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1.
A. F. Budd 《Coral reefs (Online)》2000,19(1):25-35
Occurrences of reef corals are examined at Caribbean fossil localities to determine how biodiversity has changed within the
region over the past 50 million years. Analyses of 294 species (66 genera) at 58 fossil localities show that Caribbean generic
diversity rose to 44 between 50–22 Ma, ranged from 32–39 between 22–2 Ma, and dropped to 25 afterwards. Regional species diversity
was high at 40–36 Ma, 28–22 Ma, and 5–2 Ma. Origination rates were elevated throughout each high diversity interval, but extinction
was concentrated near the end of each interval. Regional highs of origination and extinction, therefore, differed in timing
and duration, causing the observed regional diversity increases during the three remarkably long intervals of turnover. Highs
of generic origination decreased in magnitude as immigration from the Mediterranean ceased, but speciation highs increased
in association with emergence of the Central American isthmus. Peaks of extinction coincided with regional changes in climate
and oceanic circulation.
Maximum species diversities within assemblages increased to 40–60 between 50–36 Ma, and have remained relatively constant
ever since. Assemblage compositions differed among localities having similar ages and environments, suggesting that the timing
and pattern of turnover varied across the region. Stable diversities but variable compositions within assemblages suggest
that dispersal and recruitment influenced the pattern of faunal change during turnover.
Accepted: 22 August 1999 相似文献
2.
We used canopy fogging to study the high (20–26 m), intermediate (13–19 m) and low (5–6 m) strata in three European beech
patches (Fagus sylvatica) in nine months (2005–2007) and estimate species richness and diversity of arboreal spiders. Eight species (10%) were previously
unseen in European beech trees, and one of these is likely a new species. Moreover, two species are on the Bavarian red list.
Our results revealed that the high stratum of the old-growth trees provided unique resources and possessed the greatest diversity
and evenness, whereas intermediate and low strata had high similarity in respect to diversity, dominance, species, and family
composition. Since the majority of beech forests consists of mature and young trees in Central Europe, and old-growth forests
are rarely preserved, we recommend young beech be used in a sampling protocol for rapid biodiversity assessment. However,
adding samples from the two higher strata to the lowest stratum (55 species), almost doubled the estimated species richness
(102 species). This suggests that the lower stratum alone does not represent a true image of the total canopy fauna inventory
in this, and likely other, beech stands. To complete this comprehensive inventory in European beeches, the Chao1 predicted
that additional sampling would be needed in the highest stratum, where there is a high probability to find previously undetected
species in a next survey. Our study clearly shows that neglecting the crowns of the largest, tallest trees risks underestimating
the overall spider diversity in Central European forests. 相似文献
3.
I. O. Kamayev 《Entomological Review》2012,92(4):471-485
Soil-dwelling and ground spiders were studied in oligotrophic and mesotrophic bog-forest ecotones of the northern taiga (Eastern Fennoscandia) in 2005–2007. The number of spider species was greater in the forest as compared to the bog. The spider assemblages of the bogs and swampy forests was characterized by the prevalence of Lycosidae both in abundance and in species richness, whereas members of the family Linyphiidae prevailed in the forest. The species diversity of soil-dwelling spiders was lower in oligotrophic bogs than in mesotrophic ones. In all the bog-forest ecotones studied, the spider assemblages showed no edge effect (an increase in diversity and abundance), indicating a high degree of interpenetration of the spider complexes from adjacent ecosystems. Stenotopic spider species were not found in the ecotones studied either. The major ecological factors responsible for the specific features of spider assemblages in the biotopes studied are the temperature regime and soil humidity. 相似文献
4.
It is well known that a predator has the potential to regulate a prey population only if the predator responds to increases in prey density and inflicts greater mortality rates. Predators may cause such density-dependent mortality depending on the nature of the functional and numerical responses. As spiders are usually faced with a shortage of prey, the killing behavior of the spider Nesticodes rufipes at varying densities of Musca domestica was examined here through laboratory functional response experiments where spiders were deprived of food for 5 (well-fed) or 20 days (hungry). An additional laboratory experiment was also carried out to assess handling time of spiders. The number of prey killed by spiders over 24- and 168-h periods of predator–prey interaction was recorded. Logistic regression analyses revealed the type II functional response for both well-fed and hungry spiders. We found that the lower predation of hungry spiders during the first hours of experimentation was offset later by an increase in predation (explained by estimated handling times), resulting in similarity of functional response curves for well-fed and hungry spiders. It was also observed that the higher number of prey killed by well-fed spiders over a 24-h period of spider–prey interaction probably occurred due to their greater weights than hungry spiders. We concluded that hungry spiders may be more voracious than well-fed spiders only over longer time periods, since hungry spiders may spend more time handling their first prey items than well-fed spiders. 相似文献
5.
Changes in soil macroarthropod communities in relation to forest maturation through three successional stages in the Canadian boreal forest 总被引:2,自引:0,他引:2
The edaphic macroarthropod communities of three sites representative of the forest succession in the Lake Duparquet region
(situated in the southern part of the boreal forest, Abitibi, Quebec, Canada) were studied. A 47-year-old deciduous forest,
a 144-year-old mixed forest, and a 231-year-old coniferous forest form a successional forest gradient with a vegetation composition
that is a function of the time elapsed since the last forest fire. Along with forest succession, there is a reduction in macroarthropod
community biodiversity. There is a negative gradient for mean total abundance (237–41 individuals), total richness (63–23
species), density (1792–661 individuals/m2), diversity (H′ = 1.478–1.007) and equitability (J = 0.821–0.739). These community changes affect saprophagous organisms more than predators. Certain species or taxa show preferences
for a particular forest type, such as larval Diptera for the deciduous forest. A comparison of these results with the literature
suggests an inverse preference as to habitat choice between microarthropods (Acarina and Collembola) and macroarthropods.
From a conservation point of view, macroarthropod biodiversity will be favored by the protection of all forest types since
each environment possesses a particular community structure and species.
Received: 17 April 1995 / Accepted: 1 April 1996 相似文献
6.
In this study α and β diversity patterns of five leaf litter arthropod groups (ants, predatory ants, oribatid mites, spiders
and other arachnids) were described and compared in 39 sampling patches of a transformed landscape in southwestern Colombia,
that represented five vegetation types: secondary forest, riparian forest, giant bamboo forest, pasture and sugarcane crop.
It was also assessed whether some taxa could be used as diversity surrogates. A total of 6,765 individuals grouped in 290
morphospecies were collected. Species richness in all groups was lower in highly transformed vegetation types (pasture, sugarcane
crop) than in native ones (forests). In contrast, there were no clear tendencies of β diversity among vegetation types. Considering
sampling patches, 0.1–42% of the variation in α diversity of one taxonomic group could be explained from the α diversity of
another, and 0.2–33% of the variation of β diversity of a given taxon was explained by that in other groups. Contrary to recent
findings, we concluded that patterns of α diversity are more congruent than patterns of β diversity. This fact could be attributed
to a sampling effect that promotes congruence in α diversity and to a lack of a clear regional ecological gradient that could
promote congruent patterns of β diversity. We did not find evidence for an ideal diversity surrogate although diversity patterns
of predatory ants had the greatest congruencies. These results support earlier multi-taxon evaluations in that conservation
planning should not be based on only one leaf litter arthropod group. 相似文献
7.
Trans-Himalayan mountains, owing to harsh climatic conditions and a short growing season support low vegetation cover (<20%),
yet it is known to harbour a unique assemblage of flora and fauna which have not been systematically inventoried and documented
so far. This paper deals with spatial and non-spatial information on landscape units, vegetation characteristics and plant
species diversity of Nubra Valley in Ladakh, India. Based on digital – visual (on screen) interpretation of remote sensing
data coupled with knowledge-based classification we delineated 19 cover classes (11 vegetation types and 8 non-vegetation
categories). The vascular plants (angiosperms and gymnosperms) were systematically collected using stratified random sampling
of different landscape/vegetation to characterize plant communities and assess the distribution patterns of species. The study
reveals that nearly 78–80% of plant species in Nubra are restricted to the valley bottoms. In all, 414 species of vascular
plants were recorded from the study area. These belongs to 56 families and 202 genera. Of these, 102 species were reported
to be used in traditional system of medicine by Amchis over 80 species are largely associated with cultivated fields and human
habitation. As many as 49 species were cultivated which include several varieties of crop plants especially those of barley
and buckwheat. Aspects of bioprospecting and conservation of valuable species have been discussed. 相似文献
8.
The effects of immission load on spiders living on black pine (Pinus nigra Arnold) were studied in a town in Western Hungary. In three sampling periods, trunk-trap catches of spiders from black pine trees planted in a control urban area were compared with those from black pines planted in an area with high immission load. In the first two sampling periods – when apart from the exclusive dwellers on or under bark of the black pine, foliage-dwelling spiders overwintering under the bark (facultative bark-dwellers) could also be trapped – the species richness and the Shannon diversity were significantly higher in the control area than in the area highly affected by immission. In these sampling periods, the composition of spider assemblages also significantly differed in the studied areas. In the third sampling period – when only the exclusive bark-dwellers could be trapped because facultative bark-dwelling spiders returned to the foliage after the overwintering – the species richness, Shannon diversity and the composition of spider assemblages were similar in the differently affected areas. Our results suggest that spiders living exclusively on or under the bark are not significantly influenced by immission load, while foliage-dwellers are sensitive to immission. Indicator species analysis also proved the clear classification of the responses of spiders to immission load. The probable direct and indirect effects of immission, causing differences in the species richness, diversity and the composition of spider assemblages, are also discussed. 相似文献
9.
Patterns in species richness,species density,and evenness in groundfish assemblages on the continental slope of the U.S. Pacific coast 总被引:1,自引:0,他引:1
Nick Tolimieri 《Environmental Biology of Fishes》2007,78(3):241-256
For many taxa, diversity, often measured as species richness, decreases with latitude. In this report patterns of diversity
(species richness, species diversity, and evenness) in groundfish assemblages were investigated in relation to depth (200–1200 m)
and latitude (33–47°N) on the continental slope of the U.S. Pacific coast. The data originated from the 1999–2002 upper continental
slope groundfish surveys conducted by the National Marine Fisheries Service. When the data were pooled across depths, species
density and evenness were found to decline with latitude. All three diversity measures declined with depth, with the lowest
overall diversity in the 600- to 900-m depth range where longspine thornyhead Sebastolobus altivelis constituted close to 70% of the catch. When latitudinal gradients were examined within four depth zones (200–300 m, 400–500 m,
600–900 m, and 1000–1200 m) more complex patterns emerged. At depth species richness and evenness were inversely correlated
with latitude as longspine thornyhead dominated catches to the north. However, in shallower areas of the slope, species richness
and evenness were positively correlated with latitude. Latitudinal patterns of diversity in the deeper zones and when pooled
across depths were positively correlated with temperature and broadly consistent with the Ambient Energy hypothesis discussed
by Willig et al. [Annu Rev Ecol System 34:273–309 (2003)]. 相似文献
10.
K. R. Jumbam J. S. Terblanche J. A. Deere M. J. Somers S. L. Chown 《Polar Biology》2008,31(2):215-220
Despite the relative richness of spider species across the Southern Ocean islands remarkably little information is available
on their biology. Here, the critical thermal limits of an indigenous (Myro kerguelenensis, Desidae) and an introduced (Prinerigone vagans, Linyphiidae) spider species from Marion Island were studied after 7–8 days acclimation to 0, 5, 10 and 15°C. Critical thermal
minima (CTMin) were low in these species by comparison with other spiders and insects measured to date, and ranged from −6 to −7°C in M. kerguelenensis and from −7 to −8°C in P. vagans. In contrast, critical thermal maxima (CTMax) were similar to other insects on Marion Island (M. kerguelenensis: 35.0–35.6°C; P. vagans: 35.1–36.0°C), although significantly lower than those reported for other spider species in the literature. The magnitude
of acclimation responses in CTMax was lower than those in CTMin for both species and this suggests decoupled responses to acclimation. Whilst not conclusive, the results raise several important
considerations: that oxygen limitation of thermal tolerance needs to be more widely investigated in terrestrial species, that
indigenous and alien species might differ in the nature and extent of their plasticity, and that upper and lower thermal tolerance
limits might be decoupled in spiders as is the case in insects. 相似文献
11.
Kristjan Zobel 《Evolutionary ecology》2008,22(3):487-492
Although sexuality is considered evolutionarily progressive, clonality is very common in plants and the prevailing means of
reproduction in several community types. I discuss what could be the forces that have influenced the selection among sexual
versus non-sexual reproduction at community level. I propose that, among others, the probability of self-competition must
have been one of the key factors. The probability of meeting one’s own genes for wasteful competition is higher in communities
where clonality prevails (and relatively high mean intra-species relatedness is expected), and higher in communities with
low species diversity. On the other hand, lower diversity indicates a higher average fitness of species since the (finite)
total pool of resources is distributed among fewer population with high density. I show, using four community types with contrasting
diversity and clonality that community fitness (average fitness in the assemblage of species) can be expressed as the product
of two variables––anti-diversity and degree of sexuality. 相似文献
12.
Kunio Sasaki 《Ichthyological Research》1992,39(3):191-199
Two new species of the sciaenid genusJohnius (Johnius) are described:J. trewavasae from Taiwan, Hong Kong, and Singapore, differs from all other congeners in having 24–27 dorsal soft rays, 5–6 scales above
and 7–10 scales below the lateral line, 6–8 obtuse lower gill rakers, the last pleural rib on the 11th vertebra, and a shorter
lower jaw (33.8–38.4% HL);J. latifrons from Thailand and Java is characterized by 25–29 dorsal soft rays, 7–9 scales above and 11–14 scales below the lateral line,
7–9 obtuse lower gill rakers, a wide interorbital width (26.1–30.6% HL), a small eye (16.7–26.4% HL), and a short, second
anal spine (25.9–37.1% HL). Two related species,J. heterolepis Bleeker from “Suriname” andJ. cantori Bleeker from Malaya, are resurrected as valid West Pacific species of Johnius (Johnius). 相似文献
13.
14.
Rotational fallows as overwintering habitat for grassland arthropods: the case of spiders in fen meadows 总被引:1,自引:0,他引:1
Martin H. Schmidt Sabine Rocker Jamal Hanafi Andreas Gigon 《Biodiversity and Conservation》2008,17(12):3003-3012
Regular mowing of grassland is often necessary for plant conservation, but uncut vegetation is needed by many arthropods for
overwintering. This may lead to conflicting management strategies for plant and arthropod conservation. Rotational fallows
are a possible solution. They provide a spatio-temporal mosaic of mown and unmown areas that may combine benefits to both
plants and arthropods. We tested if rotational fallows enhance spider overwintering in fen meadows. Rotational fallows consisted
of three adjoining strips 10 m wide and 35–50 m long. Each year, one of these strips was left unmown (fallow) in an alternating
manner so that each strip was mown two out of three years. Spiders were sampled during spring with emergence traps in nine
pairs of currently unmown fallow strips and completely mown reference plots. Fallows significantly enhanced orb-weavers (Araneidae),
sac spiders (Clubionidae) and ground spiders (Gnaphosidae). However, only 4.7% of the total variation in community composition
was attributable to fallows. Community variation was larger between landscapes (34.5%) and sites (38.2%). Also β diversity
was much higher between landscapes (45 species) and sites (22 species) than between fallows and mown reference plots (10 species).
We conclude that the first priority for spider conservation is to preserve as many fen meadows in different landscapes as
possible. Locally, rotational fallows enhance overwintering of the above-mentioned spider families, which are sensitive to
mowing in other grassland types as well. Thus, rotational fallows would probably foster spider conservation in a wide range
of situations. However, stronger effects can be expected from larger and/or older fallow areas. 相似文献
15.
Recognizing and understanding present-day biodiversity and biogeographical patterns and how these relate to contemporary and
past climate is pivotal to predict the effect of future climate on marine biodiversity and promote adequate conservation policies.
Sponges constitute an important and dominant component of the marine benthos and are therefore an excellent model group for
such investigations. In this study, we assessed the diversity patterns and the zoogeographical affinities of the Northeast
Atlantic and Mediterranean shallow-water demosponge assemblages. Data on the distribution of 745 species throughout 28 areas
was compiled from the literature and used to build a presence/absence matrix. Diversity patterns were assessed from estimates
of species richness (S) and taxonomic distinctness (AvTD). The Mediterranean Sea proved to be more diverse both in terms of species richness and
taxonomic distinctness (S = 539, AvTD = 94.74) than the Northeast Atlantic (S = 480, AvTD = 92.42) and the two regions together were found to constitute a diversity hotspot harbouring approximately 11%
of the global demosponge diversity. We found an Atlantic N–S and a Mediterranean NW–SE gradient of increasing taxonomic distinctness
that is strongly correlated to both contemporary (R
2 = 0.5667; P < 0.01) and historical values (R
2 = 0.7287; P < 0.01) of sea surface temperature (SST) at the Last Glacial Maximum (LGM). The zoogeographical affinities examined through
classification (cluster analysis) and ordination (non-metric multidimensional scaling, nMDS) based on the Bray–Curtis similarity
index, revealed the presence of three groups approximately corresponding to the Northern European Seas, Lusitanian and Mediterranean
provinces outlined in the ‘Marine Ecoregions of the World’ (MEOW) classification system. Geographical distance and oceanographic
circulation were shown to constitute important factors in shaping the zoogeographical affinities among areas. The vast majority
of the species occurring in the Northeast Atlantic and the Mediterranean (67 and 57%, respectively) was shown to have extremely
restricted geographical ranges, as single-area or narrow-range (2–3 areas) endemics, which raises some concerns regarding
their conservation. 相似文献
16.
Sandra C. Müller Gerhard E. Overbeck Jörg Pfadenhauer Valério D. Pillar 《Plant Ecology》2007,189(1):1-14
The study of plant functional types (PFTs) has been widely emphasized when analysing plant community changes in relation to
variations in climate and disturbance regime. In this study, we search for PFTs of woody species near forest–grassland boundaries
in South Brazil where, due to climate, forests tend to expand over grassland but are being restricted by frequent fires. We
aimed at answering the questions: (i) which plant functional types of forest woody species can establish in adjacent grassland
subject to fire disturbance and (ii) which plant functional types of forest and grassland woody species are related to short-term
community dynamics in frequently burned grassland. Traits were assessed in woody plants in 156 plots (6.75 m2) arranged in 12 transects across forest–grassland boundaries with different fire history in their grassland part. The analysis
used a recursive algorithm to search for traits and PFTs maximally associated to spatial distance from forest limit in one
analysis, and elapsed time since last fire in another. As a result, nine PFTs of forest woody species were identified that
best described community patterns associated to distance from forest. Resprouting ability characterized forest plants able
to colonize grasslands. PFT diversity was higher in border plots than inside forest or grassland. Four PFTs of forest and
grassland woody species best described woody species community patterns in the grassland associated to elapsed time since
fire. Taller individuals of single-stemmed shrubs predominated in late post-fire recovery (3–4 years), while shorter multi-stemmed
shrubs in recently burned areas (3 months to 1 year). PFTs of forest trees occurred in border plots or, as established adults,
in grassland, remaining unaffected by fire. We conclude that easily measurable structural plant traits, such as those used
in our study, are sufficient to evaluate post-fire community dynamics. Forest PFTs in burned grassland are restricted to those
with resprouting ability to survive recurrent fire events. Establishment success is highest on protected sites with lesser
or low-intensity fire. 相似文献
17.
The Baltic Sea, a semi-enclosed brackish water region, has been inoculated by non-indigenous species for centuries. Today,
much of its biological diversity is of foreign origin (i.e. xenodiversity), intentionally or unintentionally moved by humans
over ecological and geographical barriers. As many as 98 introduced species have been recorded in the Baltic Sea and Kattegat.
The role and abundance of much of the unique native brackish water fauna of the Baltic Sea are threatened by these non-indigenous
species. The rate of primary introductions into the Baltic has increased since the 1950s; the secondary rate of spread of
non-indigenous species within the basin varies from 30–480 km/year. We review here the invasion histories of the brown alga
Sargassum muticum (introduced in the early 1990s), the mud snail Potamopyrgus antipodarum (1887), the barnacle Balanus improvisus (1844), the polychaetes Marenzelleria viridis (1985) and Polydora redeki (1963), the cladoceran Cercopagis pengoi (1992) and the mysid shrimp Hemimysis anomala (1962).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
The white-headed duck is a globally threatened species native to the Palaearctic with a range extending from Spain in the
west to the western edge of China in the east. Its populations have become fragmented and undergone major declines in recent
decades. To study genetic differences between populations across the range and change in genetic diversity over time, we sequenced
a portion of the mitochondrial DNA control region from 67 museum specimens (years 1861–1976) as well as 39 contemporary samples
from Spain and seven from Greece (years 1992–2003). In the historical sample, we found a lack of significant genetic structure
between populations in different areas. We found evidence that the species experienced a rapid expansion in the past, perhaps
from glacial refugia centred around the Mediterranean following the last ice age. In Spain, the population went through a
dramatic bottleneck in the 1970s and early 1980s, when only a few dozens individuals remained in the wild. Although population
size has since recovered to a few thousand individuals, we found a highly significant loss of mitochondrial haplotype diversity
between the historical and contemporary samples. Given ongoing declines in other areas, losses in genetic diversity that may
reduce the adaptive potential of white-headed ducks in the future are a continuing concern throughout the geographic range
of this species. 相似文献
19.
Plant species diversity and endemism demonstrate a definite trend along altitude. We analyzed the (i) pattern of tree diversity
and its endemic subset (ii) frequency distribution of altitudinal range and (iii) upper & lower distributional limits of each
tree species along altitudinal gradients in eastern Himalaya. The study was conducted in Subansiri district of Arunachal Pradesh.
Data on the tree species (cbh ≥ 15 cm) were gathered every 200 m steps between 200 m and 2200 m gradients. Tree diversity
demonstrated a greater variation along the gradients. A total of 336 species (of which 26 are endemic) were recorded belonging
to 185 genera and 78 families. The alpha diversity demonstrated a decreasing pattern with two maxima (i.e., elevational peaks)
along the gradients; one in 601–1000 m and the other in 1601–1800 m, corresponding to transition zones between tropical-subtropical
and subtropical-temperate forests. Pattern diversity revealed a narrow range along the gradients. Frequency of altitudinal
range was distributed between 1 and 41. Only one species (Altingia excelsa) showed widest amplitude, occurring over the entire range. Highest level of species turnover was found in 400–600 m step
at lower elevational limit whereas for upper elevational limit, the highest turn over was recorded between 800 and 1000 m.
Tree diversity decreased and its endemic subset increased along the gradients. Two maximas in tree diversity pattern correspond
to forest transition zones with subtropical-temperate transition is narrower than tropical-subtropical. The pattern observed
here could be attributed to varied microclimates or environmental heterogeneity. If altitudinal amplitude of a species is
considered as an aspect of its niche breadth, it is clear from these results that niche breadth in these organisms is in fact
independent of the diversity of the assemblage in which they occur. This analysis calls for detailed floristic studies to
determine the breadth of changes between adjacent forest types and details of local species richness in high diversity areas. 相似文献
20.
Although the number of studies focusing on the major histocompatibility complex (MHC) in non-model vertebrates is increasing,
results are often contradictory, and the structure of MHC is still poorly understood in wild species. Here, we describe the
structure and diversity of exon 3 of MHC class I in a passerine bird, the Scarlet Rosefinch (Carpodacus erythrinus). Using capillary electrophoresis single-strand conformation polymorphism, we identified 82 different MHC class I variants
in one Rosefinch population nesting at one site in the Czech Republic. Thus far, this is the highest intra-populational MHC
class I variation observed in birds. We have not found support for ‘minimal essential’ MHC in this species since individuals
exhibited between three and nine different exon 3 sequences, indicating that there may be at least five amplified MHC class
I genes. By cloning, we obtained and analysed 29 exon sequences and found that all of them could be translated into potentially
functional proteins. We also show that strong positive selection appears to be acting mainly, but not only, on previously
described antigen-binding sites in MHC class I genes. Furthermore, our results indicate that recombination has played an important
role in generating genetic diversity of these genes in the Scarlet Rosefinch; we discuss the significance of this extremely
high genetic diversity in light of the life history traits of this species, such as long-distance migration.
The sequence data described in this paper are accessible in GenBank data library under accession numbers FJ392762–FJ392790. 相似文献