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1.
Fringing reef development is limited around 22° S along the inner Great Barrier Reef, although there is substantial development
north and south of this latitude. This study examined the relationships among coral communities and the extent of reef development.
Reefs were examined to determine coral composition, colony abundance, colony size and growth form between the latitudes 20°S
and 23°S. Major reef framework builders (scler- actinian genus Acropora and families Faviidae and Poritidae) dominated reefs north and south of 22°S, but declined significantly at 22°S where foliose
and encrusting corals (Turbinaria and Montipora spp.) were most common. Porites spp. were present at 22° S but had encrusting morphologies. Consistently high turbidity at this latitude, caused by a 10
m tidal range and strong tidal flows, resuspends silts from the shallow shelf, and appears to have precluded reef development
throughout the Holocene, by limiting the abundance, stunting the growth, and shortening the life expectancies of reef framework
corals. The distinctions between ‘natural’ and ‘human-induced’ degradation may be interpreted on the basis of the relationship
between Holocene development and current benthic community longevity. A mismatch between substantial past reef building capacity (a broad and/or thick reef) and non-existent or limited present reef-building capacity could signify anything from a long-period, natural cycle to an unprecedented deterioration in ecosystem
function caused by human influence.
Accepted: 29 July 1996 相似文献
2.
During January/February 2006, we satellite-tracked two different ecotypes of killer whales (Orcinus orca) in McMurdo Sound, Ross Sea, Antarctica, using surface-mounted tags attached with sub-dermal darts. A single Type B whale
(pinniped prey specialist), tracked for 27 days, traveled an average net distance of 56.8 ± 32.8 km day−1, a maximum of 114 km day−1, and covered an estimated area of 49,351 km2. It spent several days near two large emperor penguin (Aptenodytes forsteri) colonies, a potential prey item for this form. By contrast, four Type C killer whales (fish prey specialists) tracked for
7–65 days, traveled an average net distance of 20 ± 8.3 km day−1, a maximum of 56 net km day−1, and covered an estimated area of only 5,223 km2. These movement patterns are consistent with those of killer whale ecotypes in the eastern North Pacific where mammal-eating
‘transients’ travel widely and are less predictable in their movements, and fish-eating ‘residents’ have a more localized
distribution and more predictable occurrence, at least during the summer months. 相似文献
3.
Obligate symbiotic dinoflagellates (Symbiodinium) residing within the tissues of most reef invertebrates are important in determining the tolerance range of their host. Coral
communities living at high latitudes experience wide fluctuations in environmental conditions and thus provide an ideal system
to gain insights into the range within which the symbiotic relationship can be sustained. Further, understanding whether and
how symbiont communities associated with high-latitude coral reefs are different from their tropical counterparts will provide
clues to the potential of corals to cope with marginal or changing conditions. However, little is known of the host and symbiont
partnerships at high latitudes. Symbiodinium diversity and specificity of high-latitude coral communities were explored using denaturing gradient gel electrophoresis
(PCR-DGGE) analysis of the internal transcribed spacer regions (ITS1 and ITS2) of the ribosomal DNA at Lord Howe Island (31°S;
Australia), and the Kermadec Islands (29°S; New Zealand). All but one host associated with clade C Symbiodinium, the exception being a soft coral (Capnella sp.) that contained Symbiodinium B1. Besides ‘host-generalist’ Symbiodinium types C1 and C3, approximately 72% of the Symbiodinium identified were novel C types, and zonation of symbionts in relation to environmental parameters such as depth and turbidity
was evident in certain host species. The high-latitude Symbiodinium communities showed little overlap and relatively high diversity compared with communities sampled on the tropical Great Barrier
Reef. Although host specificity was maintained in certain species, others shared symbionts and this potential reduction of
fidelity at high-latitude locations may be the result of locally challenging and highly variable environmental conditions. 相似文献
4.
The faunistic composition of pelagic ostracods of regions situated to the north and northwest of the d’Urville Sea (60°–65°S,
148°–136° and 136°–113°E) is largely similar to that of the area adjacent to the Somov Sea at the same latitudes. Alacia hettacra is the most abundant species here; Austrinoecia isocheira, Boroecia antipoda, and Obtusoecia antarctica are common species. The maximum abundance of pelagic ostracods is observed in the 100–200 m depth range; the largest contribution
to it is contributed by A. hettacra. The number of species increases with increasing depth. The 64°–65°S region between 148° and 113° E is regarded as the northern
boundary of the “Polar Antarctic zone.” 相似文献
5.
High incidence (up to 40%) of symptoms of yellowing and yellow mottling was observed in 5–8 years old orchards of kinnow mandarin
{Citrus reticulate Balanco (‘King’ × ‘Willow mandarin’)} in the Punjab state of India during a survey in January 2007. These symptoms are often
confused with nutrient deficiency and other stress related disorders. However, a greening bacterium has been attributed to
cause the disease. The disease was graft transmissible and sequencing of 16S rRNA, 16S/23S intergenic spacer region and 23S
rRNA of the greening bacterium associated with yellowing disease in kinnow mandarin confirmed it to be Candidatus Liberibacter asiaticus (‘Ca L. asiaticus’) showing maximum identity of 95.9% with ‘Ca L. asiaticus’ from USA and Brazil in 16S rRNA. The study indicates definite association of ‘Ca L. asiaticus’ with yellowing/chlorotic
mottling symptoms of greening disease of kinnow mandarin in Punjab state of India. 相似文献
6.
7.
Hemant Lata Suman Chandra Zlatko Mehmedic Ikhlas A. Khan Mahmoud A. ElSohly 《Acta Physiologiae Plantarum》2012,34(2):743-750
Germplasm conservation of a high Δ9-tetrahydrocannabinol yielding variety of Cannabis sativa L. was attempted using synthetic seed technology and media supplemented with osmotic agents. Explants of nodal segments containing
single axillary bud were excised from in vitro proliferated shoot cultures and encapsulated in high-density sodium alginate
(230 mM) hardened by 50 mM CaCl2. The ‘encapsulated’ (synthetic seeds) and ‘non-encapsulated’ nodal segments were stored at 5, 15 and 25°C for 8, 16 and 24 weeks
and monitored for the re-growth and survival frequency under the tissue culture conditions (16-h photoperiod, 25°C) on Murashige
and Skoog (MS) medium supplemented with thidiazuron (TDZ 0.5 μM). ‘Encapsulated’ nodal segments could be stored at low temperature
15°C up to 24 weeks with maximum re-growth ability and survival frequency of 60%. Similar to ‘encapsulated’ cultures, the
highest re-growth in ‘non-encapsulated’ cultures was observed in the explants kept at 15°C without osmotic agents. Furthermore,
the effect of osmotic agents mannitol and sorbitol (2 and 4% w/v, added individually and in combination to the media at culture
room conditions i.e. 25°C) on non-encapsulated shoot cultures was also evaluated. A considerable decrease in re-growth and survival was observed
in the cultures treated with osmotic agents. Among the cultures treated with different concentrations of osmotic agents, the
highest rate of re-growth and survival was observed at the lowest concentration of 2% sorbitol and 2% mannitol individually
added to the media. Well-developed plantlets regenerated from ‘encapsulated’ nodal segments were successfully acclimatized
inside the growing room with 90% survival frequency. Gas chromatography-flame ionization detection (GC-FID) was used to compare
the chemical profile and the concentration of the different cannabinoids (cannabidiol, cannabichromene, cannabigerol, cannabinol,
Δ9-tetrahydrocannabinol and tetrahydrocannabivarin) of the plants grown from ‘encapsulated’ nodal segments to that of the donor
plant. The data showed similar cannabinoid profile and insignificant differences in the cannabinoids content between the two
types of plants. This study is of high significance since the encapsulation technology would allow the prolonged storage (thus
reducing the cost of labor) of high-yielding C. sativa germplasm selected for the isolation of THC, a high-value bulk active pharmaceutic. 相似文献
8.
K. Sorkheh B. Shiran M. Khodambshi V. Rouhi S. Ercisli 《Plant Cell, Tissue and Organ Culture》2011,105(3):395-404
Eight native Iranian almond species from three sections, ‘Euamygdalus’ (Prunus communis; Prunus eleagnifolia and Prunus orientalis); ‘Lycioides’ (Prunus lycioides and Prunus reuteri) and ‘Spartioides’ (Prunus arabica, Prunus glauca and Prunus scoparia) were in vitro screened for drought tolerance using sorbitol and polyethylene glycol (PEG) as an osmoticum. Different levels
of water stress were induced using five concentrations of either sorbitol or polyethylene glycol in Woody Plant Medium (WPM).
Water potential of various media ranged from −0.80 to −2.05 MPa and water stress in culture medium adversely affected plantlet
growth. Wild species from ‘Spartioides’ were less affected than ‘Lycioides’ and ‘Euamygdalus’. At the same level of water
potential, sorbitol had lower adverse effects than PEG; the latter being severe. Prunus × sorbitol and Prunus × PEG interactions were significant. At 0.2 M sorbitol and 0.003 M PEG, ‘Spartioides’ produced significantly more roots with
higher total root length and root volume, as well as root-dry weight than those of ‘Lycioides’ and ‘Euamygdalus.’ It is concluded
that in vitro screening of native Iranian almond species under specific and limited water-stress conditions may provide a
system for effectively differentiating the wild species of almond for their expected root mass production under field conditions. 相似文献
9.
Nadia Khelifi Emna Ben Romdhane Abdeljabbar Hedi Anne Postec Marie-Laure Fardeau Moktar Hamdi Jean-Luc Tholozan Bernard Ollivier Agnès Hirschler-Réa 《Extremophiles : life under extreme conditions》2010,14(3):297-304
A novel thermophilic anaerobic and microaerophilic bacterium (optimal growth in the presence of 5–10% O2), strain Nad S1T was isolated from the terrestrial hot spring of Hammam Sidi Jdidi, Nabeul, Tunisia. Cells were motile rods having a Gram-positive
cell wall structure. Strain Nad S1T grew optimally at 55°C (range 37–70°C). Optimum pH for growth was 6.5–7.0. It was halotolerant growing with NaCl up to 7%
(optimum concentration 1.5–3.0%). It grew chemoorganotrophically on various carbohydrates, organic-acids and amino-acids as
energy sources, or chemolithotrophically on H2 using nitrate, as terminal electron acceptor. Beside oxygen (under microaerobic conditions) and nitrate, nitrite was also
used. Nitrate was completely reduced to N2. No fermentation occurred. The genomic DNA G + C content was 41.8 mol%. Based on 16S rRNA gene sequence analysis, strain
Nad S1T belongs to the Bacillaceae family within the class ‘Bacilli’. Because of its phylogenetic and phenotypic characteristics, we propose this isolate to be assigned as a novel genus and
a novel species within the domain Bacteria, Microaerobacter geothermalis gen. nov., sp. nov. The type strain is Nad S1T (=DSM 22679T =JCM 16213T). 相似文献
10.
Although seedling herbivory is an important selective filter in many plant communities, how and why seedlings are selected
is poorly understood. Here, we examined the putative role of herbivore olfaction in dictating seedling selection. Using a
Y-tube olfactometer we compared snail (Helix aspersa) preference for pellets derived from 14-day-old macerated seedlings of nine European grassland (‘Test’) species against standard
(‘Control’) pellets derived from lettuce. Snail movement towards ‘Test’ pellets was strongly correlated with seedling acceptability
(Pearson’s r
2 = 0.86, P > 0.01) and where snails exhibited a positive choice for the ‘Test’ species, the choice was made more quickly for highly
acceptable species (r
2 = 0.86, P > 0.01). In elucidating a link between seedling acceptability and olfactory response to macerated seedlings, our study suggests
that even from an early ontogenetic stage plant selection by snails may be governed by olfactory cues. This finding highlights
the need for research on the role of plant volatiles in plant–herbivore interactions to consider more fully interactions operating
at the seedling stage. 相似文献
11.
12.
J. Perry Gustafson Xue-Feng Ma Viktor Korzun John W. Snape 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,118(4):793-800
A consensus map of rye (Secale cereale L.) was constructed using JoinMap 2.0 based on mapping data from five different mapping populations, including ‘UC90’ × ‘E-line’,
‘P87’ × ‘P105’, ‘I0.1-line’ × ‘I0.1-line’, ‘E-line’ × ‘R-line’, and ‘Ds2’ × ‘RxL10’. The integration of the five mapping populations resulted in a 779-cM map
containing 501 markers with the number of markers per chromosome ranging from 57 on 1R to 86 on 4R. The linkage sizes ranged
from 71.5 cM on 2R to 148.7 cM on 4R. A comparison of the individual maps to the consensus map revealed that the linear locus
order was generally in good agreement between the various populations, but the 4R orientations were not consistent among the
five individual maps. The 4R short arm and long arm assignments were switched between the two population maps involving the
‘E-line’ parent and the other three individual maps. Map comparisons also indicated that marker order variations exist among
the five individual maps. However, the chromosome 5R showed very little marker order variation among the five maps. The consensus
map not only integrated the linkage data from different maps, but also greatly increased the map resolution, thus, facilitating
molecular breeding activities involving rye and triticale. 相似文献
13.
Fotini G. Skiada Katerina Grigoriadou Eleftherios P. Eleftheriou 《Central European Journal of Biology》2010,5(6):839-852
The effects of six basal media on in vitro shoot proliferation of the greek grapevines Vitis vinifera L. cv. ‘Malagouzia’ and ‘Xinomavro’ were investigated. Galzy and Zlenco proved to be the most effective for ‘Malagouzia’
and ‘Xinomavro’, respectively. If only BA was present in the medium, shoot development was poor and the plantlets were chlorotic.
When the medium was supplemented with BA and NAA, growth was enhanced. The best ratio (in μM) of growth regulators was 0.5/0.3
for ‘Malagouzia’, and 0.1/0.03 for ‘Xinomavro’, which resulted in the highest number of microshoots per explant and greatest
proliferation rate. The development of ‘Malagouzia’ and ‘Xinomavro’ explants at 21±2 and 26±2°C was also investigated, revealing
the higher temperature to be more effective. Regarding rooting, 0.5 μM IBA improved root formation at 26°C for ‘Malagouzia’
and 0.5 μM IBA at 21°C for ‘Xinomavro’. Moreover, 0.5 μM IBA resulted in a higher rooting percentage (>95%) and proved to
be more beneficial for the overall morphological appearance of the plantlets of ‘Malagouzia’. After acclimatization, survival
of microshoots cultivated in media with IBA was higher than those in NAA. 相似文献
14.
Cold environmental temperature is detrimental to reproduction by oviparous squamate reptiles by prolonging incubation period,
negatively affecting embryonic developmental processes, and by killing embryos in eggs directly. Because low soil temperature
may prevent successful development of embryos in eggs in nests, the geographic distributions of oviparous species may be influenced
by the thermal requirements of embryos. In the present study, we tested the hypothesis that low incubation temperature determines
the northern distributional limit of the oviparous lizard Sceloporus undulatus. To compare the effects of incubation temperature on incubation length, egg and hatchling survival, and hatchling phenotypic
traits, we incubated eggs of S. undulatus under temperature treatments that simulated the thermal environment that eggs would experience if located in nests within
their geographic range at 37°N and north of the species’ present geographic range at latitudes of 44 and 42°N. After hatching,
snout–vent length (SVL), mass, tail length, body condition (SVL relative to mass), locomotor performance, and growth rate
were measured for each hatchling. Hatchlings were released at a field site to evaluate growth and survival under natural conditions.
Incubation at temperatures simulating those of nests at 44°N prolonged incubation and resulted in hatchlings with shorter
SVL relative to mass, shorter tails, shorter hind limb span, slower growth, and lower survival than hatchlings from eggs incubated
at temperatures simulating those of nests at 37 and 42°N. We also evaluated the association between environmental temperature
and the northern distribution of S. undulatus. We predicted that the northernmost distributional limit of S. undulatus would be associated with locations that provide the minimum heat sum (∼495 degree-days) required to complete embryonic development.
Based on air and soil temperatures, the predicted northern latitudinal limit of S. undulatus would lie at ∼40.5–41.5°N. Our predicted value closely corresponds to the observed latitudinal limit in the eastern United
States of ∼40°N. Our results suggest that soil temperatures at northern latitudes are not warm enough for a sufficient length
of time to permit successful incubation of S. undulatus embryos. These results are consistent with the hypothesis that incubation temperature is an important factor limiting the
geographic distributions of oviparous reptile species at high latitudes and elevations. 相似文献
15.
Cory J. D. Matthews Sebasti��n P. Luque Stephen D. Petersen Russel D. Andrews Steven H. Ferguson 《Polar Biology》2011,34(7):1091-1096
Killer whales (Orcinus orca) occur in the eastern Canadian Arctic during the open-water season, but their seasonal movements in Arctic waters and overall
distribution are poorly understood. During August 2009, satellite transmitters were deployed onto two killer whales in Admiralty
Inlet, Baffin Island, Canada. A whale tracked for 90 days remained in Admiralty and Prince Regent Inlets from mid-August until
early October, when locations overlapped aggregations of marine mammal prey species. While in Admiralty and Prince Regent
Inlets, the whale traveled 96.1 ± 45.3 km day−1 (max 162.6 km day−1) and 120.1 ± 44.5 km day−1 (max 192.7 km day−1), respectively. Increasing ice cover in Prince Regent Inlet in late September and early October was avoided, and the whale
left the region prior to heavy ice formation. The whale traveled an average of 159.4 ± 44.8 km day−1 (max 252.0 km day−1) along the east coast of Baffin Island and into the open North Atlantic by mid-November, covering over 5,400 km in approximately
one month. This research marks the first time satellite telemetry has been used to study killer whale movements in the eastern
Canadian Arctic and documents long-distance movement rarely observed in this species. 相似文献
16.
17.
The flowers of several families of seed plants warm themselves when they bloom. In some species, thermogenesis is regulated,
increasing the rate of respiration at lower ambient temperature (T
a) to maintain a somewhat stable floral temperature (T
f). The precision of this regulation is usually measured by plotting T
f over T
a. However, such measurements are influenced by environmental conditions, including wind speed, humidity, radiation, etc. This
study eliminates environmental effects by experimentally ‘clamping’ T
f at constant, selected levels and then measuring stabilized respiration rate. Regulating flowers show decreasing respiration
with rising T
f (Q
10 < 1). Q
10 therefore becomes a measure of the biochemical ‘precision’ of temperature regulation: lower Q
10 values indicate greater sensitivity of respiration to T
f and a narrower range of regulated temperatures. At the lower end of the regulated range, respiration is maximal, and further
decreases in floral temperature cause heat production to diminish. Below a certain tissue temperature (‘switching temperature’),
heat loss always exceeds heat production, so thermoregulation becomes impossible. This study compared three species of thermoregulatory
flowers with distinct values of precision and switching temperature. Precision was highest in Nelumbo nucifera (Q
10 = 0.16) moderate in Symplocarpus renifolius (Q
10 = 0.48) and low in Dracunculus vulgaris (Q
10 = 0.74). Switching temperatures were approximately 30, 15 and 20°C, respectively. There were no relationships between precision,
switching temperature or maximum respiration rate. High precision reveals a powerful inhibitory mechanism that overwhelms
the tendency of temperature to increase respiration. Variability in the shape and position of the respiration–temperature
curves must be accounted for in any explanation of the control of respiration in thermoregulatory flowers. 相似文献
18.
U. Kumar A. K. Joshi S. Kumar R. Chand M. S. R?der 《Molecular breeding : new strategies in plant improvement》2010,26(3):477-491
Spot blotch caused by Bipolaris sorokiniana is a destructive disease of wheat in warm and humid wheat growing regions of the world. To identify quantitative trait loci
(QTLs) for spot blotch resistance, two mapping populations were developed by making the crosses between common susceptible
cultivar ‘Sonalika’ with the resistant breeding lines ‘Ning 8201’ and ‘Chirya 3’. Single seed descent derived F6, F7, F8 lines of the first cross ‘Ning 8201’ × ‘Sonalika’ were evaluated for resistance to spot blotch in three blocks in each of
the 3 years. After screening of 388 pairs of simple sequence repeat primers between the two parents, 119 polymorphic markers
were used to genotype the mapping population. Four QTLs were identified on the chromosomes 2AS, 2BS, 5BL and 7DS and explained
62.9% of phenotypic variation in a simultaneous fit. The QTL on chromosome 2A was detected only in 1 year and explained 22.7%
of phenotypic variation. In the second cross (‘Chirya 3’ × ‘Sonalika’), F7 and F8 population were evaluated in three blocks in each of the 2 years. In this population, five QTLs were identified on chromosomes
2BS, 2DS, 3BS, 7BS and 7DS. The QTLs identified in the ‘Chirya 3’ × ‘Sonalika’ population explained 43.4% of phenotypic variation
in a simultaneous fit. The alleles for reduced disease severity in both the populations were derived from the respective resistant
parent. The QTLs QSb.bhu-2B and QSb.bhu-7D from both populations were placed in the same deletion bins, 2BS1-0.53-0.75 and 7DS5-0.36-0.61, respectively. The closely
linked markers Xgwm148 to the QTL on chromosome 2B and Xgwm111 to the QTL on chromosome 7D are potentially diagnostic markers for spot blotch resistance. 相似文献
19.
M. J. van Steenis K. A. M. H. El-Khawass 《Entomologia Experimentalis et Applicata》1995,76(2):121-131
Life table data forAphis gossypii Glover (Homoptera: Aphididae), an important pest in glasshouse cucumber crops, were studied at 20, 25 and 30°C on two cucumber
cultivars (Cucumis sativus L.) in controlled climate cabinets. The development time on the cucumber cv. ‘Sporu’ ranged from 4.8 days at 20°C to 3.2
days at 30°C. Immature mortality was approximately 20% and did not differ between temperatures. Most mortality occurred during
the first instar. Reproduction periods did not differ among temperatures, but at 25 and 30°C more nymphs were produced (65.9
and 69.8 nymphs/♀, respectively) than at 20°C (59,9 nymphs/♀) because of a higher daily reproduction. Intrinsic rate of increase
was greatest at 25°C (r
m
=0.556 day−1). At 20 and 30°C the intrinsic rate of increase was 0.426 and 0.510, respectively. On cv. ‘Aramon’, the development time
ofA. gossypii was approximately 20% longer at all temperatures. Immature mortality did not differ between the two cultivars. The intrinsic
rate of increase on cv. ‘Aramon’ was 15% smaller than on cv. ‘Sporu’. The use of cucumber cultivars partially resistant to
aphids is discussed in relation to biological control of cotton aphid in glasshouses. Development time and immature mortality
on leaves of the middle and upper leaf layer of glasshouse grown cucumber plants (cv. ‘Aramon’) were comparable to development
in the controlled climate cabinets. On the lower leaves immature mortality was much higher (approximately 82%) than on leaves
of the middle (24.0%) and upper leaf layer (24.5%). Reproduction was less on the lower leaf layer (45.9, 70.5 and 70.1 nymphs/♀
on leaves of the lower, middle and upper leaf layer, respectively).
Aphids, successfully parasitized byAphidius colemani Viereck (Hymenoptera: Braconidae) only reproduced when they were parasitized after the third instar. Fecundity was 0.1 to
0.9 and 10.5 to 13.3 nymphs/♀ for aphids parasitized in the fourth instar or as adults, respectively. Reproduction of aphids
that were stung but survived the attack was lower than for aphids not stung. Average longevity of these aphids was equal to
the longevity of aphids not stung byA. colemani. 相似文献
20.
Angela Breeuwer Monique M. P. D. Heijmans Maurits Gleichman Bjorn J. M. Robroek Frank Berendse 《Plant Ecology》2009,204(1):97-111
To predict the role of ombrotrophic bogs as carbon sinks in the future, it is crucial to understand how Sphagnum vegetation in bogs will respond to global change. We performed a greenhouse experiment to study the effects of two temperature
treatments (17.5 and 21.7°C) and two N addition treatments (0 and 4 g N m−2 year−1) on the growth of four Sphagnum species from three geographically interspersed regions: S. fuscum, S. balticum (northern and central Sweden), S. magellanicum and S. cuspidatum (southern Sweden). We studied the growth and cover change in four combinations of these Sphagnum species during two growing seasons. Sphagnum height increment and production were affected negatively by high temperature and high N addition. However, the northern species
were more affected by temperature, while the southern species were more affected by N addition. High temperature depressed
the cover of the ‘wet’ species, S. balticum and S. cuspidatum. Nitrogen concentrations increased with high N addition. N:P and N:K ratios indicated P-limited growth in all treatments
and co-limitation of P and K in the high N treatments. In the second year of the experiment, several containers suffered from
a severe fungal infection, particularly affecting the ‘wet’ species and the high N treatment. Our findings suggest that global
change can have negative consequences for the production of Sphagnum species in bogs, with important implications for the carbon sequestration in these ecosystems. 相似文献