The genetic structure and the conservation of the five natural populations of Pinusradiata

1988 ◽  
Vol 18 (5) ◽  
pp. 506-514 ◽  
Author(s):  
G. F. Moran ◽  
J. C. Bell ◽  
K.G. Eldridge
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Conservation Strategies ◽  
Mainland Population ◽  
Island Populations ◽  
Expected Heterozygosity ◽  
Environmental Criteria ◽  
Total Genetic Diversity ◽  
Allozyme Loci

Pinusradiata is restricted to three mainland coastal populations in California and two island populations off Baja California, Mexico. In this study each population was divided into two geographic stands based on natural disjunctions within populations. In addition to the division mentioned above, each mainland population was also divided into a number of ecological stands based on ecological and environmental criteria. Genetic variation was measured by analysing 31 allozyme loci electrophoretically using germinated seed from 272 families across all stands and populations. Moderate levels of allozyme variation were found as shown by population averages for mean number of alleles per locus (1.79), percent polymorphic loci (46.4%, 0.99 criterion), and expected heterozygosity (0.098). In fact, the overall genetic diversity in P. radiata (HT = 0.117) is low compared with that of other conifers. In comparison with populations, the levels of allozyme variation in both ecological and geographic stands were slightly lower (means across ecological stands: A = 1.56, P = 39.3%, and He = 0.095). Of the total genetic diversity in P. radiata, 16.2% could be apportioned between populations, a high proportion for a conifer. In contrast, only 2.0 and 1.3% of the genetic diversity on average within mainland populations was between ecological and geographic stands, respectively. These results indicate a low level of genetic differentiation within populations, at least based on the ecological or geographic criteria used in this study. The implications and usefulness of these findings for the development of insitu conservation strategies are discussed.

Allozyme Variation and Population Substructuring in the Caucasian Ground Lizards Lacerta derjugini and Lacerta praticola

2011 ◽  
Vol 4 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Ross D. MacCulloch ◽  
Ilya S. Darevsky ◽  
Robert W. Murphy ◽  
Jinzhong Fu
Keyword(s):  
Genetic Diversity ◽  
Allozyme Variation ◽  
Close Proximity ◽  
Geographic Separation ◽  
Population Substructuring ◽  
Allozyme Loci ◽  
Two Populations

Genetic diversity at 35 allozyme loci was surveyed in Lacerta derjugini (3 populations) and L. praticola (2 populations). Indices of variability were consistent with those found in other Caucasian Lacerta. There was little genetic substructuring between two populations of L. praticola despite considerable geographic separation. Conversely, populations of L. derjugini in close proximity to one another exhibited considerable substructuring.

Patterns of allozyme variation within and among Douglas-fir breeding zones in southwest Oregon

1987 ◽  
Vol 17 (5) ◽  
pp. 402-407 ◽  
Author(s):  
S. A. Merkle ◽  
W. T. Adams
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Frequency ◽  
Quantitative Traits ◽  
Allozyme Variation ◽  
Douglas Fir ◽  
Expected Heterozygosity ◽  
Breeding Zone ◽  
Southwest Oregon ◽  
Environmental Distance

Gametophytes from wind-pollinated seeds of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) parent trees (mean 56) in each of 22 breeding zones in southwest Oregon were analyzed electrophoretically for gene frequency patterns at 27 loci. Allozyme variability levels were high, as shown by breeding-zone averages for the percentage of polymorphic loci (71.7%, 0.99 criterion), mean number of alleles per locus (2.46), and expected heterozygosity (0.178). Differences among zones in allele frequency were significant (p < 0.05) for only 2 of the 27 loci surveyed, and analysis of hierarchical population structure showed that less than 1% of genetic diversity was attributable to differences among breeding zones. Genetic distance between zones was small [Formula: see text] and, in general, bore no relation to geographical or environmental distance. The limited allozyme differentiation among zones contrasts strikingly with the environment-related variation in seedling quantitative traits previously reported for southwest Oregon Douglas-fir. Allozymes do not appear to be useful for mapping patterns of adaptive variation or for certifying Douglas-fir seed in this region.

Seasonal variation and clonal selection in cyclically parthenogenetic rose aphids (Macrosiphum rosae)

1985 ◽  
Vol 27 (2) ◽  
pp. 224-232 ◽  
Author(s):  
L. R. Rhomberg ◽  
S. Joseph ◽  
R. S. Singh
Keyword(s):  
Genetic Variation ◽  
Seasonal Variation ◽  
Clonal Selection ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Polymorphic Loci ◽  
Esterase Loci ◽  
Allozyme Loci ◽  
Macrosiphum Rosae ◽  
Asexual Cycle

Patterns of geographic and seasonal genetic variation were assessed in natural populations of cyclically parthenogenetic rose aphids Macrosiphum rosae (L.). Nine populations were studied for a red–green colour morph and 30 allozyme loci (20 coding for enzymes and 10 for abundant proteins). Genetic variation was found at 5 of 20 enzyme loci (20%); all 10 abundant proteins proved monomorphic. The average heterozygosity was 4.3%. At some polymorphic loci genotypic frequencies showed significant deviations from Hardy–Weinberg proportions. Six local populations from Hamilton, Ontario, were studied for seasonal variation at the colour locus and at two polymorphic esterase loci (Est-2 and Est-4). All three loci showed large changes in genotypic frequencies over the season during the asexual cycle, but only for Est-4 were changes consistent among populations. This locus undergoes a regular seasonal cycle, the directional changes during the asexual phase presumably being balanced by changes during the sexual phase. The frequencies of three-locus genotypes within each locality fluctuated dramatically over the course of a season, reflecting the domination of local infestations by a few particularly successful clones. We speculate that because of such clonal competition followed by extensive migration, much of the selectively neutral variation is purged from aphid populations. The remaining polymorphic loci, which are mostly di- or tri-allelic, are subject to balancing natural selection at the gene or at closely linked loci. The Est-4 in rose aphids is an example of such a selectively maintained polymorphism.Key words: aphids, allozyme variation, seasonal variation, parthenogenesis, clonal selection, population structure.

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.

Microgeographical Patterns of Allozyme Variation in Casuarina cunninghamiana Miq Within and Between the Murrumbidgee and Coastal Drainage Systems

1989 ◽  
Vol 37 (2) ◽  
pp. 181 ◽  
Author(s):  
NJ Moore ◽  
GF Moran
Keyword(s):  
Genetic Diversity ◽  
Large Population ◽  
Drainage System ◽  
Allozyme Variation ◽  
Distance Measures ◽  
Drainage Systems ◽  
Casuarina Cunninghamiana ◽  
Total Genetic Diversity ◽  
Geographic Clustering

Within the Murrumbidgee drainage system, 100 seedlings from each of 14 populations of Casuarina cunninghamiana were assayed for their allozyme genotypes at 14 loci. The levels of genetic variation were fairly similar in all populations. There was no geographic clustering of populations based on genetic distance measures. Only 3.8% of the total genetic diversity could be apportioned among populations within the drainage system. In six additional populations, branchlets from 50 trees per population were assayed for their allozyme genotypes at 27 loci. Three populations were from the Murrumbidgee drainage system and each of the others from a different coastal drainage. The mean expected heterozygosities for coastal and inland zones were 0.139 and 0.093 respectively. Of the total genetic diversity 10.7% could be apportioned among the four drainages. The results of this study suggest that for in situ conservtion of C. cunninghamiana within a region, more emphasis should be placed on conserving one large population from each major drainage system rather than a number of populations within one or two drainage systems.

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 Genetic diversity in natural populations of Hancornia speciosa Gomes: Implications for conservation of genetic resources

2018 ◽  
Vol 42 (6) ◽  
pp. 623-630
Author(s):  
Cristiane Gouvêa Fajardo ◽  
Daniel Ferreira da Costa ◽  
Kyvia Pontes Teixeira das Chagas ◽  
Fábio de Almeida Vieira
Keyword(s):  
Genetic Diversity ◽  
Genetic Resources ◽  
In Situ Conservation ◽  
Natural Populations ◽  
Allelic Diversity ◽  
Shannon Index ◽  
Conservation Strategies ◽  
Effective Population ◽  
Infinite Allele Model ◽  
Hancornia Speciosa

ABSTRACT The continuing fragmentation of forests has been a threat to the maintenance of genetic resources. Genetic diversity is fundamental to the survival of species in natural environments in the long term, as well as being the basis for genetic improvement. The objective of this study was to evaluate the genetic diversity in natural populations of Hancornia speciosa and to contribute to the development of conservation strategies. We sampled 105 individuals of H. speciosa, distributed in seven populations. The ISSR (Inter-Simple Sequence Repeat) markers provided 70 loci, of which 81% were polymorphic. The mean genetic diversity of Nei (h) was 0.19, and the Shannon index (I) was 0.27. The h and I diversity indices ranged respectively from 0.16 to 0.24 in the PAD (Parque das Dunas) population and from 0.21 to 0.29 in MAC (Macaíba) population. Resulting from a Bayesian analysis, the genotypes were divided into four groups (K = 4). The allelic diversity patterns observed indicated the occurrence of the genetic bottleneck in all populations, according to the stepwise mutation model (SMM). The infinite allele model (IAM) revealed an imbalance between mutation and genetic drift only in the PAD population. Genetic conservation strategies for H. speciosa should cover each genetic group that was differentially structured. We recommend in situ conservation and the creation of germplasm banks, especially with the PAD population which demonstrated the lower genetic diversity and decreased effective population size according to the two mutational models.

Genetic Diversity of Cambuci (Campomanesia Phaea) Revealed by Microsatellite Markers

2021 ◽  
Author(s):  
Rafael Oliveira Moreira ◽  
Eduardo de Andrade Bressan ◽  
Horst Bremer Neto ◽  
Angelo Pedro Jacomino ◽  
Antonio Figueira ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Microsatellite Markers ◽  
Native Species ◽  
Genetic Parameters ◽  
Genomic Library ◽  
Conservation Strategies ◽  
Paulo State ◽  
Allele Number ◽  
Expected Heterozygosity

Abstract Campomanesia phaea (Myrtaceae), known as cambuci, is a native species from the Brazilian Atlantic Forest with great potential to be developed as a new fruit crop. Microsatellite markers were developed for cambuci to characterize the genetic diversity and to investigate the genetic structure of a group of accessions originally collected at the presumed center of diversity of the species. The work involved the collection of 145 accessions from five regional groups (Juquitiba, Paraibuna, Mogi das Cruzes, Ribeirão Pires, and Salesópolis) in São Paulo state, Brazil. Fourteen loci were identified in an enriched genomic library developed from one of these accessions. Six out of 14 loci revealed to be polymorphic, disclosing 26 alleles. Based on the allele frequencies, the calculated genetic parameters of the five groups indicated an average allele number per loci (A) of 3.83, with the expected heterozygosity (He) of 0.57 and the observed heterozygosity (Ho) of 0.54. The analysis of the genetic structure indicated that most of the genetic diversity is found within each population (HS = 0.57), whereas the genetic diversity among populations was low (GST = 0.19). The genetic diversity parameter of Nei was considered low for the cambuci analyzed populations, with no evidence of inbreeding. Based on Darwin analysis, we chose 18 accessions from the five regional populations to compose a core collection that includes most of the genetic diversity found in this study. Our findings may contribute to define better conservation strategies and genetic breeding approaches for this native species in Brazil.

Genetic Diversity and Environmental Future

1978 ◽  
Vol 5 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Gabor Vida
Keyword(s):  
Genetic Diversity ◽  
Natural Selection ◽  
Human Population ◽  
Natural Populations ◽  
Wild Populations ◽  
Modern Agriculture ◽  
Total Genetic Diversity ◽  
Enormous Amount ◽  
Suitable Amount ◽  
Historical Times

Increasing evidence indicates that a major portion of the enormous amount of polymorphism present in natural populations is maintained by natural selection. This polymorphism is necessary for adaptation. In the absence of a suitable amount of genetic diversity, a species will tend to die out in a changing environment.The genetic diversity of most species has been considerably reduced in historical times. Breeding for uniformity, and reduction in the number and size of wild populations, are largely responsible for this loss. Replacement of a natural forest ecosystem by modern agriculture reduces the genetic diversity by three orders of magnitude at the very least. A comparison of the estimated prehistoric and present amount of genetic diversity leads to the alarming conclusion that we may already have lost as much as 90% of the total genetic diversity of the biosphere. Further loss is expected because of the rapid growth of human population.

A Cline in Genetic Diversity in River She-Oak Casuarina cunninghamiana

1989 ◽  
Vol 37 (2) ◽  
pp. 169 ◽  
Author(s):  
GF Moran ◽  
JC Bell ◽  
JW Turnbull
Keyword(s):  
Genetic Diversity ◽  
Significant Positive Correlation ◽  
Population Level ◽  
Geographic Range ◽  
Northern Territory ◽  
Height Growth ◽  
Western Population ◽  
Casuarina Cunninghamiana ◽  
Total Genetic Diversity ◽  
Allozyme Loci

Twenty populations of Casuarina cunninghamiana Miq. covering its large geographic range were used in a study of genetic diversity. Genetic variation was measured by analysing 19 allozyme loci using 50 seedlings from each of the populations. The overall genetic diversity (HT = 0.287) in C. cunninghamiana is high compared to many other plant species. A significant fraction (26.4%) of the total genetic diversity could be apportioned among populations. This genetic differentiation between populations was not random. Populations in the eastern part of the range had high correlation (r = 0.91) of genetic diversity with latitude and this involved changes in allelic frequencies at several loci. At the population level, there was a significant positive correlation between genetic diversity and 1 year height growth. The western population from King River in the Northern Territory was very distinct genetically from all the other populations and this supported previous suggestions that the northwest part of the range is occupied by a different race of the species.

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