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1.
Variations of shell form and shell length were studied for oysters growing in the mangroves of Gazi Creek, Kenya, and related to different environmental factors.For the study of the form, Fourier analysis was performed on the circumference of 85 oysters. The resulting coefficients were compared among specimens using cluster analysis. The correspondence between this classification and substrate diameter is virtually perfect (only one misclassification out of 85 oysters). For the clusters based on height above chart datum, 9 specimens, all on intermediate height levels, were misclassified. Orientation with respect to tidal current had 13 misclassifications. Mangrove species seemed to influence form only marginally, if at all.In the study of the size ofCrassostrea cucullata, the length of 956 oysters, growing along two transects were measured, and correlated with several environmental factors. Oyster length was not related to substrate diameter or its orientation with respect to the main current. Length was not influenced by density up to a cover of 70%. For densities higher than 70%, there was a fairly strong negative correlation (r 2 = 0.634,n = 217). Length was not correlated with height above bottom (base of the tree) for heights lower than 20 cm, while oysters growing closer to the bottom were smaller. The correlation with height above chart datum was negative but very low (r 2 = 0.060,n = 957). However, if all measurements of oysters closer than 20 cm to the bottom, and all from a density of more than 70% cover are deleted from the data set, the correlation with height increased dramatically, the slope still being negative (r 2 = 0.859,n = 543).  相似文献   

2.
The dominance of the Pyroglyphidae in house dust has been influenced by a number of factors. The humidity in houses dropped recently to such an extent that only Pyroglyphidae can survive. When temperature and relative humidity are favorable for Acarus siro and Glycyphagus destructor as well as Dermatophagoides pteronyssinus, Dermatophagoides diminished in numbers by competition. Introduction of the predator Cheyletus eruditus into this mixed breeds causes the extermination of Dermatophagoides. The vacuum cleaner trapped mites, but Dermatophagoides was protected by its habit to hide in cracks and crevices. The use of insecticides has a more killing effect on Acarus and Glycyphagus than on Dermatophagoides.  相似文献   

3.
Oxuderces dentatus and Scartelaos histophorus species were collected seasonally from the Dhamara estuary (Odhisa, India) using scoop nets, cast nets as well as by hand for a period of 1 year (January 2015–December 2015). Length–weight relationships were estimated. Total lengths (TL) for O. dentatus ranged from 42 to 80 mm, and from 58 to 122 mm for S. histophorus. Similarly, total weights of O. dentatus and S. histophorus ranged from 2.5–10.7 g to 7.7–26.5 g, respectively. The ‘b’ values estimated for O. dentatus (2.718) and S. histophorus (2.689) were below 3. The condition factors of O. dentatus and S. histophorus were minimum in summer and maximum post‐monsoon.  相似文献   

4.
We report the identification of four residual stations for Trifolium michelianum Savi (Fabaceae) in Sicily, whereas the species was documented to be extinct at the Gorgo Cerro station (western Sicily), the only locality previously reported in the literature. In addition to an update on the distribution of the species, a survey on the new Sicilian populations led to their biological, ecological and phytosociological characterization, as well as to an assessment of the risk factors. The species, here relegated to the limit of its distribution area, occurs in particularly sensitive and vulnerable environments, such as the “Mediterranean temporary ponds”, considered “priority” by the Council Directive 92/43/EEC. Moreover, a new Sicilian association (Trifolio michelianiGlycerietumspicatae ass. nova), framed in the alliance Glycerio-Sparganion (class Phragmito-Magnocaricetea), is described.  相似文献   

5.
Abstract

The most extensive and magnificent forests of Cedrus libani A. Rich. in the world are on the Taurus Mountains in Turkey. They cover an area of about 400,000 hectares. C. libani forms either pure stands or mixed stands with other tree species, such as Abies cilicica, Pinus nigra, P. brutia, Quercus species (Q. cerris, Q. infectoria, Q. libani etc.), Juniperus excelsa and J. foetidissima. In this work, the floristic composition of the cedar forests in Western Antalya has been investigated and the ecological factors have been measured. The main forest types have been established and correlated with the ecological factors. In total, 201 relevés were analyzed by numerical methods and classified into five groups of C. libani forests and one group of Q. coccifera scrublands. It was observed that the topographical gradient mainly determines the differentiation patterns of cedar forests in Western Antalya.  相似文献   

6.
In invasion processes, both abiotic and biotic factors are considered essential, but the latter are usually disregarded when modeling the potential spread of exotic species. In the framework of set theory, interactions between biotic (B), abiotic (A), and movement‐related (M) factors in the geographical space can be hypothesized with BAM diagrams and tested using ecological niche models (ENMs) to estimate A and B areas. The main aim of our survey was to evaluate the interactions between abiotic (climatic) and biotic (host availability) factors in geographical space for exotic symbionts (i.e., non‐free‐living species), using ENM techniques combined with a BAM framework and using exotic Entocytheridae (Ostracoda) found in Europe as model organisms. We carried out an extensive survey to evaluate the distribution of entocytherids hosted by crayfish in Europe by checking 94 European localities and 12 crayfish species. Both exotic entocytherid species found, Ankylocythere sinuosa and Uncinocythere occidentalis, were widely distributed in W Europe living on the exotic crayfish species Procambarus clarkii and Pacifastacus leniusculus, respectively. No entocytherids were observed in the remaining crayfish species. The suitable area for A. sinuosa was mainly restricted by its own limitations to minimum temperatures in W and N Europe and precipitation seasonality in circum‐Mediterranean areas. Uncinocythere occidentalis was mostly restricted by host availability in circum‐Mediterranean regions due to limitations of P. leniusculus to higher precipitation seasonality and maximum temperatures. The combination of ENMs with set theory allows studying the invasive biology of symbionts and provides clues about biogeographic barriers due to abiotic or biotic factors limiting the expansion of the symbiont in different regions of the invasive range. The relative importance of abiotic and biotic factors on geographical space can then be assessed and applied in conservation plans. This approach can also be implemented in other systems where the target species is closely interacting with other taxa.  相似文献   

7.
The occurrence of herbivores in nature is limited by biotic and abiotic factors which affect their development and survival. Udranomia spitzi is an endemic butterfly in the Brazilian savanna (cerrado) that feeds on young leaves of two sympatric plants, Ouratea hexasperma and O. spectabilis. It is not known which factors affect the occurrence of larvae on their hosts. Therefore, in this study we: (i) evaluated the oviposition preference of U. spitzi; (ii) evaluated the larval performance in both Ouratea species; (iii) investigated plant phenology; (iv) investigated climate (temperature and rainfall); and (v) investigated plant architecture (measured as plant height) on the abundance of skippers. Results showed that U. spitzi immatures (eggs and larvae) were far more abundant (n = 41, 96.7%) on O. spectabilis, whereas on O. hexasperma, the number of larvae was negligible (n = 1). In the laboratory, U. spitzi performed better on O. spectabilis than on O. hexasperma. The occurrence of larvae was not related to host phenology or environmental variations, but rather to plant height, since 92.7% (n = 38) of larvae were found on small O. spectabilis trees. A previous study showed that U. spitzi was not influenced by biotic factors (aggressive ants) and this study showed that plant structure plays a major role in skipper choice. The preference of U. spitzi for O. spectabilis is discussed.  相似文献   

8.
The Eocene Notharctinae provide a record of increasing fusion of the mandibular symphysis. The two sympatric genera,Notharctus andSmilodectes, differed through time in two respects.Notharctus increased in body size and evolved a partially fused mandibular symphysis.Smilodectes changed little in body size and retained an unfused symphysis. Similarities in molar morphology between these two genera and extant leaf-eating mammals suggest thatNotharctus andSmilodectes were specialized for folivory, a dietary regime correlated with partial symphyseal fusion in many extant mammals. It is concluded that the presence and the extant of symphyseal fusion is a function of body size, diet, and jaw mechanics, complicated by lineagespecific factors that vary among higher mammalian taxa.  相似文献   

9.
White-nosed bearded sakis (Chiropotes albinasus) are endemic to the Madeira–Xingú interfluvium in southern Amazonia, though recent fieldwork has produced conflicting data on the southwestern limits of the species's geographic range. We reevaluated the distribution of bearded sakis on the basis of surveys from 34 sites throughout the Brazilian state of Rondônia. Chiropotes albinasus occurred at seven sites in the eastern part of the state, including two west of the Jiparaná–Pimenta Bueno river system in the extreme south, but there is no record of their presence further north and west in the Jiparaná–Guaporé interfluvium and they were absent from the Jiparaná–Mamoré interfluvium. The data suggest that ecological, rather than geographic barriers restrict the distribution of Chiropotes albinasus in southern Rondônia, but are contradictory with regard to the possible determining factors. Chiropotes albinasus appears able to thrive in transitional, savanna-like ecosystems in southern Rondônia, but is unexpectedly absent from adjacent areas of terra firme forest. Syntopy with the only other pitheciine found in the state (Pithecia irrorata) appears to have a negative effect on the abundance of Chiropotes albinasus which implies that interspecific competition may reinforce a complex of limiting factors, such as the availability of key plant species. Despite showing that Chiropotes albinasus is widespread in southern Rondônia, we also confirm its absence from the western two thirds of the state, a significant reduction in the known range of the species.  相似文献   

10.
Presented are the length–weight and length–length relationships and condition factors for two mudskippers, Periophthalmus modestus and Periophthalmus magnuspinnatus, on the tidal flats of Korea. Values of the exponent b, estimated by nonlinear least squares from weight and length data, were 3.031 for P. modestus and 3.044 for P. magnuspinnatus. All relationships between total and standard length were linear (r2 > 0.974). The condition factors were significantly higher during the post‐spawning season than at other times for both species.  相似文献   

11.
To relate differences in phenological strategies of a group of closely related plants to biotic (pollinators, dispersers) and abiotic (water, light) factors, we studied leafing, flowering, and fruiting phenology of 12 species of Piper (Piperaceae) in a neotropical lowland forest in Panama for 28 months. We asked how Piper may partition time and vertebrate frugivores to minimize possible competition for dispersal agents. Based on habitat preferences and physiological characteristics we discriminate between forest Piper species (eight species) and gap Piper species (four species). Forest Piper species flowered synchronously mostly at the end of the dry season. Gap Piper species had broader or multiple flowering peaks distributed throughout the year with a trend towards the wet season. Both groups of Piper species showed continuous fruit production. Fruiting peaks of forest Piper species were short and staggered. Gap Piper species had extended fruiting seasons with multiple or broad peaks. Both groups of Piper species also differed in their time of ripening and disperser spectrum. Forest Piper species ripened in late afternoon and had a narrow spectrum consisting mainly of two species of frugivorous bats: Carollia perspicillata and C. castanea (Phyllostomidae). Fruits of gap Piper species, in contrast, ripened early in the morning and were eaten by a broader range of diurnal and nocturnal visitors, including bats, birds, and ants. We conclude that the differences in flowering phenology of forest and gap Piper species are primarily caused by abiotic factors, particularly the availability of water and light, whereas differences in fruiting patterns are mostly influenced by biotic factors. The staggered fruiting pattern of forest Piper species may reflect competition for a limited spectrum of dispersers. The long and overlapping fruiting periods of gap Piper species are associated with a larger spectrum of dispersers and may be a strategy to overcome the difficulty of seed dispersal into spatially unpredictable germination sites with suitable light conditions.  相似文献   

12.
Syphatineria (Africanoxys) pearsi (Baylis, 1928) was described from an African squirrel, Heliosciurus rufobrachium (Waterhouse), in Nigeria. This species is re-described from specimens collected in an Heliosciurus gambianus (Ogilby) captured in Zaire. The morphological and biological characteristics of the subgenus Africanoxys Hugot, 1981 are discussed. The subgenus Africanoxys is specific to African rain forest squirrels and, based upon the lengths of the spicule and gubernaculum, two different groups can be distinguished in this subgenus. The first group is parasitic in the Funambulini and the second one is parasitic in the Protoxerini and in Aethosciurus poensis (A. Smith). Although the taxonomic status of genus Aethosciurus is controversial, Parasitology allows us to relate Aethosciurus to the Protoxerini rather than to the Funambulini.
Etude morphologique de Syphatineria pearsi (Baylis, 1928) (Oxyuridae, Nematoda)
Résumé Syphatineria (Africanoxys) pearsi (Baylis, 1928), un oxyure décrit chez un écureuil africain, Heliosciurus rufobrachium (Waterhouse), au Nigéria, est redécrit à partir d'un matériel collecté chez un Heliosciurus gambianus (Ogilby), capturé au Zaire. Les caractéristiques du sous-genre Africanoxys Hugot, 1981 sont ensuite discutées. Le sous-genre Africanoxys est spécifique des écureuils du bloc forestier congolais. On peut distinguer deux groupes dans le sous-genre d'après la longueur du spicule et celle du gubernaculum. Les parasites du premier groupe ont tous pour hôtes des Funambulini. Les parasites du deuxième groupe ont pour hôtes des Protoxerini et Aethosciurus poensis (A. Smith). La parasitologie apporte donc des arguments à l'hypothèse d'un rapprochement d'Aethosciurus poensis (dont la position systématique est controversée), avec les Protoxerini plutôt qu'avec les Funambulini.
  相似文献   

13.
Many drug-resistant gram-negative bacilli were isolated from the intestinal tracts of yellowtails (Seriola quinqueradiata) cultured on farms in various parts of Kochi and Ehime Prefectures, Shikoku Island. They were Vibrio, Pseudomonas, Proteus, Citrobacter and some unidentified Enterobacteriaceae. Of these drug-resistant strains, Vibrio and Pseudomonas were found to carry R factors in high frequencies. These R factors had four types of resistance markers, SA, SA. CM, SM. CM. ABP. and SA. SM. CM. TC. All R factors were found to belong to the fi type. In contrast, only one drug-resistant gram-negative bacillus was detected in a cultured yellowtail on farms near Numazu City, Shizuoka Prefecture.  相似文献   

14.
Beauveria bassiana (Balsamo – Crivelli) Vuillemin based mycoinsecticides are used against agricultural, veterinary and medical insect pests. The fungus has a very diverse and extensive host range. Variation in virulence among isolates of B. bassiana to different insect species has been abundantly documented. Given the effect of multiple factors on virulence, it is not certain whether the observed difference in virulence can be labelled as host specificity. Environmental conditions and susceptibility of the insect population are two main factors that affect successful fungal infection. Keeping the environmental factors constant, if virulence of an isolate to different insect species and different populations within an insect species is compared, the scale of difference between the two responses can be estimated. If differences in virulence of an isolate to different insect species are greater than the difference in virulence to different insect populations within an insect species, then, the isolate can be considered as exhibiting specific preference to those insect species towards which it exhibits high virulence. To examine this feature, a worldwide sample of B. bassiana was bioassayed on nine insect species and two different populations within two insect species. Laboratory bioassays were done on: Bombyx mori (Lepidoptera), Spodoptera litura (Lepidoptera), Chilo partellus (Lepidoptera), Helicoverpa armigera (Lepidoptera), Epilachna vigintioctopunctata (Coleoptera), Mylabris pustulata (Coleoptera), Aphis craccivora (Homoptera), Maconellicoccus hirsutus (Hemiptera) and Oecophylla smaragdina (Hymenoptera). The range of variation in virulence of a B. bassiana isolate to different insect species was not more than that observed with different populations within a single insect species. B. bassiana is thus a generalist with no strict host preference. B. bassiana based biopesticide can be used as a broad spectrum insecticide against a myriad of insect pests.  相似文献   

15.
Neodiaptomus schmackeri and related species are redescribed. The synonymy of this species with N. strigilipes and N. handeli is discussed.  相似文献   

16.
AINTEGUMENTA (ANT) promotes initiation and growth of ovule integuments which cell fate is specified by ovule identity factors, such as SEEDSTICK (STK), SHATTERPROOF1 (SHP1) and SHATTERPROOF2 (SHP2). To study the genetic interaction between ANT and the ovule identity genes, we have obtained a stk shp1 shp2 ant quadruple mutant. The molecular and morphological characterization of the quadruple mutant and its comparison with the stk shp1 shp2 triple mutant, the shp1 shp2 ant triple mutant and the stk ant double mutant are here presented.  相似文献   

17.
The inland silverside, Menidia beryllina (Cope), is an annual zooplanktivore that occurs in estuarine and freshwater habitats along the Atlantic and Gulf of Mexico coasts and drainages of the United States. Experiments were conducted at 25 ± 1°C to quantify the relationship between mean dry weight (WD) and rates of energy gain from food consumption (C), and energy losses as a result of respiration (R) and ammonia excretion (E) during routine activity and feeding by groups of fish. The absorption efficiency of ingested food energy (A) was also quantified. Rates of C, E, and R increased with WD by factors (b in the equation y = aWDb) equal to 0.462, 0.667, and 0.784, respectively. Mean (±SE) rates of energy loss during feeding were 1.6 ± 0.1 (R) and 3.4 ± 0.6 (E) times greater than those for unfed fish. Absorption efficiency was independent of WD and estimated to be 89% of C. From these measurements, the surplus energy available for growth and activity (G) and growth efficiency (K1) were estimated. Over the range in sizes of juveniles and adults (5–500 mg WD), predicted G and K1 values decreased from 7.42 to 0.20 J mg fish?1 day?1 and 63 to 21%, respectively. Measured and predicted bioenergetic parameters are discussed within an ecological context for a northern population of this species.  相似文献   

18.
Hundsdoerfer, AK., Mende, MB., Kitching, IJ. & Cordellier, M. (2011). Taxonomy, phylogeography and climate relations of the Western Palaearctic spurge hawkmoth (Lepidoptera, Sphingidae, Macroglossinae). —Zoologica Scripta, 40, 403–417. The primary aim of this study was to analyse mitochondrial genetic variability within the Hyles euphorbiae lineage in the Western Palaearctic, where observations of morphology have indicated much greater differentiation than is implied by the current taxonomy. The scope of the study is broadened further by including an analysis of the possible influences of climatic factors on lineage distributions. Mitochondrial sequences from three genes totalling an unambiguous alignment of 2284 bp were obtained for 356 individuals of the H. euphorbiae complex (HEC) s.s. Genetic admixture, network and climatic factor analyses were used to analyse the data. Unexpected mitochondrial variability was uncovered within the distribution range of H. euphorbiae in southern Europe, with two additional distinct clusters being found, both with rather patchy occurrences. The results of the genetic analysis presented here confirm a distinct H. cretica on Crete and the Dodecanese Islands and a distinct H. robertsi in Iran that hybridises with H. euphorbiae. Comparison of the molecular data with larval morphology shows only limited correlation of genetic clusters with pattern elements. The genetic network of the HEC s.s. shows strong incongruence with traditional taxonomy. Ecological niche modelling based on climate data revealed that the three best‐sampled clusters (H. tithymali, the well‐known H. euphorbiae lineage from Europe, and the previously unknown mitochondrial H. euphorbiae lineage that occurs mainly in Italy) could all occur in southern Italy and on the Mediterranean Islands. Biotic interactions appear to explain the observed ranges better than abiotic factors alone.  相似文献   

19.
Summary

Recent years have seen an increasing number of alien praying mantis species being introduced and establishing populations across Europe. Here we add to this count, reporting a stable and spreading population of an Asian species, Statilia maculata (Thunberg, 1784), in Krasnodar Krai of Southern Russia. This is the first introduced praying mantis species in the Russian fauna and the first representative of the genus Statilia Stål, 1877 in Europe. We review what is known about biology of this species and provide diagnostic characters to distinguish nymphs, adults and oothecae from native and introduced European species of praying mantis. Our attempts at captive breeding identify humidity as one of the most important factors limiting possible spread of S. maculata. Invasion to neighbouring territories and other countries with a humid subtropical climate remains a very real possibility with an unknown outcome for local ecosystems.  相似文献   

20.
We analyzed the biomass, density and age structure of S. woodiana populations in relation to different environmental factors at new sites of its occurrence in southern Poland. The highest recorded biomass was 4,413 g m–2. Mussel density was 19 individuals m–2. The age structure was formed by juveniles as well as by specimens more than 8 years. The rapid expansion of S. woodiana in European countries is believed to be the result of accidental introduction of fishes bearing glochidia of this species. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

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