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1.
Naufraga balearica is a caespitose member of the Umbelliferae and is endemic to Majorca. We conducted a 12-year study in which permanent plots were monitored (each plot was divided into 100 cells) to assess (1) the natural population dynamics, (2) goat herbivory (1998–2003) and (3) plant competition. Using photographs and a G-test of independence, we analysed the frequency of cells in which a species was present and, for each annual transition, the frequency of cells where the species was stable, decreased or increased for each species and treatment (plots open to herbivores vs. closed plots). The natural dynamics of this threatened species showed a clear decline at the study site. Dactylis glomerata and Erodium reichardii were the species that appeared to have the greatest effect on the presence of N. balearica, especially in the closed plots. The competition effect of neighbouring species was not homogeneous throughout the 11 annual transitions analysed, suggesting that other factors affect the dynamics of the threatened species. Some herbivory pressure is beneficial to N. balearica because the species fluctuates more in the opened plots and the behaviour of the goats helps to control competing species, permitting the establishment of N. balearica. 相似文献
2.
This study addressed the response of Naufraga balearica, a critically endangered plant endemic to Mallorca (Balearic Islands, western Mediterranean Basin), and its adjacent community to climatic factors by assessing whether climate influences plant cover in N. balearica, including oscillation associated with seasonality, and whether the accompanying species influences its response to climatic factors. The cover of N. balearica and two other accompanying species (Erodium reichardii and Dactylis glomerata) were estimated quarterly from permanent plots over 12 years. The original time series of plant cover and climatic variables were transformed to obtain a smoothed and a detrended time series. The tendency of all variables was assessed using a simple linear regression of the smoothed series. The relationship among plant cover and climatic variables were tested by correlation. Naufraga balearica showed a declining trend, while E. reichardii and D. glomerata experienced a stable and an increasing population trend, respectively. However, all species showed an annual cover oscillation with a similar pattern. A new bioclimatic index combining temperature and precipitation variables was a good predictor although extreme meteorological events substantially altered the trends and patterns of the three species. The response of N. balearica to climatic factors, including extreme weather events, is exacerbated by the presence of other species, mainly those grasses with caespitose growth form and with a faster response to the changing environmental factors. In a climate change scenario, N. balearica would be limited to the shadiest grass-free zones. The current situation emphasises the importance of taking conservation action to guarantee the species conservation. 相似文献
3.
W. Okera 《Journal of fish biology》1974,6(6):801-812
Sardinella gibbosa and Sardinella albella of Dar es Salaam coast were studied from January 1969 to March 1970. Measurements on the standard length, weight, body depth, length and width of the gonads were taken and qualitative assessments of fat coverage on the alimentary canal and maturation stages were made. New size-groups of both the species appeared in the lamp-fishery at c. 6 cm SL between October 1969 and February 1970 and the largest specimens caught were 14.1 and 12.9 cm SL for the first and second species respectively. Length-weight equations of the two species show higher values of the regression coefficients for the females compared to the males. Fat content of fishes > 10 cm SL was high during March to May and low during August to December 1969. First maturation and spawning are probably attained at c. 10.5 and 10 cm SL in the first and second species respectively. Mature S. gibbosa occurred between August and November 1969 and probably the species has a single, annual spawning season of 3.4 months duration. Mature S. albella, 10.1–12.5 cm SL occurred between August 1969 and February 1970; mature females, 12.6–12.9 cm SL were encountered throughout the sampling period. 相似文献
4.
J. G. Pajuelo J. Socorro J. A. González J. M. Lorenzo J. A. Pérez-Peñalvo I. Martínez C. M. Hernández-Cruz 《Zeitschrift fur angewandte Ichthyologie》2006,22(5):430-436
Red‐banded seabream Pagrus auriga (N = 615) were caught off the Canary Islands from January 2003 to December 2004. Total length ranged from 120 to 780 mm. The species was characterized by protogynous hermaphroditism. The male :female ratio was in favour of females (1 : 8.2). The reproductive season extended from September to February, with a peak in spawning activity in October–November. Fifty percentage maturity was reached at 387 mm total length by females and 533 mm by males. The length–weight relationship for all individuals was described by the parameters: a = 0.0086 and b = 3.014, when length is given in mm and weight in grams. Otolith age readings indicated that the population consists of 19 age groups, including a very high proportion of individuals between 0 and 7 years old. Growth analysis reveals that the species is slow‐growing and relatively long lived (18 years). The von Bertalanffy growth parameters for the entire population were: L∞ = 803 mm, k = 0.081 year−1 and t0 = −2.17 year. Growth differed between males and females. The instantaneous rate of natural mortality for all fish was: M = 0.164 year−1. 相似文献
5.
Sap flow variation in selected riparian woodland species in the Okavango Delta,Botswana 总被引:1,自引:0,他引:1
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In the tropical Okavango Delta, transpiration by trees is an important process partly responsible for maintaining the basin as a freshwater environment. Quantification of evapotranspiration from terrestrial landforms of the delta, fringed by riparian woodlands, is one of the main contributors to uncertainty in current hydrological modelling. We investigated sap flow of common trees in the distal, mid‐ and upper delta in July–August 2012, November–December 2012 and February–April 2013 using the compensation heat pulse velocity method. In the distal delta, four Diospyros mespiliformis individuals of different sizes were studied. Four trees of different species were studied in the mid‐ and upper delta. Sap flow density (SFD; flow per unit cross‐sectional area) was used as a common unit to facilitate comparison. Sap flow varied with tree size, species, season and location. It was positively correlated with tree size (r2 = 0.67). Sap flow variation between seasons and across locations in all the species studied indicated two distinct groups. Group 1 transpired the least during the hottest season, November–December, and Group 2 the most. In Group 1, the highest average SFD was 1.17 l cm?2 day?1 during July–August; in Group 2, it was 1.07 l cm?2 day?1 during November–December. Changes in the hydrology of the delta would negatively affect the riparian woodland. 相似文献
6.
Sequences from the ribosomal nuclear internal transcribed spacers (ITS) have been widely used to infer evolutionary hypotheses
across a broad range of living organisms. Intraspecific sequence variation is assumed to be absent or negliable in most species,
but few detailed studies have been conducted to assess the apportionment of ITS sequence variation within and between plant
populations. Buxus balearica was chosen as a model species to assess the levels of infraspecific and intragenomic ITS variation in rare and endangered
species occurring in disjunct populations around the Mediterranean basin. Intragenomic polymorphic sites were detected for
western and eastern accessions of B. balearica and in two accessions of the sister species B. sempervirens. Overall, 19 different ribotypes were found in B. balearica after sequencing 48 clones, whereas 15 ribotypes were detected in 19 clones of B. sempervirens. The integrity and secondary structure stability of the ribosomal sequences suggest that they are not pseudogenes. The high
number of ribotypes recovered through cloning suggested that some sequences could be chimeric or generated in vivo by partial
homogenization through gene conversion or unequal crossing-over. Average sequence divergence among B. balearica clones was 0.768%, and the most divergent sequences differed by 1.62%. Available evidence does not suggest that B. balearica paralogues have been obtained from other extant Buxus species through interspecific hybridization. The presence of several ribosomal sequences in box implies that the molecular forces
driving the concerted evolution of this multigene family are not fully operational in this genus. Phylogenetic analyses of
cloned ITS sequences from B. balearica displayed very poor resolution and only two clades received moderate bootstrap support. Despite the marked intragenomic sequence
divergence found, ribosomal data suggest a clear phylogeographic split in B. balearica between western and eastern accessions. The distinct, nonchimeric sequences that are postulated as being present in each
biogeographic group suggest that box populations from Anatolia (eastern Mediterranean) are relict.
[Reviewing Editor: Dr. Rafael Zardoya] 相似文献
7.
Juan Lorite Ana González-Robles Carlos Salazar-Mendías Julio Peñas 《Plant biosystems》2018,152(5):1109-1117
Moehringia. sect. Pseudomoehringia McNeill is endemic to the western Mediterranean, having its origin and diversification centre in the Iberian Peninsula and mountains of northern Morocco. Both the relationship with the genus Arenaria as well as the taxonomy within the section have been largely controversial. To disentangle these issues, we conducted a morphometric study using herbarium material. We measured 12 relevant morphological traits from 148 selected herbarium sheets. Data were analyzed using different statistical methods: general linear models, multiple factorial analysis and linear discriminant analysis. We found significant differences between Arenaria balearica and the rest of the genus Moehringia taxa. Within this genus, we identified three well-discriminated species: Moehringia fontqueri, M. glochidisperma and M. intricata. Within M. intricata complex, we discerned virtually no differences amongst most of the subspecies (intricata, giennensis and tejedensis) with the exception of subsp. castellana. We propose: (i) to maintain A. balearica separate from Moehringia sect. Pseudomoehringia; (ii) to consider three species in the section Pseudomoehringia: M. fontqueri, M. glochidisperma and M. intricata; (iii) to recognize only two subspecies within M. intricata complex: subsp. intricata and subsp. castellana. To clarify the taxonomy of this threatened group is of great interest because it might help to prioritize conservation measures. 相似文献
8.
Age and growth of Lestrolepis japonica (Aulopiformes: Paralepididae) in Kagoshima Bay,southern Japan
Age and growth of a paralepidid, Lestrolepis japonica, were determined from sagittal otoliths of specimens collected from April 2001 to February 2002 in Kagoshima Bay, southern
Japan. Marginal growth increments indicated that the annulus was formed once a year, in August and September. Four groups
were recognized, having none, one, two, or three annuli, respectively. Age in months was assigned to each individual on the
basis of August as the birth month. The maximum recorded age was 48 months. Growth was expressed by von Bertalanffy's equation,
L
t
= 171.91{1 − exp[−0.148(t + 0.403)]}, t being the age in months and L
t
the standard length (mm) at age t.
Received: July 15, 2002 / Revised: November 18, 2002 / Accepted: December 10, 2002 相似文献
9.
Prof. Giuseppe Martinoli 《Plant biosystems》2013,147(4):557-575
Summary The occurance of Buxus balearica Willd. in Sardinia, already reported by Gennari (1864), and its indigenous state are confirmed by the present study. Its station and geographic distribution as well as the biocenosis in which this species takes part (Barbusi near Sulcis in S. Sardinia) are considered. The study of the Barbusi station, in comparison with others hitherto known, brings a general confirmation to Chiarugi's view concerning the mountainous origin of the mediterranea elements. Besides, it emphasizes the differences between the stations of B. balearica, an element of the mediterranea “macchia”, and those of B. sempervirens, an undergrowth element of mesophilous formations (deciduous woods), which only rarely belonges to more termophilous bioceneses. The author notes that both species belong to the same stage of Q. Ilex and that the altitude range in which the Q. Ilex stage is comprised is very wide in the different mediterranean regions. In addition, the author emphasizes that Buxus sempervirens occurs in Corsica and Atlas up to the upper limit of Quercetum Ilicis, together with species belonging to higher stages, whilst Buxus balearica belongs to the lower limit of Quercetum Ilicis in the underzone “Olea-Ceratonia”. The altimetric separation of these species is, therefore, obvious. Due to the compenetration of floras of mountainous origin during the phases of the Ice-period, the knowledge of the segregation epoch of these species from each other is made impossible. Buxus balearica occupies actually as eocene substratum and, therefore, shows edaphic exigences for soils of a certain age: a condition not occurring for Buxus sempervirens. Both Buxus species, together with other horeal-tertiary ones (all constituting actually, in the mediterranea countries, a special relict flora) belong to the Lauretum, in a historic sense (Chiarugi). 相似文献
10.
Rabaulichthys suzukii is described as a new species of anthiine fish, family Serranidae, from three specimens collected in 5–15 m off the Izu Peninsula,
Shizuoka Prefecture, Japan in February 1999 and February 2000. It represents the third species of the genus, the most characteristic
feature of which is the very high dorsal fin of the male. R. suzukii is most closely related to R. altipinnis Allen from New Britain, differing in its larger size (to 64.2 mm SL, compared to 45.5 mm for R. altipinnis), higher dorsal fin (29.3% SL, compared to 26.2% for R. altipinnis), lack of a filament on the caudal-fin lobes, 19 pectoral rays (modally 20 in R. altipinnis), 9–10 + 23 gill rakers (8–9 + 21–22 in R. altipinnis), and in color. Because the Izu Peninsula collection sites have been heavily dived for many years, the recent appearance
of R. suzukii is believed to the result of transport of postlarvae from a population to the south.
Received: April 20, 2000 / Revised: August 28, 2000 / Accepted: September 28, 2000 相似文献
11.
Gabriela Mendoza‐González M. Luisa Martínez Octavio R. Rojas‐Soto Gabriela Vázquez Juan B. Gallego‐Fernández 《Global Change Biology》2013,19(8):2524-2535
Climate change (CC) and sea level rise (SLR) are phenomena that could have severe impacts on the distribution of coastal dune vegetation. To explore this we modeled the climatic niches of six coastal dunes plant species that grow along the shoreline of the Gulf of Mexico and the Yucatan Peninsula, and projected climatic niches to future potential distributions based on two CC scenarios and SLR projections. Our analyses suggest that distribution of coastal plants will be severely limited, and more so in the case of local endemics (Chamaecrista chamaecristoides, Palafoxia lindenii, Cakile edentula). The possibilities of inland migration to the potential ‘new shoreline’ will be limited by human infrastructure and ecosystem alteration that will lead to a ‘coastal squeeze’ of the coastal habitats. Finally, we identified areas as future potential refuges for the six species in central Gulf of Mexico, and northern Yucatán Peninsula especially under CC and SLR scenarios. 相似文献
12.
S. V. Aibulatov 《Entomological Review》2009,89(6):645-658
The fauna of bloodsucking dipterans of the Kurgala Peninsula comprises 73 species, 34 of which belong to mosquitoes (Culicidae),
18 to blackflies (Simuliidae), 5 to biting midges (Ceratopogonidae, genus Culicoides), and 16 species to horseflies (Tabanidae). Nine species of the bloodsucking dipterans found on the Kurgala Peninsula are
new to Leningrad Province, 6 of them being also recorded for the first time for the neighboring territories of Estonia and
southern Finland. 相似文献
13.
Interspecific and interannual variation in reproductive phenology was quantified for 50 common species of trees and shrubs from a mesic savanna near Darwin, northern Australia. The presence of buds, flowers, and fruit was noted over a 30-month period, from September 1992 to February 1995. Surveys were undertaken at monthly intervals for the less common species, and at bimonthly intervals for ten of the common trees and tall shrubs. The majority of species flowered each year at about the same time. There was no evidence of sub-annual or continuous regimes of reproductive phenology. There was no supra-annual carryover of seed-bearing fruit in the canopy of any species. The peak flowering periods were the mid to late dry season (July–August) and the transition between the dry season and the wet season (October–November). The two dominant trees–Eucalyptus miniata and E, tetrodonta– flowered during the dry season, thereby providing resources for some elements of the vertebrate fauna. Flowering and fruiting were uncommon at the end of the wet season (February/March), although two species that flower and fruit at this time (E. porrecta and Terminalia ferdinandianas may provide resources to consumers at a time when floral or fruit resources are otherwise scarce. Because the peak of reproductive activity takes place during the late dry season, fruit maturity and seed dispersal have occurred prior to the onset of the rainy season for most species, and germination and seedling establishment potentially may take effect in response to the first rains. Late dry season fires, which tend to be extensive and intense, are a potential threat to the floral and fruit reserves within these savannas. 相似文献
14.
We investigated breeding seasonality and population dynamics of three rodent species, Lophuromys flavopuncatus, Grammomys dolichurus and Praomys delectorum, in the Magamba Forest, Western Usambara Mountains, north‐east Tanzania. Capture–mark–recapture studies were conducted in 2002–2004. Reproductive conditions of males and females showed temporal variations, an indication of breeding seasonality. Animals were reproductively active between February and May. Rainfall in November–January was instrumental for the onset of breeding and continued throughout the wet season. The recruitment of new individuals born during the season led to highest population densities between end of May and August. Populations declined progressively towards the end of the dry season (September–October). Only P. delectorum showed a marked density increase during January–February, indicating greater survival and/or recruitment during the November–January rains. The study shows that despite a relatively stable environment of the forest reserve, rainfall has strong influence on reproduction and population dynamics, probably because of its effect on primary food resources. 相似文献
15.
The seasonal and intra-thallus variations in the contents of C, N, proteins and amino acids, as well as in the storage carbohydrates
mannitol and laminaran, were measured in the endemic Antarctic brown alga Ascoseira mirabilis between September and February and related to seasonal changes in dark respiration and photosynthesis. Carbon contents between
31 and 37% DW were relatively constant throughout these months and no variations were detected among thallus regions. Nitrogen
contents, by contrast, were higher in September/October (3.1% DW) and decreased in January and February (1.8% DW). In general,
the basal regions had the lower N contents. Proteins reached maximum values of 13% DW in November and February and were inversely
correlated to photosynthesis (net Pmax). The amino acid content was also higher in October and November (maxima close to 10% DW), but low between December and February
(close to 5% DW), probably related to a seasonal pattern of N allocation in the alga. The storage carbohydrates mannitol and
laminaran exhibited inverse seasonal changes: low mannitol values close to 5% DW in September were coupled with high laminaran
contents varying between 7 and 15% DW. The existence of high laminaran contents in the distal blade region during September
and February suggests that this compound was effectively accumulated in this region. The low P/R ratios in spring and the
existence of a significant relationship between mannitol content and seasonal photosynthetic activity in the basal region
appear to support the hypothesis of a possible utilization of carbohydrates to power growth in A. mirabilis.
Received: 7 November 1996 / Accepted: 28 August 1997 相似文献
16.
Liu Zhensheng Wang Chunsheng Zhang Zhinan Cai Yuming Zhang Dongsheng 《Frontiers of Biology in China》2006,1(4):434-442
The species composition, biomass, abundance, and species diversity of zooplankton were determined for samples collected from
August 2002 to May 2003 from 14 stations in Yueqing Bay, China. Phytoplankton growth rate and microzooplankton grazing rate
were obtained by using the dilution method developed by Landry and Hassett. The spatial and temporal variations of zooplankton
and its relationship with environmental factors were also analyzed. The results showed that the zooplankton in the Yueqing
Bay could be divided into four ecotypes, namely coastal low saline species, estuary brackish water species, offshore warm
water species, and eurytopic species. A total of 75 species of zooplankton belonging to 56 genera and 17 groups of pelagic
larva were identified in the Yueqing Bay. The coastal low saline species was the dominant ecotype in the study area, and the
dominant species were Labidocera euchaeta, Acartia pacifica, Acrocalanus gibber, Pseudeuphausia sinica, and Sagitta bedoti among others.
There was considerable seasonal variation in zooplankton biomass and abundance in the surveyed areas. The peak biomass appeared
in August, descending in November and in May, and the lowest biomass appeared in February. Similarly, the highest abundance
of zooplankton was observed in August, with the abundance descending in the following months: May, November, and February.
There were similar horizontal distribution patterns for the biomass and the abundance of zooplankton. They both increased
from the upper to the lower bay in February and May, but decreased from the upper to the lower bay in August. Biomass and
abundance were evenly distributed in the Yueqing Bay in November. Moreover, there was marked seasonal variation in the species
diversity of zooplankton, which conformed to the abundance of zooplankton. Results of the dilution experiments indicated that
there was grazing pressure of microzooplankton on phytoplankton in the Yueqing Bay throughout the year though the rate of
microzooplankton grazing on phytoplankton varied seasonally. Phytoplanktons were growing at 0.26–2.07/d and grazed by microzooplankton
at a rate of 0.15–0.48/d in different seasons.
__________
Translated from Acta Ecologica Sinica, 2005, 25(8): 1853–1862 [译自: 生态学报, 2005, 25(8): 1853–1862] 相似文献
17.
Age and growth were studied for Gerres oyena (Forsskål, 1775) on Okinawa Island, southern Japan from November 2002 to November 2005. A total of 408 samples was collected ranging from 5.85 to 19.65 cm standard length (LSL). Male fish age was estimated at up to 6+ years, whereas females reached 8+ years as estimated by sectioned otoliths. The length–weight relationships and the von Bertalanffy growth curve were described for all individuals as: and Lt = 20.54{1 − e−0.1807(t+2.8462)}, respectively. Opaque rings were formed from April to August during the spring–summer seasons. 相似文献
18.
Harengula jaguana is a dominant species in the southern Gulf of Mexico. It is a demersal, estuarine-dependent species, distributed throughout the Campeche Sound area (12-54 m). It is found in areas influenced by coastal discharges. The size at first maturity of females is 117 mm total length. Reproduction occurs from February to October in depths 18-36 m. The juveniles are found on the shelf (<20 m) and inside the Terminos Lagoon. Recruitment is in two distinct periods, March–June and August–November, when adults and juveniles migrate to the outer shelf. Greatest abundance is observed in depths of 12-36 m. The biology and ecology of H. jaguana was analyzed in the Campeche Sound to better understand the structure and function of the demersal fish communities. It is a very important species in the trophic dynamics of the ecosystem because it transports matter and energy. A model of the biological pattern for this species in the area is proposed. 相似文献
19.
A study of the flowering and fruiting phenology was undertaken for twenty species of the xerochamaephytic communities that
characterize the mountain-crest areas of the island of Majorca (Balearic Islands, Spain). The flowering period of the species
considered extends from March to November, with the majority flowering during the spring and early summer, and a peak in June.
The flowering duration at the species level is longest for Rosmarinus officinalis var. palaui (which flowered in spring and autumn) and was shortest for Genista majorica and Rubia balearica. In this community, three strategies were observed that may serve to reduce interspecific competition between pollinators:
1) pollination specialization of white-pink flowers; 2) high diversification of yellow flower pollinators; and 3) the divergence
in flowering time of less common flower colours. The flowering duration of individual plants and whole populations are positively
correlated, which may indicate that individuals of each population optimize the time which is phenologically useful. The flowering
of the spiny cushion species of the community is characterized by a smaller intraspecific overlap in comparison to the other
species examined.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
The freshwater calanoida (crustacea : copepoda) of Singapore and Peninsular Malaysia 总被引:7,自引:7,他引:0
The systematics and geographical distribution of Malaysian and Singapore freshwater calanoid copepods are discussed in details. Neodiaptomus handeli Brehm, N. laii Kiefer, N. blachei (Brehm), N. botulifer Kiefer, N. mephistopheles Brehm, Pseudodiaptomus (Schmackeria) dauglishi Sewell, P. (S.) tollingerae Sewell and Tropodiaptomus spp. Kiefer are all present in the northwestern part of the Peninsula. There are only 4 species, namely, N. handeli, N. botulifer, N. meggitti Kiefer and Tropodiaptomus sp. in the southern half of the Peninsula. The whole of the east coast also has 4 species, i.e. N. handeli, N. malaindosinensis (n.n.), P. (S.) tollingerae and one species of Tropodiaptomus. The only species that cut across a wide range of geographical barriers are N. handeli and Tropodiaptomus. 相似文献