Genetic Diversity and the Conservation of Eucalyptus crucis Maiden

1988 ◽  
Vol 36 (4) ◽  
pp. 447 ◽  
Author(s):  
JF Sampson ◽  
SD Hopper ◽  
SH James
Keyword(s):  
Genetic Diversity ◽  
Tree Species ◽  
Distribution Patterns ◽  
Similar Distribution ◽  
Allozyme Data ◽  
Isolated Populations ◽  
Low Frequencies ◽  
Granite Outcrops ◽  
The Mean ◽  
Allozyme Loci

E. crucis Maiden occurs as small, isolated populations confined to granite outcrops in south-western Australia. The level and distribution of genetic diversity at 11 allozyme loci in 10 populations were estimated. Ten loci were polymorphic. However, many alleles were fixed in populations and occurred at low frequencies in others. The mean expected panmictic heterozygosity for populations was low when compared with tree species in general but similar to other tree species occurring in small, isolated populations. The level of population differentiation was high, as expected for small, isolated populations undergoing genetic fixation through genetic drift. The majority of the differentiation was attributable to between-population rather than between-subspecies differentiation. Analyses of allozyme data suggest that the mating system of E. crucis may be adapted to maintain diversity within populations by selection favouring heterozygous, presumably outcrossed progeny. The optimal strategy for the conservation of the genetic resources of E. crucis and other eucalypts with similar distribution patterns is considered in the light of this and previous studies.

Genetic diversity and the insular population structure of the rare granite rock species, Eucalyptus caesia Benth

1983 ◽  
Vol 31 (2) ◽  
pp. 161 ◽  
Author(s):  
GF Moran ◽  
SD Hopper
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Tree Species ◽  
Population Differentiation ◽  
Optimal Strategies ◽  
The Mean ◽  
Allozyme Loci ◽  
Granite Rocks ◽  
Insular Population

There are 15 populations of E. caesia Benth. on granite rocks in south-westem Australia which include a total of about 2120 plants. The level of genetic variation at 18 allozyme loci in 13 populations was estimated. Seven loci were monomorphic for all plants assayed. At a majority of the 11 polymorphic loci the level of polymorphism was very low in most populations. Within populations the mean number of alleles per locus was 1.31 and the genetic diversity 6.8%. However, populations differed markedly in allelic frequencies at a number of loci. The genetic diversity within populations was remarkably low for a tree species but the level of population differentiation was the highest reported for any tree species. The data suggest that genetic drift may in part have been responsible for the low overall genetic diversity and the extensive population differentiation. The optimal strategies for conservation of the genetic resources of this valuable ornamental are considered in the light of the results of this study.

Genetic Diversity and Population Genetic Structure in the Rare Chittering Grass Wattle, Acacia anomala Court

1988 ◽  
Vol 36 (3) ◽  
pp. 273 ◽  
Author(s):  
DJ Coates
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Genetic System ◽  
Small Population ◽  
Vegetative Multiplication ◽  
The Mean ◽  
Allozyme Loci

There are 10 known populations of Acacia anomala occurring in two small disjunct groups some 30 km apart. The Chittering populations reproduce sexually whereas the Kalamunda populations appear to reproduce almost exclusively by vegetative multiplication. The level and distribution of genetic variation were studied at 15 allozyme loci. Two loci were monomorphic in all populations. In the Chittering populations the mean number of alleles per locus was 2.0 and the expected panmictic heterozygosity (genetic diversity) 0.209. In the Kalamunda populations the mean number of alleles per locus was 1.15 and the expected panmictic heterozygosity 0.079, although the observed heterozygosity of 0.150 was only marginally less than the Chittering populations (0.177). These data support the contention that the Chittering populations are primarily outcrossing whereas the Kalamunda populations are clonal, with each population consisting of individuals with identical and, in three of the four populations, heterozygous, multilocus genotypes. The level of genetic diversity within the Chittering populations is high for plants in general even though most populations are relatively smsll and isolated. It is proposed that either the length of time these populations have been reduced in size and isolated is insufficient for genetic diversity to be reduced or the genetic system of this species is adapted to small population conditions. Strategies for the adequate conservation of the genetic resources of Acacia anomala are discussed.

The Breeding System, Genetic Diversity and Pollen Sterility in Eucalyptus pulverulenta, a Rare Species With Small Disjunct Populations

1990 ◽  
Vol 38 (6) ◽  
pp. 559 ◽  
Author(s):  
GB Peters ◽  
JS Lonie ◽  
GF Moran
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Rare Species ◽  
Population Genetic ◽  
Pollen Sterility ◽  
Species Range ◽  
Disjunct Distribution ◽  
Eastern Australia ◽  
The Mean ◽  
Allozyme Loci

There are eight known populations of E. pulverulenta, which has a disjunct distribution in south-eastern Australia. Levels of genetic variation were studied in four populations of about 5000 plants in all. Of a total of 16 allozyme loci examined eight were polymorphic, but the level of polymorphism was generally low. Within populations there was a mean 1.42 alleles per locus. Both the total species and mean population genetic diversities were low for a tree species (0.10 and 0.07 respectively), while the between-population genetic diversity was high at 30%. These data are consistent with the effects expected of genetic drift. Population structure may thus have been critical in determining levels of genetic diversity throughout the species' range. Analysis of half-sib arrays in three populations showed that the mean outcrossing rate (t) was 70%, comparable to values from other Eucalyptus species. The mean level of inbreeding (Wright's F) was 0.19, although both F and t varied considerably between populations. Significant levels of pollen sterility have been reported in this species, and data presented here show that this trait extends through much of the species' range. Overall, these data suggest that neither its disjunct population structure nor its tendency to male sterility caused the species' detectable level of outcrossing to differ markedly from levels reported in other eucalypt species. However, it remains possible that pollen sterility may have had some effect in at least one population. Strategies for conservation of this rare species are also considered.

Allozyme variation and population structure of Carex humilis var. nana (Cyperaceae) in Korea

2001 ◽  
Vol 79 (4) ◽  
pp. 457-463 ◽  
Author(s):  
Man Kyu Huh
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
North American ◽  
Population Level ◽  
Allozyme Variation ◽  
Population Divergence ◽  
Geographic Ranges ◽  
The Mean ◽  
Allozyme Loci

Genetic diversity and population structure of 22 Carex humilis var. nana Ohwi (Cyperaceae) populations in Korea were determined using genetic variation at 23 allozyme loci. This is a long-lived herbaceous species with a widespread distribution in eastern Asia. The 12 enzymes revealed 23 putative loci, of which 11 were polymorphic (47.8%). Genetic diversity at the varietal level and at the population level was 0.131 and 0.118, respectively. Total genetic diversity (HT = 0.274) and within population genetic diversity (HS = 0.256) were high, whereas the extent of the population divergence was relatively low (GST = 0.068). An indirect estimate of the number of migrants per generation (Nm = 3.42) indicated that gene flow was high among Korean populations. Wide geographic ranges, perennial herbaceous nature, and the persistence of multiple generations are associated with the high level of genetic variation. A distinct difference between Asian and North American Carex is shown in the proportion of genetic variation (GST) (p < 0.001). The mean GST of Asian Carex was estimated as 0.056; thus, only 5.6% of genetic variability was distributed among populations, whereas the mean GST of North American Carex was estimated as 19.5% (3.5 times higher). It is probable that the geographical distance between population pairs and presence or absence of glacial history may play roles in the substantial difference between both groups.Key words: Carex humilis var. nana, genetic diversity, population structure.

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.

Genetic diversity in Mediterranean diploid and tetraploid Bromus L. (section Bromus Sm.) populations

Genome ◽  
1995 ◽  
Vol 38 (5) ◽  
pp. 879-888 ◽  
Author(s):  
Malika Ainouche ◽  
Marie-Thérèse Misset ◽  
André Huon
Keyword(s):  
Genetic Diversity ◽  
Population Genetics ◽  
Genetic Variation ◽  
Genetic Similarity ◽  
Gene Diversity ◽  
Enzyme Electrophoresis ◽  
Allozyme Data ◽  
Fixed Heterozygosity ◽  
The Mean ◽  
Diploid Populations

The levels of genetic diversity assessed from allozyme data were investigated in 25 populations of Mediterranean Bromus intermedius, B. squarrosus, B. lanceolatus, and B. hordeaceus from Algeria. The geographically restricted diploids B. intermedius and B. squarrosus displayed less genetic diversity (the mean population gene diversity of Nei (Hu) ranged from 0.03 to 0.12) than the widespread tetraploid colonizers B. lanceolatus and B. hordeaceus (Hu = 0.07–0.27). Deviations from Hardy–Weinberg expectations in diploid populations of B. intermedius and B. squarrosus were observed owing to heterozygote excess at several loci and suggested that these self-fertilizing species may have substantial amounts of allogamy. Tetraploid populations of B. lanceolatus and B. hordeaceus were largely homozygous at homologous loci and frequently exhibited intergenomic fixed heterozygosity in accordance with their alloploid origin. Genetic variation at the infraspecific level was mostly distributed within populations in the four species, B. hordeaceus showing the lowest level of interpopulation differentiation (Gst = 0.06) and the highest level of gene flow (Nm = 3.75). Consistent gene flows are in agreement with the strongest intercontinental invasive behaviour of B. hordeaceus. Less differentiation was reported in the literature among later introduced B. hordeaceus populations from England and Australia, indicating reduced differentiation under the process of colonization. Moderate divergence occured among the four taxa, with interspecific genetic identities ranging from 0.87 to 0.93. In spite of substantial genetic similarity, species were clearly differentiated, with each tetraploid being more closely related to a diploid: B. hordeaceus to B. squarrosus and B. lanceolatus to B. intermedius.Key words: Bromus, enzyme electrophoresis, population genetics, colonizing abilities, allopolyploidy.

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.

scholarly journals Recombination and Gene Conversion in a 170-kb Genomic Region of Arabidopsis thaliana

Genetics ◽  
2002 ◽  
Vol 161 (3) ◽  
pp. 1269-1278 ◽  
Author(s):  
Bernhard Haubold ◽  
Jürgen Kroymann ◽  
Andreas Ratzka ◽  
Thomas Mitchell-Olds ◽  
Thomas Wiehe
Keyword(s):  
Genetic Diversity ◽  
Arabidopsis Thaliana ◽  
Linkage Disequilibrium ◽  
Gene Conversion ◽  
Genomic Sequence ◽  
Genomic Region ◽  
Resistance To Herbivory ◽  
Linkage Disequilibria ◽  
Coalescent Simulations ◽  
The Mean

Abstract Arabidopsis thaliana is a highly selfing plant that nevertheless appears to undergo substantial recombination. To reconcile its selfing habit with the observations of recombination, we have sampled the genetic diversity of A. thaliana at 14 loci of ~500 bp each, spread across 170 kb of genomic sequence centered on a QTL for resistance to herbivory. A total of 170 of the 6321 nucleotides surveyed were polymorphic, with 169 being biallelic. The mean silent genetic diversity (πs) varied between 0.001 and 0.03. Pairwise linkage disequilibria between the polymorphisms were negatively correlated with distance, although this effect vanished when only pairs of polymorphisms with four haplotypes were included in the analysis. The absence of a consistent negative correlation between distance and linkage disequilibrium indicated that gene conversion might have played an important role in distributing genetic diversity throughout the region. We tested this by coalescent simulations and estimate that up to 90% of recombination is due to gene conversion.

scholarly journals Whole genome sequencing reveals high differentiation, low levels of genetic diversity and short runs of homozygosity among Swedish wels catfish

Heredity ◽  
2021 ◽  
Author(s):  
Axel Jensen ◽  
Mette Lillie ◽  
Kristofer Bergström ◽  
Per Larsson ◽  
Jacob Höglund
Keyword(s):  
Genetic Diversity ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Whole Genome Sequencing Data ◽  
Peripheral Populations ◽  
Whole Genome ◽  
Runs Of Homozygosity ◽  
Sequencing Data ◽  
Isolated Populations ◽  
Native Populations

AbstractThe use of genetic markers in the context of conservation is largely being outcompeted by whole-genome data. Comparative studies between the two are sparse, and the knowledge about potential effects of this methodology shift is limited. Here, we used whole-genome sequencing data to assess the genetic status of peripheral populations of the wels catfish (Silurus glanis), and discuss the results in light of a recent microsatellite study of the same populations. The Swedish populations of the wels catfish have suffered from severe declines during the last centuries and persists in only a few isolated water systems. Fragmented populations generally are at greater risk of extinction, for example due to loss of genetic diversity, and may thus require conservation actions. We sequenced individuals from the three remaining native populations (Båven, Emån, and Möckeln) and one reintroduced population of admixed origin (Helge å), and found that genetic diversity was highest in Emån but low overall, with strong differentiation among the populations. No signature of recent inbreeding was found, but a considerable number of short runs of homozygosity were present in all populations, likely linked to historically small population sizes and bottleneck events. Genetic substructure within any of the native populations was at best weak. Individuals from the admixed population Helge å shared most genetic ancestry with the Båven population (72%). Our results are largely in agreement with the microsatellite study, and stresses the need to protect these isolated populations at the northern edge of the distribution of the species.

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