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.

scholarly journals Two different epigenetic pathways detected in wild three-spined sticklebacks are involved in salinity adaptation

2019 ◽  
Author(s):  
Melanie J. Heckwolf ◽  
Britta S. Meyer ◽  
Robert Häsler ◽  
Marc P. Höppner ◽  
Christophe Eizaguirre ◽  
...  
Keyword(s):  
Natural Selection ◽  
Gasterosteus Aculeatus ◽  
Natural Populations ◽  
Wild Populations ◽  
Epigenetic Marks ◽  
Transgenerational Plasticity ◽  
The Face ◽  
Adaptation Processes ◽  
Methylation Patterns ◽  
Rapid Emergence

AbstractWhile environmentally inducible epigenetic marks are discussed as one mechanism of transgenerational plasticity, environmentally stable epigenetic marks emerge randomly. When resulting in variable phenotypes, stable marks can be targets of natural selection analogous to DNA sequence-based adaptation processes. We studied both postulated pathways in natural populations of three-spined sticklebacks (Gasterosteus aculeatus) and sequenced their methylomes and genomes across a salinity cline. Consistent with local adaptation, populations showed differential methylation (pop-DMS) at genes enriched for osmoregulatory processes. In a two-generation experiment, 62% of these pop-DMS were insensitive to salinity manipulation, suggesting that they could be stable targets for natural selection. Two-thirds of the remaining inducible pop-DMS became more similar to patterns detected in wild populations from the corresponding salinity, and this pattern accentuated over consecutive generations, indicating a mechanism of adaptive transgenerational plasticity. Natural DNA methylation patterns can thus be attributed to two epigenetic pathways underlying the rapid emergence of adaptive phenotypes in the face of environmental change.

There Is No Evidence of Geographical Patterning among Invasive Kentucky Bluegrass (Poa pratensis) Populations in the Northern Great Plains

Weed Science ◽  
2016 ◽  
Vol 64 (3) ◽  
pp. 409-420 ◽  
Author(s):  
Lauren A. Dennhardt ◽  
Edward S. DeKeyser ◽  
Sarah A. Tennefos ◽  
Steven E. Travers
Keyword(s):  
Genetic Diversity ◽  
Great Plains ◽  
Propagule Pressure ◽  
Poa Pratensis ◽  
Natural Populations ◽  
Kentucky Bluegrass ◽  
Grass Species ◽  
Northern Great Plains ◽  
Wild Populations ◽  
High Genetic Diversity

The study of colonizing and of dominant grass species is essential for prairie conservation efforts. We sought to answer how naturalized Kentucky bluegrass in the northern Great Plains has become successful in the last 20 yr despite its long history in the northern Great Plains. We tested for evidence of geographical differentiation using flow cytometry and microsatellite markers to ascertain the population genetics of Kentucky bluegrass. Across all tested wild populations, high levels of genetic diversity were detected along with moderate levels of structure. Mantel tests of geographical patterns were not significant. Using clonal assignment, we found two major clones that made up the majority of the tested wild populations. When we compared the wild individuals to pedigree cultivars, we found virtually no genetic overlap across all tests, which did not support our hypothesis of developed cultivars contributing to high genetic diversity in natural populations. Furthermore, DNA content tests indicated a narrow range in ploidy in wild populations compared with lawn cultivars, further supporting a hypothesis of divergence between wild and pedigree cultivars. These results indicate the recent invasion of Kentucky bluegrass in the northern Great Plains is not because of adaptation or propagule pressure, but rather likely an environmental or land use shift.

Mosaic microecological differential stress causes adaptive microsatellite divergence in wild barley, Hordeum spontaneum, at Neve Yaar, Israel

Genome ◽  
2002 ◽  
Vol 45 (6) ◽  
pp. 1216-1229 ◽  
Author(s):  
Qingyang Huang ◽  
Alex Beharav ◽  
Youchun Li ◽  
Valery Kirzhner ◽  
Eviatar Nevo
Keyword(s):  
Genetic Diversity ◽  
Natural Selection ◽  
Wild Barley ◽  
Permutation Test ◽  
Balancing Selection ◽  
Real Data ◽  
Hordeum Spontaneum ◽  
Data Sets ◽  
Total Genetic Diversity ◽  
Ssr Loci

Genetic diversity at 38 microsatellite (short sequence repeats (SSRs)) loci was studied in a sample of 54 plants representing a natural population of wild barley, Hordeum spontaneum, at the Neve Yaar microsite in Israel. Wild barley at the microsite was organized in a mosaic pattern over an area of 3180 m2 in the open Tabor oak forest, which was subdivided into four microniches: (i) sun–rock (11 genotypes), (ii) sun–soil (18 genotypes), (iii) shade–soil (11 genotypes), and (iv) shade–rock (14 genotypes). Fifty-four genotypes were tested for ecological–genetic microniche correlates. Analysis of 36 loci showed that allele distributions at SSR loci were nonrandom but structured by ecological stresses (climatic and edaphic). Sixteen (45.7%) of 35 polymorphic loci varied significantly (p < 0.05) in allele frequencies among the microniches. Significant genetic divergence and diversity were found among the four subpopulations. The soil and shade subpopulations showed higher genetic diversities at SSR loci than the rock and sun subpopulations, and the lowest genetic diversity was observed in the sun–rock subpopulation, in contrast with the previous allozyme and RAPD studies. On average, of 36 loci, 88.75% of the total genetic diversity exists within the four microniches, while 11.25% exists between the microniches. In a permutation test, GST was lower for 4999 out of 5000 randomized data sets (p < 0.001) when compared with real data (0.1125). The highest genetic distance was between shade-soil and sun–rock (D = 0.222). Our results suggest that diversifying natural selection may act upon some regulatory regions, resulting in adaptive SSR divergence. Fixation of some loci (GMS61, GMS1, and EBMAC824) at a specific microniche seems to suggest directional selection. The pattern of other SSR loci suggests the operation of balancing selection. SSRs may be either direct targets of selection or markers of selected haplotypes (selective sweep).Key words: natural selection, genetic diversity, microsatellites, adaptation, Hordeum spontaneum, wild barley, microsite divergence.

scholarly journals Assessment of Genetic Diversity in Five Nicaraguan Populations of Cedrela odorata L. (Meliaceae) using RAPD Markers

Encuentro ◽  
2016 ◽  
pp. 28-39
Author(s):  
Arlen Tijerino ◽  
Lourdes Callejas ◽  
David A. Cerda-Granados
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Rapd Markers ◽  
Diversity Index ◽  
Random Amplified Polymorphic Dna ◽  
Natural Populations ◽  
Cedrela Odorata ◽  
Total Genetic Diversity ◽  
Geographical Distances ◽  
The Mean

The goal of this study was to assess the genetic diversity of Nicaraguan populations of Cedrela odorata using Random Amplified Polymorphic DNA (RAPD) markers. Thus, genomic DNA was isolated from leaf samples collected from ninety-two trees belonging to five Nicaraguan natural populations of C. odorata. The mean number of alleles per locus, effective number of alleles per locus, percentage of polymorphic loci, genetic diversity (He ) of Nei and diversity index (Ho ) of Shannon were estimated for each population assuming that the populations were in HardyWeinberg equilibrium. Total genetic diversity was partitioned in intrapopulational and interpopulational diversity using Nei’s genetic differentiation (GST) and through an Analysis of Molecular Variance (AMOVA). The ΦST matrix was used to construct a dendrogram by the neighbor-joining method. According to values of both He and Ho , Esquipulas (Deparment of Matagalpa) presented the lowest diversity level; while La Trinidad (Department of Estelí) showed the highest diversity level. Genetic differentiation was calculated obtaining a GST value of 13.36%. AMOVA also showed a similar differentiation value ΦST =13.81%). Neighbour-joining dendrogram clustered the five populations in two groups, where the group formed by La Trinidad and El Refugio (Department of Granada) presented the biggest differentiation. Correlation between genetic and geographical distances was not found.

scholarly journals Genetic Diversity and Differentiation among Natural, Production, and Introduced Populations of the Narrowly Endemic Species Coreopsis leavenworthii (Asteraceae)

2008 ◽  
Vol 133 (2) ◽  
pp. 234-241 ◽  
Author(s):  
David M. Czarnecki ◽  
Madhugiri Nageswara Rao ◽  
Jeffrey G. Norcini ◽  
Frederick G. Gmitter ◽  
Zhanao Deng
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Natural Populations ◽  
Seed Collection ◽  
Central Florida ◽  
Natural Production ◽  
Introduced Populations ◽  
Total Genetic Diversity ◽  
High Level ◽  
Introduced Population

Seeds of Coreopsis leavenworthii Torr. & Gray (Asteraceae) are being commercially produced but the lack of genetic diversity information has hindered growers and end users from addressing several critical issues affecting wild collection, commercial production, distribution, and the use of seeds. In this study, the genetic diversity and differentiation among natural, production, and introduced populations were analyzed at the molecular level using 320 amplified fragment length polymorphism (AFLP) markers. A high level of diversity [68.6% average polymorphism; total genetic diversity (H t ) = 0.309] and a moderate level of genetic differentiation [total genetic diversity residing among populations (G st ) = 0.226; Φ st = 0.244; Bayesian analog of Nei's G st (G st -B) = 0.197] was detected among six natural populations—two each from northern, central, and southern Florida. Two distance-based clustering analyses, based on an individual's AFLP phenotypes or a population's allele frequencies, grouped natural populations into three clusters, concordant with our previous results from a common garden study of phenotypic variation. Clustering of populations was mostly according to their respective geographical origin within Florida. The correlation between geographical distances and pairwise F st values between populations was very significant (r = 0.855, P < 0.0001). Two central Florida natural populations were divergent and grouped into separate clusters, indicating that the existence of factors other than physical distance alone were contributing to genetic isolation. Three production populations maintained a level of genetic diversity comparable to that in the natural populations and were grouped with the natural populations from which the production populations were derived, suggesting that the genetic identity of the seed origin was maintained under production practices. The genetic diversity of the introduced population was comparable to that of the source populations (central Florida natural populations), but genetic shift seems to have occurred, causing the introduced population to cluster with local (northern Florida) populations where planted. The observed genetic differentiation among natural populations may indicate a need to develop appropriate zones within Florida for preservation of genetic diversity during seed collection, increase, and distribution. This high level of population differentiation also suggests a need to collect and analyze more natural populations across Florida and from Alabama for a better understanding of the species' genetic diversity and population structure across its distribution range.

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.

scholarly journals GENETIC DIVERSITY AND STRUCTURE OF Oenocarpus mapora GERMPLASM CONSERVED AT EASTERN AMAZON

2015 ◽  
Vol 37 (4) ◽  
pp. 984-992
Author(s):  
ELISA FERREIRA MOURA ◽  
MARIA DO SOCORRO PADILHA DE OLIVEIRA ◽  
DIEHGO TULOZA DA SILVA ◽  
LÍGIA CRISTINE GONÇALVES PONTES
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Microsatellite Loci ◽  
Natural Populations ◽  
Brazilian Amazon ◽  
Germplasm Bank ◽  
Analysis Of Molecular Variance ◽  
Molecular Variance ◽  
Total Genetic Diversity ◽  
Genetic Diversity And Structure

ABSTRACT The aim of this study was to evaluate the genetic diversity and structure in the germoplasm of Oenocarpus mapora conserved at Eastern Amazon. Thus, 88 individuals were genotyped with five microsatellite loci. These individuals belong to 24 accessions that were sampled in eight sample places of three Brazilian Amazon states conserved at the Active Germplasm Bank (AGB) of Embrapa Eastern Amazon. All loci were polymorphic and they generated 85 alleles with an average of 17 alleles per loci. Total genetic diversity (HE) was 0.48. Sample places were considered genetically distinct, with ?p = 0.354. The analysis of molecular variance (AMOVA) identified that the genetic portion among areas was of 36.14% and within 63.86%. The Nei distances varied from 0.091 between Abaetetuba and Santo Antônio do Tauá, both in the state of Pará (PA), to 4.18, between Parintins, AM and Rio Branco, AC. By means of Bayesian analysis, it was identified nine clusters that compose the accessions of the germplasm bank, with different distributions among individuals. The study showed high fixation rates per sample area, which indicates that there may have been significant inbreeding or crossing among parental individuals. It suggests that future samples should be made of different plants in natural populations. Even though, it was verified that there is considerable genetic variation in the germplasm of O. mapora.

scholarly journals Genetic diversity, structure, and kinship analysis of Trachemys venusta venusta in Wildlife Management Units and wild populations in south Mexico. Implications for conservation and management

2020 ◽  
Author(s):  
Elsi B. Recino-Reyes ◽  
Julia M. Lesher-Gordillo ◽  
Salima Machkour-M’Rabet ◽  
Manuel I. Gallardo-Alvárez ◽  
Claudia E. Zenteno-Ruiz ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Management Plan ◽  
Freshwater Turtle ◽  
Freshwater Turtles ◽  
Wild Populations ◽  
Genetic Management ◽  
Kinship Analysis ◽  
Management Units ◽  
The Impact

AbstractThe Meso-American slider turtle (Trachemys venusta) is a freshwater turtle endemic to Mexico and Central America. Due to the overexploitation of its natural populations, it is in the at risk category formulated by the Official Mexican Standard NOM-059-ECOL-2010. In the state of Tabasco, Management Units for the Conservation of Wildlife (UMA) were created to reduce the impact of overexploitation of freshwater turtles. However, no genetic management plan was considered. This study presents the level of genetic diversity of the founder individuals in order to develop a management plan which will optimize reproduction in the UMA. Genetic diversity was compared between captive (n = 45) and wild (n = 86) individuals using 14 microsatellite molecular markers. Level of genetic diversity could be considered as low (He < 0.6) for a species of turtle and suggests that a higher level of protection is required for this particular species. Furthermore, values were slightly higher for the captive group reflecting the mix of genetic sources (founding individuals from different localities) and demonstrating that the captive population is genetically representative of natural populations. The genetic structure analysis revealed a relationship between captive and wild populations, indicating the influence of the two principal river basins in this region on the population of freshwater turtles. Finally, according to the results obtained from the analysis conducted using Storm and ML-Relate programs, we recommend the use of 19 females and 13 males, generating a potential of 247 dyads with no relationship. These first results of genetic management in a Mexican UMA, demonstrate the importance of molecular approaches at the time of managing and conserving species in captivity.

scholarly journals Genetic Variation and Population Structure of Dendropanax morbifera Lev. (Araliaceae) in Korea

2006 ◽  
Vol 55 (1-6) ◽  
pp. 7-13 ◽  
Author(s):  
S. H. Kim ◽  
Y. S. Jang ◽  
J. G. Han ◽  
H. G. Chung ◽  
S.W. Lee ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Tree Species ◽  
Natural Populations ◽  
Island Population ◽  
Starch Gel Electrophoresis ◽  
Isolated Populations ◽  
Low Level ◽  
Total Genetic Diversity ◽  
Dendropanax Morbifera ◽  
Starch Gel

Abstract Dendropanax morbifera Lev. (Araliaceae) is an economically important tree species because of its role in the production of golden varnishes as well as its use as an ornamental plant. As an endemic tree species of Korea, it is restricted to the southern parts of Korea as isolated populations. In this study, eight natural populations of D. morbifera were investigated by starch-gel electrophoresis in an attempt to determine the extent of its genetic diversity. Out of 8 natural populations, the Suak population in Jeju island showed the lowest level of genetic diversity, while the Wando island population in Jeonnam showed the highest level of genetic diversity. Levels of genetic diversity maintained in D. morbifera (A/L =1.5, P95 = 27.3%, Ho = 0.100, He = 0.095) were notably lower than those of other tree species with wider and more continuous geographic distributions. The reasons for the low level of genetic diversity in D. morbifera might be due to the genetic drift caused by artificial disturbances. Most of the total genetic diversity (96%) was found within the populations. The UPGMA dendrogram based on Nei’s genetic distance did not show any particular geographic patterns. The low level of genetic diversity suggested that there should be an urgent emphasis on the conservation study of this species.

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