Low levels of genetic variation among southern peripheral populations of the threatened herb, Leontice microrhyncha (Berberidaceae) in Korea

AbstractCaenorhabditis elegans has become one of the most widely used model research organisms, yet we have little information on evolutionary processes and recent evolutionary history of this widespread species. We examined patterns of variation at 20 microsatellite loci in a sample of 23 natural isolates of C. elegans from various parts of the world. One-half of the loci were monomorphic among all strains, and overall genetic variation at microsatellite loci was low, relative to most other species. Some population structure was detected, but there was no association between the genetic and geographic distances among different natural isolates. Thus, despite the nearly worldwide occurrence of C. elegans, little evidence was found for local adaptation in strains derived from different parts of the world. The low levels of genetic variation within and among populations suggest that recent colonization and population expansion might have occurred. However, the patterns of variation are not consistent with population expansion. A possible explanation for the observed patterns is the action of background selection to reduce polymorphism, coupled with ongoing gene flow among populations worldwide.

Download Full-text

Low levels of genetic variation inPhenakospermum guyannense (Strelitziaceae), a widespread bat-pollinated Amazonian herb

Plant Systematics and Evolution ◽

10.1007/bf00985914 ◽

1996 ◽

Vol 199 (1-2) ◽

pp. 1-15 ◽

Cited By ~ 5

Author(s):

Cheryl S. Roesel ◽

W. John Kress ◽

Brunella Martire Bowditch

Keyword(s):

Genetic Variation ◽

Low Levels

Download Full-text

Geographical Gradients of Genetic Diversity and Differentiation among the Southernmost Marginal Populations of Abies sachalinensis Revealed by EST-SSR Polymorphism

Forests ◽

10.3390/f11020233 ◽

2020 ◽

Vol 11 (2) ◽

pp. 233 ◽

Cited By ~ 1

Author(s):

Keiko Kitamura ◽

Kentaro Uchiyama ◽

Saneyoshi Ueno ◽

Wataru Ishizuka ◽

Ikutaro Tsuyama ◽

...

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Local Population ◽

Distribution Center ◽

Population History ◽

Peripheral Populations ◽

Abies Sachalinensis ◽

Marginal Populations ◽

Local Populations ◽

Longitudinal Gradients

Research Highlights: We detected the longitudinal gradients of genetic diversity parameters, such as the number of alleles, effective number of alleles, heterozygosity, and inbreeding coefficient, and found that these might be attributable to climatic conditions, such as temperature and snow depth. Background and Objectives: Genetic diversity among local populations of a plant species at its distributional margin has long been of interest in ecological genetics. Populations at the distribution center grow well in favorable conditions, but those at the range margins are exposed to unfavorable environments, and the environmental conditions at establishment sites might reflect the genetic diversity of local populations. This is known as the central-marginal hypothesis in which marginal populations show lower genetic variation and higher differentiation than in central populations. In addition, genetic variation in a local population is influenced by phylogenetic constraints and the population history of selection under environmental constraints. In this study, we investigated this hypothesis in relation to Abies sachalinensis, a major conifer species in Hokkaido. Materials and Methods: A total of 1189 trees from 25 natural populations were analyzed using 19 EST-SSR loci. Results: The eastern populations, namely, those in the species distribution center, showed greater genetic diversity than did the western peripheral populations. Another important finding is that the southwestern marginal populations were genetically differentiated from the other populations. Conclusions: These differences might be due to genetic drift in the small and isolated populations at the range margin. Therefore, our results indicated that the central-marginal hypothesis held true for the southernmost A. sachalinensis populations in Hokkaido.

Download Full-text

High Levels of Genetic Variability in an Isolated Colony of Rock-wallabies (Petrogale assimilis): Evidence from Three Classes of Molecular Markers

Australian Journal of Zoology ◽

10.1071/zo96058 ◽

1997 ◽

Vol 45 (2) ◽

pp. 199 ◽

Cited By ~ 12

Author(s):

Peter B. S. Spencer ◽

Mark Adams ◽

Helene Marsh ◽

David J. Miller ◽

Mark D. B. Eldridge

Keyword(s):

Genetic Variation ◽

Molecular Markers ◽

Genetic Variability ◽

Mating Systems ◽

Selective Pressure ◽

Multiple Mating ◽

Dna Fingerprints ◽

Average Heterozygosity ◽

Low Levels ◽

High Level

Estimates of genetic variation for a small (Ne = 39) colony of allied rock-wallabies (Petrogale assimilis) were calculated with three different categories of molecular marker. Average heterozygosity was estimated at 3·8% for allozymes, 47·3% for multilocus ‘DNA fingerprints’ and 85·5% for microsatellite markers. Overall these values indicate that this small isolated colony of rock-wallabies maintains a high level of genetic variation despite its relative isolation and the apparently low levels of migration between colonies. It is likely that mechanisms exist (such as kin avoidance, multiple mating systems, high and variable selective pressure in extreme and fluctuating environmental conditions) that promote the maintenance of high levels of genetic variation in isolated colonies of P. assimilis. These mechanisms are discussed in the context of the results obtained from the molecular markers.

Download Full-text

Unprecedented Low Levels of Genetic Variation and Inbreeding Depression in an Island Population of the Black-Footed Rock-Wallaby

Conservation Biology ◽

10.1046/j.1523-1739.1999.98115.x ◽

1999 ◽

Vol 13 (3) ◽

pp. 531-541 ◽

Cited By ~ 159

Author(s):

Mark D. B. Eldridge ◽

Juliet M. King ◽

Anne K. Loupis ◽

Peter B. S. Spencer ◽

Andrea C. Taylor ◽

...

Keyword(s):

Genetic Variation ◽

Inbreeding Depression ◽

Island Population ◽

Low Levels

Download Full-text

Unusually Low Levels of Genetic Variation among Giardia lamblia Isolates

Eukaryotic Cell ◽

10.1128/ec.00138-07 ◽

2007 ◽

Vol 6 (8) ◽

pp. 1421-1430 ◽

Cited By ~ 52

Author(s):

Smilja Teodorovic ◽

John M. Braverman ◽

Heidi G. Elmendorf

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Giardia Lamblia ◽

Diarrheal Disease ◽

Regulation Of Gene Expression ◽

Genetic Exchange ◽

Disease Etiology ◽

Noncoding Regions ◽

Low Genetic Diversity ◽

Low Levels

ABSTRACT Giardia lamblia, an intestinal pathogen of mammals, including humans, is a significant cause of diarrheal disease around the world. Additionally, the parasite is found on a lineage which separated early from the main branch in eukaryotic evolution. The extent of genetic diversity among G. lamblia isolates is insufficiently understood, but this knowledge is a prerequisite to better understand the role of parasite variation in disease etiology and to examine the evolution of mechanisms of genetic exchange among eukaryotes. Intraisolate genetic variation in G. lamblia has never been estimated, and previous studies on interisolate genetic variation have included a limited sample of loci. Here we report a population genetics study of intra- and interisolate genetic diversity based on six coding and four noncoding regions from nine G. lamblia isolates. Our results indicate exceedingly low levels of genetic variation in two out of three G. lamblia groups that infect humans; this variation is sufficient to allow identification of isolate-specific markers. Low genetic diversity at both coding and noncoding regions, with an overall bias towards synonymous substitutions, was discovered. Surprisingly, we found a dichotomous haplotype structure in the third, more variable G. lamblia group, represented by a haplotype shared with one of the homogenous groups and an additional group-specific haplotype. We propose that the distinct patterns of genetic-variation distribution among lineages are a consequence of the presence of genetic exchange. More broadly, our findings have implications for the regulation of gene expression, as well as the mode of reproduction in the parasite.

Download Full-text

Introduced Swedish Canada geese (Branta canadensis) have low levels of genetic variation as revealed by DNA fingerprinting

Journal of Evolutionary Biology ◽

10.1046/j.1420-9101.1995.8020195.x ◽

1995 ◽

Vol 8 (2) ◽

pp. 195-207 ◽

Cited By ~ 17

Author(s):

H>>kan Tegelstrom ◽

Goran Sjoberg

Keyword(s):

Genetic Variation ◽

Dna Fingerprinting ◽

Branta Canadensis ◽

Canada Geese ◽

Low Levels

Download Full-text

Genetic evaluation of seeds of highly endangered Pinus uliginosa Neumann from Węgliniec reserve for ex-situ conservation program

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.2005.030 ◽

2011 ◽

Vol 74 (3) ◽

pp. 237-242 ◽

Cited By ~ 5

Author(s):

Andrzej Lewandowski ◽

Jarosław Burczyk ◽

Witold Wachowiak ◽

Adam Boratyński ◽

Wiesław Prus-Głowacki

Keyword(s):

Genetic Variation ◽

Genetic Erosion ◽

Minimum Variance ◽

Ex Situ ◽

The Mean ◽

Low Levels ◽

Species Specific ◽

High Level ◽

Individual Trees ◽

Pinus Uliginosa

Peat-bog pine Pinus uliginosa Neumann has become extinct or rare in many parts of Europe. We have investigated the levels of genetic variation and inbreeding in seeds collected from a highly endangered reserve of this species in Poland, using allozymes as genetic markers. Generally, a high level of genetic variation was observed. The mean expected heterozygosity was 0.376, while average (Na) and effective (Ne) numbers of alleles per locus were 2.45 and 1.67, respectively. Nevertheless, we have detected relatively low levels of outcrossing, and potential biparental inbreeding. The population-wide multilocus outcrossing rate was estimated to be 0.706 (±0.091), while the minimum variance mean of single-locus estimates was distinctly lower (ts=0.611). The estimates of outcrossing calculated for individual trees ranged widely from 0.051 to 1.017, indicating the complexity of outcrossing patterns. The investigated population of P. uliginasa from Węgliniec is small and surrounded by extensive forest stands of P. sylvestris. Our three-year records of phenological observations demonstrated that flowering periods for P. uliginosa and P. sylvestris overlap, allowing for cross-pollination. The possibility of P. uliginosa pollination by P. sylvestris creates a potential danger of genetic erosion of the P. uliginosa gene pool. Nonetheless, based on a species specific cpDNA marker we have found that among 533 seedlings of P. uliginosa there were only six seedlings carrying cpDNA marker specific for P. sylvestris, indicating that such hybridization seems to be rare.

Download Full-text