Interracial and population variability of phenotypic (cranial) characters in the common shrew <Emphasis Type="Italic">Sorex araneus</Emphasis> L., 1758

Variability of the cranial properties of chromosomal races Serov, Manturovo and Petchora of the common shrew were studied. A consistent increase of scull size in the Serov race with moving from the plain to highlands and a skull size decrease from low to high latitudes was detected. Interpopulation variability among different races was shown to be comparable with interracial variability or to exceed it. This suggests microevolution at the level of local populations.     

Morphometric differentiation between the Manturovo and Serov chromosome races of the common shrewSorex araneus

Morphometric differentiation between the Manturovo and Serov chromosome races of the common shrewSorex araneus Linnaeus, 1758, in Northeastern European Russia was studied using 27 measurements of the skull in 953 specimens. Discriminant and cluster analyses showed that shrews belonging to different chromosome races were well differentiated. No regular dependence between morphological changes of the skull and longitude was observed and there was no association between geographic and morphological distance. Multiple regression analysis revealed that 24.7% of the total morphological variance could be explained by seven geoclimatic variables. We suggest that karyotypic divergence may play a significant role in differentiating skull morphology in the Manturovo and Serov races of the common shrew. We also suppose that selection may affect the skull morphology of different chromosome races in this species.     

Allozyme variability in common shrew Sorex araneus of Western Siberia

The allozyme variability of the common shrew Sorex araneus of Western Siberia is studied. The small level of genetic variability and lack of reliable differences in indices of polymorphism for taiga, subtaiga, and forest-steppe populations are revealed. A significant level of genetic differentiation in populations belonging to adjacent chromosomal races—Novosibirsk and Serov (F _st = 0.3) — has been shown.     

Hybrid zones between chromosome races of the common shrew in West Siberia

In West Siberia, the whole species range of the common shrew (Sorex araneus L.) is shared by two parapatric chromosome races — Novosibirsk and Tomsk. These races form a hybrid zone with each other. In addition, on the western margin of the range there is a hybrid zone between the Novosibirsk race and the Uralian race Serov, and in the east, the Tomsk race forms a hybrid zone with the East Siberian race Strelka hybrid. The structures of the three hybrid zones are very different and depend on the karyotypic state of the races in contact. A comparative analysis of the hybrid zones between the chromosome races of the common shrew in West Siberia is discussed together with the role of these zones in maintaining variability in natural populations.     

Western Siberia rivers and the boundaries between chromosomal races of the common shrew (<Emphasis Type="Italic">Sorex araneus</Emphasis> L. Lipotyphla,Mammalia)

In Western Siberia, most boundaries between common shrew chromosomal races have been found to pass along the banks of rivers, mainly those flowing in the meridional direction. The races Serov and Novosibirsk co-inhabited the right bank of the Irtysh. The easternmost point of the Novosibirsk race has been found on the middle Yenisei River, while the race Tomsk in this area was only on the right (eastern) bank.     

A comparative study of morphological integration in Apis mellifera (Insecta, Hymenoptera)

Morphometric correlation matrices from 11 Mediterranean and European honey bee races have been compared. The degree of integration, measured by the eigenvalue variance of the correlation matrix or by Cheverud's index of integration, varies considerably between races but covaries neither with overall body size nor with the variance of the respective sample. Hence, the degree of morphological integration does not depend on body size or the level of variability The patterns of morphometric correlation are significantly similar among all races, but some minor differences in the patterns could be detected: The similarity between the correlation matrices is independent of the degree of phylogenetic relatedness between the respective races. In all races characters belonin to the same functional and/or developmental unit (leg, wing, abdominal characters) have Eiter correlations than the average. Most of the variation in the pattern of correlation can be expfained as a side effect of variation in the degree of integration. Races with high levels of integration tend to have hiher correlations between the main groups of characters, and races with low levels of integration tave smaller correlations between the main grous of characters, while the basic pattern remains undisturbed. In summary, the comparative analysis of morphometric correlation matrices reveals a picture of stability with respect to the pattern of integration and of variation in the degree of integration, which is random with respect to body size, degree of variability, and phylogeny.     

Variability in Host Preference Among Field Populations of Heterodera glycines

Eighteen soybean fields, six each with race 3, race 4, or Bedford population of Heterodera glycines, were selected for testing of host variability. Each field was divided into three sections, and a bulk soil sample was taken from each section. The 54 bulk soil populations (BSP) and 270 single cyst populations (SCP) were subjected to race determination tests. Tests of the 18 BSP and 90 SCP from the race 3 fields revealed that race 3 was the predominant race; however, 68 of the populations tested were other races. Tests of the 18-BSP and 90 SCP from race 4 fields demonstrated that races 2 and 4 were predominant, with 38 and 39 populations; respectively. Tests of the 18 BSP and 90 SCP from the Bedford population fields revealed tremendous variability. Races 2, 4, and 6 were the predominant races, with 32, 31, and 28 populations, respectively. These results indicate that of the three races studied, the Bedford population is the most variable, race 3 shows considerable variability, and race 4 shows very little.     

Pathogenicity and its alternation with both morphological and genetic variation in Plasmopara halstedii (sunflower downy mildew)

Morphological, pathogenic and genetic variation was studied in seven Plasmopara halstedii (sunflower downy mildew) isolates of several races using five singlezoosporangium isolates per pathogen isolate. Aggressiveness criteria were analysed in one sunflower inbred line showing a high level of quantitative resistance. Genetic relationships were detected between the single zoosporangium isolates using 12 expressed sequence tags (EST)-derived markers. Analysis of the five single zoosporangium isolates for P. halstedii isolates showed variability within pathogen isolates for all aggressiveness criteria, but not for all pathogen isolates. Isolates of races 100 and 3xx were characterised with shorter latent period and higher sporulation density than the isolate of races 7xx. All pathogen isolates showed high percentage infection values and caused a large reduction in seedling size except for one isolate involved in dwarfing. There was no relation between zoosporangia form or size and race virulence profiles or aggressiveness criteria. There was no intra-genetic variation for all pathogen isolates, but it was observed an important genetic variation between single zoosporangium isolates of all races. No correlation was detected between pathogenicity traits and EST genotypes.     

Genetic diversity,seed size associations and population structure of a core collection of common beans (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.)

Cultivated common bean germplasm is especially diverse due to the parallel domestication of two genepools in the Mesoamerican and Andean centers of diversity and introgression between these gene pools. Classification into morphological races has helped to provide a framework for utilization of this cultivated germplasm. Meanwhile, core collections along with molecular markers are useful tools for organizing and analyzing representative sets of these genotypes. In this study, we evaluated 604 accessions from the CIAT core germplasm collection representing wide genetic variability from both primary and secondary centers of diversity with a newly developed, fluorescent microsatellite marker set of 36 genomic and gene-based SSRs to determine molecular diversity and with seed protein analysis to determine phaseolin alleles. The entire collection could be divided into two genepools and five predominant races with the division between the Mesoamerica race and the Durango–Jalisco group showing strong support within the Mesoamerican genepool and the Nueva Granada and Peru races showing less diversity overall and some between-group admixture within the Andean genepool. The Chile race could not be distinguished within the Andean genepool but there was support for the Guatemala race within the Mesoamerican genepool and this race was unique in its high level of diversity and distance from other Mesoamerican races. Based on this population structure, significant associations were found between SSR loci and seed size characteristics, some on the same linkage group as the phaseolin locus, which previously had been associated with seed size, or in other regions of the genome. In conclusion, this study has shown that common bean has very significant population structure that can help guide the construction of genetic crosses that maximize diversity as well as serving as a basis for additional association studies.     

Restriction Fragment Length Polymorphisms of Mitochondrial and Nuclear DNAs among Korean Races of Magnaporthe grisea

Three KJ-races of Magnaporthe grisea (virulent to only japonica type rice cultivars) and seven KI-races (virulent to either indica or japonica type cultivars) isolated from various rice-growing areas of Korea were assayed for restriction fragment length polymorphisms (RFLPs) in mitochondrial and nuclear DNAs of the fungus. The size of mitochondrial DNA of M. grisea was estimated to be approximately 39. 8 kb. No RFLP in the mt DNA was detected among the 10 Korean races, indicating an extensive conservation in the gene composition of mt DNA without sequence variation. The identical restriction patterns of mt DNA also suggest that mt DNA of M. grisea may not be responsible for pathotypic diversity and variability. Southern blot analysis with five single-copy DNA probes showed considerable polymorphisms. Much diversity was detected in the three KI-races predominated during 1978–1985 in Korea. In contrast, no genetic variation was detected between other four KI-races and three KJ-races. RFLPs in nuclear DNA were correlated to some extent with the prevailing races in Korea. However, relationship between RFLPs in nuclear DNA and virulence of M. grisea races was inconclusive.     

Genetics and the origin of human races

In the last decades, the concept of human races was considered scientifically unfounded as it was not confirmed by genetic evidence. None of the racial classifications, which strongly differ in the number of races and their composition, reflects actual genetic similarity and genealogy of human populations inferred from variability of classical markers and DNA regions. Moreover, intercontinental ("interracial") variability was shown to be far lower than that within populations: the former constitutes 7 to 10% and the latter, about 85% of the total genetic variation. It is believed that the low level of differentiation of regional population groups contradicts their race status and suggests a recent origin of humans from one ancestral population. The results of studies of various genetic systems are in agreement with last conclusion rejecting the hypothesis of regional continuity. According to this hypothesis, the populations of continents regarded as large races have developed during long evolution from local types of archaic humans, in particular, Neanderthals. Phenotypic similarity of different, sometimes unrelated, populations united into one "race" is explained by strong selection since race-diagnostic traits characterize body surface and thus are directly subjected to the influence of environmental (primarily climatic) factors. It has been recently established that variability of the most important of these traits, body and hair pigmentation, is largely controlled by one locus (MC1R), which accounts for its high evolutionary lability. Other traits used for race identification are also likely to be labile and controlled by major genes. However, the fact that the currently existing race classifications are groundless does not mean that such classifications are impossible in principle. Commonly used argumentation (races do not exist because populations are not genetically separated) does not hold water. A polytypic species is characterized by genetic continuity of allopatric populations rather than the presence of narrow genetic boundaries between them. Borderlines between races are usually conventional and arbitrary. As to intergroup variation in humans, it is indeed low but comparable with that in some other species. There are no obstacles to the development of genetic systematics of human races.     

Phenetic relationships among different races of Striga gesnerioides (Willd.) Vatke from West Africa.

Striga gesnerioides is a root hemiparasite that primarily parasitizes dicotyledonous species, including cowpea (Vigna unguiculata L.) and other legumes. Based on the differential resistance response of various cultivars, landraces, and breeding lines, it has been proposed that several distinct races of cowpea-parasitic S. gesnerioides exist in West Africa. In this study, we used amplified fragment length polymorphism profile analysis to examine the genetic variability within and among populations of cowpea-parasitic S. gesnerioides within the suspected distribution range of a particular race, and statistical clustering methods to define the phenetic relationships of the various races in West Africa. Our data indicate that genetic variability within and among populations of each of the previously recognized races of cowpea-parasitic S. gesnerioides is extremely low. On the basis of genotypic profile and host differential resistance responses, 2 previously unknown races were identified. Of the 7 races now identifiable, races SG1 (from Burkina Faso) and SG5 (from Cameroon) are the most closely related, and SG4 (from Benin) and SG3 (from Niger/Nigeria) are the most divergent. SG6, a new race of the parasite identified in Senegal, was found to be the most genetically similar to SG4 from Benin. We also demonstrate that a hypervirulent isolate of the S. gesnerioides from Zakpota, in the Republic of Benin, is genotypically distinct from other populations of SG4, thereby warranting designation as a separate race, which we called SG4z. To further support our race classification scheme, we identified a group of molecular markers that effectively discriminate each of the various races. Finally, we show that an isolate (designated SG4i) of the wild legume Indigofera hirsuta--parasitic S. gesnerioides is genetically distinct and significantly diverged from the various races of cowpea-parasitic S. gesnerioides. Our data suggest that both geographic isolation and host-driven selection are critical factors defining race formation in S. gesnerioides in West Africa.     

The evolutionary history of the two karyotypic groups of the common shrew, Sorex araneus, in Poland

Genetic variability within and among two karyotypic groups and five chromosome races of the common shrew (Sorex araneus) in Poland was assayed by sequencing a 1023 bp part of the cytochrome b gene (mtDNA) from 28 individuals. Thirty-four variable positions defined 21 distinct haplotypes with a maximum sequence divergence of 0.88%. No significant differentiation in the cytochrome b gene between Western and Eastern Karyotypic groups was found. Haplotype diversity estimates within the races and groups sampled were high (h = 0.800-0.928), while nucleotide diversity estimates were low (pi = 0.0034-0.0053). The distribution of pairwise nucleotide differences fits well with expectations of a "sudden expansion" model. High haplotype diversity was accompanied by relatively high expected heterozygosity (H(E)) values in nuclear genes (calculated over 47 enzyme loci: H(E) = 0.031 - 0.049), giving no evidence for a recent bottleneck after the process of post-Pleistocene recolonization of Poland by the shrews. Thus, for S. araneus chromosome races in Poland, the data on the cytochrome b gene variability support the hypothesis assuming the Robertsonian fusions having spread into an ancestral acrocentric distribution.     

Assessment of genetic diversity and population structure of Xanthomonas oryzae pv. oryzae with a repetitive DNA element.

A repetitive DNA element cloned from Xanthomonas oryzae pv. oryzae was used to assess the population structure and genetic diversity of 98 strains of X. oryzae pv. oryzae collected between 1972 and 1988 from the Philippine Islands. Genomic DNA from X. oryzae pv. oryzae was digested with EcoRI and analyzed for restriction fragment length polymorphisms (RFLPs) with repetitive DNA element as a probe. Twenty-seven RFLP types were identified; there was no overlap of RFLP types among the six races from the Philippines. Most variability (20 RFLP types) was found in strains of races 1, 2, and 3, which were isolated from tropical lowland areas. Four RFLP types (all race 5) were found among strains isolated from cultivars grown in the temperate highlands. The genetic diversity of the total population of X. oryzae pv. oryzae was 0.93, of which 42% was due to genetic differentiation between races. The genetic diversities of strains collected in 1972 to 1976, 1977 to 1981, and 1982 to 1986, were 0.89, 0.90, and 0.92, respectively, suggesting a consistently high level of variability in the pathogen population over the past 15 years. Cluster analysis based on RFLP banding patterns showed five groupings at 85% similarity. The majority of strains from a given race were contained within one cluster, except for race 3 strains, which were distributed in three of the five clusters.     

Identification of a soluble NADPH oxidoreductase (BmNOX) with antiviral activities in the gut juice of Bombyx mori

Silkworms show high variability in silk quality and disease resistance. Attempts are on to combine the disease tolerance of multivoltine races and the silk quality of bivoltine races to generate new races with desirable phenotypic traits. We report the identification of a 26.5-kDa protein that is overexpressed in the gut juice of disease-resistant multivoltine races and that has anti-BmNPV activity. We have characterized this protein as a soluble NADH-oxidoreductase-like protein (BmNOX). Treatment of live BmNPV particles with BmNOX inhibited the capability of the viral particles to infect BmN cells in vitro.     

Assessment of genetic diversity and population structure of Xanthomonas oryzae pv. oryzae with a repetitive DNA element.

A repetitive DNA element cloned from Xanthomonas oryzae pv. oryzae was used to assess the population structure and genetic diversity of 98 strains of X. oryzae pv. oryzae collected between 1972 and 1988 from the Philippine Islands. Genomic DNA from X. oryzae pv. oryzae was digested with EcoRI and analyzed for restriction fragment length polymorphisms (RFLPs) with repetitive DNA element as a probe. Twenty-seven RFLP types were identified; there was no overlap of RFLP types among the six races from the Philippines. Most variability (20 RFLP types) was found in strains of races 1, 2, and 3, which were isolated from tropical lowland areas. Four RFLP types (all race 5) were found among strains isolated from cultivars grown in the temperate highlands. The genetic diversity of the total population of X. oryzae pv. oryzae was 0.93, of which 42% was due to genetic differentiation between races. The genetic diversities of strains collected in 1972 to 1976, 1977 to 1981, and 1982 to 1986, were 0.89, 0.90, and 0.92, respectively, suggesting a consistently high level of variability in the pathogen population over the past 15 years. Cluster analysis based on RFLP banding patterns showed five groupings at 85% similarity. The majority of strains from a given race were contained within one cluster, except for race 3 strains, which were distributed in three of the five clusters.     

Acclimation of Plasmopara halstedii (sunflower downy mildew) in relationship with trade-off between virulence and aggressiveness in a local pathogen population

The acclimation in relationship with virulence cost was analysed for seven Plasmopara halstedii (sunflower downy mildew) isolates including five progeny isolates of several races descending from two parental isolates of races 100 and 710. Aggressiveness criteria were analysed in one sunflower inbred line showing a high level of quantitative resistance. Isolates of races 100 and 3xx were characterised with shorter latent period and higher sporulation density than isolates of races 7xx. All isolates showed high percentage infection values and caused a large reduction in seedling size except for one isolate involved in dwarfing. The seven isolates were divided, according to their virulence and aggressiveness, into two main groups as more aggressive isolates of the 100 and 3xx races which do not overcome the sunflower differential host D3, and less aggressive isolates of 7xx races which can overcome D3. Consequently, the 100 and 3xx avirulent races had a virulence cost measured by differences in aggressiveness (from 45.5 to 76.3%) compared to 7xx virulent races carrying unnecessary virulence gene.     

Variability in size of the nuclear genome in pygmy wood mouse Sylvaemus uralensis (Rodentia, Muridae)

Earlier, in an integral genetic study, the Asian and European races were distinguished within the species Sylvaemus uralensis (pygmy wood mouse) and the European race was divided into the East European and South European forms. Each of these groups differed from the others, in particular, in the quantity of the centromeric heterochromatin in karyotypes of the animals. To establish the pattern of its changes in S. uralensis, in the present study the DNA content in splenocyte nuclei in all races and forms of pygmy wood mice was assessed using DNA flow cytometry. The heterochromatin amount in karyotypes and genome size were shown to be correlated. The East European chromosomal race of S. uralensis (Central Chernozem and Non-Chernozem regions of Russia, Crimea Peninsula, Middle Volga region, and Southern Ural) and the Asian race of this species (East Kazakhstan, Uzbekistan, and East Turkmenistan), which have respectively the highest and the lowest amounts of centromeric heterochromatin in the karyotype, exhibit the greatest difference in the DNA content in the genome. On average, the difference is approximately 8% in males and 6.7% in females; in both cases, the ranges of variability were distinctly different. Against the general background of the trait variation, the Asian race, whose members have the smallest DNA amount in their cells, looks homogeneous. The genome of the South European chromosomal form of S. uralensis (Caucasus, Transcaucasia, Carpathians, and Balkan Peninsula), which exhibits an intermediate content of the centromeric heterochromatin in the karyotype, is smaller that the genome of the East European race (by 3.2% in the group of males and by 1.9%, in the group of females), but larger than that of the Asian race (by 5% in either sex). Thus, the variability of size of centromeric C-blocks in pygmy wood mouse is likely to be associated with elimination (or, conversely, an increase in the amount) of the genetically inert chromatin. It is suggested that a significant contribution to the variability of genome size in S. uralensis is made by heterochromosomes, or, more precisely, their variable regions, which seem to be largely heterochromatic.     

Mitochondrial DNA products among RAPD profiles are frequent and strongly differentiated between races of Douglas-fir

Racial differentiation and genetic variability were studied between and within the coastal, north interior, and south interior races of Douglas-fir using RAPD and allozyme markers. Nearly half of all RAPD bands scored (13:45%) were found to be amplified from mitochondrial DNA. They exhibited maternal inheritance among hybrids and back-crosses between the races, and were much more highly differentiated (G_ST= 0.62 for haplotype frequencies) than were allozymes (G_ST= 0.26). No evidence of hybridization or introgression was detected where the coastal and interior races come into proximity in central Oregon.     

Does evolution reduce the body size? A study of the four members of newly evolved nasuta‐albomicans complex of Drosophila

Our long range interracial hybridization experiments between a pair of cross fertile races, Drosophila nasuta (2n = 8) and D.albomicans (2n = 6) have resulted in the evolution of two new karyotypic strains under laboratory conditions, which are named as Cytorace 1 and Cytorace 2. These Cytoraces harbor chromosomes from both parents. Here, we compare the body size of the parental races and newly evolved Cytoraces and the relationship between the body size and fitness. Analysis reveals that the parental races have reduced fertility and are larger in body size than newly evolved Cytoraces. Thus, the newly evolved Cytoraces show reduced body size and better fitness in the course of their evolution. This revised version was published online in July 2006 with corrections to the Cover Date.