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ABSTRACT: Sal (Shorea robusta Gaertn., Dipterocarpaceae) is a wind-pollinated tropical tree species found in southern Asia. We investigated the genetic
diversity and structure at four microsatellites of 15 populations comprising continuous-peripheral and disjunct-peripheral
populations in Nepal. Estimates of genetic diversity (N
A=8.98, H
O=0.62, H
E=0.69) were similar when compared with those of other tropical tree species. A higher level of genetic diversity was observed
in continuous-peripheral populations (N
A=9.61, H
O=0.67, H
E=0.72) as compared to disjunct-peripheral (N
A=8.04, H
O=0.55, H
E=0.64). Population differentiation was higher among disjunct-peripheral populations (F
ST=0.043) than among continuous peripherals (F
ST=0.012). There was a significant association between gene flow distances and genetic differentiation (r
2=0.128, P≤0.007). No spatial arrangement of populations according to their geographical locations was found. Based on observed genetic
diversity protection of some populations in continuous-peripheral range are suggested for the sustainable conservation of
genetic resources of the species while protection of some disjunct-peripheral populations are also recommended for conserving
rare alleles.
KeywordsConservation-
Shorea robusta
-Microsatellites-Genetic diversity-Peripheral populations-Nepal
Conservation Genetics 04/2012; 11(3):977-984. · 1.61 Impact Factor
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ABSTRACT: Sal (Shorea robusta) is a tree species with very good quality timber found across tropical south Asia. Due to over-exploitation, its genetic resources are highly depleted. Here we report for the first time on molecular markers in sal. Cross-species amplification of 27 Shorea microsatellites resulted in 24 of them harboring amplicons of expected sizes. Five microsatellites were moderate to highly polymorphic (N(a)=6-19). Observed and expected heterozygosities ranged from 0.49 to 0.77 and 0.52 to 0.89, respectively. These microsatellites are found to be adaptively neutral and are useful for population genetic studies in this species.
Hereditas 03/2009; 146(1):29-32. · 0.79 Impact Factor
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ABSTRACT: A set of 107 hulless barley (Hordeum vulgare L. subsp. vulgare) landraces originally collected from the highlands of Nepal along the Annapurna and Manaslu Himalaya range were studied for genetic relatedness and population differentiation using simple sequence repeats (SSRs). The 44 genome covering barley SSRs applied in this study revealed a high level of genetic diversity among the landraces (diversity index, DI = 0.536) tested. The genetic similarity (GS) based UPGMA clustering and Bayesian Model-based (MB) structure analysis revealed a complex genetic structure of the landraces. Eight genetically distinct populations were identified, of which seven were further studied for diversity and differentiation. The genetic diversity estimated for all and each population separately revealed a hot spot of genetic diversity at Pisang (DI = 0.559). The populations are fairly differentiated (theta = 0.433, R(ST) = 0.445) accounting for > 40% of the genetic variation among the populations. The pairwise population differentiation test confirmed that many of the geographic populations significantly differ from each other but that the differentiation is independent of the geographic distance (r = 0.224, P > 0.05). The high level of genetic diversity and complex population structure detected in Himalayan hulless barley landraces and the relevance of the findings are discussed.
Theoretical and Applied Genetics 08/2006; 113(4):715-29. · 3.30 Impact Factor
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ABSTRACT: Allozyme and PCR-based molecular markers have been widely used to investigate genetic diversity and population genetic structure in autotetraploid species. However, an empirical but inaccurate approach was often used to infer marker genotype from the pattern and intensity of gel bands. Obviously, this introduces serious errors in prediction of the marker genotypes and severely biases the data analysis. This article developed a theoretical model to characterize genetic segregation of alleles at genetic marker loci in autotetraploid populations and a novel likelihood-based method to estimate the model parameters. The model properly accounts for segregation complexities due to multiple alleles and double reduction at autotetrasomic loci in natural populations, and the method takes appropriate account of incomplete marker phenotype information with respect to genotype due to multiple-dosage allele segregation at marker loci in tetraploids. The theoretical analyses were validated by making use of a computer simulation study and their utility is demonstrated by analyzing microsatellite marker data collected from two populations of sycamore maple (Acer pseudoplatanus L.), an economically important autotetraploid tree species. Numerical analyses based on simulation data indicate that the model parameters can be adequately estimated and double reduction is detected with good power using reasonable sample size.
Genetics 02/2006; 172(1):639-46. · 4.01 Impact Factor
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ABSTRACT: We investigated five population pairs of Dalbergia sissoo in Nepal for variation of cpDNA and at the isozyme gene locus Gdh-A. Each population pair consisted of one natural population and a neighboring plantation. Two or three different cpDNA-haplotypes were observed in each population with a total of eight different haplotypes. The differentiation of cpDNA haplotypes between the group of natural populations and the group of plantations was almost complete. Thus, the plantations did not originate from any of the investigated natural populations, but reproductive material was transported over long distances during plantation establishment. All plantations proved to be fixed at the Gdh‑A gene locus, which showed considerable polymorphism in natural populations indicating different adaptive potentials of plantations and natural stands. Mise en évidence de transferts à longue distance de matériel de reproduction utilisé pour des plantations de Dalbergia sissoo Roxb. au Népal par l’utilisation de marqueurs moléculaires. On a étudié la variabilité d’ADNcp et de l’isozyme du locus Gdh-A dans cinq paires de populations de Dalbergia sissoo situées au Népal. Chaque paire comportait une population naturelle et une plantation située à proximité ; on a observé l’existence de deux ou trois ADNcp haplotypes dans chaque population avec, au total, huit haplotypes différents. La différenciation pour les ADNcp haplotypes entre le groupe des populations naturelles et celui des plantations était presque générale. Il en résulte que les plantations ne sont pas issues des populations naturelles étudiées ; le matériel de reproduction a été transporté sur de longues distances au cours des opérations de plantation. Aucune variation du niveau du locus du gène Gdh-A n’a été trouvée pour toutes les plantations, alors qu’il existe un polymorphisme considérable dans les populations naturelles. Il en résulte un potentiel d’adaptation différent entre plantations et peuplements naturels.
http://dx.doi.org/10.1051/forest:2004056.
