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1.
The Mediterranean monk seal Monachus monachus , is a critically-endangered species of which only two populations, separated by c . 4000 km, remain: the eastern Mediterranean (150–300 individuals) and the Atlantic/western Sahara populations (100–130 individuals). We measured current levels of nuclear genetic variation at 24 microsatellite loci in 12 seals from the eastern Mediterranean and 98 seals from the western Sahara population and assessed differences between them. In both populations, genetic variation was found to be low, with mean allelic richness for the loci polymorphic in the species of 2.09 and 1.96, respectively. For most loci, the observed allele frequency distributions in both populations were discontinuous and the size ranges similar. The eastern Mediterranean population had 14 private alleles and the western Sahara had 18, but with a much larger sample size. Highly significant differences in allele frequencies between the two populations were found for 14 out of 17 loci. F ST between the two populations was 0.578 and the estimated number of migrants per generation was 0.046, both clearly indicating substantial genetic differentiation. From a conservation perspective, these results suggest that each population may act as a source for introducing additional genetic variation into the other population. 相似文献
2.
Distribution and frequencies of shark-inflicted injuries to the endangered Hawaiian monk seal (Monachus schauinslandi) 总被引:1,自引:0,他引:1
P. Bertilsson-Friedman 《Journal of Zoology》2006,268(4):361-368
I analyzed the frequencies of wounds inflicted by sharks to the endangered Hawaiian monk seal Monachus schauinslandi at three colonies in the Northwestern Hawaiian Islands between 1990 and 2000. I applied specific criteria typical of shark bites to all injuries to avoid bias. Pooling data from all years and the three colonies revealed several patterns. Sharks injured more pups (nursing and weaned) and juveniles (1–2 years old) than adults and subadults. More female pups and male juveniles than any other size classes were injured by sharks. Almost all (97%) of the injured pups were from French Frigate Shoals. More juveniles than expected were wounded at Laysan Island and Lisianski Island. Most shark wounds were between the diaphragm and the pelvic girdle, but pups were bitten most often just behind the pelvis compared with adults who were bitten more often near the head and neck. 相似文献
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4.
The aim of the present study is to investigate the demographic structure and to identify some aspects of the biology of an exploited population of Medorippe lanata (Brachyura: Dorippidae) in the eastern Ligurian Sea, western Mediterranean. 1364 specimens (639 males and 725 females) of M. lanata were collected on a monthly basis from January to December 2001, in a wide area of the eastern Ligurian Sea usually exploited by the Viareggio ‘rapido’ trawl fleet. M. lanata represented an important fraction of the discard, both in weight and in number of individuals. Maximum abundance of this species occurred in late summer-early autumn (up to 3369 ind. km−2 and 50.6 kg km−2 in August). The overall females:males sex-ratio was 1.13:1, while the monthly sex-ratio did not differ statistically from 1:1 in all months, except in September and October, when females significantly outnumbered males. The sampled population was composed of two cohorts from November to April. Sizes ranged from 10 to 29 mm carapace length (CL) for females and from 9 to 29 mm CL for males. The von Bertalanffy growth curve, computed for both sexes, gave a higher growth rate in males than in females. Recently moulted males and females were observed throughout the year, except in summer, when the highest number of ovigerous females was present. Females with external eggs were collected from March to November, with peaks in August and September. The monthly evolution of the ovarian maturity stages showed no clear temporal trend. At 21 mm CL, 50% of females were ovigerous or showed macroscopically mature ovaries. According to the dimorphism in chelae size, the presence of adult males (post-puberty stage) was observed all year round, from 18 to 29 mm CL, without evident temporal trends. 相似文献
5.
Alina Tunin‐Ley Jean‐Philippe Labat Stphane Gasparini Laure Mousseau Rodolphe Leme 《Journal of phycology》2007,43(6):1149-1163
We examined the well‐documented and species‐rich dinoflagellate genus Ceratium Schrank in the northwest Mediterranean Sea as a possible model for marine phytoplankton diversity and as a biological indicator of global climate change. First, we investigated the influence of counting effort; we then documented temporal changes in Ceratium specific and infraspecific taxa over 2 years (2002 and 2003) in the Villefranche Bay based on a monthly net sampling. Finally, we tried to identify factors associated with shifts in biodiversity. The calculation of taxonomic diversity, regularity, and richness were highly dependent on counting effort. We determined that a minimal sample volume of ~70 L was needed to obtain a good estimation of species richness. The annual cycle was characterized by a seasonal trend of high winter species richness followed by low spring biodiversity. Infraspecific variability not only appeared to depend on water temperature but also seemed to be influenced by bottom‐up control and was strongly affected by top‐down control. Thus, the occurrence of high concentrations of salps (Thalia democratica) and copepods larger than 2 mm (Calanus helgolandicus) coincided with a drastic decrease of Ceratium abundance and diversity during spring 2003. Ceratium is sensitive to both abiotic and biotic factors and could prove to be a good candidate as a biological indicator of global change. 相似文献
6.
Carl-Erik Cantell 《Hydrobiologia》1988,156(1):105-113
The anatomy of an insufficiently described species of heteronemertine, Cerebratulus hepaticus, is redescribed. The species is characterized by, inter alia, a cephalic lacuna with strands of longitudinal muscle fibres, a proboscis with three muscle layers, neurochord cells in the brain, a dermis in the foregut region with no or few longitudinal muscle fibres which is separated from the outer longitudinal muscle layer by connective tissue. The taxon is compared with two other Cerebratulus species, C. fuscus and C. marginatus. The material was collected at Banyuls-sur-Mer (France) in the Mediterranean. 相似文献
7.
Polychaete assemblages associated to the sponge Geodia cydonium were investigated at two sampling sites in the Mediterranean Sea: Porto Cesareo Basin (Apulia) and Marsala Lagoon (Sicily), both characterized by sheltered hydrodynamic conditions. Samples were seasonally performed during 1997, in order to compare the assemblages coming from the two localities studied, considering separately the internal and external tissues of the sponge, and with the aim of evaluating the influence of sponge size on polychaete colonization. The examined sponge is characterized by a peculiar stratification of its tissues: an external thick and hard layer, the cortex, and an internal softer one, the choanosome. Statistical analysis showed that this was the main factor controlling polychaete assemblage, with the internal tissue, less rich and diversified, appearing impoverished with respect to the external layer. A similarity in species composition was observed between sites, even though some differences were evidenced in the abundance of some species, mainly reflecting differences in local environmental conditions. Species richness and density increased with the increasing sponge size. Such a situation is particularly evident at Porto Cesareo, where sponges are covered by an algal layer which is particularly rich on the largest specimens, thus suggesting that most of the species of polychaetes were linked more to the neighbouring environment than to the sponge itself. 相似文献
8.
Abstract Cordylecladia guiryi sp. nov. is described from the Mediterranean Sea, after a comparison of habit, morphology and reproduction with C. erecta, the only species of the genus. The species is characterized by the small dimension of its axes which arise single from the basal crust and by its habitat, growing epiphytically on Posidonia oceanica Delile leaves. Tetrasporangial and gametangial plants as well as the development of the carposporophyte have been studied in detail. The carpogonial branch is 4-celled and it is formed on a supporting cell that also bears a 3-celled auxiliary branch. Tetrasporangia are cruciately divided. The reproductive details confirm Sparling's view about the great variation existing in the organization of the procarp in members of this order. 相似文献
9.
Nino Mariotti 《Geobios》2002,35(2):213
About three hundred belemnite rostra were collected from Lower Kimmeridgian beds of a structural high sequence cropping out at Mt. Nerone (central Apennines, Pesaro Province, Italy). The belemnite fauna is composed mainly of new species. Nine species were recognised, ascribed to five genera, which include Hibolithes semisulcatusMünster, 1830; H. pignattii nov. sp.; Acutibelu0s sp. cf. acuariformisRiegraf, 1981; Belemnopsis neronensis nov. sp., Duvalia matteuccii nov. sp., D. nicosiai nov. sp., D. pallinii nov. sp., D. raymondi nov. sp. and Rhopaloteuthis massimoi nov. sp.; moreover a single specimen is treated in open nomenclature as Belemnopseidae incertae sedis. The stratigraphic and palaeobiogeographic significance of the new fauna is discussed. The taphonomy of the belemnite-rich level is described, with reference to borings found on the belemnite rostra.La fauna a belemniti risulta composta quasi esclusivamente da specie nuove. Sono state riconosciute le seguenti specie: Hibolithes semisulcatusMünster, 1830; H. pignattii nov. sp.; Acutibelus sp. cf. acuariformisRiegraf, 1981, Belemnopsis neronensis nov. sp., Duvalia matteuccii nov. sp., D. nicosiai nov. sp., D. pallinii nov. sp., D. raymondi nov. sp. and Rhopaloteuthis massimoi nov. sp. Inoltre un esemplare è stato discusso con nomenclatura aperta come Belemnopseidae incertae sedis. Alcuni nuovi dati stratigrafici e paleobiogeografici sono stati analizzati ed integrati con i dati della letteratura. E’ stata anche esaminata la tafonomia del livello a belemniti e le perforazioni presenti sulla superficie dei rostri. 相似文献
10.
A total number of 40 potentially toxic microalgae and 5 taxa causing discolorations have been identified along the coasts of the Campania region (South Tyrrhenian Sea, Mediterranean Sea). This number is based on results of over 20 years of research at a coastal station in the Gulf of Naples, 4 years of monitoring activity along the Campania coasts and of a series of scattered and sporadic observations. Several species of the recently erected genera Karenia and Takayama are reported for the first time in the area. Information on the period of highest abundances or most probable period of occurrence indicates the late spring and summer as the periods of maximum risk of harmful events. Despite the variety of potentially toxic species, no human health problems nor fish kills have ever been recorded in Campania. The reasons for this apparent paradox are probably to be found in the ecological factors that regulate the abundance, toxicity and spatial distribution of the potentially harmful species and reflect as well the relatively low number of aquaculture plants in the area. 相似文献
11.
Ana-mabel Martí nez Primitivo Caballero Trevor Williams 《Biocontrol Science and Technology》2004,14(2):193-200
The incorporation of stilbene-derived optical brighteners into baculovirus formulations can substantially enhance virus infectivity and persistence of inoculum in the field. We evaluated the effect of the optical brightener Tinopal UNPA-GX (Sigma Chemical Co.) on the weight, development time, adult emergence and sex ratio of the principal pest of maize in the Americas, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Tinopal UNPA-GX was incorporated into semi-synthetic diet at a final concentration of 0.1 or 0.05% (w/v) and larvae of S. frugiperda were individually reared on the Tinopal-treated or an untreated control diet. In both Tinopal treatments, the weights of larvae and pupae were significantly reduced by up to 36 and 13%, respectively. The duration of larval development was increased by up to 30% compared to the controls. Adult emergence was high in all treatments (≈90%) and was not affected by the presence of Tinopal in the diet. Significant differences in the proportion of adult females were observed in the 0.05% Tinopal treatment but not in the control or 0.1% Tinopal treatments. By affecting the integrity of the peritrophic membrane and the rate of sloughing of intestinal epithelial cells, natural pest populations exposed to optical brightener residues from bioinsecticide applications are likely to suffer a reduction in growth rate and other correlates of insect fitness. 相似文献
12.
Donatella Serio 《Plant biosystems》2013,147(6):941-973
Abstract A study on Cystoseira spinosa community and Cystoseira zosteroides community from Catania (Eastern coast of Sicily) is presented. It is based on monthly samples carried out throughout a year. That permitted to better characterize the communities as regards their periodism and floristic composition. From the comparative examination of samples made, resulted that the communities differ each other mainly in the Cystoseira species since their floristic composition are on the whole quite similar. 相似文献
13.
Bryopsidella ostreobiformis sp. nov. is presented as the second species of the genus. The latter is amended to accomodate this new species. The derbesioid sporophyte is capable of producing three- to eight-rayed stellate propagules. The dioecious gametophyte is a heterotrichous thallus with branched, prostrate filaments and unbranched, erect ones, and does not resemble Bryopsis. The life cycle is distinctly diplohaplontic, with a diploid sporophyte and a haploid gametophyte. B. ostreobiformis is postulated as the starting point of a hypothetical evolutionary sequence of life histories in the Derbesia/Bryopsis complex. 相似文献
14.
Monica Guerrini Giovanni Forcina Panicos Panayides Rita Lorenzini Mathieu Garel Petros Anayiotos 《分类学与生物多样性》2013,11(5):472-483
The mouflon population of Cyprus (Ovis orientalis ophion) comprises historically preserved feral descendants of sheep domesticated during the Neolithic. We determined genetic identity of this taxon in order to elucidate its systematic placement and enforce its protection. We used 12 loci of microsatellite DNA to infer genetic relationships between the Cypriot mouflon and either long-time isolated (Corsica, Sardinia) or recently introduced (central Italy) European mouflons (O. o. musimon). We also sequenced the mitochondrial DNA (mtDNA) Cytochrome-b gene to infer the origin of the Cypriot mouflon including many National Centre for Biotechnology Information (NCBI) entries of European and Near Eastern conspecifics. Microsatellites disclosed net divergence between Western Mediterranean and Cypriot mouflon. The latter was included in the highly heterogeneous Near Eastern O. orientalis mtDNA group, Iran representing the most credited region as the source for its ancient introduction to Cyprus. Both international and national legislation protect the mouflon of Cyprus as a wild taxon (O. o. ophion). However, the IUCN Red List of Threatened Species and NCBI include the Cypriot mouflon as subspecies of its respective domestic species, the sheep (O. aries). Unfortunately, people charged with crime against protected mouflon may benefit from such taxonomic inconsistency between legislation and databases, as the latter can frustrate molecular DNA forensic outcomes. Until a definitive light can be shed on Near Eastern O. orientalis systematics, we suggest that the Cypriot mouflon should be unvaryingly referred to as O. o. ophion in order not to impair conservation in the country where it resides. 相似文献
15.
This study evaluated the growth and population structure of Xiphopenaeus
kroyeri in Babitonga Bay, southern Brazil. Monthly trawls were conducted from July 2010 through June 2011, using a shrimp boat outfitted with double-rig nets, at depths from 5 to 17 m. Differences from the expected 0.5 sex ratio were determined by applying a Binomial test. A von Bertalanffy growth model was used to estimate the individual growth, and longevity was calculated using its inverted formula. A total of 4,007 individuals were measured, including 1,106 juveniles (sexually immature) and 2,901 adults. Females predominated in the larger size classes. Males and females showed asymptotic lengths of 27.7 mm and 31.4 mm, growth constants of 0.0086 and 0.0070 per day, and longevities of 538 and 661 days, respectively. The predominance of females in larger size classes is the general rule in species of Penaeidae. The paradigm of latitudinal-effect does not appear to apply to seabob shrimp on the southern Brazilian coast, perhaps because of the small proportion of larger individuals, the occurrence of cryptic species, or the intense fishing pressure in this region. The longevity values are within the general range for species of Penaeidae. The higher estimates for longevity in populations at lower latitudes may have occurred because of the growth constants observed at these locations, resulting in overestimation of this parameter. 相似文献
16.
Well-preserved opal planktic assemblages containing diatom and silicoflagellate species were discovered in the finely laminated sapropels S5 and S7 from Site 67, core GeoTüKL51 during “RV Meteor”-Cruise 40, Leg 4 (34° 48 N; 27° 17 E). The siliceous microflora, composed quasi-exclusively of warm water species, is here studied for taxonomy, stratigraphy and ecology, as well as for quantitative distribution. The diatom assemblage is very diverse and dominated by rhizosolenids, which are generally characteristic of stratified, oligotrophic waters. A significant shift to higher abundances of Pseudosoleniacalcar-avis is observed in the upper part of Sapropel S5, with a simultaneous decrease in the abundances of Thalassionema bacillaris/frauenfeldii,T.nitzschioides,T. oestrupii and Chaetoceros sp., which is probably due to nutrient - poor conditions in the surface waters. 相似文献
17.
Sand and nest temperatures were monitored during the 2002–2003 nesting season of the green turtle, Chelonia mydas, at Heron Island, Great Barrier Reef, Australia. Sand temperatures increased from ∼ 24°C early in the season to 27–29°C in the middle, before decreasing again. Beach orientation affected sand temperature at nest depth throughout the season; the north facing beach remained 0.7°C warmer than the east, which was 0.9°C warmer than the south, but monitored nest temperatures were similar across all beaches. Sand temperature at 100 cm depth was cooler than at 40 cm early in the season, but this reversed at the end. Nest temperatures increased 2–4°C above sand temperatures during the later half of incubation due to metabolic heating. Hatchling sex ratio inferred from nest temperature profiles indicated a strong female bias. 相似文献