首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 156 毫秒
1.
We compared the trophic niches of freshwater sculpins Cottus spp. with those of other co-habiting forage fishes in two groups of boreal lakes with distinct habitats and fish communities. Near North Lakes (45° 00′ to 47° 30′ N) were deeper, stratified and contained lake trout Salvelinus namaycush as the apex piscivore, whereas Far North Lakes (51° 10′ to 52° 20′ N) were shallower, did not stratify and contained pike Esox lucius and walleye Sander vitreus as the apex piscivores. Trophic niches of sculpins and other forage fishes were compared based on niche metrics calculated from muscle stable carbon (δ13C) and nitrogen (δ15N) isotope ratios. In Near North Lakes, sculpins were found almost exclusively in deep, offshore waters and their niche positions reflected a greater reliance on pelagic production (lower δ13C) and a higher trophic elevation (higher δ15N) compared with most other forage fishes. Furthermore, sculpins in Near North Lakes tended to have larger trophic niches (occupied greater area in δ13C– δ15N space), particularly in the food chain (δ15N) dimension, than other cohabiting forage fishes. In contrast, sculpins in Far North Lakes were commonly found in the nearshore and had trophic niche positions and sizes that were similar to those of the other cohabiting forage fishes. This study illustrates the flexibility in the realised trophic niches of sculpins in relation to habitat availability and fish community composition in boreal lakes.  相似文献   

2.
Cryotolerance of seeds has been studied in 103 plant species of 33 families from five regions of the Russian Far East. In 89.1% of these species, seed viability has not decreased in the course of cryogenic storage. Six species have shown interpopulation variation in the seed response to extremely low temperature (?196°C). Freezing in liquid nitrogen, which results in deep anabiosis, can be used as a means for long-term seed storage. A preliminary assessment of genetic diversity at the population level provides for the maximum possible mobilization of the species gene pool. The results of this study contribute to the development of a scientific basis for creating a seed bank of the Far Eastern flora with the purpose to conserve and restore biological resources of the region.  相似文献   

3.
A review of the species of the genus Hoplia from the Russian Far East is given. Lectotypes are designated for Anisoplia cincticollis Faldermann and Hoplia djukini Jacobson. Hoplia cincticollis (Faldermann) is recorded from the Russian Far East for the first time. An original key to the species of the genus Hoplia of the Russian Far East fauna is provided.  相似文献   

4.
A seed response to cryopreservation has been studied in 11 endemic plant species from the Russian Far East to determine the possibility of their long-term storage. It has been shown that the cryogenic treatment does not kill seeds. The viability of 10 species did not decrease (or even increased) after their cryogenic storage. We have not revealed any deviations in the development of plants germinated from seeds stored at an extremely low temperature (−196°C). To monitor germination after long-term storage, procedures of seed germination under laboratory conditions have been developed. The results of this study contribute to the creation of low-temperature seed banks, able to conserve and restore a floral biological diversity.  相似文献   

5.
The first capture of the Greenland (or Black) halibut Reinhardtius hippoglossoides in the Arctic Ocean on the border with the East Siberian Sea (79°03′–79°08′ N 139°59′–141°16′ E, 259–277 m) and the repeated findings of the species in the Laptev Sea (78°03′–78°04′ N 132°56′–133°04′ E, 307 m; 78°33′–78°35′ N 138°44′–138°48′ E, 125 m) are reported. Fish (79 specimens with the length of 15.0–44.5 cm) were caught during four bottom trawlings on the edge of the continental shelf of the two seas in the transformed waters of Atlantic origin, as evidenced by the discovery of the indicator species of these waters—the Glacier lanternfish Benthosema glaciale (Myctophidae)—in one of the stomachs of halibut. The other captures of Greenland halibut in the Arctic were also reviewed.  相似文献   

6.
We studied 654 healthy ten- to twelve-year-old children living in the Russian Far North (Taimyr peninsula) and in Siberia (town of Krasnoyarsk). The state of the body oxygenation and the systems responsible for oxygen delivery were studied according to the length of time living in the Russian Far North and season of the year. An examination of newcomer children revealed the following changes during the first year of living in the Russian Far North: an increased respiration rate and changes in its circadian rhythm; an increase in the heart rate, cardiac output, and cardiac index; an increase in the mean corpuscular volume in the red blood system; the activation of lipid peroxidation, and the changes in electrolyte balance of cells. The control mechanisms of oxygen transport system gradually stabilized during the ages of two to five years. In children living more than five years in the Russian Far North, the increased oxygen demand was met by the activation of cardiovascular and red blood systems aimed at more effective and adequate oxygen delivery to tissues.  相似文献   

7.
Many organisms use proton pump to earn energy for living. Some proton pumps start to work by light and one of the famous proteins are called proteorhodopsin (PR). From recent study it used not only protons but also mono-valent cations, divalent cations, or mono-valent anions during pumping activity. The goal of this study is to find new types of proton pumping proteins in the surface of the ocean. Metagenome samples were collected from the beach in Taean-gun and Incheon (Kkotji beach (36°30′0′′N, 126°19′56′′E), Kkotji mud (36°30′8′′N, 126°19′60′′E), Duegi beach (36°31′6′′N, 126°19′39′′E), Sorae salt pond (37°24′25′′N, 126°44′41′′E), swamp (37°24′59′′N, 126°44′54′′E) and reservoir (37°24′39′′N, 126°45′5′′E) in West Sea of Korea. Genomic DNA of each sample was isolated and used for PCR with specific primers for PR and sodium pumping rhodopsin. As a result, we obtained an unidentified PR in Duegi beach sample. The unidentified PR was expressed with chimeric expression system. It has 528 nm absorption maximum at pH 7. By the light differential spectrum measurement, putative M and O photo-intermediates were detected at around 400 and 600 nm, respectively. Similar to GPR, it has light driven outward proton transfer activity.  相似文献   

8.
Questions: Fire is a strong filter in fire‐prone communities and is expected to assemble closely related species when functional traits are conserved in plant lineages. Do frequent fires assemble savannas with closely related species (phylogenetic clustering)? If so, what are the clades pruned by fire in the phylogenetic trees? Are species of semi‐deciduous seasonal forests, where fires are not frequent, less related than expected by chance (phylogenetic over‐dispersion)? Are life forms conserved in the phylogeny of the species? Location: Central and SE Brazilian savannas (Emas National Park, 18°18′S, 52°54′W; Brasília, 15°56′–15°57′S, 47°53′–47°56′W and Corumbataí‐Itirapina, 22°13′–22°15′S, 47°37′–47°39′W); and close semi‐deciduous seasonal forests (in Pirenópolis, 15°45′S, 49°04′W; Brasília, 15°33′S, 47°51′W; and São Carlos, 21°55′S, 47°48′W). Methods: We recorded woody species in savannas under different fire regimes and in semi‐deciduous seasonal forests. We obtained data from the literature and from field sampling. We compared mean phylogenetic distance of species of savanna and of nearby semi‐deciduous seasonal forest sites. We obtained significance by randomizing the species among the tips of phylogenetic trees. We also assessed whether life forms were evolutionary conserved across phylogeny of the studied plants (phylogenetic signal) with tests based on the variance of phylogenetic independent contrasts. Results: Some sites of savanna under high fire frequency were characterized by phylogenetic over‐dispersion of woody species whereas, in contrast, some sites of semi‐deciduous seasonal forest were characterized by phylogenetic clustering. We found phylogenetic signals in the traits across the phylogeny of the 801 species investigated. Conclusion: Fire may have different roles in assembling plant species in Brazilian savannas than in other fire‐prone communities. We postulate that the absence of phylogenetic clustering in the cerrado is mainly due to the persistence of long‐lived resprouting species from different plant lineages.  相似文献   

9.
The size and sex compositions, spawning period, and length at sexual maturity of the gilt sardine Sardinella aurita dwelling in the Central Eastern Atlantic in the area of 15°31′–26°32′ N and 14°09′–17°50′ W were examined from material of many years (1968–2004). The age and rate of linear growth and the relation of length and weight were determined.  相似文献   

10.
The metazoan parasites of 403 specimens of the southern ray's bream Brama australis from three localities in southern Chile (Lebu 36° 70′ S; 73° 40′ W, Calbuco 41° 50′ S; 73° 08′ W and Punta Arenas 53° 10′ S; 70° 50′ W) were recorded. More than 23 400 parasite specimens belonging to 12 taxa were registered. Metazoan parasites were dominated by the copepod Hatschekia conifera, constituting 97% of the total number of parasites; the larval cestode Hepatoxylon trichiuri was the second most important parasite (2·1% of the total number of parasites). The remaining 10 species constituted <1% of the metazoan parasites. Parasitological evidence, based on univariate and multivariate analysis, does not support the existence of discrete stocks in the studied zone.  相似文献   

11.
Genetic diversity of Siberian roe deer Capreolus pygargus, 1771 from the Russian Far East was studied based on polymorphism analysis of a mtDNA control region fragment (390 bp). Three phylogenetic lines were found in the animals examined. The trend for change of haplotypes of different phylogroups was shown to occur from north to south in Sikhote-Alin. The haplotype distribution of Siberian roe deer in the Russian Far East correlated with data on morphologiocal variability.  相似文献   

12.
Issues associated with newly emerging viruses, their genetic diversity, and viral evolution in modern environments are currently attracting growing attention. In this study, a phylogenetic analysis was performed and the evolution rate was evaluated for such pathogenic flaviviruses endemic to Russia as tick-borne encephalitis virus (TBEV) and Powassan virus (PV). The analysis involved 47 nucleotide sequences of the TBEV genome region encoding protein E and 17 sequences of the PV NS5-encoding region. The nucleotide substitution rate was estimated as 1.4 × 10−4 and 5.4 × 10−5 substitutions per site per year for the E protein-encoding region of the TBEV genome and for the NS5 genome region of PV, respectively. The ratio of non-synonymous to synonymous nucleotide substitutions (dN/dS) in viral sequences was calculated as 0.049 for TBEV and 0.098 for PV. The highest dN/dS values of 0.201–0.220 were found in the subcluster of Russian and Canadian PV strains, and the lowest value of 0.024 was observed in the cluster of Russian and Chinese strains of the Far Eastern TBEV genotype. Evaluation of time intervals between the events of viral evolution showed that the European subtype of TBEV diverged from the common TBEV ancestor approximately 2750 years ago, while the Siberian and Far Eastern subtypes emerged approximately 2250 years ago. The PV was introduced into its natural foci of the Russian Primorskii krai only approximately 70 years ago; these strains were very close to Canadian PV strains. The pattern of PV evolution in North America was similar to the evolution of the Siberian and Far Eastern TBEV subtypes in Asia. The moments of divergence between major genetic groups of TBEV and PV coincide with historical periods of climate warming and cooling, suggesting that climate change was a key factor in the evolution of flaviviruses in past millennia.  相似文献   

13.
Investigations were conducted upon the epipelic algal community of a shallow eutrophic lake in central Alberta, Canada. The lake was Hastings Lake (longitudes 112° 50′ and 113° 00′ W; latitudes 53° 15′ and 53° 50′ N). The epipelic algae displayed both spatial and temporal distributions for species composition, standing crop as well as productivity. In situ cross incubation experiments showed the potential photosynthetic viability of epipelic algae living below the 1% irradiance level.  相似文献   

14.
Abstract Due to the risk of extinction and ornamental value of the swallowtail butterfly, Sericinus montelus Gray (Lepidoptera: Papilionidae) in China, knowledge about local adaptations is important for the conservation and economical utilization of the species. In the present study, photoperiodic diapause induction and diapause intensity of S. montelus populations from Jiamusi (46°37′N), Beijing (40°15′N), Zibo (36°48′N), Fangxian (32°36′N), Wuhan (30°33′N) and Huaihua (27°33′N) were characterized at 25°C. Logistic regression analysis revealed a significant population × hours of light interaction, confirming that photoperiodic responses varied among populations. The critical photoperiod was positively correlated with latitude and increased toward the north at a rate of about 1 h for each 6.67 degrees of latitude. Survival analyses indicated that survival time of diapausing pupae before adult eclosion differed significantly among populations at 25°C and 16 : 8 L : D h. The mean duration of pupal diapause was also positively correlated with latitude. Our study reveals geographic variation in the critical photoperiod for diapause induction and in diapause intensity of S. montelus. These results provide useful information for our general understanding about seasonal adaptation in insects and may also be used to predict how geographic populations respond to climate warming.  相似文献   

15.
燕山地区表土花粉与植被间的数量关系   总被引:25,自引:0,他引:25       下载免费PDF全文
 根据表土花粉分析和植被样方调查,燕山地区各植被带的表土孢粉组合在总体面貌上代表了植被组成,但孢粉组合不等于植被组成,而影响其差异的原因是孢粉保存、孢粉产量、外来孢粉和孢粉鉴定。表土花粉的代表性因种属不同而差异颇大,乔木植物花粉中松(Pinus)、桦(Betula)、胡桃  相似文献   

16.
Classical potential functions (CPF) calculations on 3′-mononucleotides, the building blocks of nucleic acids, predict a correlation between the sugar ring pucker and the torsion angle Φ′ around the C3′? O3′ bond. In ribonucleotides, the value of Φ′ depends on the sugar pucker, viz. the C2′-endo sugar pucker is associated with Φ′ = 210° and 270°, while the C3′-endo sugar pucker favors only Φ′ = 210°. On the other hand, in deoxyribonucleotides, both sugar puckers show a preference for Φ′ = 180°. These theoretical predictions are fully corroborated by the results obtained from x-ray and nmr studies on mono-, di-, and polynucleotides.  相似文献   

17.
Hoplitomeryx Leinders was originally described only on cranial characters. The type specimens were found during the 1970's in karstic fissure fillings, most likely of Messinian age, in Gargano (Apulia, southeastern Italy), between Poggio Imperiale (41°49′30′ N, 15°21′58′ E) and Apricena (41°47′06′ N, 15°26′41′ E). During the 1990's, Hoplitomeryx remains were also discovered in the lower Tortonian layered calcarenites near Scontrone (Abruzzo, central Italy; 41°45′15.55′ N, 14°02′13.23′ E). The skull fragments, teeth, and jawbones from both localities have been examined. The dental characters had never been described before, and also some maxillaries and jawbones were not part of the original sample that was analyzed to establish the genus. Because they possess two lacrimal orifices and closed metatarsal gulley, hoplitomerycids have been linked more closely with Cervids, and accommodated in Cervoidea. A cladistic analysis of a character-taxon matrix of 121 morphological features (48 cranial, 51 dental and 22 postcranial characters) is performed. The analysis shows that hoplitomerycids stem either between antilocaprids and bovids, or antilocaprids and giraffids. They are not linked directly with cervids. Hoplitomerycids likely stemmed from a primitive ruminant stock, perhaps around 29 Ma when a land bridge connected the Abruzzo-Apulia platform with the Balkans across the Adriatic Sea. In the new land, hoplitomerycids developed a mosaic of apomorphic and homoplastic (convergent) character states that recall those found in other higher ruminants.  相似文献   

18.
The study presents length–weight relationships (LWRs) and length–length relationships (LLRs) for three algae‐scraper species; Capoeta coadi from the Kouhrang River (Iran; 32°23′N, 50°08′E) a part of the Tigris drainage basin, Capoeta pyragyi from Cheshmeh Langan River (32°55′N, 50°10′E) a part of Zayanderud River basin and Capoeta umbla from Chooman River (35°57′N, 45°47′E). Fish were sampled by electro fishing (Samus1000; Power Out: 200 watts) in August, September and October 2017. Sampling was carried out each months in sites covering an area of about 100 m2 including runs, riffles and pools at a water depth of 10–60 cm. The obtained LWRs and LLRs showed a high level of correlation (r> 0.99).  相似文献   

19.
Aim This paper examines the migration of the tropical nectarivorous bat Leptonycteris curasoae considered as a latitudinal migrant that breeds in south-west United States and northern Mexico in spring and migrates southward during fall. We tested the hypothesis that the latitudinal migration occurs only locally given by the local availability of bat resources, leading to migratory movements in zones with seasonal scarcity of resources and to resident bat populations where resources are available throughout the year. Localization We analysed the presence of L. curasoae along its distribution range in North America (between 14°N and 33°N). Study cases were also conducted in three Mexican localities: the Tehuacán Valley (17°48′–18°58′N and 96°48′–97°43′W), Sonoran Desert (28°41′N and 110°15′W), and the coast of Jalisco (19°32′N and 105°07′W). Methods Geographic evidence for latitudinal migration of L. curasoae was analysed using 94-year capture records housed in twenty-two collections of North America. Records were analysed using a Geographical Information System (GIS), in which floral resources and capture records were integrated. Monthly captures in the Tehuacán Valley were conducted during three years and bats abundance and reproductive status were correlated with the phenology of bat resources. Bat captures were also conducted during two consecutive years in an extratropical desert during winter and spring, and during one spring in the coast of Jalisco. Results The latitudinal migration of L. curasoae in North America only occurs at latitudes near 30°N, whereas bats may be residents at latitudes lower than 21°N. Captures were associated always to the availability of floral resources in both geographical and local scales. Main conclusions The existence of resident populations in the tropics with two reproductive events support the hypothesis that migration only occurs in the northern distribution limit of this nectar-feeding bat.  相似文献   

20.
Length‐weight relationship parameters were calculated for six fish species from São Marcos Bay, in Northeast Brazil (the segment between 02°35′55″S and 44°20′58″W; 02°34′53″S and 44°21′48″W; 02º42′25″S and 44º26′46″W). The specimens were caught quarterly from April 2010 to February 2013, using monofilament gillnets (2, 4 and 6 cm between knots) from 100 m to 3,000 m long and 4 m to 6 m high. The present study covers a much wider size range for four species and adds new information for the maximum length of Notarius bonillai.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号