Genetic Distance Coefficients Research Articles

Genetic Diversity of Indigenous Cattle Populations in Bhutan: Implications for Conservation

The Genetic diversity and relationship of native Siri (Bos indicus) cattle populations of Bhutan were evaluated using 20 microsatellite markers. A total of 120 Siri cattle were sampled and were grouped into four populations according to their geographical locations which were named Siri West, Siri South, Siri Central and Siri East cattle. For each, 30 individuals were sampled. In addition, 30 samples each of Indian Jaba (B. indicus), Tibetan Goleng (B. taurus), Nepal Hill cattle (B. indicus), Holstein Friesian (B.taurus) and Mithun (B. frontalis) were typed. The mean number of alleles per loci (MNA) and observed heterozygosity (Ho) were high in the Siri populations (MNA=7.2±0.3 to 8.9±0.5 and Ho=0.67±0.04 to 0.73±0.03). The smallest coefficient of genetic differentiation and genetic distance (FST=0.015 and DA=0.073) were obtained between Siri West and Siri Central populations. Siri East population is genetically distinct from the other Siri populations being close to the Indian Jaba (FST=0.024 and DA=0.084). A high bootstrap value of 96% supported the close relationship of Siri South, Siri Central and Siri West, while the relationship between Siri East and Jaba was also supported by a high bootstrap value (82%). Data from principal component analysis and individual assignment test were in concordance with the inference from genetic distance and differentiation. In conclusion we identified two separate Siri cattle populations in Bhutan at the genetic level. One population included Siri cattle sampled from the West, Central and South of the country and the other Siri cattle was sampled from the East of the country. We suggest that Siri cattle conservation program in Bhutan should focus on the former population as it has received less genetic influence from other cattle breeds. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 7 : 946-951)

Effect of white pine blister rust (Cronartium ribicola) and rust-resistance breeding on genetic variation in western white pine (Pinus monticola).

Western white pine (Pinus monticola) is an economically and ecologically important species from western North America that has declined over the past several decades mainly due to the introduction of blister rust (Cronartium ribicola) and reduced opportunities for regeneration. Amplified fragment length polymorphism (AFLP) was used to assess the genetic variation in northern Idaho populations of western white pine (including rust-resistant breeding stock) in relation to blister rust. A total of 176 individuals from four populations was analyzed using 163 AFLP loci. Within populations, an average 31.3% of the loci were polymorphic (P), and expected heterozygosity (H(e)) was 0.123. Genetic differentiation values (G(st)) showed that 9.4% of detected genetic variation was explained by differences among populations. The comparison between the rust-resistant breeding stock and a corresponding sample derived from multiple natural populations produced similar values of P (35% vs. 34.4%) and H(e) (0.134 vs. 0.131). No apparent signs of a genetic bottleneck caused by rust-resistance breeding were found. However, a comparison of two natural populations from local geographic areas showed that the population with low pressure from blister rust had higher polymorphism and heterozygosity than the population that had experienced high mortality due to blister rust: P (30.7% vs. 25.1%) and H(e) (0.125 vs. 0.100), respectively. In addition, the population from low blister-rust pressure had twice as many unique alleles as the blister rust-selected population. The genetic distance and Dice's similarity coefficients among the four populations indicated that the local population that survived high blister-rust pressure was genetically similar to the rust-resistant breeding stock.

Phylogenetic analysis of Bacillus thuringiensis based on PCR amplified fragment polymorphisms of flagellin genes.

Phylogenetic analysis of 35 strains of Bacillus thuringiensis was performed based on PCR amplified fragment polymorphisms of flagellin genes (PCR-AFPF). From coefficient matrix, the genetic distance coefficient D among them ranged from 0.14286 to 0.81818. Ten clusters were divided by the taxonomic threshold of 0.42 from the UPGMA dendrogram, demonstrating that the genetic dissimilarities existed among 35 strains of B. thuringiensis corresponding to 35 different serovars. This method could provide a fast, convenient and accurate way to classify all subspecies of B. thuringiensis including strains that can not be classified using the H-antigen method.

A Systematic Relationship of the Korean Euphorbia L. ( Euphorbiaceae ) based on RAPD analysis

We examined the infrageneric system and discuss the genetic realtionships with 12 taxa of Euphorbia in Korea using the RAPD. Two hundred twenty scorable RAPD markers were found from the PCR reactions with 14 random oligoprimers and were analyzed by Nei-Li's genetic distance coefficient with 21 populations of Korean Euphorbia. Based on the RAPD results, from 8.4 to 40.2 percent of genetic variations were showed among the species of subgenus Esula. Also, 16.9-40.2% between sect. Esula and sect. Tithymalus and 10.5-26.4% among subgenus Chamaesyce of genetic variations were found. In addition, 2.1-10.6% of genetic variation were showed among the populations of Korean Euphorbia. Based on the UPGMA tree and NJ tree from RAPD analyses, three major groups (group 1:sect. Helioscopiae, subsect. Verticillate and subsect. Galarrhoei; group 2: subgen. Chamaesyce; group 3: subsect. Esulae) were recognized. The current infrageneric systems proposed by several taxonomists have some problems. The result suggested that reexamination on the taxonomic status of E. helioscopia were needed and subsect. Esulae might be a natural group. RAPD analysis was very useful to delimit the taxa and to explain the relationships among the species of Euphorbia in Korea.

Microsatellite polymorphism in natural populations of wild emmer wheat, Triticum dicoccoides, in Israel

Diversity in 20 microsatellite loci of wild emmer wheat, Triticum dicoccoides, was examined in 15 populations (135 genotypes) representing a wide range of ecological conditions of soil, temperature, and water availability, in Israel and Turkey. An extensive amount of diversity at microsatellite loci was observed despite the predominantly selfing nature of this plant species. The 20 Gatersleben wheat microsatellites (GWM), representing 13 chromosomes of genomes A and B of wheat, revealed a total of 364 alleles, with an average of 18 alleles per GWM marker (range: 5-26). The proportion of polymorphic loci per population averaged 0.90 (range: 0.45- 1.00); genic diversity, He, averaged 0.50 (range 0.094- 0.736); and Shannon's information index averaged 0.84 (range 0.166-1.307). The coefficients of genetic distance between populations were high and averaged D=1.862 (range 0.876-3.320), an indication of sharp genetic divergence over short distances. Interpopulation genetic distances showed no association with geographic distance between the population sites of origin, which ruled out a simple isolation by distance model. Genetic dissimilarity values between genotypes were used to produce a dendrogram of the relationships among wild wheat populations by the unweighted pair-group method with arithmetic averages (UPGMA). The results showed that all the wild emmer wheat populations could be distinguished. Microsatellite analysis was found to be highly effective in distinguishing genotypes of T. dicoccoides, originating from diverse ecogeographical sites in Israel and Turkey, with 88% of the 135 genotypes correctly classified into sites of origin by discriminant analysis. Our present microsatellite results are non-random and in agreement with the previously obtained allozyme and RAPD patterns, although the genetic-diversity values obtained with microsatellites are much higher. Significant correlates of microsatellite markers with various climatic and soil factors suggest that, as in allozymes and RAPDs, natural selection causes adaptive microsatellite ecogeographical differentiation, not only in coding, but most importantly in non-coding genomic regions. Hence, the concept of "junk DNA" needs to be replaced by at least partly regulatory DNA. The obtained results suggest that microsatellite markers are useful for the estimation of genetic diversity in natural populations of T. dicoccoidesand for the tagging of agronomically important traits derived from wild emmer wheat.

Genetic diversity across natural populations of three montane plant species from the Western Ghats, India revealed by intersimple sequence repeats.

We analysed genetic diversity across the natural populations of three montane plant species in the Western Ghats, India; Symplocos laurina, Gaultheria fragrantissima and Eurya nitida using intersimple sequence repeat (ISSR) markers. These markers revealed genetic diversity within the populations of these plants from Nilgiri and also between two populations of S. laurina from Nilgiri and Amboli. Genetic variation within and between populations was analysed using various parameters such as total heterozygosity (HT), heterozygosity within population (HS), diversity between populations (DST), coefficient of population differentiation (GST), genetic distance (D) and gene flow (Nm). Total heterozygosity (HT) was higher for S. laurina (0.238) than for G. fragrantissima (0.172) and E. nitida (0.182). Two populations of S. laurina, separated by > 1000 km, showed a high within-population variation (53.7%) and a low gene flow (Nm = 0.447). upgma phenograms depicted a tendency of accessions to group according to their geographical locations in all the three plant species. The insight gained into the genetic structure of these plant populations might have implications in developing in situ and ex situ conservation strategies.

DNA Fingerprinting to Identify Nine Anthurium Pot Plant Cultivars and Examine Their Genetic Relationship

Randomly amplified polymorphic DNA (RAPD) markers were utilized to determine the genetic relationships of nine morphologically similar pot plant cultivars of Anthurium sp. by developing DNA fingerprints (DFP). Of 25 arbitrary primers screened, nine generated DFPs that were used in computing the genetic distance (d) and similarity coefficient (C) values. All cultivars tested exhibited a high degree of genetic similarity. `Lady Ann' and `Lady Beth' possessed the closest relationship with d and C values of 0.06 and 0.98, respectively. The next closest genetic relationship was between `Red Hot' and `Southern Blush' (d = 0.33, C = 0.89). These two cultivars exhibited a more distant relationship to the other seven cultivars as indicated by higher `d' values. However, this study showed that the nine Anthurium cultivars examined were genetically closely related. These cultivars share specific DNA bands with three possible parental species (A. andraeanum Linden ex Andre, A. antioquens L., and A. amnicola Dressler) included in this study, which may indicate similarities in their pedigree. This study shows that RAPDs can be a useful tool to distinguish Anthurium pot plant cultivars as well as identify their genetic relationships.

Genetic differences among host-associated populations of water mites (Acari: Unionicolidae: Unionicola): allozyme variation supports morphological differentiation.

Unionicola poundsi and U. lasallei are recognized as closely related, morphologically distinct species of water mites living in symbiotic association with the mussels Villosa villosa and Uniomerus declivus, respectively. However, results of a transplant experiment suggested that the morphological characters used to separate these species are plastic and are influenced by the host species in which these mites metamorphose. These results indicate that U. poundsi and U. lasallei are variants of the same species. To test the validity of these contrasting notions, the genetic structure of mite populations from Uniomerus declivus and V. villosa was compared. An examination of allozyme variation at 9 enzyme loci revealed a high degree of genetic differentiation between these host-associated populations, with mites from U. declivus and V. villosa being fixed for different alleles at 3 loci and exhibiting significant allele heterogeneity at 71% of their polymorphic loci. Coefficients of genetic similarity and genetic distance for mites from U. declivus and V. villosa were 0.36 and 0.95, respectively. The results of this study suggest that mite populations from U. declivus and V. villosa are genetically distinct and complement morphological data recognizing them as valid species.

Genetic and morphological characterization of the Aedes (Ochlerotatus) dorsalis (Diptera: Culicidae) group in North America.

An examination of the electrophoretically detectable variation among the North American members of the Aedes (Ochlerotatus) dorsalis group revealed large genetic differences among all 4 species. At least 9 of 18 loci examined (50%) were diagnostic for each species pair. However, morphological variation observed among species was low. Only Aedes canadensis (Theobald) was separated readily from the other members of this group [Aedes dorsalis (Meigen), Aedes melanimon Dyar and Aedes campestris Dyar & Knab] in all life stages. Characters traditionally used to separate the remaining 3 species were less reliable. In the adult female, Ae. melanimon may be distinguished from Ae. campestris by the scaling patterns of the wings and abdomen, but Ae. dorsalis could not be distinguished reliably by these characters. Adults of Ae. dorsalis may be separated reliably from those of Ae. campestris and Ae. melanimon only by the length of the subapical tooth relative to the length of the tarsal claw. Ae. melanimon was identified in the larval stage by the short mesothoracic hair 1. Eight larval characters differed between Ae. dorsalis and Ae. campestris. However, the ranges of these characters overlapped and no character was truly diagnostic. Genetic variation within species was low as measured by average heterozygosity and Nei's genetic distance coefficients. No allozymes were diagnostic for coastal and inland populations of Ae. dorsalis, and the pattern of genetic differentiation within this species did not correspond to the geographic location of the populations examined. Therefore, the genetic data did not support the hypothesis that Ae. dorsalis represents a complex of 2 or more cryptic species.

Temporal and spatial genetic variation within and among populations of the mosquito Culex tarsalis (Diptera: Culicidae) from California.

The genetic structure of 11 populations of Culex tarsalis Coquillett from California and 1 population from Nevada was examined at 18 loci using polyacrylamide gel electrophoresis. Six populations from northern and southern California were sampled repeatedly to determine if the genetic structure of Cx. tarsalis changes seasonally. Significant differences in allele frequencies at 13 different loci were seen in 3 populations over time as determined by contingency chi-square tests. Nei's genetic distance coefficients among different sampling dates was consistently < 0.025. The number of alleles per locus in these populations ranged from 1.6 to 2.7, whereas the average heterozygosity ranged from 0.086 to 0.228. No single locus was found to vary in a consistent pattern within all populations that were sampled repeatedly. These results indicate that Cx. tarsalis populations are genetically stable over time and that temporal variation is due to fluctuations in population size or immigration of genetically distinct individuals. In contrast, Cx. tarsalis did exhibit some differences in genetic structure that were related to geographical features including the Sierra Nevada and the Tehachapi Mountains of southern California. Genetically differentiated populations occurred in Nevada, southern and northeastern California, and the Central Valley of California. Little differentiation was observed among populations located in the Central Valley of California and those located at high elevations in the Sierra Nevada. Thus, in the populations examined, mountain ranges or arid conditions that limit the number of larval development sites appeared to be important barriers to the dispersal of Cx. tarsalis.

Hierarchical structure of genetic distances: Effects of matrix size, spatial distribution and correlation structure among gene frequencies

Geographic structure of genetic distances among local populations within species, based on allozyme data, has usually been evaluated by estimating genetic distances clustered with hierarchical algorithms, such as the unweighted pair-group method by arithmetic averages (UPGMA). The distortion produced in the clustering process is estimated by the cophenetic correlation coefficient. This hierarchical approach, however, can fail to produce an accurate representation of genetic distances among populations in a low dimensional space, especially when continuous (clinal) or reticulate patterns of variation exist. In the present study, we analyzed 50 genetic distance matrices from the literature, for animal taxa ranging from Platyhelminthes to Mammalia, in order to determine in which situations the UPGMA is useful to understand patterns of genetic variation among populations. The cophenetic correlation coefficients, derived from UPGMA based on three types of genetic distance coefficients, were correlated with other parameters of each matrix, including number of populations, loci, alleles, maximum geographic distance among populations, relative magnitude of the first eigenvalue of covariance matrix among alleles and logarithm of body size. Most cophenetic correlations were higher than 0.80, and the highest values appeared for Nei's and Rogers' genetic distances. The relationship between cophenetic correlation coefficients and the other parameters analyzed was defined by an "envelope space", forming triangles in which higher values of cophenetic correlations are found for higher values in the parameters, though low values do not necessarily correspond to high cophenetic correlations. We concluded that UPGMA is useful to describe genetic distances based on large distance matrices (both in terms of elevated number of populations or alleles), when dimensionality of the system is low (matrices with large first eigenvalues) or when local populations are separated by large geographical distances.

Genetic diversity in porcine Oesophagostomum dentatum and O. quadrispinulatum and their delineation by isoenzyme analysis.

The genetic diversity in eight strains of Oesophagostomum dentatum and O. quadrispinulatum was investigated by the electrophoresis study of ten enzyme systems. The loci Idh-2, Fbp, Sdh, and Pgm were found to be diagnostic between the species examined. Both the proportion of fixed allelic differences (26.3%) and the genetic distance coefficient (D = 0.54) are well above the range for differentiation of valid species. Isoenzyme patterns of susceptible and resistant lines of O. dentatum showed at polymorphic loci a reduced genetic heterogeneity in the latter group. No qualitative difference in terms of the presence/absence of alleles was observed among susceptible and resistant isolates with the enzymes studied. The detection of one possible hybrid indicates that introgression in O. dentatum and O. quadrispinuatum may occur.

Coffea arabica L., a new host plant for Acetobacter diazotrophicus, and isolation of other nitrogen-fixing acetobacteria.

Acetobacter diazotrophicus was isolated from coffee plant tissues and from rhizosphere soils. Isolation frequencies ranged from 15 to 40% and were dependent on soil pH. Attempts to isolate this bacterial species from coffee fruit, from inside vesicular-arbuscular mycorrhizal fungi spores, or from mealybugs (Planococcus citri) associated with coffee plants were not successful. Other acid-producing diazotrophic bacteria were recovered with frequencies of 20% from the coffee rhizosphere. These N2-fixing isolates had some features in common with the genus Acetobacter but should not be assigned to the species Acetobacter diazotrophicus because they differed from A. diazotrophicus in morphological and biochemical traits and were largely divergent in electrophoretic mobility patterns of metabolic enzymes at coefficients of genetic distance as high as 0.950. In addition, these N2-fixing acetobacteria differed in the small-subunit rRNA restriction fragment length polymorphism patterns obtained with EcoRI, and they exhibited very low DNA-DNA homology levels, ranging from 11 to 15% with the A. diazotrophicus reference strain PAI 5T. Thus, some of the diazotrophic acetobacteria recovered from the rhizosphere of coffee plants may be regarded as N2-fixing species of the genus Acetobacter other than A. diazotrophicus. Endophytic diazotrophic bacteria may be more prevalent than previously thought, and perhaps there are many more potentially beneficial N2-fixing bacteria which can be isolated from other agronomically important crops.

Genetic polymorphism and relationships among several swine populations of landrace, large white and duroc breeds

The data of three protein polymorphisms were used to investigate the genetic relationships among the Landrace, Large White and Duroc swine breeds reared in Brazil, 12 other populations of these same breeds from various countries and a population of Belgium Landrace. The dendrogram, constructed from matrix of genetic distance coefficients, disclosed three large groups clustered by breed. Among them, the Landrace and the Large White showed in average closer resemblance (D= 0.203) than between them and Duroc (D= 0.241). It the three breeds, the smallest genetic distances were found between Brazilian and Cuban pig populations (Landrace: D = 0.060; Large White: D = 0.052; Duroc: D = 0.065), although there were not reports of pig exchanges between these two countries.

Geographic Patterns in Genetic and Life History Variation in Pumpkinseed Populations from Four East-Central Ontario Watersheds

Abstract We examined the geographic distribution of biochemical genetic and life history characteristics of 16 populations of pumpkinseed Lepomis gibbosus within four east-central Ontario watersheds to determine (1) if populations within watersheds were more alike for either of these traits than populations among watersheds, (2) if the distribution of genetic and life history characteristics among watersheds coincided with each other, and (3) if the distribution of genetic and life history characteristics among watersheds showed some geographic pattern. Pumpkinseeds collected early in the reproductive season in the years 1990–1993 were assessed for reproductive maturity, gonadosomatic index (females only), and juvenile growth. Allele frequencies at six polymorphic loci were determined by protein electrophoresis. Cluster analysis based upon genetic distance coefficients showed three distinct groups, one containing populations from the Rideau River watershed, a second containing populations from the Crowe R...

Synthetic DNA-based genetic markers reveal intra- and inter-species DNA sequence variability in the Bubalus bubalis and related genomes.

A series of synthetic oligonucleotide probes were developed as markers for genetic analysis and molecular systematics of Bubalus bubalis and other eutherian mammals. A very high level of heterozygosity (approximately 95%) was observed in the bubaline genome, with an overall band-sharing probability of 2.08 x 10(-11) using (TGG)6 and Hinf I probe-enzyme combination. Breed affiliation studies on different buffalo breeds, viz. Toda, Surti, Mehsana, and Murrah, revealed that the semiwild Toda breed belonged to a distinct group. The desired genotypes in each successive generation in an actual breeding program were also identified by employing a DNA fingerprinting approach using these markers. Estimation of genetic distances by calculating the mean allelic frequencies at (CA)n, (TGG)n, and (GGAT)n repeat loci between buffalo and other related animals such as horse (order Perisodactyla), rabbits (order Lagomorpha, (pigs, cattle, goat, and sheep (order Artiodactyla) revealed that with respect to the genetic distance coefficient (GDC), goat (caprine) was closer to buffalo (GDC = 0.0005) than sheep (ovine) (GDC = 0.0007). The genetic distance between horse and buffalo was calculated to be 0.4085, indicating that compared to other animals, horse was distantly related to buffalo. The understanding of overall allelic variations and breed affiliation of the bubaline genome will contribute to the propagation and conservation of the desired germ plasm and better management of this species.

Genetic diversity of North American and Old World Saccharum assessed by RAPD analysis

Saccharum (= Erianthus) native to North America is an untapped germplasm for genetic improvement of sugarcane (Saccharum spp. hybrids). There are five species and two varieties native to North America: S. alopecuroideum, S. baldwinii, S. brevibarbe vars. brevibarbe and contortum, S. coarctatum, and S. giganteum. There are three cytotypes of S. giganteum (2n = 30, 60, 90), and they overlap in gross morphology. Our objectives were to compare genetic diversity of North American and Old World members of Saccharum. Bulked DNA for five North American species, three Old World Erianthus spp. sect. Ripidium clones, and five sugarcane cultivars was tested by PCR with 13 RAPD primers. A total of 283 repeatable RAPD bands was scored for the nine taxa. Genetic distance coefficients ranged from 0.365 to 0.767 indicating substantial diversity among taxa. Taxa were assigned to one of three cluster groups: 1) S. baldwinii, S. brevibarbe var. contortum, S. coarctatum, and S. giganteum 2n = 90; 2) S. gig anteum 2n = 30 and 2n = 60, S. alopecuroideum, and sugarcane cultivars; and 3) Old World Erianthus spp. The RAPD analysis indicated that sugarcane was genetically more similar to North American Saccharum than it was to Old World Erianthus. This was unexpected given that North American Saccharum is geographically, cytologically, morphologically, and possibly reproductively isolated from Old World Erianthus and sugarcane. The data support the taxonomic separation of cytotypes of S. giganteum.

Discriminatory power and application of ribotyping of Yersinia enterocolitica O:3 in an epidemiological study.

Ribotyping performed with five restriction endonucleases was used in an attempt to subtype Yersinia enterocolitica serotype O:3 and also as a tool for clonal analysis. DNA from organisms under study (48 isolates from diarrheic human feces, 24 from food, and 5 reference strains) was tested by Southern hybridization using a DNA probe carrying an rRNA operon from Escherichia coli. Strains were grouped into seven ribotypes by the HindIII restriction endonuclease, into five ribotypes by Ncil, Bg/l, and Sa/l; and into two ribotypes by EcoRI, resulting in a discrimination index (DI) of 0.37, 0.17, 0.43, 0.13, and 0.03 for the five endonucleases. By combining the results obtained with two or more restriction endonucleases, a further discrimination was registered, the most efficient combination (in terms of discriminatory power vs. cost in work, time, and money) for routine typing being HindIII-Bg/l (9 types, DI=0.58). In the clonal analysis, results obtained with the five restriction endonucleases allowed us to define 11 groupings or clonal lines, which showed a remarkable degree of genetic heterogeneity (genetic distance coefficients between 0.03 and 0.73) and were grouped into two major clusters. One cluster included 93% of the strains and eight lines. At least two of the most frequent lines can be considered endemic in Asturias, Spain, because organisms belonging to these lines have been circulating and causing human yersiniosis in recent years and have also been isolated from commercial raw meat products. Two Ncil ribotypes from the series under study (92.2% of strains included in the prevalent cluster) were similar but not identical to ribotypes of 0.3 organisms from other geographic areas described in the literature, indicating that the genetic structure of prevalent human pathogens of this serotype is basically clonal.

Genetic Variation in Naturalized Rainbow Trout ( Oncorhynchus mykiss) from Minnesota Tributaries to Lake Superior

Genetic variation at 27 polymorphic loci that code allozymes was compared among collections of naturalized, anadromous-form rainbow trout ( Oncorhynchus mykiss) from Lake Superior tributaries in Minnesota and among four hatchery strains. Genetic differences were observed among collections from naturalized populations from tributary streams and among hatchery strains (P < 0.01). In naturalized populations, most genetic variation observed occurred among individuals within samples (95.5%) and was comparable to values reported for other naturalized Lake Superior populations of rainbow trout. Cluster analysis of genetic distance coefficients revealed two main groups. One group included a subgroup of samples from heavily stocked streams (Devil Track, Flute Reed, and Baptism rivers) and the Michigan hatchery strain which had been used to stock these streams. The second group included collections from the Knife River drainage and Knife River hatchery fish. Collections from Indian Camp Creek and of the “kam-loops” hatchery strain were the most differentiated of the samples and showed little genetic affinity to each other or the two main groups. The “kamloops” strain did not exhibit allelic frequencies expected for rainbow trout derived from the Kamloops region of the upper Fraser River of British Columbia. No evidence was found to support the contention that the “kamloops” hatchery strain had interbred with wild populations. Widespread stocking of Michigan strain fish may have reduced genetic differences among naturalized, wild populations along Minnesota's Lake Superior shoreline. Population-specific management of rainbow trout by tributary is a justifiable approach to consider. If maintenance of the genetic differences among the wild, naturalized populations is desired, “kamloops” and the Michigan hatchery strains should not be stocked. Stocking programs instead should use gametes from returning adults of a river for subsequent juvenile propagation and stocking back into the same river.

Enzyme and storage protein electrophoresis in varietal identification of sugar beet

Different methods of classification, based on total protein patterns as well as on specific isoenzyme patterns, were compared in order to establish an identification system for sugar beet varieties and lines. Single seed patterns and bulk extractions of total and fractionated proteins were compared on SDS-PAGE. Due to important intra-populational variation contrasting with similarity at the varietal level no method proved to be sufficiently discriminatory. Twelve sugar beet lines have been genotypically fingerprinted on the basis of five allozyme systems. The allele frequencies of each variety have been measured by using 60-100 individuals. From the data, genetic distance coefficients have been calculated in order to group the different entries by cluster analysis. In addition, a comparison has been made between two seed lots independently obtained from the same parental lines, to test the stability over years. Seeds from the same parental lines, but produced in different localities (Denmark, Italia and USA), were compared to test the influence of the environment on the classification. It has been concluded that isozymes could provide a useful tool for cultivar distinction. The variability at the level of allele frequencies within localities was small. The stability of different generations of the strains was relatively constant. Different strains originating from the same seed firm were less distinct than strains originating from different seed firms.