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1.
Based on a biochemical-genetic approach, heterozygosity and divergence of structural genes of 30 enzyme loci were analyzed in six dace species. In addition, intra- and interspecific divergence of gene expression was analyzed based on a sample of 12 to 15 loci. Mean heterozygosities per individual varied as follows: Tribolodon species, Hobs = 0.007 +/- 0.007 and Hexp = 0.007 +/- 0.007; T. ezoe, Hobs = 0.045 +/- 0.016 and Hexp = 0.067 +/- 0.029. Several variants of genetic distances were estimated. Standard Nei's distances (DN) varied from 0.145 to 0.284 in four dace species studied. As related to Tribolodon dace species, the following genetic distances were obtained for two members of other genera: Pseudaspius leptocephalus, DN = 0.269; Leuciscus waleckii, DN = 0.769. Based on the distance matrices, different clustering algorithms were realized. The main feature shared by different dendrograms was a separate position of the cluster joining Far-Eastern dace species, to which P. leptocephalus and L. waleckii are successively added. Among the species studied, the proportion of loci similar by expression (E) varied from 87 to 100%. The greatest difference was found between anadromous and nonanadromous ecotypes of T. hakonensis, E = 67%. The following conclusions can be made: (1) Four studied species of the genus Tribolodon are rather well genetically differentiated. Diagnostic loci are available. (2) A nominal dace species, T. species, should be considered the fourth isolated species of this genus, which is confirmed by its recent zoological acceptance of this species. (3) The origin and divergence of dace species belonging to the genus Tribolodon are relatively late (1 to 3 Myr ago) historical events. (4) Taxonomically, the genus Tribolodon belong to the tribe Pseudaspinini together with P. leptocephalus, which is confirmed by genetic data. (5) Data on heterozygosity and the divergence of structural and regulatory elements of genome, along with the proposed scheme of speciation types, suggest the following speciation modes for the species studied: for four species, adaptive divergence and for two species, genetic transformation.  相似文献   

2.
To solve some systematic questions as well as to study genetic variability and evolutionary relationships in two groups of fish belonging to the Mugilid (Mugilidae) and Cyprinid (Cyprinidae) families, we have used restriction fragment length polymorphism analysis of mitochondrial DNA (mtDNA) fragments amplified in polymerase chain reaction. The analysis of three mtDNA fragments of 7220 bp total length of six Mugilid species has shown that Mediterranean Liza aurata, L. ramada, L. saliens, and Chelon labrosus form a common cluster, L. aurata and C. labrosus being the closest relatives, whereas L. haematocheilus (syn. C. haematocheilus) of the Sea of Japan forms a sister group to the Mediterranean cluster. It was found that Chelon and Liza genera are paraphyletic, and therefore their division into two genera is unnatural and they should be synonymized. According to priority, Liza species should be ascribed to Chelon genus. Mugil cephalus is the most distant compared to the rest of the species studied. The level of genetic divergence between allopatric samples of M. cephalus from the Sea of Japan and the Mediterranean Sea has proved to be very high—4.5% of nucleotide substitutions. The analysis of four mtDNA fragments of 9340 bp total length of six Cyprinid species has shown that L. waleckii is the most genetically distant. Pseudaspius leptocephalus is a sister group to Tribolodon species. All Tribolodon species form a common cluster with T. sachalinensis as a root. The remaining species form two branches, one of which includes T. nakamurai and T. brandtii, another one combines T. hakonensis and a new form of Tribolodon revealed that is close to T. hakonensis by its mtDNA (2.4% of nucleotide substitutions). This new form might be an independent species. Published in Russian in Biokhimiya, 2007, Vol. 72, No. 12, pp. 1651–1658.  相似文献   

3.
Genetic variation of Siberian dwarf pine Pinus pumila (Pall.) Regel was characterized in three marginal populations in southwestern, southern and eastern parts of the natural species range (Baikal Area, Primorye, Kamchatka) using isozyme analysis. Analysis involving 16 isozyme loci encoding ten enzyme systems was conducted. Our results confirm that P. pumila is one of the most polymorphic species in the genus Pinus. Three marginal populations exhibited high genetic variation (P 95 = 68.8%, H o = 0.247, H e = 0.291). Populations heterogeneity and significantly high level of divergence in coniferous (F ST = 0.050, D N = 0.044) reflect their genetic originality. In summary, it was shown that the level of genetic variation characteristic for P. pumila in other parts of the not only is reproduced in the populations examined but even is close to maximum there.  相似文献   

4.
The Caesalpinia hintonii complex is formed by five endemic species (C. hintonii, C. laxa, C. macvaughii, C. melanadenia and C. epifanioi) occurring in central Mexico. This species complex is under incipient genetic divergence as by-product of local adaptations in reproductive and morphological traits to different habitats. We estimate the genetic variation and structure of populations of this species complex to assess the extent of genetic differentiation among populations and related species along its geographic distribution. Estimations of genetic diversity and structure were done based on ten enzymes and 18 loci. Mean number of alleles per locus ranged from 1.5 to 1.9. Polymorphic loci ranged from 42.1 to 68.4. Observed (Ho: range 0.191–0.275) and expected (He: range 0.205–0.317) heterozygosities in this complex were higher compared with other endemic and legume species. Neis genetic diversity estimates showed that most genetic variation was found within (HS = 0.325) rather than among populations (DST = 0.085). Populations of the species C. hintonii showed a considerable genetic differentiation (FST = 0.207). The results of genetic diversity and structure within and among populations are in accord with the great morphological differentiation described for this species complex.  相似文献   

5.
The genetic structure of ten natural populations of Arabidopsis thaliana (L.) Heynh. at eight isozyme loci was studied. The populations were located in the northern part of the species range, 200 km from the north to the south along the Onega Lake coast in Karelia. Considerable genetic diversity (P 99% = 43.7, H obs = 0.003) was revealed that is not typical of populations of self-pollinating plant species. A direct correlation between the proportion of polymorphic loci and geographical latitude was shown (r = 0.68; P < 0.05). It is suggested that a high polymorphism level in Karelian Arabidopsis thaliana (L.) populations increasing from the south to the north is due to extreme environmental conditions in the northern part of the species range. The distribution of genetic diversity within and between populations is typical of self-pollinating species: the larger part of the total diversity resides among populations (G ST = 0.583).  相似文献   

6.
Molecular genetic analysis of Altai osmans of the genus Oreoleuciscus from two different parts of the range was carried out. In this study, based on the mitochondrial Co-1 gene sequence, a total of 25 fish specimens belonging to four genera were examined: (1) O. humilis, 2 specimens; O. potanini, 13 specimens; (2) Pseudaspius leptocephalus, 1 specimen; (3) Tribolodon brandtii, T. hakonensis, and T. sachalinensis from the GanBank database, 9 speciens; and (4) Leuciscus waleckii, 1 specimen (used as an outgroup). The p-distances were very low both within and between the species: (1) 0.20 ± 0.03%; (2) 0.40 ± 0.12%; and (1–2) 0.80 ± 0.04%. To visualize the relationships among all of the species examined, the neighbor joining (NJ), maximum parsimony (MP), Bayesian (BA), and maximum likelihood (ML) trees were constructed. The results obtained using these methods were very similar. It was demonstrated that species assignment of the individuals (barcoding) with the help Co-1 gene was effective, despite of very low divergence of the two osman taxa, which was comparable with typical intraspecific values in other animal groups. Taxonomic status of O. potanini and O. humilis requires further investigation with paying attention to low genetic distances between these species along with the lack of material from sympatric parts of the ranges.  相似文献   

7.
We determined the genetic diversity and population structures ofCarex breviculmis (Cyperaceae) populations in Korea, using genetic variations at 23 allozyme loci.C. breviculmis is a long-lived herbaceous species that is widely distributed in eastern Asia. A high level of genetic variation was found in 15 populations. Twelve enzymes revealed 23 loci, of which 11 were polymorphic (47.8%). Genetic diversity at the speciesand population levels were 0.174 and 0.146, respectively. Total genetic diversity (HT = 0.363) and within-population genetic diversity (Hs = 0.346) were high, whereas the extent of the population divergence was relatively low (GST = 0.063). Deviation from random mating (Fis) within the 15 populations was 0.206. An indirect estimate of the number of migrants per generation(Nm = 3.69) indicated that gene flow was extensive among Korean populations of this species. Analysis of fixation indices revealed a substantial heterozygote deficiency in some populations and at some loci. Genetic identity between popu-lations was high, exceeding 0.956.  相似文献   

8.
Summary The diversity of four esterase loci was studied electrophoretically in 690 individual spikes representing 12 populations of wild barley (Hordeum spontaneum C. Koch.) collected from central, peripheral and marginal regions of its distribution in Jordan. A minimum of 6, 10, 5 and 5 alleles were observed at the Est-1, Est-2, Est-4 and Est-5 loci, respectively. Est-2 and Est-4 were the most diverse loci (Hc=0.53±0.05 and 0.46±0.07, respectively). Est-5 was intermediate (Hc=0.33+0.07) and Est-1 was the lowest (Hc=0.22±0.04). Polymorphism was highest in the central populations (He=0.52±0.04), followed by the peripheral (He=0.40±0.05) and the marginal (He=0.22±0.05) populations. Average allelic diversity between (Gst=0.49) and within (Hs=0.51) populations reflects a high allelic differentiation among these populations. Log-linear analyses revealed that four two-locus terms and two three-locus terms were significantly associated (P<0.05). Geographical distances between populations were not significantly correlated with Nei's genetic similarity index (r=0.16; P<0.19). It is postulated that diversifying selection is a major factor in the population genetic differentiation of these esterase loci.  相似文献   

9.
Reliable estimates of phylogenetic relationships and divergence times are a crucial requirement for many evolutionary studies, but are usually difficult because fossils are scarce and their interpretation is often uncertain. Frogs are fresh water animals that generally are unable to cross salt water barriers (their skin is readily permeable to both salt and water). The geologically determined ages of salt water barriers that isolate related frog populations thus provide an independent measure of the minimum date of genetic divergence between pairs of such populations. For the genetically well-studied western Palearctic water frogs (Rana esculenta group), the Aegean region provides an ideal area for determining the relationship between genetic divergence and time of spatial isolation, using a nested set of geologically determined isolation times (12,000 yr, 200,000 yr, 1.8 Myr, 2–3 Myr, and 5.2 Myr). Using 31 electrophoretic loci for 33 pairs of neighboring frog populations, a linear relationship between geologically determined isolation time and Hillis' modified Nei genetic distance was found: D*Nei = (0.04 ± 0.01) + (0.10 ± 0.01) isolation time [Myr] corresponding to an average divergence rate (“molecular clock” pace) of 0.10 D*Nei/Myr (0.10 DNei/Myr). This rate is in the range of previous estimates reported for protein electrophoretic data; the value is conservative because relatively few of the loci used are “fast evolvers” (13%; sAAT, ALB, EST-5, MPI). Removing these fast evolvers from the analysis results in 0.08 D*Nei/Myr (0.08 DNei/Myr). The confidence limits for estimation of the divergence time given the genetic distance are large, but unusually narrow for this kind of study; they permit us to estimate divergence times during the Pliocene and Miocene. Few previous studies, including sequence analyses, have provided reasonable estimates of divergence time for the Pliocene. A test using the outgroup taxa Rana perezi and Rana saharica (also isolated for 5.2 Myr by the Strait of Gibraltar) fits the calibration well: observed genetic Nei distance D*Nei = 0.55, expected D*Nei = 0.56. The calculated divergence times, based on this absolute molecular clock, suggest a series of speciation events after the Messinian (5.2 Myr), possibly triggered by the rapid ecological changes accompanying the desiccation and refilling of the Mediterranean Basin.  相似文献   

10.
Among the 14 extant species of the genus Marmota the Vancouver Island marmot (Marmota vancouverensis) is the most endangered. In 2007 as few as 85 individuals were left in the wild, with an additional 162 individuals maintained in captivity. To facilitate genetic monitoring of both wild and captive populations, polymorphic genetic markers were identified. Thirty-three different microsatellite loci were tested for amplification and variability in ≥30 wild-born individuals. Only 11 of these loci proved to be polymorphic and were subsequently analysed in 105 samples collected from wild Vancouver Island marmots. The average number of alleles (A) at those 11 loci was only 2.1, and the intraspecific variation (H E between 8 and 23% within colonies) was low compared to other marmot species. Variation within the small and geographically isolated Mt. Washington colony was particularly low (A = 1.3, H E = 0.08). Genetic distances between the Mt. Washington colony (11 individuals) and those of the Nanaimo Lakes region (94 individuals) on southern Vancouver Island were large (D values ranging from 0.42 to 0.50), while genetic distances among colonies within the latter area were much smaller (D values from 0.01 to 0.13). Given the low within-population genetic variation, and the resulting risk of inbreeding depression at Mt. Washington, we support the decision to maximize overall genetic variation of the species by crossbreeding marmots from the two different areas despite the possibility of local adaptation.  相似文献   

11.
Comparative analysis of genetic structure of northern natural populations of two Arabidopsis species with different degrees of panmixia was performed. The variability of 121 RAPD loci in seven populations of model plant A. thaliana possessing high degree of self fertility was studied together with 93 RAPD loci in population of cross-pollinating species A. lyrata ssp. petraea. The population of A. l. petraea demonstrated higher level of genetic variability (P 99% = 62.50%; H exp = 0.169) than the populations of A. thaliana, which is obviously connected with biological features of reproduction of the species. A significant level of genetic variability (P 99% = 42.27%; H exp = 0.126) was revealed in populations of A. thaliana, which is not typical for self-pollinating plant species. The high population polymorphism of A. thaliana in the northern part of its range may be connected with adverse environmental conditions. The genetic distances between populations of the species studied (average D N = 0.494) confirm close relatedness between A. thaliana and A. l. petraea.  相似文献   

12.
Ginseng (Panax ginseng) is one of the most important herbal remedies used in East Asia. The present study investigated six polymorphic microsatellite markers (PG29, PG281, PG287, PG668, PG1319, and PG1481) in samples of cultivated and wildP. ginseng collected in Korea. Total allelic number observed in this study was 27 (average allelic numbers per locus: 4.5). All examined loci exhibited deviation from the Hardy-Weinberg equilibrium and deficiency of heterozygosity in both cultivated and wild groups. Although the wild ginseng group exhibited slightly more polymorphic behavior (mean PIC=0.392, GD=0.454 and Hobs=0.129), compared with the cultivated group (mean PIC=0.383, GD=0.438 and Hobs=0.105), no significant differences of allele frequencies and genotype distributions were revealed. By combined analysis of six loci in 100 cultivated ginsengs, 71 different types were observed. The analyzed microsatellite loci in this study will be helpful for understanding genetic variation, QTL mapping and phylogenic studies inPanax species.  相似文献   

13.
This study presents a comparative hierarchical analysis of variance applied to three classes of molecular markers within the blue marlin (Makaira nigricans). Results are reported from analyses of four polymorphic allozyme loci, four polymorphic anonymously chosen single-copy nuclear DNA (scnDNA) loci, and previously reported restriction fragment length polymorphisms (RFLPs) of mitochondrial DNA (mtDNA). Samples were collected within and among the Atlantic and Pacific Oceans over a period of several years. Although moderate levels of genetic variation were detected at both polymorphic allozyme (H = 0.30) and scnDNA loci (H = 0.37), mtDNA markers were much more diverse (h = 0.85). Allele frequencies were significantly different between Atlantic and Pacific Ocean samples at three of four allozyme loci and three of four scnDNA loci. Estimates of allozyme genetic differentiation (θO) ranged from 0.00 to 0.15, with a mean of 0.08. The θO values for scnDNA loci were similar to those of allozymes, ranging from 0.00 to 0.12 with a mean of 0.09. MtDNA RFLP divergence between oceans (θO = 0.39) was significantly greater than divergence detected at nuclear loci (95% nuclear confidence interval = 0.04–0.11). The fourfold smaller effective population size of mtDNA and male-mediated gene flow may account for the difference observed between nuclear and mitochondrial divergence estimates.  相似文献   

14.
In natural populations of Arabidobsis thaliana (L.) Heynh., occupying northern limits of the species range (Karelia), the level of genetic diversity was evaluated. In two insular and one mainland population variability at 82 RAPD loci was tested. Considerable genetic diversity revealed (P = 4.5%; H exp = 0.177) was not typical of self-pollinating plant species. It was demonstrated that genetic differentiation among the populations (G ST = 0.680) was rather high, pointing to the low level of gene flow in the isolated insular populations. It was suggested that the high level of Arabidopsis population polymorphism in Karelia could be associated with extreme growing conditions at the northern limits of the species range.  相似文献   

15.
Habitat fragmentation weakens the connection between populations and is accompanied with isolation by distance (IBD) and local adaptation (isolation by adaptation, IBA), both leading to genetic divergence between populations. To understand the evolutionary potential of a population and to formulate proper conservation strategies, information on the roles of IBD and IBA in driving population divergence is critical. The putative ancestor of Asian cultivated rice (Oryza sativa) is endangered in China due to habitat loss and fragmentation. We investigated the genetic variation in 11 Chinese Oryza rufipogon populations using 79 microsatellite loci to infer the effects of habitat fragmentation, IBD and IBA on genetic structure. Historical and current gene flows were found to be rare (mh = 0.0002–0.0013, mc = 0.007–0.029), indicating IBD and resulting in a high level of population divergence (FST = 0.343). High within‐population genetic variation (HE = 0.377–0.515), relatively large effective population sizes (Ne = 96–158), absence of bottlenecks and limited gene flow were found, demonstrating little impact of recent habitat fragmentation on these populations. Eleven gene‐linked microsatellite loci were identified as outliers, indicating local adaptation. Hierarchical AMOVA and partial Mantel tests indicated that population divergence of Chinese O. rufipogon was significantly correlated with environmental factors, especially habitat temperature. Common garden trials detected a significant adaptive population divergence associated with latitude. Collectively, these findings imply that IBD due to historical rather than recent fragmentation, followed by local adaptation, has driven population divergence in O. rufipogon.  相似文献   

16.
Cyclical parthenogenesis allows study of the genetic and evolutionary characteristics of groups exhibiting both asexual and sexual reproduction. The cladoceran genus Daphnia contains species which vary with respect to the relative incidence of sexual reproduction; pond species tend to undergo sexual reproduction more regularly than species found in large lakes. Previous genetic studies have focused on pond populations, generating expectations about large-lake populations that have not been fully met by recent studies. The present study of the Palearctic species Daphnia galeata further examines the genetic structure of large-lake populations. Nine local populations, from lakes in northern Germany, are examined for genetic variation at seven enzyme loci. Populations exhibit similar allelic arrays and often similar allele frequencies at the five polymorphic loci; values of Nei's genetic distance (D) ranged from 0.002 to 0.239, with a mean of 0.084. FST values range from 0.012 to 0.257, and spatial autocorrelation coefficients range from -0.533 to 0.551, for the eight alleles analyzed. With few exceptions, within-population genotypic frequencies were in Hardy-Weinberg equilibrium. There was, however, significant heterogeneity in genotypic frequencies among populations. The number of coexisting clonal groups, as determined by three locus genotypes, is high within populations. Clonal groups are widely distributed among localities. The amount of genetic divergence observed among these large-lake populations is smaller than that previously observed among pond populations and suggests that different processes may be important in determining the genetic structure and subsequent phenotypic divergence of lake versus pond populations.  相似文献   

17.
Methods of estimating within- and between-population gene diversity in parthenogenetic species using mini- and microsatellite DNA markers and modified Wright's F ST statistic are presented with special reference to model populations of lizards of the genus Darevskia(D. dahli, D. armeniaca, D. unisexualis). We used DNA fingerprinting data for several populations of these species examined earlier. The effects of variation in M13 minisatellite, (GACA) n - and (TCC) n -microsatellite loci on the formation of within-population gene diversity in parthenogenetic species D. dahli and D. armeniaca were shown to be different. The equality of the realized gene diversity Hand its maximum possible value H max in two populations of D. dahli (H max = 0.032, H = 0.031, P 0.0431; H max = 0.024, H = 0.027, P = 0.09) and D. armeniaca (H max = 0.05, H = 0.053, P = 0.03; H max= 0.054, H = 0.055, P= 0.02) suggests that variation in (GACA) n loci substantially contributes to the maintenance of within-population genetic diversity. Analysis of between-population genetic diversity using loci M13, (GACA) n , and (TCC) n showed differentiation of D. dahli populations from northeastern and northwestern Armenia (F ST = 0.0272, P = 3 × 10–13) and genetic homogeneity of the Armenian and introduced to the Ukraine populations of D. armeniaca characteristic of one clone (F ST = 0, P = 1).  相似文献   

18.
We examined protein polymorphism of Chinese pangolins (Manis pentadactyla) from Yunnan Province of China, including two forms of three brown and nine dusky Chinese pangolins. Sixty-two genetic loci were screened; 12 loci were found to be polymorphic. The percentage of polymorphic loci (P) is 0.194, the mean individual heterozygosity (H) is 0.078, and the mean number of alleles (A) is 1.258. Furthermore, we calculated the genetic distance (D) between the two forms and found a low level of genetic divergence (D=0.0206) between them, which indicates an almost-indistinguishable divergence at the level of proteins.  相似文献   

19.
The necessity for conservation of the geneticcomponent of biodiversity is now widelyrecognised. A broad genetic base is required tomaintain evolutionary potential and thepopulation erosion occurring in much of theworld's forests threatens the genetic integrityof many tree species. Spanish Cedar (Cedrela odorata L.) has been under severepressure for generations and is now the focusof a study aimed at assessing the levels anddistribution of genetic diversity in remainingpopulations. Ten Costa Rican populations wereanalysed using chloroplast and AFLP markers.The overall level of diversity was as expectedfor an outcrossing, long-lived, woody species(H T = 0.27). However, this concealeda deep divergence within the species, forchloroplast and AFLP (CT = 0.83)markers. Populations were differentiated in twogroups that exhibited contrasting habitatpreferences and two ecotypes, wet and dry, wereidentified. Within the ecotypes, all but onepopulation were fixed for a single chloroplasthaplotype and within populations, total genomicdiversity levels were low (H S= 0.03–0.13). Populations possessing the dryecotype maintained significantly more diversitythan those from wet regions. Within the wetecotype group, pairwise genetic distancebetween populations fitted an isolation bydistance model. The group was stronglysubdivided and showed isolation by distancearound the southern edge of the centralmountain ranges. The genetic divergence of thetwo ecotypes, observed at both organellar andnuclear loci, identifies evolutionarilysignificant units that, taken together withprevious studies of the species, provide arational basis on which to build a conservationpolicy for the species.  相似文献   

20.
In this paper we describe the isolation and characterization of six polymorphic microsatellite loci from the orchid Serapias vomeracea. This species is widely distributed in the Mediterranean region. Microsatellite loci were isolated from an enriched library and primer pairs were designed for 18 loci. Primer pairs for six loci amplified well and were tested on samples from southern Italy. Levels of genetic variability detected at these six loci are high, with numbers of alleles per locus ranging from 3 to 6, and observed heterozygosity (HO) ranging from 0.35 to 0.86. All primer pairs tested amplified DNA from four other Serapias species, indicating that the primers are useful for population genetic studies throughout the genus.  相似文献   

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