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1.
Genetic variation is a key component for improving a stock through selective breeding programs. Randomly amplified polymorphic DNA (RAPD) markers were used to assess genetic variation in three wild population of the catla carp (Catla catla Hamilton 1822) in the Halda, Jamuna and Padma rivers and one hatchery population in Bangladesh. Five decamer random primers were used to amplify RAPD markers from 30 fish from each population. Thirty of the 55 scorable bands were polymorphic, indicating some degree of genetic variation in all the populations. The proportion of polymorphic loci and gene diversity values reflected a relatively higher level of genetic variation in the Halda population. Sixteen of the 30 polymorphic loci showed a significant (p < 0.05, p < 0.01, p < 0.001) departure from homogeneity and the F(ST) values in the different populations indicated some degree of genetic differentiation in the population pairs. Estimated genetic distances between populations were directly correlated with geographical distances. The unweighted pair group method with averages (UPGMA) dendrogram showed two clusters, the Halda population forming one cluster and the other populations the second cluster. Genetic variation of C. catla is a useful trait for developing a good management strategy for maintaining genetic quality of the species.  相似文献   

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The ovaries of female lac insects, Kerria chinensis Mahd (Sternorrhyncha: Coccoidea: Kerridae), at the last nymphal stage are composed of several balloon‐like clusters of cystocytes with different sizes. Each cluster consists of several clusters of cystocytes arranging in rosette forms. At the adult stage, the pair of ovaries consists of about 600 ovarioles of the telotrophic‐meroistic type. An unusual feature when considering most scale insects is that the lateral oviducts are highly branched, each with a number of short ovarioles. Each ovariole is subdivided into an anterior trophic chamber (tropharium) containing six or seven large trophocytes and a posterior vitellarium harbouring one oocyte which is connected with the trophic chamber via a nutritive cord. No terminal filament is present. Late‐stage adult females show synchronized development of the ovarioles, while in undernourished females, a small proportion of ovarioles proceed to maturity.  相似文献   

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In DNA barcoding, a short standardized DNA sequence is used to assign unknown individuals to species and aid in the discovery of new species. A fragment of the mitochondrial gene cytochrome c oxidase subunit 1 is emerging as the standard barcode region for animals. However, patterns of mitochondrial variability can be confounded by the spread of maternally transmitted bacteria that cosegregate with mitochondria. Here, we investigated the performance of barcoding in a sample comprising 12 species of the blow fly genus Protocalliphora, known to be infected with the endosymbiotic bacteria Wolbachia. We found that the barcoding approach showed very limited success: assignment of unknown individuals to species is impossible for 60% of the species, while using the technique to identify new species would underestimate the species number in the genus by 75%. This very low success of the barcoding approach is due to the non-monophyly of many of the species at the mitochondrial level. We even observed individuals from four different species with identical barcodes, which is, to our knowledge, the most extensive case of mtDNA haplotype sharing yet described. The pattern of Wolbachia infection strongly suggests that the lack of within-species monophyly results from introgressive hybridization associated with Wolbachia infection. Given that Wolbachia is known to infect between 15 and 75% of insect species, we conclude that identification at the species level based on mitochondrial sequence might not be possible for many insects. However, given that Wolbachia-associated mtDNA introgression is probably limited to very closely related species, identification at the genus level should remain possible.  相似文献   

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More than 90% of birds are socially monogamous, although genetic studies indicate that many are often not sexually monogamous. In the present study, DNA fingerprinting was used to estimate the genetic relationships between nestlings belonging to the same broods to evaluate the mating system in the socially monogamous macaw, Ara ararauna. We found that in 10 of 11 broods investigated, the nestlings showed genetic similarity levels congruent with values expected among full-sibs, suggesting that they shared the same parents. However, in one brood, the low genetic similarity observed between nestlings could be a result of intraspecific brood parasitism, intraspecific nest competition or extra-pair paternity. These results, along with available behavioral and life-history data, imply that the blue-and-yellow macaw is not only socially, but also genetically monogamous. However, the occurrence of eventual cases of extra-pair paternity cannot be excluded.  相似文献   

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Diversity in 26 microsatellite loci from section Caulorrhizae germplasm was evaluated by using 33 accessions of A. pintoi Krapov. & W.C. Gregory and ten accessions of Arachis repens Handro. Twenty loci proved to be polymorphic and a total of 196 alleles were detected with an average of 9.8 alleles per locus. The variability found in those loci was greater than the variability found using morphological characters, seed storage proteins and RAPD markers previously used in this germplasm. The high potential of these markers to detect species-specific alleles and discriminate among accessions was demonstrated. The set of microsatellite primer pairs developed by our group for A. pintoi are useful molecular tools for evaluating Section Caulorrhizae germplasm, as well as that of species belonging to other Arachis sections.  相似文献   

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Trichieurina haladai sp. n. (Diptera, Chloropidae), is described from Zambia. All known Trichieurina species are keyed and main differential characters are illustrated.  相似文献   

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The 2C DNA values in 38 species and accessions of the genus Lupinus (Fabaceae) from the New World have been analysed using flow cytometry. They are representatives of North and South American species (the Atlantic and the Andean regions). Estimated 2C DNA values ranged from 1.08 pg in L. pusillus to 2.68 pg in L. albicaulis (both from North America), that is a variation of more than 2.5-fold. The variation for North American lupins was much higher than that for South American ones. Statistical analysis of the data resulted in a grouping that showed for North American lupins some correlation with the length of life cycle. Discussion concerns some aspects of the evolution of the genus.  相似文献   

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Pseudoogeton maoxianum sp. n. is described from Sichuan, China. A key to the males of the species of Pseudoogeton Masumoto, 1989 is presented.  相似文献   

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We used RAPDs (Random Amplified Polymorphic DNA) to test genetic divergence between two populations of Bosmina spp. in Lake Östersjön, Sweden. Previous taxonomic studies on European species within the genus Bosmina have been based on morphological characters alone. RAPD markers distinguished the two populations and supported the specific status of B. coregoni and B. longispina based on morphological characters. Furthermore, juveniles with a long antennule and a mucro were classified as B. coregoni. RAPDs also revealed genetic differences among the tested individuals, suggesting several clones within each species.  相似文献   

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Heather plants were collected from 34 populations in Great Britain, which differed according to their geographical location and associated management histories. Comparisons of differential grazing regimes were made across 10 sites in the first year of study, whereas the influence of differential burning regimes was considered at four sites during the second year. The extent of genetic variation, both within and between the selected heather populations, was examined using polymerase chain reaction (PCR)-based DNA fingerprinting methodologies. Initially, high genetic variation within populations obscured differences between populations. Heather stands that were geographically close proved to be genetically similar. Site latitude and longitude were strongly associated with genetic differences between heather populations; however, a range of grazing and burning management treatments had no consistent effect upon genetic diversity. The results represent the first national survey of genetic variation at the DNA level within UK populations of this important heathland species. They provided insights into the genetic structure of heather-dominated heathlands, revealing a lack of clonal dominance within populations, but rather a much more varied genetic makeup than might have been expected given the species' ability to propagate vegetatively. The processes that influence genetic diversity in heather populations are discussed, and the potential role of molecular techniques in heathland conservation is considered.  相似文献   

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Random amplified polymorphic DNA (RAPDs) were used to investigate the intraspecific variability among 19 geographic isolates of Globodera tabacum solanacearum from eight counties in Virginia and one county in North Carolina. Globodera tabacum tabacum, G. t. virginiae, and the Mexican cyst nematode (MCN) were included as outgroups. Six primers were used and 119 amplification products were observed. Each primer yielded reproducible differences in fragment patterns that differentiated the isolates and species. Hierarchical cluster analysis was performed to illustrate the relatedness among isolates and species. The average Jaccard''s similarity index among isolates of G. t. solanacearum was 74%, possibly representing greater variation than that reported in the literature across different pathotypes of the potato cyst nematode, Globodera pallida, in studies where RAPD were also employed. The RAPD markers described here may be useful for the development of specific primers or probes that could improve the identification of TCN populations. Such improvements in the characterization of TCN genotypes would facilitate the effective deployment of existing and future resistant cultivars to control these economically important pests.  相似文献   

14.
A new species, Notopygus longiventris Sun & Sheng, sp. n., collected from Benxi County, Liaoning Province, China, and N. emarginatus Holmgren, 1857, reared from Neurotoma sibirica Gussakovskij (Hymenoptera, Pamphiliidae) from Haicheng, Liaoning Province, are reported. The new species is placed within existing key to species.  相似文献   

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Cano EB  Schuster JC 《ZooKeys》2012,(194):81-87
Oileus gasparilomisp. n. is described from nine specimens from the mountains of Quiché in Guatemala, from cloud forest at 1795 m elevation. This represents the second species of the genus for Guatemala, differing from the closely related Mexican species Oileus rimator (Truqui) in having a straight anterior clypeal border, the postocular sulcus divided by a keel and the pronotum almost straight (not clearly bilobed). A key to the species of Oileus is given.  相似文献   

18.
Xin S  Jian-Xiu C  Louis D 《ZooKeys》2011,(78):27-41
In this paper, we describe a new species of the genus Allonychiurus Yoshii, 1995, characterized by the presence of an apical swelling on the fourth antennal segment as well as a combination of chaetotaxic and pseudocellar characters. The genus Allonychiurus is redefined. Four of its species are considered as incertae sedis: Allonychiurus michelbacheri (Bagnall, 1948), Allonychiurus spinosus (Bagnall, 1949), Allonychiurus caprariae (Dallai, 1969) and Allonychiurus sensitivus (Handschin, 1928). The three species Allonychiurus borensis (Beruete, Arbea & Jordana, 1994), Allonychiurus sensilatus (Thibaud & Massoud, 1979) and Allonychiurus vandeli (Cassagnau, 1960) are removed from Allonychiurus and placed in Micronychiurus Bagnall, 1949, Thalassaphorura Bagnall, 1949 and Spinonychiurus Weiner, 1996 respectively. The synonymy of Thibaudichiurus Weiner, 1996 with Allonychiurus is rejected and Allonychiurus foliatus (Rusek, 1967) and Allonychiurus mariangeae (Thibaud & Lee, 1994) are re-allocated to Thibaudichiurus. List and identification key to the world species of the genus are given.  相似文献   

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