Low levels of genetic variation within populations of the four rare orchids Gymnadenia cucullata, Gymnadenia camtschatica, Amitostigma gracile, and Pogonia minor in South Korea: indication of genetic drift and implications for conservation

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.

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Effects of Genetic Drift and Gene Flow on the Selective Maintenance of Genetic Variation

Genetics ◽

10.1534/genetics.113.149781 ◽

2013 ◽

Vol 194 (1) ◽

pp. 235-244 ◽

Cited By ~ 9

Author(s):

Bastiaan Star ◽

Hamish G. Spencer

Keyword(s):

Genetic Variation ◽

Gene Flow ◽

Genetic Drift ◽

Selective Maintenance

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Genetic variation in allozymes of western larch

Canadian Journal of Forest Research ◽

10.1139/x86-177 ◽

1986 ◽

Vol 16 (5) ◽

pp. 1013-1018 ◽

Cited By ~ 25

Author(s):

Lauren Fins ◽

Lisa W. Seeb

Keyword(s):

Genetic Variation ◽

Genetic Drift ◽

Fire History ◽

Glacial History ◽

Geographic Proximity ◽

Electrophoretic Variation ◽

Inland Empire ◽

Genetic History ◽

Expected Heterozygosity ◽

History Of

Seed samples from 19 stands of Larixoccidentalis Nutt. were analyzed for electrophoretic variation at 23 loci. Because sample sizes consisted of only 9 or 10 trees per stand (18–20 alleles per locus per stand), samples were grouped by geographic proximity into four larger samples. For all measures of variation, this species scored lower than most, but within the range observed for other western conifers. Most of the variation was found within rather than between the population groups. The single southern sample appeared to be genetically distinct from the others. Although some variation was observed between individual stand samples in expected heterozygosity, the consistently low values for all samples suggest that genetic drift has played a major role in the genetic history of the species in the Inland Empire, both through its glacial history in postulated refugia and through fire history in recent times.

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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

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Conservation genetics of the threatened plant species Physaria filiformis (Missouri bladderpod) reveals strong genetic structure and a possible cryptic species

PLoS ONE ◽

10.1371/journal.pone.0247586 ◽

2021 ◽

Vol 16 (3) ◽

pp. e0247586

Author(s):

Christine E. Edwards ◽

Brooke C. Tessier ◽

Joel F. Swift ◽

Burgund Bassüner ◽

Alexander G. Linan ◽

...

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Genetic Structure ◽

Plant Species ◽

Genetic Drift ◽

Rare Species ◽

Ex Situ ◽

Ouachita Mountains ◽

Genetic Diversity And Structure ◽

Genetic Clusters

Understanding genetic diversity and structure in a rare species is critical for prioritizing both in situ and ex situ conservation efforts. One such rare species is Physaria filiformis (Brassicaceae), a threatened, winter annual plant species. The species has a naturally fragmented distribution, occupying three different soil types spread across four disjunct geographical locations in Missouri and Arkansas. The goals of this study were to understand: (1) whether factors associated with fragmentation and small population size (i.e., inbreeding, genetic drift or genetic bottlenecks) have reduced levels of genetic diversity, (2) how genetic variation is structured and which factors have influenced genetic structure, and (3) how much extant genetic variation of P. filiformis is currently publicly protected and the implications for the development of conservation strategies to protect its genetic diversity. Using 16 microsatellite markers, we genotyped individuals from 20 populations of P. filiformis from across its geographical range and one population of Physaria gracilis for comparison and analyzed genetic diversity and structure. Populations of P. filiformis showed comparable levels of genetic diversity to its congener, except a single population in northwest Arkansas showed evidence of a genetic bottleneck and two populations in the Ouachita Mountains of Arkansas showed lower genetic variation, consistent with genetic drift. Populations showed isolation by distance, indicating that migration is geographically limited, and analyses of genetic structure grouped individuals into seven geographically structured genetic clusters, with geographic location/spatial separation showing a strong influence on genetic structure. At least one population is protected for all genetic clusters except one in north-central Arkansas, which should therefore be prioritized for protection. Populations in the Ouachita Mountains were genetically divergent from the rest of P. filiformis; future morphological analyses are needed to identify whether it merits recognition as a new, extremely rare species.

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Genetic Variation of Pinus densiflora Populations in South Korea Based on ESTP Markers

Korean Journal of Plant Resources ◽

10.7732/kjpr.2015.28.2.279 ◽

2015 ◽

Vol 28 (2) ◽

pp. 279-289

Author(s):

Ji Young Ahn ◽

Kyung Nak Hong ◽

Jei Wan Lee ◽

Yong Pyo Hong ◽

Hoduck Kang

Keyword(s):

Genetic Variation ◽

South Korea ◽

Pinus Densiflora

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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.

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