Assessing Genetic Differentiation in Geographic Populations of Labeo calbasu Using Allozyme Markers

The population structure of Labeo calbasu from 11 rivers belonging to the Indus, Ganges, Bhima, Mahanadi, and Godavari basins was investigated using allozyme marker systems. Seven out of 20 allozyme loci (35%) were polymorphic (P < 0.99). Both probability and score tests indicated significant deviation of genotype proportions from Hardy–Weinberg expectations at two loci, XDH* (Mahanadi, Bhima, and Godavari) and G6PDH* (Mahanadi). A pairwise genetic homogeneity test and F _ST values indicated a low-to-moderate level (0.0515) of genetic structuring in the wild population of L. calbasu. AMOVA analysis also indicated moderate differentiation among the samples from different river basins. Analysis for genetic bottleneck was performed under the infinite allele model. The study revealed nine genetic stocks of L. calbasu from the natural population across Indian rivers. Evidence of genetic bottlenecks in some rivers was also revealed.     

鲤科鱼蓝黑鲮微卫星位点的种间扩增(英文)

本研究使用105对微卫星引物对7种鲤科鱼类进行跨越种间PCR扩增,共得到14个多态性微卫星位点.其中9个扩增效果较好的位点用于分析来自帕吉勒提河(Bhagirathi, n=20)和戈达瓦里河(Godavari, n=25)的蓝黑鲮(Labeo calbasu)样品的遗传多样性.结果显示,前者在每个位点的平均等位基因数为7.33,而后者为8 1,期望杂合度介于0.795(Bhagirathi)和0.801(Godavari)之间;4个位点MFW11* (Godavari)、R1*(Godavari)、R3* (Bhagirathi) 和 Lr38*(Bhagirathi和Godavari)都表现出明显的杂合子缺失和哈迪温伯格平衡偏离;而任意两位点间都未观测到连锁不平衡现象;位点R3*极可能存在无效等位基因.上述结果表明这些多态性微卫星位点作为共显性标记在蓝黑鲮群体遗传学研究中有着较好的应用前景.     

使用多态异型酶标记物估计野鲮的遗传变异性

本文首次分析了野鲮鱼 (Labeodyocheilus)等位酶的变异情况。通过对 17个酶系统的研究 ,发现 2 8个可以稳定检测的位点 ,其中 8个位点具有多态性。使用这 8个等位酶位点 ,分析了取自不同河流 ,即Satluj、Yamuna和Tons河的样本的遗传多样性情况。结果显示 ,不同样本间存在显著的遗传异质性 ,各位点的表观杂合度介于 0 0 392 (Yamuna河 )与 0 0 4 87(Tons河 )之间。因此 ,本研究所筛选出的多态性等位酶位点为研究该野鲮鱼的种群遗传结构奠定了基础     

Evaluation of Genetic Variation in the Clown Knifefish, Chitala chitala, Using Allozymes, RAPD, and Microsatellites

Twenty-seven enzyme systems, six random amplified polymorphic DNA (RAPD) primers, and two microsatellite loci were tested to determine intraspecific divergence in the natural population of the endangered Indian featherback fish, Chitala chitala, for the first time. The 262 samples of C. chitala were collected from six riverine locations in India: the Satluj, Ganga (Ghagra, Bhagirathi, and Brahmaputra), Mahanadi, and Narmada river systems. The analysis revealed population subdivisions, with an F_ST value from 0.1235 (95% confidence 0.0868–0.1621) for RAPD and a combined F_ST of 0.0344 (95% confidence 0.0340–0.0350) for microsatellite loci. An analysis of 38 allozyme loci did not reveal any polymorphism in the samples from any of the riverine localities; a possible explanation for this could be that the ancestors of Chitala could have faced a population reduction in prehistoric periods, as low allozyme variation is also reported for other species of Chitala from south Asia.     

Population genetic structure and phylogeography of cyprinid fish, <Emphasis Type="Italic">Labeo dero</Emphasis> (Hamilton, 1822) inferred from allozyme and microsatellite DNA marker analysis

We examined population structure of Labeo dero (Hamilton, 1822) from different riverine locations in India using 10 polymorphic allozyme and eight microsatellite loci. For analysis, 591 different tissue samples were obtained from commercial catches covering a wide geographic range. Allozyme variability (An = 1.28–1.43, Ho = 0.029–0.071) was much lower than for microsatellites (An = 4.625–6.125, Ho = 0.538–0.633). Existence of rare alleles was found at three allozyme (MDH-2*, GPI* and PGDH*) and at two microsatellite loci (R-3* and MFW-15*). Deviation from Hardy–Weinberg equilibrium (P < 0.05, after the critical probability levels were adjusted for sequential Bonferroni adjustment) could be detected at three loci (EST-1*, -2* and XDH*) whereas, after correction for null alleles, two microsatellite loci (MFW-1*,-15*) deviated from HWE in the river Yamuna. Fst for all the samples combined over all allozyme loci was found to be 0.059 suggesting that 5.9% of the total variation was due to genetic differentiation while microsatellite analysis yielded 0.019 which was concordant to mean Rst (0.02). Hierarchical partition of genetic diversity (AMOVA) showed that greater variability (approx. 95%) was due to within population component than between geographical regions. Based on distribution of genetic differentiation detected by both markers, at least five different genetic stocks of L. dero across its natural distribution could be identified. These results are useful for the evaluation and conservation of L. dero in natural water bodies.     

印度恒河蓝黑鲮与南亚黑鲮杂交个体的分子检测

利用鉴别性的同工酶位点从印度恒河水系的支流Banganga中检测到了蓝黑鲮(Labeo calbasu)与南亚黑鲮(Labeorohita)的一个杂交个体。线粒体DNA的单倍型模式进一步确认这个杂交个体的母本是河蓝黑鲮。     

Mitochondrial DNA variation in natural populations of endangered Indian Feather-Back Fish, Chitala chitala

Genetic variation at mitochondrial cytochrome b (cyt b) and D-loop region reveals the evidence of population sub-structuring in Indian populations of highly endangered primitive feather-back fish Chitala chitala. Samples collected through commercial catches from eight riverine populations from different geographical locations of India were analyzed for cyt b region (307 bp) and D-loop region (636–716 bp). The sequences of the both the mitochondrial regions revealed high haplotype diversity and low nucleotide diversity. The patterns of genetic diversity, haplotypes networks clearly indicated two distinct mitochondrial lineages and mismatch distribution strongly suggest a historical influence on the genetic structure of C. chitala populations. The baseline information on genetic variation and the evidence of population sub-structuring generated from this study would be useful for planning effective strategies for conservation and rehabilitation of this highly endangered species.     

Polymorphic microsatellite markers isolated from partially enriched genomic library of Chitala chitala

A total eight polymorphic microsatellite loci were obtained from genomic library of Indian feather back, Chitala chitala (order Osteoglossiformes, family Notopteridae) and the 46 samples were analysed to determine genetic variation. The mean number of alleles per locus ranged from 4.50 to 5.25, and expected heterozygosity ranged from 0.124 to 0.852. Deviation from Hardy–Weinberg equilibrium expectations (P < 0.002) was observed at loci Cch2, Cch9 (Bhaghirathi) and Cch9 (Brahmaputra). The identified microsatellite loci were found promising for population genetics studies of C. chitala and related species Notopterus notopterus (family Notopteridae).     

Genetic divergence in wild population of <Emphasis Type="Italic">Labeo rohita</Emphasis> (Hamilton, 1822) from nine Indian rivers,analyzed through MtDNA cytochrome b region

The present study examined partial cytochrome b gene sequence of mitochondrial DNA for polymorphism and its suitability to determine the genetic differentiation in wild Labeo rohita. The 146 samples of L. rohita were collected from nine distant rivers; Satluj, Brahmaputra, Son, Chambal Mahanadi, Rapti, Chauka, Bhagirathi and Tons were analyzed. Sequencing of 307 bp of Cyto b gene revealed 35 haplotypes with haplotype diversity 0.751 and nucleotide diversity (π) 0.005. The within population variation accounted for 84.21% of total variation and 15.79% was found to among population. The total Fst value, 0.158 (P < 0.05) was found to be significant. The results concluded that the partial cyto b is polymorphic and can be a potential marker to determining genetic stock structure of L. rohita wild population.