Genetic diversity among natural populations of Agathis borneensis (Araucariaceae), a tropical rain forest conifer from Brunei Darussalam, Borneo, Southeast Asia

1992 ◽  
Vol 70 (10) ◽  
pp. 1945-1949 ◽  
Author(s):  
Keiko Kitamura ◽  
Mohamad Yusof Bin Abdul Rahman
Keyword(s):  
Genetic Diversity ◽  
Southeast Asia ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Natural Populations ◽  
Conservation Strategy ◽  
Restricted Gene Flow ◽  
Isozyme Electrophoresis ◽  
Brunei Darussalam ◽  
Population Component

Agathis is a genus of tropical conifers that occurs mainly in Southeast Asia. Because of its production of good softwood, many stands of Agathis have been harvested. We provide an estimate of genetic variation within and among populations of Agathis borneensis in Brunei Darussalam, Southeast Asia. Five populations were investigated using isozyme electrophoresis. We investigated a total of 17 putative loci, five of which were polymorphic. Estimated total heterozygosity was 0.122. Heterozygosity within populations was 0.106. The population structure did not deviate significantly from Hardy–Weinberg expectations. Nei's coefficient of gene differentiation indicated that the among-population component of genetic diversity represents 14% of the total population component. The low level of genetic diversity and the large diversity among populations were the opposite of that for conifers in the temperate zone, because of the small size of each population. The large diversity among populations indicated the restricted gene flow resulting from the asynchronous flowering of this species. The genetic distance indicated that A. borneensis in Brunei could be classified in two groups, with one isolated population considerably different from the others both genetically and ecologically. The conservation strategy is discussed from the viewpoint of genetic resources. Key words: Agathis borneensis, Araucariaceae, Brunei Darussalam, genetic diversity, isozyme, tropical rain forest.

Morphological and isozyme variation in Cerastium arvense (Caryophyllaceae) in the southern Andes

2002 ◽  
Vol 80 (7) ◽  
pp. 786-795 ◽  
Author(s):  
María Paula Quiroga ◽  
Andrea C Premoli ◽  
Cecilia Ezcurra
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Common Garden ◽  
High Elevation ◽  
Genetic Differences ◽  
Restricted Gene Flow ◽  
Common Garden Experiment ◽  
Southern Andes ◽  
Isozyme Electrophoresis ◽  
Ecotypic Variation

We tested the hypothesis that South Andean populations of the highly polymorphic and mostly Northern Hemisphere perennial forb Cerastium arvense L. show ecotypic variation along distinct habitats. We compared differences in morphology and flowering phenology among six natural populations occurring in different environments. Genetic differences were analyzed by a common-garden experiment and isozyme electrophoresis. Several of the morphological differences observed in the field were maintained after more than a year of cultivation in the common garden (e.g., plant height and leaf width). Mean tests and multivariate analyses on morphological traits generally distinguished high-elevation populations from the rest, and a similar grouping of populations was obtained from isozyme data at 10 loci. Cerastium arvense had genetic polymorphism levels of >50% in all populations and an average genetic diversity (HT = 0.254) of which approximately 20% was distributed among populations. These marked genetic differences are probably maintained by restricted gene flow due to variation in flowering time. Morphological and genetic differences suggest ecotypic variation in C. arvense in the southern Andes, which seems to have originated by disruptive selective pressures in different environments and the effect of genetic drift in response to the extreme climatic changes occurring during the Pleistocene.Key words: common-garden experiment, ecotypic variation, elevation and precipitation, genetic diversity, Patagonian Andes, phenology.

scholarly journals Genetic variation and outcrossing rate of Dipterocarpus dyeri in the Tan Phu tropical rain forest (Dong Nai), Vietnam

2019 ◽  
Vol 41 (1) ◽  
Author(s):  
Nguyen Minh Duc ◽  
Vu Dinh Duy ◽  
Dang Phan Hien ◽  
Tran Thi Viet Thanh ◽  
Nguyen Thi Phuong Trang ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Habitat Destruction ◽  
Outcrossing Rate ◽  
Conservation Strategy ◽  
Ex Situ ◽  
Mixed Mating ◽  
Mating Rate

Dipterocarpus dyeri (Dipterocarpaceae) is widely distributed in lowland rainforests in southeastern Vietnam. Due to over- exploitation and habitat destruction in the 1980s and 1990s, this species is listed as threatened. Understanding the genetic variation and mating rate among D. dyeri population that occurs in forest patches is necessary to establish effectively conservation strategies for this species. To conserve the species in tropical forests, genetic diversity and mating rate were investigated using eight microsatellites (single sequence repeat, SSR) as markers. All of the eight loci were polymorphic. A total of 36 different alleles were observed across the loci screened. The SSR data indicated high genetic diversity (NA = 4.5; HO = 0.542 and HE = 0.667) and high inbreeding value, FIS= 0,182. The mating system parameters were determined using the mixed mating model and the results indicated high outcrossing rate (tm=0.81 and ts=0.675) and lowselfing rate (0.19). Difference of tm-ts value indicated that inbreeding contributed to selfing rate for this species in the Tan Phu tropical rain forest. The results reflected that D. dyeri habitat in this area has been restored and the number of individuals was high, about 500 individuals. However, seedlings were not found so far in this study. These results indicated the importance of conserving of the genetic resources of Dipterocarpus dyeri species in the Tan Phu rain forest. The conservation strategy should include an establishment of an ex-situ conservation site with new big population for this species from all genetic groups, which might improve its fitness under different environmental stresses.  

scholarly journals Chloroplast microsatellites reveal genetic diversity and population structure in natural populations of Himalayan Cedar (Cedrus deodara (Roxb.) G. Don) in India

2020 ◽  
Vol 69 (1) ◽  
pp. 86-93
Author(s):  
H. S. Ginwal ◽  
Rajesh Sharma ◽  
Priti Chauhan ◽  
Kirti Chamling Rai ◽  
Santan Barthwal
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Natural Populations ◽  
Conservation Strategies ◽  
Restricted Gene Flow ◽  
Chloroplast Microsatellites ◽  
Timber Species ◽  
Western Himalayas ◽  
Cedrus Deodara ◽  
High Level

AbstractHimalayan cedar (Cedrus deodara) is one of the most important temperate timber species of Western Himalayas and is considered to be among the endangered conifer species in the region. Knowledge of genetic diversity and population structure will help guide gene conservation strategies for this species. Ten polymorphic chloroplast microsatellites (cpSSR) were used to study genetic diversity and population structure in twenty one natural populations of C. deodara throughout its entire distribution range in Western Himalayas. When alleles at each of the 10 loci were jointly analysed, 254 different haplotypes were identified among 1050 individuals. The cpSSRs indicate that C. deodara forests maintain a moderately high level of genetic diversity (mean h = 0.79 ). AMOVA analysis showed that most of the diversity in C. deodara occurs within populations. Bayesian analysis for population structure (BAPS) revealed spatial structuration of the variation (22 % of the total variation) and substructuring captured nineteen genetic clusters in the entire divisions of the populations. Most of the populations were clustered independently with minor admixtures. The distribution of genetic diversity and sub-structuring of C. deodara may be due to restricted gene flow due to geographic isolation, genetic drift, and natural selection. These findings indicated existence of genetically distinct and different high diversity and low diversity clusters, which are potential groups of populations that require attention for their conservation and management. The results are interpreted in context of future conservation plans for C. deodara.

scholarly journals DNA profiling and assessment of genetic diversity of relict species Allium altaicum Pall. on the territory of Altai

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10674
Author(s):  
Oxana Khapilina ◽  
Olesya Raiser ◽  
Alevtina Danilova ◽  
Vladislav Shevtsov ◽  
Ainur Turzhanova ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Endangered Species ◽  
Biological Diversity ◽  
Vegetative Reproduction ◽  
Natural Populations ◽  
Mobile Genetic Elements ◽  
Ice Age ◽  
Conservation Strategy ◽  
Relict Species ◽  
Genetic Elements

Analysis of the genetic diversity of natural populations of threatened and endangered species of plants is a main aspect of conservation strategy. The endangered species Allium altaicum is a relict plant of the Ice Age and natural populations are located in extreme climatic conditions of Kazakstan’s Altai Mountains. Mobile genetic elements and other interspersed repeats are basic components of a eukaryote genome, which can activate under stress conditions and indirectly promote the survival of an organism against environmental stresses. Detections of chromosomal changes related to recombination processes of mobile genetic elements are performed by various PCR methods. These methods are based on interspersed repeat sequences and are an effective tool for research of biological diversity of plants and their variability. In our research, we used conservative sequences of tRNA primer binding sites (PBS) when initializing the retrotransposon replication as PCR primers to research the genetic diversity of 12 natural populations of A. altaicum found in various ecogeographic conditions of the Kazakhstani Altai. High efficiency of the PBS amplification method used was observed already at the intrapopulation level. Unique amplicons representative of a certain population were found at the intrapopulation level. Analysis of molecular dispersion revealed that the biodiversity of populations of mountainous and lowland A. altaicum is due to intrapopulation differences for climatic zones of habitation. This is likely conditional upon predominance of vegetative reproduction over seed reproduction in some populations. In the case of vegetative reproduction, somatic recombination related to the activity of mobile genetic elements are preserved in subsequent generations. This leads to an increase of intrapopulation genetic diversity. Thus, high genetic diversity was observed in populations such as A. altaicum located in the territory of the Kalbinskii Altai, whereas the minimum diversity was observed in the populations of the Leninororsk ecogeographic group. Distinctions between these populations were also identified depending on the areas of their distribution. Low-land and mid-mountain living environments are characterized by a great variety of shapes and plasticity. This work allowed us to obtain new genetic data on the structure of A. altaicum populations on the territory of the Kazakhstan Altai for the subsequent development of preservation and reproduction strategies for this relict species.

Cyanogenic polymorphism as an indicator of genetic diversity in the rarespecies Eucalyptus yarraensis (Myrtaceae)

2002 ◽  
Vol 29 (12) ◽  
pp. 1445 ◽  
Author(s):  
Jason Q. D. Goodger ◽  
Ian E. Woodrow
Keyword(s):  
Genetic Diversity ◽  
Effective Means ◽  
Natural Populations ◽  
Population Variation ◽  
Conservation Strategy ◽  
Narrow Sense Heritability ◽  
Specialist Herbivores ◽  
Cyanogenic Plants ◽  
Physical And Chemical ◽  
First Time

The rare Australian tree Eucalyptus yarraensis Maiden & Cambage is cyanogenic, a quantitative trait potentially indicative of genetic diversity. Cyanogenic plants are capable of releasing cyanide from endogenous cyanide-containing compounds. Cyanide is toxic or deterrent to generalist or non-adapted specialist herbivores. Consequently, cyanogenic plants are afforded an effective means of chemical defense. In this paper we characterize quantitative variation in cyanogenic capability, known as cyanogenic polymorphism, in E. yarraensis for the first time. We show that the cyanogenic glucoside prunasin (R-mandelonitrile-β-D-glucoside) is the only cyanogenic compound in E. yarraensis foliage. We also show that two natural populations of E. yarraensis display extensive intra- and inter-population variation in foliar prunasin concentration. The high prunasin concentrations reported in this paper represent the highest yet recorded for mature eucalypt leaves. The cyanogenic variation could not be attributed to measured physical and chemical parameters, supporting the hypothesis that the variation is genetically based. A preliminary progeny trial also supports this hypothesis, with narrow sense heritability estimated at 1.17 from three half-sibling families. The variation in cyanogenic capability may be a useful tool in the development of a conservation strategy for the species.

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

scholarly journals The invention of biodiversity: social perspectives on the management of biological variety in Africa

Africa ◽  
1996 ◽  
Vol 66 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Jane Guyer ◽  
Paul Richards
Keyword(s):  
Genetic Diversity ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Social Perspectives ◽  
Number Of Species ◽  
Unknown Species ◽  
Object Of Study ◽  
Or Genes ◽  
Species Biodiversity

Biodiversity means, in its broadest sense, the variety of life. More specifically it can refer to the number of species, genetic diversity or the variety of environments in which species or genes are to be found. The concept is in some ways an odd one, since biodiversity is quantitative without necessarily being quantifiable. As an object of study biodiversity is a bit like an iceberg—most of it is hidden from view, and (like the underwater portion of an iceberg) indefinite in shape and extent. The notion of global species biodiversity is often expressed in the form (estimates vary): 1·5 million species known to science, 5 million (or 30 million) yet remaining to be discovered (Primack, 1993). The rider to this surprising formulation is that most of the unknown species are probably insects in the tropical rain forest.

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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