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1.
Orientation tests performed with Emlen funnels show much variation. This scatter in responses can be partially explained by considering the birds’ personalities.We studied a Passerine migrant, the Sedge Warbler (Acrocephalus schoenobaenus), on autumn passage at Kalimok Biological Station, Bulgaria. Birds caught in the morning were kept in cages with known and regularly controlled amounts of food. In the evening they were tested for orientation, the next morning they were observed for 3 min in an unfamiliar cage, then released.Birds that ate on the first day oriented in the expected, southward direction, non-eating birds were scattered.Eating behaviour was related to the exploration pattern on the next day. Eating birds moved and flew less, hopped, looked around and explored the cage more, and were quicker in eating a food item if present.Lean birds ate and explored more but also oriented better, contrary to expectations where fat reserves indicate readiness for migration. A hypothesis is discussed where fat, migration and personality may be linked.Personality aspects may influence the individuals’ ability to cope with an experimental situation and influence the outcome of the tests, therefore its analysis can help in predicting the birds’ performance in apparently unrelated experiments.  相似文献   

2.
Lindernia procumbens and L. dubia are common annual weeds in flooded rice fields of Japan. Two subspecies of L. dubia, subsp. major and subsp. dubia, are usually recognized in Japan but they are both regarded as synonyms of L. dubia elsewhere. In a cluster analysis based on AFLP, most L. dubia subsp. major formed a separate cluster from L. dubia subsp. dubia although 11% of haplotypes classified using AFLP were not coincident with classification using the shape of leaf bases, which is the commonly used identification trait. Artificial F1 plants between L. procumbens and L. dubia subsp. major, and between L. procumbens and L. dubia subsp. dubia did not produce seed. Forty percent of capsules produced by F1 plants from these two subspecies were slimmer and 80% pollen were sterile in slimmer capsules. However, seed number of most F1 capsules was not different from that of self-fertilized plants, suggesting that there was no complete reproductive isolation between the subspecies. Natural hybridization of these subspecies may have occurred but we are not aware of it because F1 plants are rare and F2 plants are indistinguishable from these subspecies.  相似文献   

3.
Migrant white-throated sparrows (Zonotrichia albicollis) were released from boxes carried aloft by balloon and tracked with radar. All birds were released on clear nights when winds were light and opposed to the normal migration direction for the season. Birds were treated in one of two ways: Lens birds were fitted with frosted lenses prior to release; No Lens birds were released without lenses. No Lens birds that engaged in straight and level flight generally headed in the predicted migratory direction and as a group were not oriented with respect to wind direction. Lens birds did not head in the predicted migratory direction, but instead oriented downwind. This orientation behaviour is consistent with the relationship of orientation cues inferred from the field observations described in part I of this paper. The data show that flying birds deprived of all detailed form vision can determine wind direction.  相似文献   

4.
Lymphocyte responses in the blood, peritoneal fluid and both mesenteric and hepatic lymph nodes of cDNA-FhPGK/pCMV vaccinated and/or Fasciola hepatica infected rats of both sexes were investigated to provide an insight into the immune responses that develop in different body compartments. The immune response that developed in cDNA-FhPGK/pCMV vaccinated females contributed to partial protection against F. hepatica infection (54% reduction in fluke recovery), while more liver flukes were found in the livers and bile ducts of cDNA-FhPGK/pCMV vaccinated male rats than in unvaccinated animals (increase of 13%). Rat sex not only affected the ultimate effectiveness of vaccination but also lymphocyte responses following vaccination and/or infection. Different CD4 + and CD8 + T cell profiles were noted in peritoneal fluid and lymph nodes, but not in blood, during acute and chronic fasciolosis. Moreover, independent lymphocyte responses developed in distinct body compartments. Immune responses of rats were polarized towards Th2/Treg with lymphocytes isolated from male rats showing higher IL-4 and IL-10 production than females. Lymphocyte proliferative capacities in response to mitogen (PHA) or vaccine antigen (FhPGK) were impaired in both sexes with a considerably higher reduction observed for males and restored lymphocyte proliferative capacities reported for females vaccinated with cDNA-FhPGK/pCMV during chronic fasciolosis.  相似文献   

5.
Bacteriological and serological characteristics of three Bacillus thuringiensis isolates obtained in Japan were investigated. They formed typical rhomboidal parasporal inclusions but flagellar (H) antigens of these isolates were different from those of the known 17 H serotypes of B. thuringiensis. The three isolates were divided into two new serotypes (serotypes 18 and 19). The serotype 18 isolate (3–71) produced thermostable exotoxin and the inclusions of this isolate were toxic to larvae of the silkworm, Bombyx mori, but nontoxic to larvae of the mosquito, Aedes aegypti. The other isolate (119-72) belonging to serotype 18 produced inclusions nontoxic to larvae of B. mori and A. aegypti and did not produce thermostable exotoxin. However, other bacteriological properties of the isolate 119-72 were similar to those of the isolate 3–71. The serotype 19 isolate (117-72) produced inclusions nontoxic to larvae of B. mori and A. aegypti and did not produce thermostable exotoxin. Acid production from saccharose and the production of brownish purple pigment were observed in the two serotype 18 isolates, while neither of them was observed in the serotype 19 isolate. In other 29 biochemical properties tested, there was no difference among the three isolates. Based on these characteristics, the following two subspecies names are proposed: Bacillus thuringiensis subsp. kumamotoensis (serotype 18) for the type strain 3–71 and Bacillus thuringiensis subsp. tochigiensis (serotype 19) for the type strain 117-72.  相似文献   

6.
Biochemical genetics was applied to elucidate the taxonomic position of the spider crab Pisoides bidentatus. Two morphologically similar spider crabs, P. bidentatus and Pugettia quadridens, were compared with four sympatric brachyuran species, Eriocheir japonicus, Hemigrapsus sanguineus, Hemigrapsus penicillatus (Varunidae), and Cancer amphioetus (Cancridae), using 20 allozyme loci. High genetic identity-value between P. bidentatus and P. quadridens (I = 0.758 ± 0.092) suggests that they should evidently be placed to one genus. This conclusion is supported by the similar identity-value between two species of the genus Hemigrapsus (I = 0.821 ± 0.078) and the low genetic similarity (I = 0.125 ± 0.05) between different genera, Hemigrapsus and Eriocheir, within the family Varunidae.  相似文献   

7.
I have tried to show (a) that results in the literature suggest that blue tits and coal tits survive better in their usual habitats of broad-leaved and conifer woods respectively; (b) that the higher mortality in the ‘wrong’ habitat may be attributed at least in part to an inability to acquire an adequate supply of food; (c) from my own and other people's field observations, that wild coal tits and blue tits use different feeding techniques; (d) from my own laboratory experiments, that each species is ‘best’ at the feeding techniques which it in general uses in the wild, and also that each species prefers to use the feeding techniques at which it is ‘best’; (e) that the feeding techniques of coal tits may be adapted to exploit the type of food supply found in conifers, while those of blue tits may be adapted for feeding in broad-leaved trees.  相似文献   

8.
Halacsya and Paramoltkia are two monotypic genera of the Balkan ultramafic outcrops, both classified as paleoendemics. They show close phylogenetic relationship, similar ecology and partially sympatric range, but contrasting life-history traits, patterns of distribution and chromosomal features. We performed a study to compare their infraspecific genetic structure using AFLP fingerprinting. Within-population heterozygosity (HS) and total heterozygosity (HT) were lower in diploid H. sendtneri than in polyploid P. doerfleri (0.121 and 0.142 vs. 0.165 and 0.178, respectively). Number of polymorphic loci was also higher in the latter species. Halacsya showed significant levels of among-population variation (14.5%) and population differentiation (FST = 0.145), as well as a structuring in four main geographic groups connected by low gene flow. Combined with inability for long-distance dispersal, these data suggest that present-day range fragmentation in this species is the result of historical losses of intervening populations and support its status of paleoendemic surviving in refugial serpentine “islands”. Populations of P. doerfleri were instead genetically very close (FST = 0.049), and variation was partitioned almost exclusively among individuals (95.1%). Lack of population groupings and higher levels of gene flow suggested a single, panmictic group, fitting more a metapopulation than a “classical” paleoendemic model.  相似文献   

9.
Pachypodium namaquanum (Nyley ex Harb.) Welw., an unusual arborescent stem succulent from the succulent karoo of the arid Richtersveld in north-western South Africa and adjacent Namibia, is characterized by a striking curvature of the terminal 20–60 cm of the trunk toward the north. This orientation displays the single terminal whorl of drought-deciduous leaves with their flat surface angled at a mean inclination of 55° from horizontal. Inclination of 50–60° was found in 65% of individuals sampled, and 85% were inclined between 45 and 65°. Northward azimuth was also quite regular, but varied slightly between populations. The fixed leaf orientation in P. namaquanum maximizes radiation absorption during the winter months when leaves are present. Leaves normally form in early fall (April) and abscise early in spring (October). Growing season conditions in the Richtersveld are relatively mild, with mean maximum temperature dropping only to 21.6°C in July, the coldest month of the year. Frosts are rare. By the fixed orientation of its leaf whorl, P. namaquanum is able to maintain nearly twice the midwinter radiation absorptance that it would have with horizontal orientation. Over an annual cycle the angled leaves receive more radiation than would horizontal leaves for each of the 6 months in which they are present on the plant. This increased winter irradiance is hypothesized to singificantly increase net primary production by concentrating growth activities in winter months and allowing the species to remain dormant during the hyperarid conditions of the hot summer months. Midwinter flowering from apical buds in P. namaquanum may also be aided by its stem orientation. The evolution of this characteristic pattern of winter growth phenology and nodding stem orientation may have come about because of low but relatively regular autumn precipitation and moderate winter temperatures. Slow and regular growth of P. namaquanum leads to long lifespans which may reach 300 years or more.  相似文献   

10.
Two new gregarines in the recently erected genus Psychodiella (formerly Ascogregarina), Psychodiella sergenti n. sp. and Psychodiella tobbi n. sp., are described based on morphology and life cycle observations conducted on larvae and adults of their natural hosts, the sand flies Phlebotomus sergenti and Phlebotomus tobbi, respectively. The phylogenetic analyses inferred from small subunit ribosomal DNA (SSU rDNA) sequences indicate the monophyly of newly described species with Psychodiella chagasi. Ps. sergenti n. sp. and Ps. tobbi n. sp. significantly differ from each other in the life cycle and in the size of life stages. The sexual development of Ps. sergenti n. sp. (syzygy, formation of gametocysts and oocysts) takes place exclusively in blood-fed Ph. sergenti females, while the sexual development of Ps. tobbi n. sp. takes place also in males and unfed females of Ph. tobbi. The susceptibility of Phlebotomus perniciosus, Phlebotomus papatasi, Ph. sergenti, Ph. tobbi, and Phlebotomus arabicus to both gregarines was examined by exposing 1st instar larvae to parasite oocysts. High host specificity was observed, as both gregarines were able to fully develop and complete regularly the life cycle only in their natural hosts. Both gregarines are considered as serious pathogens in laboratory-reared colonies of Old World sand flies.  相似文献   

11.
Paxillus involutus is a model species for ecological or physiological studies of ectomycorrhizal agaricomycetes. Three to six groups or species linked to it have been ecologically and morphologically distinguished. Phylogenetic studies have revealed the existence of four species in Europe: Paxillus ammoniavirescens, Paxillus obscurisporus, P. involutus, and a fourth as yet not described species. We studied 47 collections from 24 French and Italian locations, supplemented with GenBank data, in order to genetically and taxonomically delineate these species. Phylogenetic analyses of three nuclear DNA regions (rDNA internal transcribed spacer (ITS), tef1-α, and gpd) confirmed the four European species. Morphology, culture, and ecology features allowed us to delineate species boundaries and to describe the fourth species we named Paxillus cuprinus since it turns coppery with age. As there is no existing original herbarium specimen for P. involutus, one of our collections was chosen as the epitype. The low genetic diversity found in P. cuprinus correlates with stable morphological traits (basidiome colour, ovoid–amygdaliform spores with an apical constriction) and with ecological preferences (association with Betulaceae in open and temperate areas). In contrast, P. ammoniavirescens is characterized by a high genetic diversity and a high variation of its morphological and ecological features.  相似文献   

12.
Two fossil taxa Tubulifloridites antipodica and T. viteauensis recovered from the Eocene Knysna Lignite of South Africa were examined with scanning (SEM) and transmission electron microscopy (TEM). The details of their sculpturing and wall structure are similar to the same species of fossil dispersed pollen taxa recovered from southwestern Africa and South America. Fifteen species of the woody South African taxa, Brachylaena (9 species) and Tarchonanthus (6 species) were investigated with SEM and TEM. All of the taxa are tricolporate, spherical to slightly prolate, microechinate to echinate and have a bilayered columellate infrastructure, except B.ilicifolia, which has a single columellate infrastructural level with the “granularization” of the outer portion of the infrastructural layer or the inner layer of the tectum. There is a similar distribution of plesiomorphic and derived pollen characters in a number of aster subfamilies and tribes suggesting a similar evolutionary progression of pollen, and pollen wall character evolution was occurring synchronously in a variety of aster subfamilies during the middle Tertiary and that these unique pollen features may be important to the evolution and diversification of the Asteraceae.  相似文献   

13.
14.
Samples of two subspecies of the Houbara bustard (Chlamydotis undulata undulata and C. u. macqueenii) were studied using protein electrophoresis, to evaluate their genetic variability and differentiation. Levels of polymorphism and gene diversity were higher than mean values for birds, and intersubspecies differentiation (measured by Nei's genetic distance) was in the range of the values known at this taxonomic level. These results suggest that the decrease in numbers associated with the recent reduction of these subspecies' ranges has not yet resulted in significant genetic impoverishment. This information is of prime importance in designing captive-breeding programmes for reintroduction purposes. The genetic distance between the two subspecies suggests a relatively recent differentiation, which already has resulted in marked behavioural differences.  相似文献   

15.
16.
Atlantic (Pecten maximus) and Mediterranean (Pecten jacobaeus) scallops have been traditionally considered as distinct species, but recent genetic studies have shown that they are races or subspecies separated by the Almeria-Oran oceanographic front in SE Spain. We have scored the nucleotide polymorphism of a 511 base pairs long fragment of the mitochondrial 16S ribosomal RNA gene in 85 individuals from 4 populations of P. maximus and 3 of P. jacobaeus. The populations were characterized by sharing the 2 most common haplotypes. We found no significant differences in haplotype frequencies among populations or species. However, slight, significant differentiation between taxa appeared when haplotypes were pooled in two groups according to their phylogenetic relationships and after analysis of molecular variance, in agreement with previous allozyme studies. Levels of within-population nucleotide diversity were similar in all populations except in P. jacobaeus from the northern Adriatic Sea, suggesting a smaller effective population size in that area which could be due to variable recruitment. Finally, populations showed an excess of rare haplotypes. The mismatch distribution and several population genetic statistics indicate that the excess of rare variants is due to a population expansion which occurred in the second half of the Pleistocene period, less than 0.9 my before present, and probably well after the origin of the two scallop races.  相似文献   

17.
Pollen deposition on stigmas and pollen tube growth in two apocarpous species, Ranalisma rostratum and Sagittaria guyanensis ssp. lappula (Alismataceae), were examined with fluorescence microscopy. The reallocation of pollen tubes among pistils was observed in both species. The percentage of pollinated stigmas per flower was only 22.0% in R. rostratum and 51.0% in S. guyanensis, though the seed/ovule ratios are higher than 65% in both species. The number of pollen grains on each single stigma ranged from 0 to 96 in R. rostratum, and from 0 to 125 in S. guyanensis. When more than one pollen grain deposited on a stigma, all pollen tubes grew to the ovary, but only one of them turned towards the ovule and finally entered the nucleus. The other tubes grew through the receptacle tissue into ovules of adjacent carpels whose stigmas were unpollinated or pollinated later. The intercarpellary growth of pollen tubes could be a mechanism to increase the efficiency of sexual reproduction in an apocarpous gynoecium with low pollination on the pistils.  相似文献   

18.
Trehalose is the main haemolymph sugar in many insect species. To be utilized trehalose must be hydrolysed into its glucose units by trehalase (EC 3.2.1.28). Inhibitors of trehalase have attracted interest as possible pesticides and tools for studying the regulation of trehalose metabolism in insects. To make full use of these inhibitors requires knowledge of their fate and effects in vivo. To this end we have measured trehazolin in locusts using a method based on the specific inhibition of a trehalase preparation. After injection of 20 μg, trehazolin decreased in haemolymph with a half-life of 2.6 days and after 10 days almost 95% had disappeared. Trehazolin did not reach the intracellular water space of locust tissues, but appeared with full inhibitory potency in locust faeces, suggesting that it was not metabolized, but quantitatively eliminated via the gut. Haemolymph trehalose increased transiently upon trehazolin injection, it was maximal after 3 days, then decreased and reached control level after 10 days. Inhibition of flight muscle trehalase by trehazolin was prolonged and still conspicuous 21 days post injection, suggesting that trehazolin inhibits trehalase activity irreversibly in vivo and that recovery requires de novo enzyme synthesis.  相似文献   

19.
Cytochrome P450c17 (CYP17, 17α-hydroxylase/17, 20-lyase) plays a critical role in the production of androgens and estrogens in vertebrates. We isolated the full length cDNAs of P450c17-I and P450c17-II from Sebastes schlegeli. The cDNA sequences of P450c17-I and P450c17-II encoded 515 and 533 amino acid residues respectively. The putative P450c17-I and P450c17-II enzymes of Korean rockfish share high sequence identity with that of Japanese flounder (92% and 81%) respectively. Our current study describes that P450c17s of Korean rockfish are mainly expressed in gonads, head kidney and kidney by RT-PCR. Quantitative real-time PCR showed that the expression patterns of Korean rockfish P450c17s were developmental stage-dependency. In addition, the testosterone (T) and gonadosomatic index (GSI) levels further support the important role of P450c17-I during shift in steroidogenesis. Taken together, this study provides information about the Korean rockfish P450c17s characterization and mRNA expression as such helps in further understanding of its function in gonadal development.  相似文献   

20.
The Cryphonectriaceae includes important tree pathogens, especially on the Myrtales. During a routine disease survey in the Western Cape Province of South Africa, a fungus resembling the Eucalyptus pathogen Holocryphia eucalypti was observed on native Metrosideros angustifolia (Myrtales). The aims of this study were to identify the fungus and to expand surveys for fungi in the Cryphonectriaceae on M. angustifolia. Fungi were identified based on DNA sequence comparisons and morphological features, and their pathogenicity was tested on M. angustifolia under field conditions. Based on morphology and multigene phylogenetic analyses of DNA sequence data from six gene regions, we describe a new genus including a single species and three new species of Holocryphia (Cryphonectriaceae) from M. angustifolia. These fungi are provided with the names Diversimorbus metrosiderotis gen. et sp. nov., Holocryphia capensis sp. nov., Holocryphia gleniana sp. nov., and Holocryphia mzansi sp. nov. We also revise H. eucalypti, the type of the genus, to include only isolates from Eucalyptus in South Africa. Research results indicated that H. mzansi may undergo host shifts between different tree genera in the Myrtaceae. Inoculation tests showed that isolates of all the newly described species can cause lesions on the branches of M. angustifolia, indicating that they are all pathogens of this tree.  相似文献   

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