Genetic Markers and Quantitative Genetic Variation in Medicago truncatula (Leguminosae): A Comparative Analysis of Population Structure

Genetics ◽  
1996 ◽  
Vol 143 (4) ◽  
pp. 1795-1805 ◽  
Author(s):  
Isabelle Bonnin ◽  
Jean-Marie Prosperi ◽  
Isabelle Olivieri

Abstract Two populations of the selfing annual Medicago truncatula Gaertn. (Leguminoseae), each subdivided into three subpopulations, were studied for both metric traits (quantitative characters) and genetic markers (random amplified polymorphic DNA and one morphological, single-locus marker). Hierarchical analyses of variance components show that (1) populations are more differentiated for quantitative characters than for marker loci, (2) the contribution of both within and among subpopulations components of variance to overall genetic variance of these characters is reduced as compared to markers, and (3) at the population level, within population structure is slightly but not significantly larger for markers than for quantitative traits. Under the hypothesis that most markers are neutral, such comparisons may be used to make hypotheses about the strength and heterogeneity of natural selection in the face of genetic drift and gene flow. We thus suggest that in these populations, quantitative characters are under strong divergent selection among populations, and that gene flow is restricted among populations and subpopulations.

2017 ◽  
Vol 51 (1) ◽  
pp. 31-36
Author(s):  
K. E. Ogbuebunu ◽  
M. O. Awodiran

Abstract Thirty Lates niloticus (Linnaeus, 1758) from three Nigerian waterbodies were genotyped on six RAPD primers and five microsatellites loci. RAPD revealed that effective number of alleles (AE) at population level per locus was within the range of 1.641 ± 0.066 to 1.645 ± 0.041 while the mean number of alleles (AN) across populations equals 2.000. Characterization on five microsatellites loci revealed genetic diversity within and among studied populations. Observed heterozygousity (HO) was within the range of 0.317 ± 0.335 to 0.523 ± 0.315 while expected heterozygousity (HE) was within the range of 0.414 ± 0.306 to 0.715 ± 0.097. Proportion of differentiation (FST) within populations was 0.236. Overall gene flow (Nm) among populations equals 0.806. This study established the successful use of RAPD and microsatellite as tools for studying population structure of fish species, especially L. niloticus. Thus, it can be concluded that L. niloticus in the three (3) sampled Nigerian waterbodies is undergoing evolution.


2017 ◽  
Vol 37 (03) ◽  
pp. 149-162 ◽  
Author(s):  
Sweta Kumari U. Yadav ◽  
Jyotsna Singh ◽  
B. Padmanaban ◽  
Lalitha Sunil Kumar

AbstractCosmopolites sordidus(Germar), commonly known as banana corm weevil, is an important economic pest in Asia that can cause severe yield loss depending upon the stage at which infestation occurs. In spite of its economic importance, little is known about the population structure of this pest in India. Random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) were used to characterize the population genetic structure ofC. sordiduscollected from five hot spot locations in India. Nineteen RAPD primers and five selective AFLP primer combinations generated 147 and 304 amplification products, respectively. UPGMA dendrograms generated with both marker systems failed to reveal populations clustered based on geographic distance, which was confirmed by the Mantel test, which did not show a strong correlation between genetic distance and geographic distance. Values of indices of genetic identity showed that the populations were closely related. Though the gene flow estimate (Nm) between the populations was 0.469, suggesting restricted gene flow, the populations are not genetically distinct. These observations suggest that the range expansion of this banana pest in India has taken place through transport of infested corms and plant material, resulting in genetically close populations that are geographically distinct. These results provide important information on the population structure of this pest in India, which will aid in designing suitable strategies for its control and management, especially with respect to insecticide resistance.


Genome ◽  
2003 ◽  
Vol 46 (4) ◽  
pp. 529-535 ◽  
Author(s):  
Odeth Ulloa ◽  
Fernando Ortega ◽  
Hugo Campos

Red clover is an important forage legume species for temperate regions and very little is known about the genetic organization of its breeding populations. We used random amplified polymorphic DNA (RAPD) genetic markers to address the genetic diversity and the distribution of variation in 20 breeding populations and cultivars from Chile, Argentina, Uruguay, and Switzerland. Genetic distances were calculated for all possible pairwise combinations. A high level of polymorphism was found and the proportion of polymorphic loci across populations was 74.2%. A population derived from a non-certified seedlot displayed a higher proportion of polymorphic loci than its respective certified seedlot. Gene diversity values and population genetics parameters suggest that the populations analyzed are diverse. An analysis of molecular variance (AMOVA) revealed that the largest proportion of variation (80.4%) resides at the within population level. RAPD markers are a useful tool for red clover breeding programs. A dendrogram based on genetic distances divided the breeding populations analyzed into three distinct groups. The amount and partition of diversity observed can be of value in identifying the populations that parents of synthetic cultivars are derived from and to exploit the variation available in the populations analyzed.Key words: red clover, AMOVA, plant breeding.


2016 ◽  
Vol 68 (3) ◽  
pp. 669-675
Author(s):  
Yancai Shi ◽  
Xiao Wei ◽  
Jiqing Wei ◽  
Yongtao Li ◽  
Shengfeng Chai ◽  
...  

Heteroplexis microcephala Y. L. Chen. is an endemic and endangered species found only in karst limestone regions in the Yangshuo County of the Guangxi Zhuang Autonomous Region in China: it is a habitat representative of species in the Heteroplexis genus. To provide basic genetic information for its conservation, in this study we evaluated the genetic variation and differentiation among six wild populations of H. microcephala by random amplified polymorphic DNA markers (RAPD). The leaves of 141 individuals were sampled. Based on 12 primers, 113 DNA fragments were generated. Genetic diversity was low at the population level (Nei?s gene diversity (h)=0.0579; Shannon information index (I)=0.0924; percentage of polymorphic bands (PPB)=23.30%), but relatively high at the species level (h=0.1701; I=0.2551; PPB=46.34%). The coefficient of genetic differentiation based on Nei?s genetic diversity analysis (0.6661) was high, indicating that there was significant genetic differentiation among populations, which was confirmed by AMOVA analysis exhibiting population differentiation among populations of 68.77%. Low gene flow among populations (0.2507) may result from several factors, such as a harsh pollination environment, population isolation and low seed dispersal distance. Limited gene flow and self-compatibility are the primary reasons for the high genetic differentiation observed for this species. We propose the collection of seeds from more populations with fewer individuals and core populations for ex situ conservation and suggest methods to increase seed germination rates.


2011 ◽  
Vol 4 (2) ◽  
pp. 102-114 ◽  
Author(s):  
Evgenyi N. Panov ◽  
Larissa Yu. Zykova

Field studies were conducted in Central Negev within the breeding range of Laudakia stellio brachydactyla and in NE Israel (Qyriat Shemona) in the range of an unnamed form (tentatively “Near-East Rock Agama”), during March – May 1996. Additional data have been collected in Jerusalem at a distance of ca. 110 km from the first and about 170 km from the second study sites. A total of 63 individuals were caught and examined. The animals were marked and their subsequent movements were followed. Social and signal behavior of both forms were described and compared. Lizards from Negev and Qyriat Shemona differ from each other sharply in external morphology, habitat preference, population structure, and behavior. The differences obviously exceed the subspecies level. At the same time, the lizards from Jerusalem tend to be intermediate morphologically between those from both above-named localities, which permits admitting the existence of a limited gene flow between lizard populations of Negev and northern Israel. The lizards from NE Israel apparently do not belong to the nominate subspecies of L. stellio and should be regarded as one more subspecies within the species.


Author(s):  
Richard W. Jobson ◽  
Paulo C. Baleeiro ◽  
Cástor Guisande

Utricularia is a morphologically and ecologically diverse genus currently comprising more than 230 species divided into three subgenera—Polypompholyx, Utricularia, and Bivalvaria—and 35 sections. The genus is distributed worldwide except on the poles and most oceanic islands. The Neotropics has the highest species diversity, followed by Australia. Compared to its sister genera, Utricularia has undergone greater rates of speciation, which are linked to its extreme morphological flexibility that has resulted in the evolution of habitat-specific forms: terrestrial, rheophytic, aquatic, lithophytic, and epiphytic. Molecular phylogenetic studies have resolved relationships for 44% of the species across 80% of the sections. Scant data are available for phylogeography or population-level processes such as gene flow, hybridization, or pollination. Because nearly 90% of the species are endemics, data are urgently needed to determine how to protect vulnerable species and their habitats.


2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Maysa Tiemi Motoki ◽  
Dina Madera Fonseca ◽  
Elliott Frederic Miot ◽  
Bruna Demari-Silva ◽  
Phoutmany Thammavong ◽  
...  

Abstract Background The Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse) is an important worldwide invasive species and can be a locally important vector of chikungunya, dengue and, potentially, Zika. This species is native to Southeast Asia where populations thrive in both temperate and tropical climates. A better understanding of the population structure of Ae. albopictus in Lao PDR is very important in order to support the implementation of strategies for diseases prevention and vector control. In the present study, we investigated the genetic variability of Ae. albopictus across a north-south transect in Lao PDR. Methods We used variability in a 1337-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), to assess the population structure of Ae. albopictus in Lao PDR. For context, we also examined variability at the same genetic locus in samples of Ae. albopictus from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA. Results We observed very high levels of genetic polymorphism with 46 novel haplotypes in Ae. albopictus from 9 localities in Lao PDR and Thailand populations. Significant differences were observed between the Luangnamtha population and other locations in Lao PDR. However, we found no evidence of isolation by distance. There was overall little genetic structure indicating ongoing and frequent gene flow among populations or a recent population expansion. Indeed, the neutrality test supported population expansion in Laotian Ae. albopictus and mismatch distribution analyses showed a lack of low frequency alleles, a pattern often seen in bottlenecked populations. When samples from Lao PDR were analyzed together with samples from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA, phylogenetic network and Bayesian cluster analysis showed that most populations from tropical/subtropical regions are more genetically related to each other, than populations from temperate regions. Similarly, most populations from temperate regions are more genetically related to each other, than those from tropical/subtropical regions. Conclusions Aedes albopictus in Lao PDR are genetically related to populations from tropical/subtropical regions (i.e. Thailand, Singapore, and California and Texas in the USA). The extensive gene flow among locations in Lao PDR indicates that local control is undermined by repeated introductions from untreated sites.


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