a trade for horticultural introductions. Although only 7% of respondents had heard
of the St Louis Voluntary Codes of Conduct, the majority (57%) reported having participated in at least two of seven preventive
measures, and most (78%) reported willingness to engage in the majority of preventive measures. We found that several factors
significantly predict increased participation in preventive measures, particularly awareness of invasive plants and involvement
in trade associations. We also identified incentives and obstacles to participating in preventive behaviors, including “concern
for the environment” and “lack of information,” respectively. Our results suggest that participation in voluntary initiatives
will improve through increased outreach, and we provide specific recommendations for improving participation in voluntary
programs in the horticulture trade. 相似文献
11.
We made a quantitative analysis of the responses of urban and rural residents in Sweden to arguments supporting and opposing
conservation of large carnivores. The most important arguments in favour of conservation were: “I want them [the large carnivores] to exist in Sweden, even if I will never see any of them”, “Sweden should share the responsibility of conserving the large
carnivores” and “We owe it [conservation of large carnivores] to future generations”. We found only small differences between rural and urban residents. For arguments opposing conservation,
the difference between rural and urban areas was slightly greater. The most important arguments opposing conservation of large
carnivores were: “They may have serious negative impact on livestock farming”, “They may have serious negative impact on reindeer
husbandry” and “May inflict suffering on injured livestock”. We conclude that there seems to be less support for direct use
values such as hunting, ecotourism or just experiencing large carnivores, this may imply that the minimum viable population
size can be used as a long-term management goal for large carnivore populations, possibly with an exception for bears. We
also conclude that a separate conservation or management plan is needed for each species, since the conflicts with human interests
vary greatly between the different carnivore species. 相似文献
12.
Walter W. Ferguson 《Primates; journal of primatology》1992,33(2):273-279
In response to a critique byFerguson (1989),Leonard (1991) reiterates most of his original arguments for supporting “Australopithecus afarensis”Johanson, White, andCoppens, 1978 as a single species. He disregards the principle of morphological equivalence by comparing the dental metrics and morphology
of a hominid with those of species of the Pongidae, which do not correspond with the degree of variation in hominids, instead
of with those of species of the Hominidae. He fails to refute clear evidence that the range of variation of dental metrics
and morphology in “A. afarensis” exceeds that seen in species of the Hominidae. On the basis of extreme variation, “A. afarensis” is, therefore, interpreted as representing a composite species. 相似文献
13.
Stefan Dullinger Ingrid Kleinbauer Johannes Peterseil Manfred Smolik Franz Essl 《Biological invasions》2009,11(10):2401-2414
Forecasting the spatial spread of invasive species is important to inform management planning. Niche-based species distribution
models offer a well-developed framework for assessing the potential range of species. However, these models assume equilibrium
between the species’ distribution and its ecological requirements. During range expansion, invasive species are not in such
equilibrium due to both dispersal limitation and frequent casual occurrence in sites unsuitable to persistent populations.
In this article we use the example of the invasive annual plant Ambrosia artemisiifolia in Austria to evaluate if model accuracy can be enhanced in such non-equilibrium situations by taking account of propagule
pressure and by restricting model calibration to naturalized populations. Moreover, we test if model accuracy increases during
invasion history using distribution data from 1984 to 2005. The results suggest that models calibrated with naturalized populations
are much more accurate than those based on the total set of records. Proxies of propagule pressure slightly but significantly
improve goodness of fit, accuracy, and Type I and II error rates of models calibrated with all available records but have
less consistent effects on models of naturalized populations. Model accuracy did not increase during the recent invasion history,
probably because the species is still far from an equilibrium distribution. We conclude that even a coarse assessment of population
status with records of invasive species delivers important information for predictive modelling and that proxies of propagule
pressure should be included into such models at least during early to intermediate stages of the invasion history. 相似文献
14.
The intentional introduction of exotic species can increase the level of local biodiversity, enrich people’s material lives,
and bring significant social and economic benefits that are also the symbols of human progress. However, along with the frequent
intercourse among countries and regions, the frequency of uncontrolled crossregional migration of species is increased and
there is a lack of scientific management strategy for the intentional introduction of exotic species. Exotic species invasion,
which is behind habitat fragmentation, has become the second largest threatening factor to the maintenance of the global-scale
level of biological diversity. Exotic species invasion can destroy the structure of an ecosystem, disturb the economic life
of a society, and do harm to human health. In this paper, the authors review some of the ecological explanations for issues
such as “what causes or mechanisms have led to the successful invasion of exotic species”, including the “ideal weeds characteristics”,
“biodiversity resistance hypothesis”, “enemies release hypothesis”, “evolution of increased competitive ability hypothesis”,
“niche opportunity hypothesis”, and “novel weapon hypothesis”. The authors also analyze and evaluate the background and theoretical
basis of the hypotheses, providing explanations for some phenomena, as well as the deficiencies of these explanations. 相似文献
15.
Jeannina A. Smith 《Current fungal infection reports》2010,4(1):38-45
The number of commercially available tumor necrosis factor (TNF)-α inhibitors has been increasing, including two new agents
licensed since 2008. In addition to an expanding number of agents, there are also increasing licensed and “off label” clinical
applications for the TNF inhibitors for the treatment of a variety of inflammatory or granulomatous disorders. Unfortunately,
use of the TNF inhibitors has been associated with a wide variety of opportunistic infections, including fungal infections.
Higher rates of morbidity and mortality from fungal infection in TNF inhibitor-treated patients have been observed, likely
due to a delay in the diagnosis of invasive fungal infections and a tendency for these patients to develop severe and disseminated
disease. Therefore, the US Food and Drug Administration issued a “black box” warning for clinicians in September 2008 to alert
providers to the risks of fungal infections in patients treated with TNF-α inhibitors. 相似文献
16.
Biological Invasions - Identifying the mechanisms that result in a “high impact” invasive species can be difficult. Coexistence theory suggests that detrimental invasive species can be... 相似文献
17.
Microrheological properties (aggregation and deformability) of erythrocytes separated by centrifugation at 30000×g density gradient into “young” and “old” (the upper and lower fractions, respectively) were studied. The erythrocytes were
taken from physically active persons (PAP) and from those with elevated arterial pressure (EAP). A significant difference
in microrheological properties of the “young” and “old” erythrocytes was found. The aggregation degree of “old” cells was
nearly twice that of “young” cells. The deformability of the erythrocyte subpopulations was significantly different, though
the difference was not so pronounced as in the case of aggregation. The aggregation of “young” and “old” erythrocytes in the
PAP group was the least (28% lower than in the control). Note, that “old” erythrocytes in the PAP group had better microrheological
properties than in the other groups. All erythrocyte populations in the EAP group were characterized by higher aggregation,
decreased deformability, and decreased capacity for oxygen transport. 相似文献
18.
Yuzuru Hamada 《Primates; journal of primatology》1984,25(4):485-506
A method based on the Fourier analysis is proposed, which describes and analyzes the contour morphology of carpal bones by
separating morphology into factors of shape and size. Here, “size” refers to the average diameter of the contour. The “shape”
is expressed byshape factors which are derived from the Fourier series and the “shape” of a monkey is expressed by ashape index which is calculated fromshape factors. The age change in the morphology of the lunate and capitate ofMacaca fuscata fuscata was analyzed by this method. The development of “shape” approximately completes by 3 years of age, whereas increase in “size”
begins its spurt at that age as do body weight and anterior trunk length. By applying this method to other macaque species,
it was found thatM. mulatta, M. f. yakui andM. cyclopis exhibit similar patterns of growth and development of carpal bones to those ofM. f. fuscata. Patterns found inM. fascicularis differ in that its bones develop faster than in the other macaques with respect to the “shape,” but remain small with respect
to the “size.” 相似文献
19.
François Mankessi Aubin R. Saya Frédéric Boudon Yann Guédon Fabienne Montes Marc Lartaud Jean-Luc Verdeil Olivier Monteuuis 《Trees - Structure and Function》2010,24(4):743-752
Shoot apical meristem (SAM) domes derived from five different outdoor and in vitro sources of juvenile and mature Eucalyptus urophylla × Eucalyptus grandis akin genotypes were compared. Overall measurements of SAM dome height H and diameter D ranged from 2 to 35 μm and 20 to 80 μm, with significant differences according to the various physiological origins of plant
material investigated. SAM domes from the mature trees “Mat” were taller than those from the rejuvenated ministock plants
“Rej”; from the in vitro microcuttings “IVM” of the same clone and also from the in vitro juvenile seedlings “IVJ”, whereas
outdoor seedlings “Juv” exhibited intermediate SAM dome height. SAM domes from the rejuvenated material “Rej”, from the in
vitro mature “IVM” and juvenile “IVJ” origins were also narrower than those from the outdoor seedlings “Juv” and to lesser
extent than those from the mature trees “Mat”. Overall, the mature source “Mat” displayed bigger and somehow sharper hemispherical
domes than those from “Rej” and “Juv”, physiologically more juvenile, or those from the in vitro origins “IVM” and “IVJ” which
looked flatter and smaller. SAM dome height, diameter D and H/D values varied also significantly according to the plastochron. More specifically, H, D, and H/D SAM differences between the five origins were not significant during the early plastochron phase corresponding to leaf initiation,
to become more salient as leaf structures started to elongate and to differentiate. This was particularly obvious for mature
tree “Mat” SAM dome shapes which showed at this stage much higher H/D values than the other SAM sources. A shape index S used for characterizing more accurately dome shape confirmed these trends. These observations provide additional arguments
to the view that juvenility in trees becomes more and more time- and shoot-tip restricted as ageing increases in the course
of time during the ontogenetical process and could be ultimately confined to the most organogenic phase of SAM, from which
shoot characteristics derive. 相似文献
20.
The Laurentian Great Lakes have been subject to numerous introductions of nonindigenous species, including two recent benthic
fish invaders, Eurasian ruffe (Gymnocephalus cernuus) and round gobies (Neogobius melanostomus), as well as the benthic bivalve, zebra mussel (Dreissena polymorpha). These three exotic species, or “exotic triad,” may impact nearshore benthic communities due to their locally high abundances
and expanding distributions. Laboratory experiments were conducted to determine (1) whether ruffe and gobies may compete for
habitat and invertebrate food in benthic environments, and (2) if zebra mussels can alter those competitive relationships
by serving as an alternate food source for gobies. In laboratory mesocosms, both gobies and ruffe preferred cobble and macrophyte
areas to open sand either when alone or in sympatry. In a 9-week goby–ruffe competition experiment simulating an invasion
scenario with a limited food base, gobies grew faster than did ruffe, suggesting that gobies may be competitively superior
at low resource levels. When zebra mussels were added in a short-term experiment, the presence or absence of mussels did not
affect goby or ruffe growth, as few zebra mussels were consumed. This finding, along with other laboratory evidence, suggests
that gobies may prefer soft-bodied invertebrate prey over zebra mussels. Studies of interactions among the “exotic triad”,
combined with continued surveillance, may help Great Lakes fisheries managers to predict future population sizes and distributions
of these invasive fish, evaluate their impacts on native food webs, and direct possible control measures to appropriate species. 相似文献