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1.
Massimiliano Scalici Stefania Chiesa Stefano Scuderi Deborah Celauro Giancarlo Gibertini 《Biological invasions》2010,12(5):1415-1425
In 2006 an unusual find of Procambarus clarkii, today considered one of the most dangerous exotic crayfish, was made within the preserved brackish Mediterranean biotope
“Palude di Torre Flavia” (Rome, Italy). Here the investigation on the population structure and dynamics of P. clarkii inhabiting this brackish wetland is presented in an attempt to describe the life history pattern in this type of habitat.
The present study showed that this species has a lower growth rate and higher longevity than other studied European P. clarkii populations, and that it can damage brackish habitats and human livelihoods. The main results of this study chiefly concern
the differences found between several life-history parameters of the studied population and those obtained in previous studies.
These results showed the high ecological plasticity of P. clarkii, indicate the need to intervene before the species spreads further in brackish water, for the conservation of Mediterranean
coastal habitats. 相似文献
2.
Overwintering population of Cercopagis is represented by resting eggs which hatch generally in May. Although representatives of the first parthenogenetic generation
(the spring form individuals) differ morphologically from individuals of the subsequent generations (the summer form individuals)
and could be keyed to a separate species – Cercopagis (Apagis) ossiani – our analysis confirm that there is only one Cercopagis species in the Gulf of Riga: Cercopagis pengoi. Notable seasonal dynamics was observed for the gamogenetic mode of reproduction, being strongly associated with the total
population density. Gamogenetic females develop since the end of June and reach the maximum absolute abundance in July whereas
their proportion is generally the highest in fall. The gamogenetic absolute fecundity drops to the lowest level late July
but increased afterwards until the late August. One resting egg was, an average, found in 45.4%, two in 53.4% and three in
1.2% of females. Parthenogenetic fecundity was significantly higher in May–June compared to other months studied. Brood pouch
of parthenogenetic females was found to contain 11.6 ± 1.0 and 10.2 ± 0.3 embryos in the spring and summer form individuals,
respectively. Variation in the two modes of reproduction and fecundity is probably solely not controlled by temperature, but
also by food availability and population density. 相似文献
3.
Zhensheng Liu Xiaoming Wang Liwei Teng Duoying Cui Xinqing Li 《Ecological Research》2008,23(2):393-400
The monitoring of animal populations is necessary to conserve and manage the rare or harvest species and to understand the
population change over several years. We used distance sampling methods to estimate seasonal density of blue sheep in a 2,740 km2 area of Helan Mountain region by walking along 32 transect lines from winter 2003 to autumn 2005. In all, 367–780 blue sheep
were observed in 91–143 groups in the surveys during the seasons. Observed mean group size ranged from 3.42 to 8.35 individuals;
encounter rate, the number of groups detected per kilometre, varied from 0.19 to 0.30 during the seasons. A hazard rate key
function with cosine series expansion and a half-normal key function with either cosine or simple polynomial series expansion
were the best fitting models based on the lowest value of Akaike’s information criterion (AIC). Density estimates varied between
3.627 sheep per square kilometre in spring 2004 and 4.635 per square kilometre in summer 2005. There were no detectable differences
in estimated density among seasons (P = 0.887). The estimated density of blue sheep was negatively correlated with the total number of deaths (P < 0.05), number of sub-adult males’ deaths (P < 0.05), number of sub-adult females’ deaths (P < 0.05), and number of male lambs’ deaths (P < 0.05). We concluded that distance sampling surveys should be used to monitor long-term population trends to provide the
best quantitative estimates of blue sheep populations in the Helan Mountains region. 相似文献
4.
In this paper we addressed the phylogeographical genetic structure of the economically important red shrimp, Aristeus
antennatus (Crustacea, Aristeidae) in the Western Mediterranean. Partial mitochondrial regions of the cytochrome c oxidase subunit I
(514 bp) and ribosomal 16S subunit (547 bp) were sequenced in 137 individuals collected at three localities: Catalan Sea,
Ligurian Sea and the southern Tyrrhenian Sea. Values of haplotypic diversity were h = 0.552–0.724, whereas those for nucleotide diversity were π = 0.0012–0.0026. Among-sample genetic diversity was not significant and no geographical patterns in the distribution of haplotypes
were apparent. Results of the present study are consistent with a past population expansion that occurred <2,000 years ago.
Despite the current fishing pressure, genetic variability appears to be sufficiently high to keep A. antennatus populations stable over time. Dispersal-related life history traits may account for the shallow genetic structure. Our results
are not in contrast with the hypothesis of sustainability of Western Mediterranean red shrimp fisheries predicted on the basis
of previously obtained biological results. 相似文献
5.
Francesca Marini Simone Ceccobelli Corrado Battisti 《Wetlands Ecology and Management》2011,19(2):159-164
Following an apparent increase of local population density of coypu (Myocastor coypus) in a Mediterranean remnant wetland, we developed a pilot study aimed to evaluate a specific control program. Inside the
study area, we performed three transects per month from August 2008 to July 2009, grouping data in bimonthly periods. The
water level in the study area showed a maximum in December–January, significantly decreasing from late spring to summer and
significantly increasing from late summer to winter. Sampled individuals mainly occurred in Phragmites reed beds and in rush beds (dominance of Carex sp., Juncus sp. Bolboschoenus sp.). The index of mean relative density of coypu individuals ranged between 1.40 (February–March) and 5.72 (October–November)
with an evident increase in late summer–autumn. During this period, mean density of runways was higher in reed beds than in
rush beds, with differences tending to significance. In summer, the network of channels in reed beds, locally used for fishery
farm, may maintain a water level suitable for the coypu. These results (preference for reed beds and increase of coypu density
in late summer–autumn) should be considered when coypu populations are under control program, at least in the Mediterranean
region where there is a scarcity of available data. 相似文献
6.
Habitat degradation led to local extinction of the San Francisco forktail damselfly (Ischnura gemina) in Glen Canyon Park, San Francisco, California. In this study, we reintroduced I. gemina into Glen Canyon after the damselfly’s habitat was restored. Upon release, we carried out a mark- release-recapture study
to monitor the damselfly’s population dynamics. Our data were compared to two “baseline” studies on I. gemina, conducted in the park prior to the damselfly’s demise. Our recapture rates were significantly lower than the prior studies
due to a large initial decline in marked individuals upon release. Despite a lower recapture rate, the reintroduction was
initially successful since the damselflies reproduced throughout the summer and the following year. However, the population
failed to persist during the second year when the habitat became degraded with excess vegetation. Future success is contingent
on the continual management and upkeep of the habitat. 相似文献
7.
C. G. Di Camillo M. Coppari I. Bartolucci M. Bo F. Betti M. Bertolino B. Calcinai C. Cerrano G. De Grandis G. Bavestrello 《Hydrobiologia》2012,687(1):299-313
Most works concerning growth and reproduction of Mediterranean sponges have been performed in the oligotrophic western Mediterranean
while little is known about sponge dynamics in the North-western Adriatic Sea, a basin characterized by low winter temperature
and eutrophy. In order to deepen our understanding of sponges in the North Adriatic Sea and verify how its peculiar trophic
and physical conditions affect sponge life cycles, temporal trend of sponge cover (%) and reproductive timing of Chondrosia reniformis and Tedania (Tedania) anhelans were studied over a 1-year period looking for a possible relation with variations of temperature or food availability. In
C. reniformis, although little variations of sponge cover were evidenced around the year, the number of individuals and their size increase
during spring. Asexual reproduction, via drop-like propagules, mainly occurs in spring and summer, while sexual reproduction is characterized by a maximum number
of oocytes in August. T. anhelans progressively grows from spring to summer and develops propagules on its surface that reach their maximum size in July. In
autumn, the sponge undergoes a process of progressive shrinkage and almost disappears in winter when temperature reaches 7–8°C.
Larvae occur during summer. In the North Adriatic Sea sponges have larger sizes, higher density and a wider period of oocytes
production compared with the same species from the Mediterranean Sea, suggesting these differences could be due to high food
availability characterizing the eutrophic Adriatic basin. On the contrary, the sharp water temperature variations and the
very low winter temperature, 5–6°C lower than what has been reported for the Mediterranean Sea, regulate temporal variations
in abundance and cause the disappearance of thermophile species during winter. 相似文献
8.
During three cruises, carried out in March 1991, October 1991, and January 1992 off the Iberian Peninsula and Morocco, the
abundant calanoid copepodCalanus helgolandicus (Claus) was collected from a depth of 1000 m to the surface. Differences in depth preference were correlated with the life
stage and geographically differing vertical salinity structures. In autumn and winter, only stage V copepodids (CV) and adults
were found, in spring also younger copepodid stages. Within the range of the Mediterranean outflow water (MOW), a sharp decline
of abundances of all stages was evident during all cruises. In autumn 1991, the bulk of the population was recorded south
of the MOW, in winter 1992 north of it. During winter, numbers had declined by 70%, supporting the idea that winter individuals
represent the same generation as was encountered in autumn, and that they had been transported northwards. CV stages preferred
the depth layer 400–800 m, in autumn and winter. Adults were found in autumn at the same depth south of the MOW, while they
preferred the 0–400 m layers north of it. In winter, the abundance of adults increased, males preferred the 400–600 m depth
layer, while females stayed at 200–400 m. In spring 1991, stages younger than CV were found in high densities, all stages
concentrating in the upper 200 m. During the crosslope survey in spring off Portugal, an absolute abundance maximum of females
was found. In contrast, offshore densities were very low. On the basis of these findings, the hypothesis of a Mediterranean
centre of distribution and dispersal into the Atlantic is questioned. It is suggested that a separate, reproductively active
population ofC. helgolandicus exists off NW. Africa. 相似文献
9.
Aphanomyces astaci (Saprolegniales, Oomycetes) is classified among the 100 world’s worst invasive species. This species is endemic to North
America and has been introduced into Europe by imports of their hosts, the North American crayfish species. As a consequence,
extensive mass mortalities involved several populations of the European crayfish. Here, we checked its occurrence in four
Italian populations of Procambarus clarkii, the most widespread alien crayfish in Italy. Digital image analyses and image processing techniques were used to select
micro-melanized areas in the subabdominal cuticle of 2–10 crayfish per population. All the selected areas tested positive
for A. astaci ITS nrDNA specific primers; moreover, the obtained sequences clearly corresponded to A. astaci, thus revealing that P. clarkii is an active carrier of this oomycete in Italy. Decisions are to be urgently made to control the spread of both P. clarkii and A. astaci for the conservation of the indigenous crayfish biodiversity. 相似文献
10.
Maren Huck Marcelo Rotundo Eduardo Fernandez-Duque 《International journal of primatology》2011,32(5):1133-1152
Life history predicts that in sexually dimorphic species in which males are the larger sex, males should reach sexual maturity
later than females (or vice versa if females are the larger sex). The corresponding prediction that in sexually monomorphic
species maturational rates will differ little between the sexes has rarely been tested. We report here sex differences in
growth and development to adulthood for 70 female and 69 male wild owl monkeys (Aotus azarai). In addition, using evidence from natal dispersal and first reproduction (mean: 74 mo) for 7 individuals of known age, we
assigned ages to categories: infant, 0–6 mo; juvenile, 6.1–24 mo; subadult, 24.1–48 mo; adult >48 mo. We compared von Bertalanffy
growth curves and growth rates derived from linear piecewise regressions for juvenile and subadult females and males. Growth
rates did not differ between the sexes, although juvenile females were slightly longer than males. Females reached maximum
maxillary canine height at ca. 2 yr, about a year earlier than males, and females’ maxillary canines were shorter than males’. Thus apart from canine eruption
and possibly crown–rump length, the development of Azara’s owl monkeys conforms to the prediction by life history that in
monomorphic species the sexes should develop at similar paces. 相似文献
11.
Moleón M Sánchez-Zapata JA Gil-Sánchez JM Ballesteros-Duperón E Barea-Azcón JM Virgós E 《Oecologia》2012,168(3):679-689
How predators impact on prey population dynamics is still an unsolved issue for most wild predator–prey communities. When
considering vertebrates, important concerns constrain a comprehensive understanding of the functioning of predator–prey relationships
worldwide; e.g. studies simultaneously quantifying ‘functional’ and ‘numerical responses’ (i.e., the ‘total response’) are
rare. The functional, the numerical, and the resulting total response (i.e., how the predator per capita intake, the population
of predators and the total of prey eaten by the total predators vary with prey densities) are fundamental as they reveal the
predator’s ability to regulate prey population dynamics. Here, we used a multi-spatio-temporal scale approach to simultaneously
explore the functional and numerical responses of a territorial predator (Bonelli’s eagle Hieraaetus fasciatus) to its two main prey species (the rabbit Oryctolagus cuniculus and the red-legged partridge Alectoris rufa) during the breeding period in a Mediterranean system of south Spain. Bonelli’s eagle responded functionally, but not numerically,
to rabbit/partridge density changes. Type II, non-regulatory, functional responses (typical of specialist predators) offered
the best fitting models for both prey. In the absence of a numerical response, Bonelli’s eagle role as a regulating factor
of rabbit and partridge populations seems to be weak in our study area. Simple (prey density-dependent) functional response
models may well describe the short-term variation in a territorial predator’s consumption rate in complex ecosystems. 相似文献
12.
Ecklonia maxima is an economically important kelp in South Africa. The harvested kelp is used mainly as feed for cultured Haliotis midae (abalone) on farms all along the South African South and West Coast. The effects that different harvesting methods have on the growth of sub-canopy kelps, kelp population structure and kelp recruitment were tested in a kelp bed at Bordjies Rif near Cape Town. Two 30 × 10 m sites were set up, about 100 m apart, in near monoculture stands of E. maxima. Each 30×10 m area was subdivided into three treatments. In treatment 1 (T1) the whole ‘head’ of each kelp sporophyte that reached the surface was cut off between the bulb and the primary blade (‘lethal’ method). In treatment 2 (T2) (‘non-lethal’ method), the secondary fronds of all sporophytes that reached the surface were cut 20–30 cm from their junction with the primary blade, and removed. In the control plot, the kelp plants were not treated. Harvesting treatments were done approximately every four months, at low spring tide, from 3 March 2003 to 3 November 2003 (three treatments). The effects of harvesting on the kelps depend largely on the size of plant and the time the fronds were removed; however, no seasonal pattern could be observed. The different treatments had no effect on the growth rate, population structure or recruitment of the kelp. This means that factors other than light play an important role in the growth, structure and recruitment of the kelp beds in False Bay. Results are discussed in relation to current commercial harvesting practices. 相似文献
13.
Castanea squinii Dode, an endemic tree widely distributed in China, plays an important role both in chestnut breeding and forest ecosystem
function. The spatial genetic structure within and among populations is an important part of the evolutionary and ecological
genetic dynamics of natural populations, and can provide insights into effective conservation of genetic resources. In the
present study, the spatial genetic structure of a panmictic natural population of C. sequinii in the Dabie Mountain region was investigated using microsatellite markers. Nine prescreened microsatellite loci generated
29–33 alleles each, and were used for spatial autocorrelation analysis. Based on Moran’s I coefficient, a panmictic population of C. sequinii in the Dabie Mountain region was found to be lacking a spatial genetic structure. These results suggest that a high pollen-mediated
gene flow among subpopulations counteract genetic drift and/or genetic differentiation and plays an important role in maintaining
a random and panmictic population structure in C. sequinii populations. Further, a spatial genetic structure was detected in each subpopulation’s scale (0.228 km), with all three subpopulations
showing significant fine-scale structure. The genetic variation was found to be nonrandomly distributed within 61 m in each
subpopulation (Moran’s I positive values). Although Moran’s I values varied among the different subpopulations, Moran’s I in all the three subpopulations reached the expected values with an increase in distances, suggesting a generally patchy
distribution in the subpopulations. The fine-scale structure seems to reflect restricted seed dispersal and microenvironment
selection in C. sequinii. These results have important implications for understanding the evolutionary history and ecological process of the natural
population of C. sequinii and provide baseline data for formulating a conservation strategy of Castanea species.
__________
Translated from Acta Phytoecologica Sinica, 2006, 30(1): 147–156 [译自: 植物生态学报] 相似文献
14.
Monthly variations in the somatic indexes and energetic content of organs were investigated in Loxechinus albus from the Beagle Channel. Samples were collected monthly from May 2004 to May 2005. Lantern and test indexes did not vary
significantly. A major peak of gonad index (GI) was observed in winter (sexual maturation period), with a strong declination
in November suggesting a spawning period in spring. In coincidence a shortening of feeding activities was expressed by the
lower values of gut index (Gut I), suggesting that the gut is a storage organ. The values of gonad energetic content (GEC)
and total gonad energetic content (TGEC) showed minimum values in winter (ripe stage) and the maximum in spring (spawned stage).
The TGEC reached higher monthly average values (50–200 kJ) than total gut energetic content (TGuEC) (20–40 kJ). These differences
indicate that the gonads constitute the most important store organs in L. albus. Moreover, organic stores are built up in the gonads after spawning, and then utilized during gamete production. 相似文献
15.
Grant WS 《Genetica》2005,125(2-3):293-309
Genetic architectures of marine fishes are generally shallow because of the large potential for gene flow in the sea. European
anchovy, however, are unusual among small pelagic fishes in showing large differences among sub-basins and in harbouring two
mtDNA phylogroups (‘A’ & ‘B’), representing 1.1–1.85 million years of separation. Here the mtDNA RFLP dataset of Magoulas
et al. [1996, Mol. Biol. Evol. 13: 178–190] is re-examined to assess population models accounting for this subdivided population
structure and to evaluate the zoogeographical origins of the two major phylogroups. Haplotype and nucleotide diversities are
highest in the Ionian Sea and lowest in the Aegean and Black seas. However, this gradient is absent when ‘A’ and ‘B’ haplotypes
are examined separately. Neither the self-sustaining nor the basin population models adequately describe anchovy population
behaviour. Tests for neutrality, mismatch and nested clade analyses are concordant in depicting recent expansions of both
phylogroups. Unimodel mismatch distributions and haplotype coalescences dating to the last (Eemian) interglacial (‘B’) and
the Weichselian pleniglacial period (‘A’) indicate separate colonizations of the Mediterranean Basin. Phylogroup ‘A’ is unlikely
to have arisen through continuous long-term isolation in the Black Sea because of climate extremes from displaced subpolar
weather systems during the ice ages. Ancestors of both groups appear to have colonized the Mediterranean from the Atlantic
in the late Pleistocene. Hence, zoogeographic models of anchovy in the Mediterranean must also include the eastern (and possibly
southern) Atlantic. 相似文献
16.
M. G. Giacobbe A. Penna E. Gangemi M. Masò E. Garcés S. Fraga I. Bravo F. Azzaro N. Penna 《Hydrobiologia》2007,580(1):125-133
Summer outbreaks of the dinoflagellate Alexandrium taylorii Balech are recurrent events in nearshore waters of Sicily (Italy)—a central region in the Mediterranean Sea—producing dense
yellowish–green patches. Beyond the local phenomenon, the problem covers a broader geographic scale, involving also other
European localities, mostly in Spain.
Biological, environmental, and molecular data are reported here from a semi-closed bay of Sicily (Vulcano Island, Tyrrhenian
Sea, 2000–2003), showing in summer the recurrence of high-biomass blooms and events of water discolouration. Without underestimating
the setbacks to the tourism industry, the ecological impact of A. taylorii blooms may be important considering the high levels of biomass produced (West Bay, Vulcano: up to a magnitude order of 107 cells l−1, 50–180 μg-Chla l−1, June 2002 and 2003) and coincident conditions of oxygen supersaturation of the waters (130–170%). Trophic trends in the
Tyrrhenian site indicate high amounts of nutrients linked to the increased anthropogenic activity in summer, although recently
there has been an apparent shift of the marked eutrophic conditions towards a slighter eutrophy.
Genetic data on isolates of A. taylorii from the Mediterranean Sea are also discussed. Molecular analyses implied the sequencing of target rDNA regions (5.8S rDNA
and ITS regions) of several isolates from different Mediterranean localities, as well as the application of species-specific
PCR assays for rapid species identification in preserved field samples. The confirmation of the specific identity provided
new insights into the biogeography of this species and further evidence of the occurrence of A. taylorii in a number of Mediterranean localities, both in the western side (the Catalan coast of Spain) and the eastern area (Greece).
Analyses of the molecular diversity of geographically distinct isolates of A. taylorii from Italy, Spain, and Greece based on the 5.8S rDNA-ITS region sequences showed a high level of similarity, indicating the
existence of an unique Mediterranean population. 相似文献
17.
Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered tree in eastern China. Habitat destruction has resulted in fragmentation of remnant populations
and extinction of local populations. AFLP and cpDNA markers were used to determine the population structure of remnant populations
of B. wilsonii var. pubipetiolata. Moderate nuclear genomic diversity was found within each of the four remnant populations (H
S = 0.141–0.172), while the cpDNA haplotype diversity in each population ranged from 0.356 to 0.681. Six haplotypes were identified
by a combined cpRFLP and cpSSR analysis in a total of 89 individuals. AMOVA revealed significantly AFLP genetic differentiation
within and between regions (ΦSC = 0.196, ΦCT = 0.396, respectively), and a high cpDNA haplotype differentiation between regions (ΦCT = 0.849). The results suggest low gene flow between populations of B. wilsonii var. pubipetiolata. Strong genetic divergence between two regional populations as revealed by both AFLP and cpDNA markers provided convincing
evidence that two distinct evolutionary lineages existed, and should be recognized as ‘evolutionary significant units’ (ESUs)
for conservation concerns. 相似文献
18.
The aim of this work is to provide an account of alien species richness and composition in a remnant Mediterranean coastal
wetland of Central Italy. Data were obtained from different taxa-specific methods, in 2001–2005 (terrestrial vertebrates)
and in 2005 (fish, arthropoda, mollusca).
Among the 353 species sampled, 17 (4.8 %) are aliens (7.1% if we consider only vertebrates).Data on abundance, introduction
type and status of alien species are reported. A crustacean, Procambarus clarkii, a fish, Gambusia sp. and three rodents, Myocastor coypus, Rattus norvegicus and Mus domesticus are the naturalized invasive species that locally could constitute a threat on economic and ecological levels. Data on Agapornis nigrigenis and Quelea cardinalis represent the first records for Italy. We also report evidence of a food chain on three levels, among the most invasive species
(predation of Gambusia sp. by Procambarus clarkii and of Rattus norvegicus on Procambarus clarkii).
相似文献
19.
During vegetative period 2004–2005 powdery mildew (Erysiphe graminis DC. f. sp. hordei Em. Marchal) field resistance of spring barley cultivars was investigated at the Lithuanian Institute of Agriculture. The
spring barley genotypes tested were Lithuania-registered cultivars, cultivars from genetic resources collection, and the new
cultivars used for initial breeding. In total, 23 resistance genes were present in the 84 cultivars studied. Among mono-genes
only mlo and 1-B-53 showed very high resistance. Slight powdery mildew necroses (up to 3 scores) formed on cultivars possessing these genes.
The maximal powdery mildew (PM) severity reached a score of 8.5 and the area under disease progress curve (AUDPC) a value
of 1216.8. The cultivars ‘Primus’, ‘Astoria’, ‘Power’, ‘Harrington’ and ‘Scarlett’ were the most resistant among the non mlo cultivars. Severity of PM on ‘Primus’ reached a score of 3.5 (3.0 of PM necrosis) in average, the other cultivars were diseased
from 4.5 (3.0) to 5.0 (2.0). The AUDPC values for these cultivars except ‘Scarlett’ were the lowest (85.0–145.3) among the
other cultivars. The highest contrast in development of the other leaf diseases was between highly resistant and susceptible
to PM cultivar groups. The fast development of PM depressed development of the other diseases 4.7 times. 相似文献
20.
Elements of the biology and ecology of A. robiniae were studied in Poland during the period of 2008–2009. The term of spring hatching, number of generations per season, developmental
time of particular generations, lifespan of specimens and fecundity of particular generations were all defined. The dynamics
of the species’ occurrence on its host plant were also determined. The two-year study showed a maximum of 11 aphid generations
can develop on Robinia pseudoacacia. Females of the second and third generations were found to be the most fertile. These findings indicate that the species
has adapted well in Poland and its biological predispositions have enabled it to rapidly increase in population. 相似文献