Evidence for low genetic diversity and metapopulation structure in Canada yew (Taxus canadensis): considerations for conservation

2001 ◽  
Vol 31 (1) ◽  
pp. 110-116 ◽  
Author(s):  
Sauphie Senneville ◽  
Jean Beaulieu ◽  
Gaëtan Daoust ◽  
Marie Deslauriers ◽  
Jean Bousquet
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Great Majority ◽  
Population Level ◽  
Deciduous Forests ◽  
Northeastern North America ◽  
Low Genetic Diversity ◽  
Taxus Canadensis ◽  
Metapopulation Structure ◽  
Canada Yew

Canada yew (Taxus canadensis Marsh.) is a gymnosperm that grows in the understory of mixed and deciduous forests of northeastern North America. This shrub had no economic importance until the discovery of paclitaxel, or TAXOL®, which is a compound found in plant tissue and used in cancer treatment. With the intensifying harvesting pressure on natural populations of this species, the natural gene pool might be affected. The objective of this study was to estimate the levels of genetic diversity and population structure in Canada yew, before any sizeable effects resulting from harvesting appear. Six natural populations of Canada yew were sampled in Quebec. Genetic diversity was estimated at 22 loci coding for 12 enzyme systems. At the population level, the number of alleles per locus was 1.32, the percentage of polymorphic loci was 26.5%, and the observed heterozygosity was 0.102. These results show that Canada yew is genetically less diverse than other yew species and the great majority of gymnosperms. However, the amount of population differentiation was substantially higher (FST = 10.2%) than that for other conifer and tree species growing in the boreal-temperate zone. Hypotheses related to the biogeography of the species and a likely metapopulation structure are proposed to explain the observed trends.

Evidence for low genetic diversity and metapopulation structure in Canada yew (Ta×us canadensis): considerations for conservation

2001 ◽  
Vol 31 (1) ◽  
pp. 110-116 ◽  
Author(s):  
Sauphie Senneville ◽  
Jean Beaulieu ◽  
Gaëtan Daoust ◽  
Marie Deslauriers ◽  
Jean Bousquet
Keyword(s):  
Genetic Diversity ◽  
Low Genetic Diversity ◽  
Metapopulation Structure ◽  
Canada Yew

Low genetic diversity at allozyme loci in Juglans cinerea

2000 ◽  
Vol 78 (9) ◽  
pp. 1238-1243 ◽  
Author(s):  
Ricardo Morin ◽  
Jean Beaulieu ◽  
Marie Deslauriers ◽  
Gaëtan Daoust ◽  
Jean Bousquet
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Deciduous Forest ◽  
Polymorphic Locus ◽  
Natural Populations ◽  
Minor Component ◽  
Temperate Deciduous Forest ◽  
Juglans Cinerea ◽  
Low Genetic Diversity ◽  
Allozyme Loci

Butternut (Juglans cinerea L.) is a minor component of the temperate deciduous forest region of northeastern North America, but it is severely affected by the butternut canker (Sirococcus clavigignenti-juglandacearum Nair, Kostichka, and Kuntz) in the southern part of its natural range. Genetic diversity and population structure in as-yet unaffected or only slightly affected natural populations were evaluated at 12 isozyme loci. The genetic diversity estimates were low with values much below those estimated in other species of the same genus or in boreal tree species, with 25 and 13.9% polymorphic loci at the species and population levels, respectively; 1.3 and 2.3 alleles per locus and per polymorphic locus, respectively, at the species level; and an average observed heterozygosity of 0.028. Population differentiation was low, with the exception of one unique population. The implications for advanced conservation are discussed.Key words: butternut, isozymes, Sirococcus, canker, population structure.

scholarly journals Characterization of Trichodesmium spp. by Genetic Techniques

2002 ◽  
Vol 68 (5) ◽  
pp. 2236-2245 ◽  
Author(s):  
K. M. Orcutt ◽  
U. Rasmussen ◽  
E. A. Webb ◽  
J. B. Waterbury ◽  
K. Gundersen ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Natural Populations ◽  
Sargasso Sea ◽  
Closely Related Species ◽  
Trichodesmium Erythraeum ◽  
Low Genetic Diversity ◽  
Gradient Gel Electrophoresis ◽  
Genetic Techniques

ABSTRACT The genetic diversity of Trichodesmium spp. from natural populations (off Bermuda in the Sargasso Sea and off North Australia in the Arafura and Coral Seas) and of culture isolates from two regions (Sargasso Sea and Indian Ocean) was investigated. Three independent techniques were used, including a DNA fingerprinting method based on a highly iterated palindrome (HIP1), denaturing gradient gel electrophoresis of a hetR fragment, and sequencing of the internal transcribed spacer (ITS) of the 16S-23S rDNA region. Low genetic diversity was observed in natural populations of Trichodesmium spp. from the two hemispheres. Culture isolates of Trichodesmium thiebautii, Trichodesmium hildebrandtii, Trichodesmium tenue, and Katagnymene spiralis displayed remarkable similarity when these techniques were used, suggesting that K. spiralis is very closely related to the genus Trichodesmium. The largest genetic variation was found between Trichodesmium erythraeum and all other species of Trichodesmium, including a species of Katagnymene. Our data obtained with all three techniques suggest that there are two major clades of Trichodesmium spp. The HIP1 fingerprinting and ITS sequence analyses allowed the closely related species to be distinguished. This is the first report of the presence of HIP1 in marine cyanobacteria.

The ecology of Canada Yew (Taxus canadensis Marsh.): A review

Botany ◽  
2011 ◽  
Vol 89 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Steve K. Windels ◽  
David J. Flaspohler
Keyword(s):  
North America ◽  
Growth Form ◽  
Deciduous Forests ◽  
Future Research ◽  
Forest Types ◽  
Isolated Populations ◽  
Taxus Canadensis ◽  
Intensive Forest Management ◽  
Canada Yew ◽  
Common Plant

Canada yew (Taxus canadensis Marsh.) is a shade-tolerant evergreen shrub native to the understories of the boreal and deciduous forests of northeastern North America. Canada yew has a relatively unique growth form, with low sprawling branches capable of forming dense clusters of stems. Historic accounts suggest that before Euro-American settlement, Canada yew was a common plant across its range in many forest types and that it was locally abundant or dominant in 5%–20% of forest stands in the northern part of its range. Canada yew’s range has declined during the last century as a result of browsing by native ungulates, fire, intensive forest management, and clearing of land for agriculture and other development. It is considered uncommon throughout most of its present North American range, except for often isolated populations in areas that remain free from heavy browsing pressure by moose and deer (e.g., islands, areas with heavy snow cover, or areas naturally low in ungulate abundance). Its decline has likely resulted in changes to abiotic and biotic conditions, including structure and composition of understory vegetation and concomitant effects on understory vertebrates. Increasing white-tailed deer populations and reduced snowfall as a result of climate change in eastern North America threaten to extirpate this species from additional parts of its range in the next century. Suggestions for future research are discussed.

Genetic structure and proposed conservation strategy for natural populations of Calycanthus chinensis Cheng et S.Y. Chang (Calycanthaceae)

2008 ◽  
Vol 88 (1) ◽  
pp. 179-186 ◽  
Author(s):  
Chu-Chuan Fan ◽  
Nicola Pecchioni ◽  
Long-Qing Chen
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Genetic Distance ◽  
Gene Diversity ◽  
Genetic Relationships ◽  
Natural Populations ◽  
Population Level ◽  
Conservation Strategy ◽  
Information Index

Calycanthus chinensis Cheng et S.Y. Chang, a tertiary relic species in China, is a shade-loving and deciduous bush withan elegant shape and beautiful flower of high ornamental value. It was widely planted in gardens and miniature scapes in China.The objective of this study was to characterize the genetic variation and structure in the three extant populations of the species, in order to provide useful information for a future conservation strategy. Twenty-two of 120 RAPD primers were selected and a total of 257 stable and clear DNA fragments were scored. Calycanthus chinensis showed a lower level of genetic diversity. At the population level, the percentage of polymorphic loci, Nei's gene diversity and Shannon’s information index were 40.9%, 0.1641 and 0.2386, respectively; while at the species level, the corresponding values were 59.1%, 0.2097 and 0.3123, respectively. The estimates of genetic differentiation based on Shannon’s information index (0.2360), Nei’s gene diversity (0.2175) and AMOVA (24.94%) were very similar, and significantly higher than the average genetic differentiation reported in outcrossed spermatophyte. So it suggested high genetic differentiation emerged among populations of C. chinensis. Genetic relationships among populations were assessed by Nei’s standard genetic distance, which suggested that the Tiantai population was genetically distinct from the other two populations. Moreover, the genetic distance was significantly correlated with geographical distance among populations (r = 0.997, t > t0.05). The gene flow (Nm) was 0.8994, indicating that gene exchange among populations was restricted. A conservation strategy was proposed based on the low gene flow and habitat deterioration, which are contributing to the endangered status of this species. Key words: Genetic diversity, endangered plant, population genetics, RAPD

Assessing genetic diversity of protected coho salmon (Oncorhynchus kisutch) populations in California

2007 ◽  
Vol 64 (1) ◽  
pp. 30-42 ◽  
Author(s):  
Katherine A Bucklin ◽  
Michael A Banks ◽  
Dennis Hedgecock
Keyword(s):  
Genetic Diversity ◽  
Coho Salmon ◽  
Random Mating ◽  
Oncorhynchus Kisutch ◽  
Legal Protection ◽  
Population Level ◽  
Population Subdivision ◽  
Minimal Impact ◽  
Low Genetic Diversity ◽  
Microsatellite Dna Markers

California coho salmon (Oncorhynchus kisutch) are under legal protection owing to significant declines in abundance over the last decades. Previously, California coho salmon were characterized as having low genetic diversity and weak population subdivision, attributable potentially to homogenization by out-of-basin hatchery releases. Here, diversity at seven highly polymorphic microsatellite DNA markers is assessed within and among 32 collections of coho salmon from 16 California watersheds. In 71% of local populations, genotypic composition deviates significantly from that expected under the assumption of random mating. We develop and apply methods to adjust for two potential causes of deviation from random mating expectations: (i) Wahlund effects, owing to heterogeneous collections of individuals, and (ii) the "Allendorf–Phelp's effect", owing to closely related juveniles in samples. Such population-level "adjustments" reduce within-region and increase among-region variance; after adjustment, we find strong concordance of genetic and geographic distances. We conclude that stock transfers have had minimal impact on population structure and that California coho salmon populations likely comprise small numbers of endemic breeders, potentially experiencing high levels of genetic drift and inbreeding.

Genetic Diversity Within and Among Populations of Shorea Robusta Roxb. Ex Gaertn. In Bangladesh and Its Implications for Conservation

2021 ◽  
Vol 50 (2) ◽  
pp. 405-412
Author(s):  
Pragga Saha Sharmi ◽  
Md Abul Kashem ◽  
Rifat Samad ◽  
Mohammad Zabed Hossain
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Isolation By Distance ◽  
Genetic Erosion ◽  
Mantel Test ◽  
Small Population ◽  
Deciduous Forests ◽  
Shorea Robusta ◽  
Low Genetic Diversity ◽  
Geographical Regions

Fragmentation and reduction of natural population size render threats to the conservation of forest resources through depletion of genetic diversity. Hence, information on genetic structure of Sal (Shorea robusta Roxb. ex Gaertn.) populations is relevant for proper management and conservation of the tropical deciduous forests. The present study focused on assessing the genetic diversity of the populations of Sal which was the dominant tree species of the deciduous forests of Bangladesh. Plant leaf samples were collected from the three populations of Sal distributed in the three geographical regions including Madhupur tract in the districts Tangail and Gazipur and that of the districts of Cumilla and Dinajpur. DNA band profiles were generated using eight ISSR primers for a total of 13 samples taken from the three populations. Statistical analysis was done using PopGen 32 and GenAlEx 6.5 softwares. Principal coordinate analysis done on the DNA band profiles revealed that Sal populations of Madhupur tract and Cumilla positioned nearby while Dinajpur showed maximum genetic distance with that of Cumilla. Mantel test showed significant (p=0.05) correlation between genetic and geographic distances indicating “Isolation by Distance”. Data of the present study indicated higher genetic polymorphism (68.87%) in the Sal population of Madhupur tract compared to other two populations. Small population size of Sal of Dinajpur forest might be related with its low genetic diversity. Data of the present study suggest immediate attention for the conservation of Sal forests in Bangladesh before further genetic erosion occurs. Bangladesh J. Bot. 50(2): 405-412, 2021 (June)

scholarly journals Genetic diversity and core subset selection in ex situ seed collections of the banana crop wild relative Musa balbisiana

2019 ◽  
Vol 17 (6) ◽  
pp. 536-544 ◽  
Author(s):  
Yves Bawin ◽  
Bart Panis ◽  
Samuel Vanden Abeele ◽  
Zhiying Li ◽  
Julie Sardos ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Crop Wild Relatives ◽  
Ex Situ ◽  
Musa Balbisiana ◽  
Centre Of Origin ◽  
Low Genetic Diversity ◽  
Feral Populations ◽  
Unique Variation ◽  
Seed Collections

AbstractCrop wild relatives (CWRs) play a key role in crop breeding by providing beneficial trait characteristics for improvement of related crops. CWRs are more efficiently used in breeding if the plant material is genetically characterized, but the diversity in CWR genetic resources has often poorly been assessed. Seven seed collections of Musa balbisiana, an important CWR of dessert and cooking bananas, originating from three natural populations, two feral populations and two ex situ field collections were retrieved and their genetic diversity was quantified using 18 microsatellite markers to select core subsets that conserve the maximum genetic diversity. The highest genetic diversity was observed in the seed collections from natural populations of Yunnan, a region that is part of M. balbisiana's centre of origin. The seeds from the ex situ field collections were less genetically diverse, but contained unique variation with regards to the diversity in all seed collections. Seeds from feral populations displayed low genetic diversity. Core subsets that maximized genetic distance incorporated almost no seeds from the ex situ field collections. In contrast, core subsets that maximized allelic richness contained seeds from the ex situ field collections. We recommend the conservation and additional collection of seeds from natural populations, preferentially originating from the species' region of origin, and from multiple individuals in one population. We also suggest that the number of seeds used for ex situ seed bank regeneration must be much higher for the seed collections from natural populations.

Low genetic diversity and inbreeding depression in Queensland Koalas

1993 ◽  
Vol 20 (2) ◽  
pp. 177 ◽  
Author(s):  
JMW Wilmer ◽  
A Melzer ◽  
F Carrick ◽  
C Moritz
Keyword(s):  
Genetic Diversity ◽  
Mitochondrial Dna ◽  
Inbreeding Depression ◽  
Natural Populations ◽  
Small Population ◽  
Phascolarctos Cinereus ◽  
Low Genetic Diversity ◽  
History Of ◽  
Biased Sex Ratio ◽  
Two Populations

The amount of genetic variation in two natural populations of Queensland koalas (Phascolarctos cinereus adustus) was assessed by analysis of mitochondrial DNA. Levels and any adverse effects of inbreeding (inbreeding depression) were estimated from the pedigree of a well-characterised captive colony. Genetic diversity of mitochondrial DNA was found to be exceedingly low both within and between the two populations, but the variation detected was found to be strongly structured geographically. Inbreeding levels in the captive colony were moderate to high yet the only apparent evidence of inbreeding depression was a male-biased sex ratio. There was no evidence for decreased juvenile survivorship or growth rate with inbreeding. Because of the limited data it would be premature to conclude that koalas are relatively resistant to the effects of inbreeding. However, we suggest the hypothesis that koalas have a history of small population size, resulting in reduced susceptibility to inbreeding depression.

scholarly journals Clonal Reproduction and Low Genetic Diversity in Northern Australian Santalum lanceolatum (Santalaceae) Populations Highlights the Need for Genetic Rescue of This Commercially Significant Species

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 741
Author(s):  
Aaron Brunton ◽  
David J. Lee ◽  
Gabriel Conroy ◽  
Steven Ogbourne
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Life History Strategy ◽  
Conservation Strategy ◽  
Regional Differentiation ◽  
Genetic Rescue ◽  
Environmental Pressures ◽  
Northern Margin ◽  
Low Genetic Diversity ◽  
Wild Harvesting

Genetic diversity and the extent of clonality in a plant species can significantly influence its reproductive success. Whilst clonality can be an effective life-history strategy, in harsh environments it can lead to low levels of diversity and sexual reproductive failure. Santalum lanceolatum (Santalaceae) is a hemi-parasitic shrub endemic to the monsoonal dry tropics of northern Australia, which was harvested for its oil-rich heartwood from natural populations in Cape York, Australia. Despite wild harvesting ending over 70 years ago, populations in the region are currently declining. The aims of this study were to examine genetic variation, population genetic structure, inbreeding and clonality of six S. lanceolatum populations from this northern margin of the species range. Analyses of twelve microsatellite markers showed S. lanceolatum had low genetic diversity (AR = 2.776, HE = 0.409), evidence of regional differentiation (FST = 0.307–0.424) and negligible inbreeding levels (F = −0.052). Clonality investigations revealed 135 genets among 200 samples, suggesting that the clonal structure of S. lanceolatum may be limiting the potential for sexual reproduction and natural recruitment. We recommend a conservation strategy involving genetic rescue to prevent the further decline and potential local extinction from a variety of environmental pressures and human activities.

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