Genetic systems in the south-west flora: implications for conservation strategies for Australian plant species

2000 ◽  
Vol 48 (3) ◽  
pp. 341 ◽  
Author(s):  
Sidney H. James
Keyword(s):  
Genetic Diversity ◽  
Genetic Load ◽  
Allelic Diversity ◽  
Genetic System ◽  
Plant Population ◽  
Conservation Strategies ◽  
Population System ◽  
Australian Plant ◽  
South West ◽  
Genetic Systems

Is genetic diversity a reliable indicator of evolutionary capability? A comparative study of genetic systems in Australian native plants, particularly from south-west Australia, suggests the primitive condition to be recombinationally capable with low allelic diversity. Diversity has accumulated in some nursery lineages in association with lethal equivalent polymorphisms. This generated an elevated evolutionary capability which allowed escape from the benign nursery into the demanding arid playground. Lethal equivalent polymorphisms also generate a high genetic load which drives genetic system evolution towards the minimisation of that load. Many of the devices which reduce the genetic load, including chiasma localisation at meiosis and reduced chromosome numbers, are impedimenta to recombination and they must reduce evolutionary capability. Thus, to correctly interpret the levels and patterns of genetic diversity within an Australian plant population system we need to know how its genetic system operates and how much it is recombinationally impeded. It may be true that in many Australian plant population systems, the more genetic diversity we see, the less evolutionary potential there is. Conservation strategies based on a misunderstanding of the relevance of genetic diversity in population systems may be quite disastrous.

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.

scholarly journals Phenotypic Characterisation for Growth and Nut Characteristics Revealed the Extent of Genetic Diversity in Wild Macadamia Germplasm

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 680
Author(s):  
Thuy T. P. Mai ◽  
Craig M. Hardner ◽  
Mobashwer M. Alam ◽  
Robert J. Henry ◽  
Bruce L. Topp
Keyword(s):  
Genetic Diversity ◽  
Growth Traits ◽  
Principal Component ◽  
Conservation Strategies ◽  
Wild Germplasm ◽  
Phenotypic Characterisation ◽  
Wide Range ◽  
Genetic And Environmental Factors ◽  
Positive Correlations ◽  
Wild Accessions

Macadamia is a recently domesticated Australian native nut crop, and a large proportion of its wild germplasm is unexploited. Aiming to explore the existing diversity, 247 wild accessions from four species and inter-specific hybrids were phenotyped. A wide range of variation was found in growth and nut traits. Broad-sense heritability of traits were moderate (0.43–0.64), which suggested that both genetic and environmental factors are equally important for the variability of the traits. Correlations among the growth traits were significantly positive (0.49–0.76). There were significant positive correlations among the nut traits except for kernel recovery. The association between kernel recovery and shell thickness was highly significant and negative. Principal component analysis of the traits separated representative species groups. Accessions from Macadamia integrifolia Maiden and Betche, M. tetraphylla L.A.S. Johnson, and admixtures were clustered into one group and those of M. ternifolia F. Muell were separated into another group. In both M. integrifolia and M. tetraphylla groups, variation within site was greater than across sites, which suggested that the conservation strategies should concentrate on increased sampling within sites to capture wide genetic diversity. This study provides a background on the utilisation of wild germplasm as a genetic resource to be used in breeding programs and the direction for gene pool conservation.

scholarly journals Genetic Investigation of Four Beluga Sturgeon (Huso huso, L.) Broodstocks for its Reintroduction in the Po River Basin

Environments ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 25
Author(s):  
Caterina M. Antognazza ◽  
Isabella Vanetti ◽  
Vanessa De Santis ◽  
Adriano Bellani ◽  
Monica Di Francesco ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Mitochondrial Dna ◽  
Genetic Variability ◽  
River Basin ◽  
Captive Breeding ◽  
Conservation Strategies ◽  
Huso Huso ◽  
Po River ◽  
Beluga Sturgeon ◽  
Po River Basin

The reintroduction of the extinct beluga sturgeon (Huso huso L.), an anadromous species with economic and traditional relevance, is a priority in next conservation strategies in Northern Italy. The EU-LIFE NATURA project aims to reintroduce the beluga sturgeon in the Po River basin through a captive breeding program. Critical requirements for the success of the program are river connectivity and knowledge of genetic diversity of the selected broodstocks to ensure self-sustainability of reintroduced populations. Here, the four broodstocks used for the reintroduction of beluga sturgeon have been genetically screened, genotyping 13 loci and sequencing mitochondrial DNA cytochrome b (Cyt b) gene and the entire mitochondrial DNA control region (D-Loop). The four broodstocks showed a medium-high level of nuclear genetic variability and the presence of two sub-populations, evidencing a total level of inbreeding coefficients able to sustain the good potential as future breeders. Mitochondrial analyses showed a genetic variability comparable to wild populations, further strengthening the positive potential of the investigated broodstock. Therefore, this study, showed how the degree of genetic diversity found within the four broodstocks used for H. huso reintroduction in the Po River basin could be suitable to ensure the success of the program, avoiding the inbreeding depression associated with founder effect and captive breeding.

Genetic diversity of the extremely rare Habenaria dentata and the rare Habenaria linearifolia (Orchidaceae) in South Korea: implications for population history and conservation

2018 ◽  
Vol 151 (1) ◽  
pp. 48-60
Author(s):  
Mi Yoon Chung ◽  
Hoa Thi Quynh Le ◽  
Sungwon Son ◽  
Huai Zhen Tian ◽  
Myong Gi Chung
Keyword(s):  
Genetic Diversity ◽  
Southern China ◽  
Geographic Location ◽  
Population History ◽  
Population Variation ◽  
Conservation Strategies ◽  
Ancestral Population ◽  
Allozyme Diversity ◽  
Glacial Origin

Background and aims – Since historical events often leave an indelible mark on levels of genetic diversity of plant populations, one may indirectly infer their evolutionary history with the help of current patterns of genetic diversity. The terrestrial orchid Habenaria dentata, an element of warm-temperate/subtropical vegetation, reaches its northernmost limits in the Korean Peninsula, and thus it is extremely rare there. As H. dentata was absent from the Peninsula during the Last Glacial Maximum (LGM), it is likely to be of post-glacial origin having arrived from either a single refugium or multiple refugia. However, its rare, temperate/boreal congener H. linearifolia might have persisted in situ in either macrorefugia or microrefugia on the Peninsula during the LGM.Methods – To test which hypothesis is most appropriate for each species, we investigated levels of allozyme-based (17 loci) genetic diversity and population genetic structure in the two only known populations of H. dentata and in 12 populations of H. linearifolia.Key results – No allozyme diversity was found in H. dentata (He = 0.000), whereas H. linearifolia exhibited low within-population variation (He = 0.060) and high among-population differentiation (FST = 0.237). We found little association between populations in relation to their geographic location; several populations presented individuals belonging to different clusters.Conclusions – Our results suggest that H. dentata likely originated from a single ancestral population (perhaps from southern Japan or southern China) through post-glacial dispersal, whereas H. linearifolia probably survived the LGM in situ in microrefugia situated at low to mid-elevated regions. We further suggest that separate conservation strategies for each species should be employed, given that the two taxa have different ecological and demographic traits and harbour different levels of genetic diversity.

scholarly journals Microsatellite markers-based characterisation of elephant grass (Pennisetum purpureum) harvested from selected locations in South-West Nigeria

2020 ◽  
Vol 37 (1) ◽  
pp. 38-45
Author(s):  
O.A. Okukenu ◽  
A.A. Olajide ◽  
P.A. Dele ◽  
M. Wheto ◽  
B.T. Akinyemi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Microsatellite Markers ◽  
Dna Extraction ◽  
Morphological Characterization ◽  
Ethanol Solution ◽  
Pennisetum Purpureum ◽  
Elephant Grass ◽  
South West ◽  
Ssr Primers ◽  
Genetic Index

This study was carried out to characterise Pennisetum purpureum harvested from some selected locations in S outh-W estern Nigeria using microsatellite markers. Leaf parts of growing young elephant grass (Pennisetum purpureum) were harvested and immediately preserved in ethanol solution before DNA extraction. Two (2) SSR primers (CTM59 and Xtxp278) were used to assess genetic diversity in Pennisetum purpureum. The result shows that 72% of the molecular variations in the elephant grass exists within the population with 28% among the population; there were no unique characteristics among the Nine (9) populations. Nei genetic index ranged from 0.067 (lowest) observed between Isokan and Odeda populations to 0.158 (highest), between Ifedore and Ikoyi Populations. Morphological characterization showed moderate diversity with two major clusters and one minor cluster. Keyword: Elephant grass; cultivars; locations; markers

Geographic patterns of genetic variation and population structure in Pinus aristata, Rocky Mountain bristlecone pine

2012 ◽  
Vol 42 (1) ◽  
pp. 23-37 ◽  
Author(s):  
Anna W. Schoettle ◽  
Betsy A. Goodrich ◽  
Valerie Hipkins ◽  
Christopher Richards ◽  
Julie Kray
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Bark Beetles ◽  
Climatic Factors ◽  
Rocky Mountain ◽  
Conservation Strategies ◽  
Restricted Gene Flow ◽  
Populations At Risk ◽  
Bristlecone Pine ◽  
Pinus Aristata

Pinus aristata Engelm., Rocky Mountain bristlecone pine, has a narrow core geographic and elevational distribution, occurs in disjunct populations, and is threatened by rapid climate change, white pine blister rust, and bark beetles. Knowledge of genetic diversity and population structure will help guide gene conservation strategies for this species. Sixteen sites across four mountain ranges in the core distribution of P. aristata were sampled and genetic diversity was assessed with 21 isozyme loci. Low species and population level genetic diversity (He = 0.070 and 0.062, respectively) occurred with moderate among-population differentiation (FST = 0.131). Genetic diversity correlated with longitude, latitude, and elevation and a strong mountain island effect may contribute to substructuring and isolation. Using multiple complementary analyses, sampled trees were assigned to three genetic lineages that varied in diversity and admixture and were associated with different climatic factors. The distribution of genetic diversity and substructuring of P. aristata may be an outcome of a combination of restricted gene flow due to geographic and phenological isolation, random processes of genetic drift, life history traits, natural selection, and postglacial migrations. The combination of low genetic diversity, moderate population isolation, and a protracted regeneration dynamic puts populations at risk for extirpation by novel stresses.

Overt and Concealed Genetic Loads Revealed by QTL Mapping of Genotype-dependent Viability in the Pacific Oyster Crassostrea gigas

Genetics ◽  
2021 ◽  
Author(s):  
Xiaoshen Yin ◽  
Dennis Hedgecock
Keyword(s):  
Genetic Diversity ◽  
Crassostrea Gigas ◽  
Pacific Oyster ◽  
Genetic Load ◽  
High Density ◽  
High Genetic Diversity ◽  
High Fecundity ◽  
Recessive Mutations ◽  
Genotype Frequencies ◽  
The Pacific

Abstract Understanding the genetic bases of inbreeding depression, heterosis, and genetic load is integral to understanding how genetic diversity is maintained in natural populations. The Pacific oyster Crassostrea gigas, like many long-lived plants, has high fecundity and high early mortality (type-III survivorship), manifesting a large, overt, genetic load; the oyster harbors an even greater concealed genetic load revealed by inbreeding. Here, we map viability QTL (vQTL) in six interrelated F2 oyster families, using high-density linkage maps of single nucleotide polymorphisms generated by genotyping-by-sequencing (GBS) methods. Altogether, we detect 70 vQTL and provisionally infer 89 causal mutations, 11 to 20 per family. Genetic mortality caused by independent (unlinked) vQTL ranges from 94.2% to 97.8% across families, consistent with previous reports. High-density maps provide better resolution of genetic mechanisms, however. Models of one causal mutation present in both identical-by-descent (IBD) homozygotes and heterozygotes fit genotype frequencies at 37 vQTL; consistent with the mutation-selection balance theory of genetic load, 20 are highly deleterious, completely recessive mutations and 17 are less deleterious, partially dominant mutations. Another 22 vQTL require pairs of recessive or partially dominant causal mutations, half showing selection against recessive mutations linked in repulsion, producing pseudo-overdominance. Only eight vQTL appear to support the overdominance theory of genetic load, with deficiencies of both IBD homozygotes, but at least four of these are likely caused by pseudo-overdominance. Evidence for epistasis is absent. A high mutation rate, random genetic drift, and pseudo-overdominance may explain both the oyster’s extremely high genetic diversity and a high genetic load maintained primarily by mutation-selection balance.

scholarly journals Allelic diversity in populations of Solanum lycocarpum A. St.-Hil (Solanaceae) in a protected area and a disturbed environment

2011 ◽  
Vol 25 (4) ◽  
pp. 937-940 ◽  
Author(s):  
Tânia Maria de Moura ◽  
Alexandre Magno Sebbenn ◽  
Karina Martins ◽  
Maria Andreia Moreno ◽  
Giancarlo Conde Xavier Oliveira ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Protected Areas ◽  
Allelic Diversity ◽  
Rare Allele ◽  
Conservation Unit ◽  
Long Distance ◽  
Disturbed Area ◽  
Disturbed Areas ◽  
Pasture Area ◽  
Two Populations

This study aimed to compare the genetic diversity of populations of Solanum lycocarpum A.St.-Hil between natural and human disturbed environments, with the assumption that protected areas have greater genetic diversity than disturbed areas. For this study, two populations were sampled in Goiás State, Brazil. One was located in a conservation unit, Serra de Caldas Novas State Park, in the Caldas Novas municipality. The other was located in a pasture area in the municipality of Morrinhos. The two populations are 41 km apart. We sampled 60 individuals from each population, which were genotyped with five microsatellite loci (SSR). The highest number of alleles was recorded in the population of the conservation unit, where we found 11 exclusive and five rare alleles. In the disturbed area, we recorded only three exclusive alleles and one rare allele. Although we did not observe significant inbreeding in these populations, genetic divergence between them was high (G ST (Hedrick)=0.147 =0.147) for a species with long distance seed dispersal. The results corroborate the hypothesis that the population in the less disturbed area harbors greater allelic diversity. They also confirm the effectiveness of using protected areas to preserve the genetic diversity of the species.

scholarly journals Genetic variability and relationship among different accessions of Froriepia subpinata Bail (Gijavash) an endangered medicinal plant from Iran revealed by ISSR and IRAP markers

2021 ◽  
Vol 35 (1) ◽  
Author(s):  
Abbas Jorkesh ◽  
Yousef Hamidoghli ◽  
Jamalali Olfati ◽  
Habibollah Samizadeh ◽  
Davood Bakhshi
Keyword(s):  
Genetic Diversity ◽  
Cluster Analysis ◽  
Genetic Variability ◽  
Medicinal Plant ◽  
Genetic Information ◽  
Conservation Strategies ◽  
Polymorphic Band ◽  
Mean Values ◽  
Endangered Medicinal Plant ◽  
Irap Markers

The genetic variability of Froriepia subpinata Ledeb. Bail., an endangered Iranian endemic species, has been estimated with a total of 52 accessions using 20 markers including ISSR and IRAP. The results showed the polymorphic band produced by primers was 82.3%. The best mean values of genetic diversity parameters observed in ISSRs markers, being UBC873, UBC811, and UBC873 the best primers tested. The similarity range among accessions was 34.45% to 93.3%. The cluster analysis classified the accessions into five main groups that in totally, accessions with similarity in region generally were clustered in the same group. Overall, present study could provide elementary information for formulation of conservation strategies and invaluable elementary genetic information for next breeding or designing conservation programs.

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