Genetic variation and population structure of Holothuria polii from the eastern and western Mediterranean coasts in Tunisia

2011 ◽  
Vol 91 (8) ◽  
pp. 1599-1606 ◽  
Author(s):  
Aicha Gharbi ◽  
Khaled Said
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Genetic Variability ◽  
Mediterranean Sea ◽  
Coastal Waters ◽  
Western Mediterranean ◽  
Hardy Weinberg Equilibrium ◽  
Allozyme Loci ◽  
Two Populations ◽  
Holothuria Polii

Seven populations of Holothuria polii were sampled from the eastern and western Mediterranean coastal waters of Tunisia and screened electrophoretically for genetic variation at 11 allozyme loci. Six among the seven polymorphic loci were out of Hardy–Weinberg equilibrium (HWE) in at least one population. In the same way, the multilocus test showed deviation from HWE in all populations. These populations showed heterozygote deficiency. Genetic variability was relatively low. The number of alleles per locus ranged from 2.09 to 2.27 (average = 2.15), and the observed heterozygosity varied between 0.14 and 0.20 (average = 0.17). The observed overall differentiation among populations was slight but significant, with a mean FST value of 0.024 (P < 0.001). Pairwise FST values reflected the differentiation of the two populations, which were at the margins of the range sampled, from all the others. Our data suggest a population structure consistent with separation by Mediterranean Sea basins that might reflect different local biogeographical zones.

scholarly journals Identifying the main sources of silicate in coastal waters of the Southern Gulf of Valencia (Western Mediterranean Sea)

Oceanologia ◽  
2018 ◽  
Vol 60 (1) ◽  
pp. 52-64 ◽  
Author(s):  
Javier Sospedra ◽  
L. Felipe H. Niencheski ◽  
Silvia Falco ◽  
Carlos F.F. Andrade ◽  
Karina K. Attisano ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Coastal Waters ◽  
Western Mediterranean ◽  
Western Mediterranean Sea

scholarly journals How diverse can rare species be on the margins of genera distribution?

AoB Plants ◽  
2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Alice Backes ◽  
Geraldo Mäder ◽  
Caroline Turchetto ◽  
Ana Lúcia Segatto ◽  
Jeferson N Fregonezi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Genetic Variability ◽  
Habitat Loss ◽  
Evolutionary History ◽  
Founder Effects ◽  
Geographical Isolation ◽  
Genetic Diversity And Structure ◽  
Genetic Patterns

Abstract Different genetic patterns have been demonstrated for narrowly distributed taxa, many of them linking rarity to evolutionary history. Quite a few species in young genera are endemics and have several populations that present low variability, sometimes attributed to geographical isolation or dispersion processes. Assessing the genetic diversity and structure of such species may be important for protecting them and understanding their diversification history. In this study, we used microsatellite markers and plastid sequences to characterize the levels of genetic variation and population structure of two endemic and restricted species that grow in isolated areas on the margin of the distribution of their respective genera. Plastid and nuclear diversities were very low and weakly structured in their populations. Evolutionary scenarios for both species are compatible with open-field expansions during the Pleistocene interglacial periods and genetic variability supports founder effects to explain diversification. At present, both species are suffering from habitat loss and changes in the environment can lead these species towards extinction.

Genetic polymorphism in Proteocephalus exiguus shown by enzyme electrophoresis

1996 ◽  
Vol 70 (4) ◽  
pp. 345-349 ◽  
Author(s):  
V. Šnábel ◽  
V. Hanzelová ◽  
S. Mattiucci ◽  
S. D'Amelio ◽  
L. Paggi
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Polymorphism ◽  
Genetic Variability ◽  
Balancing Selection ◽  
Outcrossing Rate ◽  
Enzyme Electrophoresis ◽  
Factors Affecting ◽  
Hardy Weinberg Equilibrium ◽  
Coregonid Fishes

AbstractEnzyme electrophoresis has been used to examine genetic diversity in a population of Proteocephalus exiguus La Rue, 1911 (Cestoda: Proteocephalidae), parasitizing salmonid and coregonid fishes. Among 16 loci tested, three polymorphic loci (Ada, Got, Pgm-2) were found. Six different genotypes at the Got locus distributed in Hardy-Weinberg equilibrium suggest remarkable genetic flexibility of P. exiguus. Balancing selection is proposed as the mechanism maintaining genetic variation within the species. Data of genetic variability parameters (Ho = 0.064; He = 0.07; P = 0.19) and outcrossing rate (t = 0.842) of P. exiguus population have been provided. Possible factors affecting these data are discussed.

Genetic diversity studies of alfalfa germplasm (Medicago sativa L. subsp. sativa) of United States origin using microsatellite analysis

2017 ◽  
Author(s):  
Shuying Yin ◽  
Yanrong Wang ◽  
Zhibiao Nan
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Polymorphic Information Content ◽  
The United States ◽  
Microsatellite Analysis ◽  
Information Index ◽  
Diversity Studies ◽  
Two Populations

This study aimed to understand the genetic diversity and population structure of alfalfa germplasm from the United States. In this study, the population structure and genetic diversity of six alfalfa cultivars of United States origin were investigated by microsatellite analysis with 40 individuals per cultivar. A total of 312 discernible alleles were amplified from the whole genome with an average of 31.2 alleles per locus. The average values of polymorphic information content and Shannon’s information index were 0.928 and 0.133, respectively, showing high levels of genetic diversity. Two populations were identified by STRUCTURE software with principal coordinate analysis and neighbour-joining clustering. Analysis of molecular variance analysis (AMOVA) revealed that the majority of genetic variation was within cultivars (96.42%) rather than between cultivars (3.58%). In conclusion, analyses of genetic diversity and population structure may be useful for the genetic analysis and utilization of genetic variation in alfalfa breeding.

Allozyme variation and population structure of Carex humilis var. nana (Cyperaceae) in Korea

2001 ◽  
Vol 79 (4) ◽  
pp. 457-463 ◽  
Author(s):  
Man Kyu Huh
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
North American ◽  
Population Level ◽  
Allozyme Variation ◽  
Population Divergence ◽  
Geographic Ranges ◽  
The Mean ◽  
Allozyme Loci

Genetic diversity and population structure of 22 Carex humilis var. nana Ohwi (Cyperaceae) populations in Korea were determined using genetic variation at 23 allozyme loci. This is a long-lived herbaceous species with a widespread distribution in eastern Asia. The 12 enzymes revealed 23 putative loci, of which 11 were polymorphic (47.8%). Genetic diversity at the varietal level and at the population level was 0.131 and 0.118, respectively. Total genetic diversity (HT = 0.274) and within population genetic diversity (HS = 0.256) were high, whereas the extent of the population divergence was relatively low (GST = 0.068). An indirect estimate of the number of migrants per generation (Nm = 3.42) indicated that gene flow was high among Korean populations. Wide geographic ranges, perennial herbaceous nature, and the persistence of multiple generations are associated with the high level of genetic variation. A distinct difference between Asian and North American Carex is shown in the proportion of genetic variation (GST) (p < 0.001). The mean GST of Asian Carex was estimated as 0.056; thus, only 5.6% of genetic variability was distributed among populations, whereas the mean GST of North American Carex was estimated as 19.5% (3.5 times higher). It is probable that the geographical distance between population pairs and presence or absence of glacial history may play roles in the substantial difference between both groups.Key words: Carex humilis var. nana, genetic diversity, population structure.

scholarly journals Genetic Diversity and Population Structure of a Threatened African Tree Species,Milicia excelsa,Using Nuclear Microsatellites DNA Markers

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Christine Ouinsavi ◽  
Nestor Sokpon ◽  
Damase P. Khasa
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Isolation By Distance ◽  
In Situ Conservation ◽  
Agroforestry Systems ◽  
Microsatellites Dna ◽  
Geographical Distances ◽  
Hardy Weinberg Equilibrium ◽  
Milicia Excelsa

To accurately estimate the genetic diversity and population structure for improved conservation planning ofMilicia excelsatree, 212 individuals from twelve population samples covering the species' range in Benin were surveyed at seven specific microsatellite DNA loci. All loci were variable, with the mean number of alleles per locus ranging from 5.86 to 7.69. Considerable genetic variability was detected for all populations at the seven loci (AR=4.60;HE=0.811). Moderate but statistically significant genetic differentiation was found among populations considering bothFST(0.112) andRST(0.342). All of the populations showed heterozygosity deficits in test of Hardy-Weinberg Equilibrium and significantly positiveFISvalues due to inbreeding occurring in the species. PairwiseFSTvalues were positively and significantly correlated with geographical distances (r=0.432;P=.007, Mantel's test) indicating that populations are differentiated by “isolation by distance.” Bayesian analysis of population structure showed division of the genetic variation into four clusters revealing the existence of heterogeneity in population genetic structure. Altogether, these results indicate that genetic variation inMilicia excelsais geographically structured. Information gained from this study also emphasized the need for in situ conservation of the relict populations and establishment of gene flow corridors through agroforestry systems for interconnecting these remnant populations.

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