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1.
Parasitoid complexes of two species of the genus Phyllonorycter (Ph. apparella and Ph. populifoliella) reared from 2 plants (Populus tremula and P. nigra) were studied in Ul’yanovsk Province, Russia. Twenty species of parasitoids are new for Ph. apparella and 12 are new for Ph. populifoliella. Minotetrastichus frontalis and Pnigalio agraules are the dominant species for both parasitoid complexes. The highest relative abundance was observed for Ph. apparella on Populus tremula (75%) and for Ph. populifoliella on P. nigra (61%). The parasitoid complexes of Ph. apparella and Ph. populifoliella show high similarity (the Jaccard coefficient is 0.65).  相似文献   

2.
The problems of delimitation of species of Prosopis originate from the few morphological discontinuities which exist among some of them; some, however, originated as a result of wide distribution of germplasm without proper knowledge of the species, in particular, much material catalogued as P. juliflora, but being of other species, was distributed for reforestation projects worldwide. This work tests the morphological results obtained for P. pallida and P. limensis of the Peruvian–Ecuadorian coast and for P. juliflora of the Caribbean Basin of Colombia and Venezuela utilizing a study of AFLPs and a study of the morphology of plantlets developed in a conventional garden study. The phenogram obtained for the AFLPs demonstrates each of the three species to be a well differentiated cluster and the molecular variance between them is significantly greater than the variance within each species. Study of the plantlets also indicates statistically significant differences for four morphological characters between P. juliflora and the other two species (P. pallida and P. limensis). These results, in addition to the morphological differentiation evident between adult plants of P. pallida and P. limensis and the clear separation of these two species from P. juliflora, corroborate the genetic identity of the three taxa analyzed.  相似文献   

3.
The symbionts of the macronuclei of Paramecium bursaria and P. caudatum, “Holospora curviuscula” 02AZ16 and H. obtusa 88Ti, respectively, were obtained and investigated. The 16S rDNA nucleotide sequences of “Holospora curviuscula” were obtained for the first time. The differences in 16S rDNA (3.4%) suggest their classification within the genus Holospora. Molecular phylogenetic analysis of the symbionts revealed that these intranuclear symbionts of the ciliates belonged to the order Rickettsiales, forming within a compact cluster of related species.  相似文献   

4.
Genetic transformation of androgenic-derived amphidiploid Festulolium plants (Lolium perenne L. × Festuca pratensis Huds., 2n = 4x = 28) by Agrobacterium tumefaciens has been achieved. Anther culture-induced calli of Festulolium “Bx351” were inoculated with Agrobacterium tumefaciens strain LBA4404 carrying pIG121-Hm encoding the hygromycin resistance (hph) and β-glucuronidase (uidA) genes under the control of a CaMV 35S promoter. Twenty-three putative transformants were obtained from the hygromycin selection, 19 of which (82.6%) showed GUS activity. The integration of transgene was detected by using genomic DNA PCR analysis, RT-PCR analysis and Southern blot hybridization, respectively, which revealed that foreign gene was integrated into the genomes of dihaploid transformants (2n = 2x = 14). The haploid embryogenic system offers a stable means of transformation, as the introduced trait can be readily fixed through chromosome doubling. An erratum to this article can be found at  相似文献   

5.
6.
The effects of β-lactam antibiotics (penicillin, carbenicillin and cefotaxime), cytokinins, and auxins including phenylacetic acid, a β-lactam breakdown product, were evaluated during in vitro shoot morphogenesis in two hybrid aspens; P. tremuloides × P. tremula (XTTa) and P. x canescens × P. grandidentata (XCaG). Although different callus and shoot induction media were used for both hybrids, the β-lactams often engendered similar responses. At concentrations of 1,000 mg l−1, carbenicillin adversely impacted shoot elongation and, to a lesser degree, shoot regeneration. Cefotaxime enhanced caulogenesis for all of the concentrations evaluated (125–500 mg l−1) especially when the cytokinin thidiazuron was used for shoot induction. The shoots formed faster and in greater numbers; and the improvements were significant (α = 0.05) for both hybrids. However, hyperhydricity was more problematic when cefotaxime was included in the media. The incidence of shoot hyperhydricity for the XCaG hybrid was more than twice as great for the highest cefotaxime concentration evaluated (500 mg l−1) than for the control (>90% vs. ~40%). Penicillin had an opposite effect. Hyperhydricity frequencies for the XCaG hybrid were lower when the media were supplemented with penicllin and the reductions were statistically significant at concentrations of 500–1,000 mg l−1. The effects of the antibiotics were generally not reproduced by the auxins (0.1–100 μM), including phenylacetic acid, or the other potential β-lactam degradation products evaluated (e.g. phenylmalonic acid, aminopenicillanic acid). The antibiotics may have affected shoot hyperhydicity indirectly via changes in the time course of shoot regeneration.  相似文献   

7.
8.
9.
(R)-2-Aryl-2-tropinone (9) was synthesized from (R)-2-carbomethoxy-3-tropinone (5) and was used as the key intermediate for the synthesis of (R)-2β,3β- and (R)-2α,3α-diaryltropanes. Inhibition of radioligand binding studies at the dopamine, serotonin, and norepinephrine transporters showed that the (R)-3β-(4-methylphenyl)-2β-phenyltropane (3b, RTI-422) possessed an IC50 value of 1.96 nM at the dopamine transporter and was highly selective for this transporter relative to the serotonin and norepinephrine transporters.  相似文献   

10.
Zusammenfassung Ein Paar des HonigsaugersNectarinia kilimensis wurde in der Brutzeit beim Nestbau 21 Stunden beobachtet. Über die Bauaktivität gibt Abb. 2 Aufschluß. 140 von 144 Anflügen mit Nistmaterial waren auf 8 Stunden von 8h–16h konzentriert. Das Nistmaterial bestand fast ausschließlich aus Halmen, Pflanzenwolle und Spinnweben; dieses Material wurde von Anfang an abwechselnd verwendet. Nur das hat gebaut. Die Baumethoden werden beschrieben, ebenso verschiedene Balzhandlungen des . Der Nestbau dauerte 4 1/2, beim folgenden Nest 3 1/2 Tage.Beim Brüten waren Schnabel und Oberkopf des sichtbar. Während der Bauzeit wurde ein ausgeflogenes juv. nur vom gefüttert. Als es mindestens 17 Tage alt war, wurde es vom , 6 Tage später auch vom aggressive gejagt, doch war dieses juv. mehr als 3 Wochen nach dem Ausfliegen noch im Revier.
Day-time activity, nest-building method and breeding behaviour of Bronze SunbirdNectarinia (Aidemonia) kilimensis in Central Africa
Summary A pair of Bronze SunbirdsNectarinia kilimensis was observed nest building over a period of 21 hours in the breeding season. Fig. 2 gives information on building activity. Of 144 arrivals with nest material 140 were concentrated in 8 hours from 08.00 to 16.00 hrs. Nest material consisted almost exclusively of grasses, plants, down and spider's webs; this material was, from the outset, used in an alternating pattern. The alone did the building. Nest-building methods are described, also various courtship activities of the . Nest building took 4 1/2 days, in the case of a second nest, 3 1/2 days.The 's bill and crown were visible when she was incubating. One young that had left the nest was fed by the alone. At least 17 days after this young one had fledged, it was chased aggressively by the , 6 days later also by the ; despite this, the same young bird was still in the territory more than three weeks after it had fledged.
  相似文献   

11.
The in vitro effect of four isolates of the nematophagous fungi Duddingtonia flagrans (AC 001), Monacrosporium sinense (SF 53) and Pochonia chlamydosporia (VC 1 and VC 4) on eggs of Schistosoma mansoni was examined. One thousand S. mansoni eggs were plated on 2% water–agar with the grown isolates and control without fungus. After 7, 14 and 21 days, the eggs were removed and classified according to the following parameters: type 1, lytic effect without morphological damage to eggshell; type 2, lytic effect with morphological alteration of embryo and eggshell; and type 3, lytic effect with morphological alteration of embryo and eggshell, besides hyphal penetration and internal egg colonization. Significant differences (P < 0.01) were found among the studied fungal isolates for ovicidal activity, confirming type 3 effect for the isolates VC 1 and VC 4, which characterizes the ovicidal activity of a fungus. Type 3 effect was only found for P. chlamydosporia (VC 1 and VC 4) with 26.6 and 17.2%, 25.6 and 22.6%, 27.4 and 23.9% in the 7, 14 and 21 days respectively (P < 0.01). P. chlamydosporia can thus be a potential biological control agent for S. mansoni eggs.  相似文献   

12.
Chromosome mapping of three common markers, ie major and 5S rRNA genes (rDNA) and telomeric repeats, and conventional chromosome bandings were applied to two sibling species, Apodemus sylvaticus Linnaeus, 1758 and A. flavicollis Melchior, 1834, to further investigate intra- and interspecific karyological differentiation in the genus Apodemus. A slight variation of the rDNA-patterns was detected between the two Apodemus species. In both of them, the major NORs were located on autosome pairs 8, 11, 12 and 22, while the two other rDNA sites detected on chromosomes 7 and 21 were variable in, respectively, A. sylvaticus and A. flavicollis. Several tiny rDNA sites were present on the sex chromosomes in both species, but their incidence was lower in A. flavicollis. Single 5S rDNA chromosomal sites were conserved on chromosome pair 20. No interstitial sites of telomeric repeats were present in either species. In the Sicilian population of A. sylvaticus, the constitutive heterochromatin pattern corresponded to the “sylvaticus-E1” cytotype, while A. flavicollis had a species-specific pattern restricted to centromeres of all chromosomes. The results are discussed in relation to cytogenetic data available for the genus, with emphasis on the Sylvaemus group/subgenus.  相似文献   

13.
Summary We have molecularly cloned the rDt transposon, one component of the classic Dotted two-element system of controlling elements. The rDt transposon was identified as a DNA insertion in each of two independent mutation events of the maize A1 gene, a gene necessary for the biosynthesis of anthocyanin pigment. Both mutant alleles result in a stable, anthocyaninless phenotype in all plant tissues. When the transposon Dotted, (Dt), is present in the genome each allele exhibits a characteristic mutable phenotype (spots of anthocyanin pigmentation). The DNA insertion has been designated rDt, for it responds to or is regulated by the Dt element to allow expression of the otherwise mutated gene, and it had not been named in earlier genetic studies. Sequence analysis revealed the rDt element to be an identical 704 bp insertion within the two mutable alleles, but in opposite orientation and in different exons of the gene. rDt contains an imperfect terminal inverted repeat with similarity to transposable elements of various species. A duplication of 8 bp of the target host site is formed upon integration of the element, and the element is excised from the locus in a germinal revertant. The difference in phenotype of the two unstable alleles, a1 and am-1:Cache, is discussed.  相似文献   

14.
Zusammenfassung Gemeinsame Verhaltensmerkmale ganzer Gruppen wurden bis jetzt nur selten zusammengestellt. Die Notwendigkeit einer derartigen zusätzlichen Kennzeichnung für die meisenartigen Vügel ergibt sich aus der Vielfalt der Auffassungen. Vor allem die Stellung der GattungenAegithalos undTichodroma ist unklar und in den wissenschaftlichen Werken uneinheitlich.Es wurde deshalb versucht, die wichtigsten Verhaltensweisen der GattungenParus undAegithalos einerseits darzustellen, andererseits die der GattungSitta gegenüberTichodroma undCerthia. Parus Alle bisher bekannten Arten dieser Gattung zerkleinern Nahrung, indem sie diese mit dem Fuß festhalten und Teile davon abzupfen bzw. die Schale von Samen zertrümmern. Dieses Verfahren beherrschen schon Jungvögel, die noch nicht selbständig Nahrung aufnehmen. Alle Meisen sind Höhlenbrüter; die Methode, Höhlen der verschiedensten Größen mit Moos weitgehend auszufüllen, wird als Anpassung an die Verschiedenartigkeit vorgefundener, meist durch Fäulnis entstandener Baumhöhlen gedeutet. Das Bedecken des unvollständigen Geleges kann Nestfeinde daran hindern, das Gelege beim Einblick in die Baumhöhle zu erkennen, da Meisenhöhlen im allgemeinen infolge der Unförmigkeit des Höhleneinganges nicht völlig dunkel sind. Die Nestlingszeit von rund 20 Tagen stellt wohl sicher eine Anpassung an das Brüten in einer geschützten Höhle dar. Ausführlich wird die Drohkombination besprochen, die bei allen Meisen festzustellen ist, die im Nest gestört werden. Diese Kombination, bestehend aus einem Zischlaut, dem Zuklappen des aufgesperrten Schnabels und gleichzeitigen Schlagen der Flügel an die Höhlenwände, kommt nur in einer Höhle zur vollen Wirkung und ist ein Zeichen dafür, daß Meisen phylogenetisch sehr alte Höhlenbrüter sind. Befiederte Jungmeisen wenden sie ebenso an wie in einer Höhle bedrängte Meisen- . Bei der Balz unterscheiden sich Meisen nicht grundlegend von anderen Passeres. Zum Sammeln von Vorräten sind nicht alle Arten von Meisen befähigt, sondern hauptsächlich solche, die im Winterhalbjahr vorwiegend von Samen leben. Kohl- und Blaumeisen sind möglicherweise nicht von Anbeginn Samenfresser gewesen; sie sammeln keine Vorräte. BeiParus major öffnet eine indische Rasse im Käfig keine Samen.Aegithalos Schwanzmeisen unterscheiden sich von denParus-Arten durch eine starke soziale Bindung an Artgenossen. Außer der Brutzeit trifft man nie einzelne Schwanzmeisen an, während Meisen auch mit anderen Arten vorlieb nehmen. Schwanzmeisen nächtigen stets in gegenseitiger Berührung und die Jungen rufen sich mit einem spezifischen Laut immer wieder zusammen. Schwanzmeisen sind nicht territorial. Mindestens beiAegithalos sowie bei dem amerikanischenPsaltriparus können mehr als zwei Altvögel am Nestbau und der Jungenaufzucht beteiligt sein. Von den Lautäußerungen der Schwanzmeisen hat nur einer eine gewisse Ähnlichkeit mit Meisenrufen, alle anderen sind stark verschieden; dies gilt auch für den Warnruf gegenüber Luftfeinden. Die Nestlingszeit der Schwanzmeisen entspricht der von Freibrütern; sie ist deutlich kürzer als bei Meisen. Am Nestbau beteiligen sich und , während bei denParus-Arten nur das baut.Sitta Während die Fähigkeit, abwärts zu klettern, nicht für alleSitta-Arten gilt, zerkleinern alle bisher bekannten Arten Nahrung, indem sie diese in Spalten stecken und mit dem Kopf nach unten hängend daraufklopfen. Dies ist ein grund-legender Unterschied zu allenParus-Arten. Alle holarktischenSitta-Arten sammeln Vorräte, alle sind Höhlenbrüter, die große Bruthöhlen, ähnlich wie die Meisen, verkleinern. Im Unterschied zu den Meisen fehltSitta ein Drohverhalten bei Störung im Nest. Eine Reihe von Arten schützt jedoch den Nesteingang teils durch eine Mauer aus Lehm, teils durch Beschmieren mit frischem Harz oder dadurch, daß Insekten am Flugloch so verrieben werden, daß ein Insektenduft entsteht. Bei Felsenkleibern sind diese Methoden kombiniert.Tichodroma Neuerdings wird der Mauerläufer eher zu den Kleibern gestellt als zuCerthia. Tatsächlich erinnert nur die Schnabelform an letztere Gattung. Es scheint, daß der Mauerläufer für seine Brut die Nähe von Felsschluchten oder Sturzbächen bevorzugt. Dort waren die Rufe flügger Junger im Nest nicht zu hören. Das auffallende Farbmuster kann eine ökologische Anpassung sein. Bettelnde Jungvögel schlagen die Flügel nach dem Ausfliegen viel höher und auffallender als andere Passeres. In der Lebensweise gleichtTichodroma vielfach dem FelsenkleiberS. neumayer, indem sie zur Brutzeit mehr Geröllfelder und den Rand von Schluchten aufsucht als Steilwände. Höhenunterschiede werden stets mit den Flügeln überwunden. Die auffallende Größe der Flügel läßt sich aus der Funktion leicht erklären. Das periodische Flügelzucken entspricht weitgehend dem vonSitta neumayer, nur mit dem Unterschied, daß es dafür beim Mauerläufer keiner erkennbaren Erregung bedarf. An der Bruthöhle wurde ein einziges Mal eine Pendelbewegung beobachtet, wie sie nur bei Kleibern vorkommt. Die Länge von Brutdauer und Nestlingszeit entspricht vor allem der der Kleiber.Certhia Der Stützschwanz ermöglichtCerthia eine völlig andersartige Klettermethode gegenüberSitta undTichodroma. Baumläufer sind an das Brüten in schmalen Spalten angepaßt. Die Brutdauer liegt zwischen der der Meisen und der Kleiber. Die Jungen sind sehr empfindlich und verlassen das Nest, bevor sie fliegen können, bei der geringsten Störung. Damit weichen sie ebenso von anderen Höhlenbrütern ab wie die brütenden , die gleichfalls sofort das Nest verlassen, wenn sie eine Gefahr wahrnehmen. Wenn das dem den zukünftigen Brutplatz demonstriert, schlüpft es ein und führt nach dem Herauskommen eine ritualisierte Schüttelbewegung aus, die Meisen und Kleibern fehlt. Auch die Schlafgewohnheiten sind verschieden.Es wird vorgeschlagen, die Schwanzmeisen als eigene Familie von den Meisen zu trennen. Den Kleibern gebührt ein eigener Familien-Status. Der Mauerläufer ist keinesfalls mitCerthia nahe verwandt, sondern sollte den Kleibern als Unter-familie zugeteilt werden, sofern er nicht eine eigene Familie darstellt.
Summary Up to the present time general behavioral characteristics of entire groups have rarely been synthesized. The necessity of an additional characterization of this kind for the tit-like birds is revealed in the multiplicity of taxonomic interpretations. The positions of the generaAegithalos andTichodroma are especially unclear and are diversely treated in scientific writings.Therefore it was attempted, on the one hand, to present the most important behavior patterns of the generaParus andAegithalos, and on the other hand, those of the genusSitta contrasted withTichodroma andCerthia. Parus All species of this genus known to date break up food items by holding them with the foot and picking off pieces or breaking off the hulls of seeds. Even young which do not yet feed independently have this behavior. All tits are hole nesters. The procedure of the extensive filling in of cavities of the most varied sizes with moss is explained as an adaptation to the variation in tree cavities encountered, largely as the result of rotting. The covering of an incomplete clutch can prevent predators' recognition of the clutch when looking in the hole, for tit holes are generally not completely dark as a result of the irregularity of the entrance. The nestling period of about twenty days certainly represents an adaptation to nesting in a protected cavity. The threat combination present in all tits when disturbed in the nest is discussed in detail. This combination, consisting of a hissing sound, snapping closed of the open bill and concomitant blows of the wings against the sides of the cavity, is fully elicited only in a cavity, and is an indication that hole nesting appeared quite early in the phylogeny of tits. Feathered young utilize this behavior just as do male tits which are disturbed in a cavity. Tits do not differ basically from other passerines in courtship. Not all species of tits store food; those which do are mainly those which feed predominantly on seeds during the winter. Coal and Blue Tits were perhaps not originally seed eaters; they do not store food. The Indian race ofParus major does not eat seeds in captivity.Aegithalos Long-tailed Tits differ fromParus species in their strong social ties to conspecifics. Lone Long-tailed Tits are never encountered outside of the breeding season, whereas other tits even show a preference for other species. Long-tailed Tits always spend the night in mutual contact and the young are brought together repeatedly with a specific call. They are not territorial. At least inAegithalos and the AmericanPsaltriparus more than two adults can take part in nest building and rearing of the young. Only one of the vocalizations of the Long-tailed Tit has a certain similarity to the calls of other tits; all the others differ markedly, also the warning call against aerial predators. The nesting period of the Long-tailed Tit corresponds to that of open nesters; it is clearly shorter than that of other tits. Both male and female participate in nest building, whereas in theParus species only the female builds.Sitta Whereas the ability to climb downwards does not hold for allSitta species, all species known to date break up food items by putting them in crevices and hammering on them with the head hanging downward. This is a basic difference from allParus species. All Holarctic species ofSitta store food and all are hole nesters which, like the tits, reduce the size of large nesting holes. As opposed to the tits,Sitta lacks a threat display when disturbed in the nest. However, a number of species protect the nest entrance, in part by a mud wall, and partly by smearing fresh resin about, or by rubbing insects around the hole so that an insect odor results. Rock Nuthatches combine these methods.Tichodroma The Wall Creeper has recently been placed closer to the nuthatches than toCerthia. Actually only the form of the bill resembles this genus. It seems that the Wall Creeper prefers the vicinity of rocky ravines or waterfalls for breeding. The calls of fledged young in the nest were not heard. The striking color pattern can be an ecological adaptation. After leaving the nest, begging young beat their wings much more widely and conspicuously than other passerines.Tichodroma bears a strong resemblance to the Rock Nuthatch,S. neumayer, in its way of life, in that for the breeding season it seeks out more boulderstrewn fields and ravine edges than steep cliffs. Vertical movements are always accomplished by flight. The striking size of the wing can be easily explained from its function. The periodic wing flashing corresponds closely to that ofSitta neumayer, and differs in the Wall Creeper only in the fact that no recognizable stimulus is needed for it to occur. A single observation was made of an oscillating movement at the nesting cavity, which only occurs in nuthatches. The length of the incubation and nestling periods corresponds especially well to that of the nuthatches.Certhia The prop-like tail makes possible a completely different method of climbing in contrast toSitta andTichodroma. Tree Creepers are adapted for breeding in narrow crevices. The length of the incubation period is intermediate between that of the tits and that of the nuthatches. The young are easily disturbed and will leave the nest, before they can fly, at the least disturbance. They also differ from other hole nesters in that the female will leave the nest immediately if she perceives danger. When the male shows the female the prospective nesting site he slips in and, after coming out, performs a ritualized shaking movement which is not found in tits and nuthatches. The sleeping habits also differ.It is suggested that the Long-tailed Tits and Bush Tits be separated from the other tits, and placed in a family by themselves. The nuthatches deserve familial status. The Wall Creeper is by no means closely related toCerthia, and ought to be designated a subfamily of the nuthatches, in so much as it does not represent a separate family.


Prof. Dr. Konrad Lorenz zum 60. Geburtstag gewidmet

Da uns nun nach Nestbau, Jugendbedaunung, Sperrachen, Stimme, Bewegungsweise z. B. Baum- und Mauerläufer oder Schwanz- und Waldmeisen untereinander durchaus nicht näher zu stehen scheinen als z. B. Waldmeisen und Kleiber, so begnügen wir uns mit den GattungenO. und M. Heinroth  相似文献   

15.
The method of polymerase chain reaction with random primers (RAPD PCR) was used to identify the progeny of the crosses between three sturgeon species, Amur sturgeon (Acipenser schrenckii Brandt, 1869), Siberian sturgeon (A. baerii Brandt, 1869), and sterlet (A. ruthenus Linnaeus, 1758). Using ten primers, genetic variation in 70 yearlings, produced in seven individual crosses: Acipenser schrenckii × A. schrenckii, A. baerii × A. baerii, A. ruthenus × A. ruthenus, A. schrenckii × A. baerii, A. baerii × A. schrenckii, A. schrenckii × A. ruthenus, and A. ruthenus × A. schrenckii was described and evaluated. It was demonstrated that the samples composed of hybrids from individual crosses were more variable than the samples of parental species. On the other hand, pooled samples of hybrids from two cross directions were genetically less variable than the pooled samples of their parents. The three main features of the hybrid RAPD profiles identified included: (1) preservation of marker DNA fragments of both parents in one genome; (2) presence of specific DNA fragments, absent from both parents; and (3) dependence of the frequency of some DNA fragments from the cross direction. Multidimensional scaling clearly distinguishes in the space of three coordinates the individuals of original species and the hybrid progeny with differentiation in the groups of direct and backcross hybrids. Analysis of relationships (UPGMA and NJ) pointed to substantial differentiation between the species, as well as between the species and hybrid progeny. Close genetic relationships between direct and backcross hybrids were demonstrated. Multilocus RAPD markers in association with statistical methods are considered to be the useful tool for discrimination of interspecific hybrids of sturgeon. Possible reasons for the differences in the hybrid RAPD profiles are discussed. Original Russian Text ? K.V. Rozhkovan, G.N. Chelomina, E.I. Rachek, 2008, published in Genetika, 2008, Vol. 44, No. 11, pp. 1453–1460.  相似文献   

16.
Host and microhabitat or site selection is universal among parasites, although to varying degrees between species and groups. The selection of a specific site by a copepod parasite is determined by a set of mostly unknown factors. The spatial distribution of Kroyeria dispar, Kroyeria papillipes and Eudactylina pusilla on the gill filaments of Galeocerdo cuvier was investigated to determine whether niche restriction occurs in the different planes on the gills. In order to do this, the complete sets of left gills of 14 tiger shark hosts were examined and the species, location (hemibranch, horizontal distribution, longitudinal distribution), orientation and gender of each copepod noted. Kroyeria dispar was dominant on most hosts and exhibited a prevalence of 100% and a mean intensity of 73 individuals per shark. Kroyeria papillipes was dominant on the remaining hosts and displayed a prevalence of 78.6% and a mean intensity of 33 individuals per shark while E. pusilla had a prevalence of 85.7% and a mean intensity of 20 individuals per shark on the examined hosts. No evidence of intra- or interspecific competition or microniche restriction was found even though all three species occupy the same fundamental niche. However, distributional preference was observed, and the compound populations of all three species on tiger sharks were aggregated, most likely as a result of their need to reproduce. Handling editor: S. I. Dodson  相似文献   

17.
To evaluate the genetic diversity of a mangrove species and clarify the genetic structure of its populations, we studied nucleotide polymorphism in two DNA regions of Bruguiera gymnorhiza collected from the southern islands of Japan, Thailand, Malaysia, Indonesia, Micronesia, and India. The two DNA sequences were the chloroplast (cp) intergenic spacer between trnL and trnF genes (ca. 300 bp), and a part (ca. 550 bp) of the nuclear gene coding for glyceraldehyde-3-phosphate dehydrogenase (GapCp). Little polymorphism was found within each of the three geographical regions, Pacific Ocean, Bay of Bengal and Arabian Sea. Throughout the vast regions east of the Malay peninsula including Indonesia, Thailand, Micronesia and the southern islands of Japan (Pacific Ocean), essentially only one haplotype (apart from variation in number of a T repeat) was present. A second haplotype was present on the western coast of Malay Peninsula and the eastern coast of India (Bay of Bengal). On the southwest of Malay Peninsula both of these haplotypes were present. Finally a third haplotype was found only on the western coast of India (Arabian Sea). When taken over all geographic populations, total nucleotide variation within the species was large (μ = 0.006, average of the two genes). Our results are consistent with the hypothesis that this low genetic diversity within any local population and differentiation between the different oceans or regions are caused by very low gene flow between each of the different oceans coupled with frequent fluctuation of population sizes due to the change in sea level. The significance of these results is discussed from evolutionary point of the mangrove forests.  相似文献   

18.
A revision of Leptotheca Thélohan, 1895 is presented. The boundaries that separate Leptotheca from Ceratomyxa Thélohan, 1892 and Sphaerospora Thélohan, 1892 are vague and have been highlighted as an area of concern within myxosporean classification. A survey of the literature revealed 63 species that are currently assigned to Leptotheca and a further 11 species that have been relegated as synonyms in Ceratomyxa, Sphaerospora or Myxobolus Bütschli, 1882. The placement of some species in the genus is unclear and demonstrates the need for a revision. The type-species of Leptotheca (L. agilis Thélohan 1892) has many Ceratomyxa-like characters, such that a minor amendation of the diagnosis of Ceratomyxa will then accept the type-species of Leptotheca, rendering the latter genus its synonym. We propose the suppression of Leptotheca, with all species currently assigned to that genus reassigned to Ceratomyxa, Ellipsomyxa K?ie, 2003, Myxobolus or Sphaerospora on the basis of appropriate morphological and biological traits. The diagnoses of Ceratomyxa and Ellipsomyxa are amended appropriately. Molecular analysis may change the placement of some species in the future; however, the aim of this review was to eliminate the ambiguity of assignment of species in the genera Leptotheca, Ceratomyxa and Sphaerospora by suppressing Leptotheca.  相似文献   

19.
20.

Background  

The filamentous ascomycete Hypocrea jecorina (anamorph Trichoderma reesei) is primarily known for its efficient enzymatic machinery that it utilizes to decompose cellulosic substrates. Nevertheless, the nature and transmission of the signals initiating and modulating this machinery are largely unknown. Heterotrimeric G-protein signaling represents one of the best studied signal transduction pathways in fungi.  相似文献   

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