Swiss Populations Research Articles

Intra-specific variability of ozone sensitivity in Centaurea jacea L., a potential bioindicator for elevated ozone concentrations

Brown knapweed ( Centaurea jacea L.) has been suggested as a potential bioindicator for tropospheric ozone (O 3 ), but little is known about the intra-specific variation in O 3 sensitivity in this wild species. The aim of this study was to quantify the differences in O 3 sensitivity among and within five populations, and to relate the differences to morphological, phenological, and genetic characteristics. These parameters were periodically recorded in two consecutive experiments on a total of 357 plants from five different European countries (Norway, Hungary, Switzerland, Italy, Slovenia). They were grown from seed in natural soil under ambient conditions at a site with seasonally elevated O 3 concentrations (Cadenazzo, southern Switzerland). The populations differed significantly both in frequency and extent of O 3 injury, as well as in phenological development. The observed degree of O 3 injury was highest in the Slovenian and the Swiss populations, while only few Hungarian and Norwegian plants showed slight symptoms of injury. Plants were generally most sensitive to O 3 when reaching the reproductive stage, and insensitive at the rosette stage. Amplified fragment length polymorphism analysis (AFLP) demonstrated genetic distinctiveness of the five C. jacea populations. All individuals of four of the five populations were correctly assigned to the respective populations based on principal component analysis. Cluster analysis quite accurately reflected the geographic origin of each population. Overall, the analysis revealed a high degree of intra-specific variability in O 3 sensitivity in C. jacea , and underlined the important influence of the climate-dependent population-specific plant development on O 3 sensitivity. These observations may constrain the development of a standardized biomonitoring system.

Dynamics of genetic variation in Taxus baccata: local versus regional perspectives

Increasing loss of habitat tends to reduce biodiversity at the inter- and intra-specific levels. Within species, the remaining diversity is often partitioned so that a great amount of neutral genetic variation is assigned to among-population variation. This implies reduced gene flow as a consequence of population isolation. We tested whether random amplified polymorphic DNA (RAPD) markers indicate population and (or) regional differentiation in Swiss populations of English yew (Taxus baccata L.), a dioecious forest tree species with scattered distribution. Our sampling included three northern Swiss regions, each containing four populations, and a central-Alpine region with two populations. Four RAPD primers, giving rise to 41 scorable marker bands, identified all but two sampled individuals as unique genotypes. Analyses of molecular variance (AMOVA) detected no significant differentiation among the three northern Swiss regions yet a marginally significant differentiation of these regions versus the central-Alpine region. Concordantly, Mantel tests revealed isolation by distance only when considering all 14 populations. We postulate that the inferred level of gene flow, through wind-borne pollen and occasional long-distance seed dispersal, prevents isolation by distance in northern Switzerland, where stands of T. baccata are relatively abundant. This perpetuates a coherent regional network of occurrences of T. baccata, as might be expected in a metapopulation.Key words: genetic variation, isolation by distance, metapopulation, population differentiation, RAPD-PCR, Taxus baccata.

Female colour polymorphism covaries with reproductive strategies in the tawny owlStrix aluco

Variation in coloration with a strong underlying genetic basis is frequently found in birds, insects, anurans, molluscs and plants. Although such a variation can be large, little is known about its functional value. Correlative data, however, can help suggest testable hypotheses about potential covariation between reproductive parameters and a colour polymorphism displayed by individuals belonging to a single population. In this context, we studied two Swiss populations of tawny owlsStrix aluco, a polymorphic species that varies in coloration from reddish‐brown to grey. Observations in the first population showed that although greyer females had shorter tarsi, they produced heavier offspring in two of three years. Pairing with respect to plumage coloration was not significantly disassortative, indicating that these correlations were probably not inflated by plumage coloration of the mate. In the second population, where breeding females had been monitored for 14 years, the proportion of all breeding females that were reddish‐brown was greater in years when the breeding density was lower. Capture‐recapture analyses show that the latter result is explained by the fact that greyish females bred less often than reddish‐brown females, although their survival probability was similar. The number of greyer breeding females was greater when spring/summer temperatures were lower. When combined, the results from the two populations lend support to the hypothesis that grey females do not breed every year, but produce offspring of higher quality. Whatever the mechanism underlying the correlations reported in this study, colour polymorphism in female tawny owls appears to reflect some components of individual quality.

Genetic depletion in Swiss populations of Rana latastei: conservation implications

Rana latastei, the Italian Agile Frog, is found over a restricted range in Central Europe, with populations in Switzerland (Tessin) occurring at the very margin of the species distribution. We used microsatellite DNA polymorphisms to study the genetic diversity of Swiss populations of Rana latastei and compared them with several Italian populations located in the central and western parts of the species’ range. On average, Swiss populations showed a much lower level of within-population genetic diversity relative to their Italian counterparts. Existing Swiss conservation efforts do not include genetic considerations and our results show that any attempt to increase genetic diversity within Switzerland would require a collaborative effort with Italian wildlife agencies.

Strain-specific microsatellite markers in the entomopathogenic fungus Beauveria brongniartii

We have identified ten microsatellite markers in the entomopathogenic fungus Beauveria brongniartii from three genomic libraries enriched for (AAG)n-, (TG)n-, or (TC)n-repeats. The levels of polymorphism of the identified microsatellite loci were assessed in a collection of Beauveria strains originating from different countries, areas, and host insects. Two geographically separated Swiss populations of B. brongniartii originating from European cockchafer (Melolontha melolontha) were also analysed. Microsatellites containing (AAG)n-repeats generally displayed high levels of polymorphism, whereas microsatellites containing either (TG)n- or (TC)n-repeats displayed lower levels of polymorphism. Cluster analysis revealed that strains isolated from M. melolontha larvae, and two strains isolated from Melolontha hippocastani or Amphimallon solstitiale larvae, formed one cluster which was separated from strains isolated from adult M. melolontha and other adult insects. A high degree of biodiversity was detected among B. brongniartii strains of the two separated Swiss populations. Distinct haplotypes were identified in 29 of 35 B. brongniartii strains from population A and in 12 of 28 B. brongniartii strains from population B. The high discrimination power of the identified microsatellites makes them a valuable tool, suited for the characterization and identification of B. brongniartii strains used as biocontrol agents. In addition, they may be applied to monitor biological control strains of B. brongniartii in the field and possibly to investigate their interactions with indigenous B. brongniartii isolates.

Genetic differentiation of the common toad (Bufo bufo) in the Swiss Alps

AbstractWe analysed the genetic differentiation of tadpoles from 24 Swiss populations of Bufo b. bufo and B. b. spinosus, using horizontal starch gel electrophoresis of eight enzymes coded by ten loci. For comparison, we included ten populations from more distant localities. Populations of Bufo calamita were included as outgroup. A very low level of genetic differentiation was found among populations from the Alpine region, including B. b. bufo populations from the Czech Republic and northern Germany, and B. b. spinosus populations from northern Italy. Genetic differentiation within populations was much higher than differentiation among populations or regions. In contrast, the southern French B. b. spinosus populations were clearly differentiated by allele substitution at three out of ten loci scored. These alleles of the French populations, however, were also found in low frequencies in some populations from western Switzerland and Italy. This is interpreted to result from gene flow. Morphometric data of adult B. bufo (13 populations, 174 adult toads) turned out to be strongly size dependent. However, relative arm length and density of large warts ventral to the parotoids showed differences between the two subspecies.

Differential performance among LDH-B genotypes in Rana lessonae tadpoles.

The European pool frog, Rana lessonae, is widely polymorphic for two common alleles (b,e) at the lactate dehydrogenase-B (LDH-B) locus. We compared fitness-related larval life-history traits among LDH-B genotypes, which originated from segregation in heterozygous parents, in an artificial pond experiment where tadpoles of R. lessonae from a Swiss population were raised together with tadpoles of the hemiclonal hybrid R. esculenta at two densities. In R. lessonae, LDH-B e/e homozygotes at each density had a higher proportion of metamorphs among survivors, reached metamorphosis earlier, and were heavier at metamorphosis than b/b homozygotes; b/e heterozygotes had intermediate values. That e/e individuals were superior to b/b in both time to and mass at metamorphosis is surprising because these two life-history traits are thought to reflect a performance trade-off; e/e genotypes apparently compensated for shorter time to metamorphosis by a higher growth rate. The two alleles showed the same performance ranking when combined in hybrids with a R. ridibunda allele: When R. esculenta from Swiss populations reared in the same ponds had received the e allele rather than the b allele from their R. lessonae parent, they reached metamorphosis earlier, but did not differ in mass at metamorphosis. The degree of linkage disequilibrium in the source population of the eight R. lessonae used as parents of the R. lessonae tadpoles is unknown, so we cannot exclude the possibility that the performance differences are caused by some anonymous tightly linked gene, rather than the LDH-B locus, that constitutes the genomically localized target of natural selection. A causal involvement of LDH-B is plausible, nevertheless, because this enzyme takes part in the central energy-metabolizing processes and has been reported to underlie fitness differences in other animals; also, differential performance of LDH-B genotypes has been observed in R. lessonae larvae from another population. The present results suggest strong directional selection for allele e; the sum of available data, including an independent laboratory experiment, suggests that partial environment-dependent overdominance combined with balancing selection favoring e/e homozygotes under some and b/b homozygotes under other conditions may be partially responsible for the broad maintenance of the LDH-B polymorphism in R. lessonae.

DIFFERENTIAL PERFORMANCE AMONG LDH-B GENOTYPES IN RANA LESSONAE TADPOLES

The European pool frog, Rana lessonae, is widely polymorphic for two common alleles (b, e) at the lactate dehydrogenase-B (LDH-B) locus. We compared fitness-related larval life-history traits among LDH-B genotypes, which originated from segregation in heterozygous parents, in an artificial pond experiment where tadpoles of R. lessonae from a Swiss population were raised together with tadpoles of the hemiclonal hybrid R. esculenta at two densities. In R. lessonae, LDH-B e/e homozygotes at each density had a higher proportion of metamorphs among survivors, reached metamorphosis earlier, and were heavier at metamorphosis than b/b homozygotes; b/e heterozygotes had intermediate values. That e/e individuals were superior to b/b in both time to and mass at metamorphosis is surprising because these two life-history traits are thought to reflect a performance trade-off; e/e genotypes apparently compensated for shorter time to metamorphosis by a higher growth rate. The two alleles showed the same performance ranking when combined in hybrids with a R. ridibunda allele: When R. esculenta from Swiss populations reared in the same ponds had received the e allele rather than the b allele from their R. lessonae parent, they reached metamorphosis earlier, but did not differ in mass at metamorphosis. The degree of linkage disequilibrium in the source population of the eight R. lessonae used as parents of the R. lessonae tadpoles is unknown, so we cannot exclude the possibility that the performance differences are caused by some anonymous tightly linked gene, rather than the LDH-B locus, that constitutes the genomically localized target of natural selection. A causal involvement of LDH-B is plausible, nevertheless, because this enzyme takes part in the central energy-metabolizing processes and has been reported to underlie fitness differences in other animals; also, differential performance of LDH-B genotypes has been observed in R. lessonae larvae from another population. The present results suggest strong directional selection for allele e; the sum of available data, including an independent laboratory experiment, suggests that partial environment-dependent overdominance combined with balancing selection favoring e/e homozygotes under some and b/b homozygotes under other conditions may be partially responsible for the broad maintenance of the LDH-B polymorphism in R. lessonae.Corresponding Editor: E. Brodie III

Genetic and morphological variability in cestodes of the genus Proteocephalus: geographical variation in Proteocephalus percae populations

Genetic and morphological variability was studied in the tapeworm Proteocephalus percae (Müller, 1780) (Cestoda: Proteocephalidae), a parasite of perch (Perca fluviatilis L.). Geographic variation in isoenzyme patterns, random amplified polymorphic DNA (RAPD) profiles, and morphological characters were found within six natural populations of P. percae from Slovakia and Switzerland. All approaches used showed that similarity was substantially higher among Swiss populations than among Slovak populations. Proteocephalus percae specimens from the Dobšiná water reservoir (Slovakia) differed significantly from all other population sample sets in that they exclusively expressed the genotype Acp92/Acp92 and possessed a specific RAPD profile after amplification with the primer p78 and distinct measurements of the scolex (scolex width and apical sucker). The unique position of the P. percae population from Dobšiná could be related to the contamination of this locality with heavy metals (cadmium), through the possible impact of these metals on the alterations observed. The taxonomic relevance and stability of the morphological characters related to the scolex in the Proteocephalus tapeworm group is confirmed.

Haptoglobin (HPA)-Subtypen in schweizerischen Populationen

A subtyping of the haptoglobins of thirteen small Swiss populations, who live in mountainous regions of the Alps, and four larger Swiss populations has been undertaken. The impact of population and sample size on allele frequencies is discussed.

Intraspecific molecular variation inHieracium sect.Alpina (Asteraceae), an apomictic group

Intraspecific variation of four agamospecies of Hieracium sect. Alpina was studied using RAPD and isozyme techniques. No variation in either multiprimer RAPD or multi-enzyme phenotypes was observed within H. holosericeum, suggesting that this widespread species consists of only a single genotype. A low level of within-population isozyme variation was seen in H. tenuifrons and H. calenduliflorum, the origin of which appears to be consistent with somatic mutation. Most isozyme and all RAPD variation in these two species was partitioned between populations. A strong correlation with geography suggests that its cause may be due to polytopic (=polyphyletic?) origin or perhaps to mutation and dispersal. The most variable species was H. alpinum, in which isozyme variation occurred mostly within populations rather than between them, suggesting occasional sexual events or that the parents of H. alpinum were heterozygous. RAPD variation in this species, in contrast, was partitioned between Scottish and Swiss populations, suggesting the existence of geographical races.

Stolon characteristics related to winter survival in white clover

SUMMARYChanges in the stolon carbohydrate contents (water-soluble and total non-structural) of four white clover populations were measured at the beginning and end of winter. Three of the populations were of Swiss origin - two of these were from high-altitude pastures, and the other from a valley location. Grasslands Huia was measured as a control variety. Levels of both types of carbohydrate declined during the winter in all populations. The Swiss populations from high altitudes contained the highest levels of both carbohydrate types.An artificial freezing test was carried out on stolon segments collected from a range of clover populations (including the two high-altitude Swiss clovers) growing in field plots in January, and values of ‘lethal dose 50’ (LD50) were calculated. The two Swiss populations had the lowest LD50 values, indicating a greater intrinsic tolerance to freezing in those plants than in the other populations (of lowland temperate origin).One of the Swiss populations, Ac3785, was grown under two temperature regimes and short daylength to determine whether its tolerance to freezing increased with time. Significant increases in tolerance occurred after 8 days at 2 °C, but plants grown at 8 °C showed no change in tolerance even after 30 days.The results suggest that (i) stolon carbohydrate content is an important factor in the overwintering of white clover, (ii) there is a considerable amount of genetic variation in cold tolerance within white clover, (iii) artificial freezing tests can provide a method of predicting the survival of clover stolons during winter and (iv) the cold hardiness of white clover increases with time spent at temperatures near 0 °C under short daylengths.

Biochemical genetic description of German and Swiss populations of red deer Cervus elaphus

A total of 228 red deer Cervus elaphus Linnaeus, 1758 from 5 sampling sites in Germany and 2 sampling sites in Switzerland were analysed for allozyme variability by means of various electrophoretic techniques. Based on 26 presumptive structural loci scored, the proportion of polymorphic loci ( P) ranged from 3.8% to 11.5%, and average heterozygosity ( H) varied between 0.8% and 2%. These values are among the lowest ones as yet detected in population genetic studies of red deer. A correlation between genetic and geographic distances could be demonstrated and significant allele frequency differences were observed, especially between the German and the Swiss populations examined. Levels of relative genetic differentiation ( G st ) among populations in Germany and Switzerland were low and amounted to 3.9% and 1.5%, respectively. When compared with all other German samples, a private allele at the Mpi-1 locus and remarkably different allelic frequencies at the Sod-2 locus were detected in the game preserve Reinhardswald. These findings were interpreted to result from a release of Hungarian and Hungarian x Yugoslavian red deer in the 1980s. Veterinarmedizinische Genetik und Zytogenetik, Justus-Liebig-Universitat Giesen, Hofmannstrase 10, D-35392 Giesen, Germany

Isérables: a Bedouin village in Switzerland?

Isérables is an alpine village--about 1000 inhabitants--which remained isolated till these recent years because of its particular geographical situation. The Isérables inhabitants call themselves "Bedjuis" (Bedouin in local dialect) and regard themselves as descendants of the Sarrazins who invaded the Alps during the VIII-X centuries. Our goal, in studying several DNA-VNTR polymorphims, in addition to some blood groups, within the Isérables community, was to see if there was any evidence supporting this popular belief. As a preliminary phase of this project, the allelic frequencies for six VNTR loci analysed for 102 individuals of the village (all descendants of nine original families) are presented. The results are compared with those reported for Swiss and white populations.

Der Faktor 13 B (FSF)-Polymorphismus in schweizerischen Populationen, mit Betrachtungen über europäische Häufigkeitsgradienten

Phenotype and allele frequencies of the coagulation factor 13 B (FSF B) of three Swiss populations (Northern Switzerland, upper Rhone valley and valley of Safien) have been determined after electrophoresis and passive immunoblotting and are discussed with respect to the geographical distribution and to the history of these populations. The populations of the upper Rhone valley and the valley of Safien reveal a closer genetical relationship obviously due to the migration of the antecedents of the recent Safier from the Rhone valley to the Safien valley from the 13th to 14th century. The allele frequencies of the Swiss German population fit rather well the North-South genetical cline which has to be considered in the light of the early settlement of Central Europe and of the numerous migrations thereafter.

The relationships between stolon characteristics, winter survival and annual yields in white clover (Trifolium repens L.)

AbstractFive white clover populations of Swiss origin and three bred varieties were grown in binary mixtures with two perennial ryegrass varieties, Aurora and S23. The seasonal yields of clover and grass plus clover were measured under a cutting regime during the second and third years after establishment. A series of destructive detailed sward measurements was made during the late autumn to spring period preceding each harvest year. In this way changes in the amounts of stolon, leaf plus petiole and numbers of growing points were monitored during the winter.There were large differences in clover yield between populations in both years. These were evident from the first (spring) harvest in each year. Higher‐yielding clovers in spring tended to produce higher annual clover yields. No grass × clover interaction was evident at any harvest. Large differences between clovers were also apparent in the morphological characteristics measured, with the Swiss material generally having greater amounts of stolon, leaf plus petiole and numbers of growing points present in early spring. It is proposed that these factors contribute to the high spring yield in the Swiss populations. Loss of stolon length over each winter was less in the Swiss material, indicating that its good spring growth was not obtained at the expense of winter hardiness. Annual clover yield was found to be significantly positively correlated with the amount of stolon present in spring, exemplifying the importance of stolon survival over the winter.

Postmating reproductive isolation and modification of the ‘sex ratio’ trait inDrosophila subobscura induced by the sex chromosome gene arrangement A2+3+5+7

Drosophila subobscura males were trapped in Tunis, and mated to different lab strains. The offspring from 15% of these wild Tunisian males consisted of more than 90% females. Chromosome analysis showed that these males had carried the A2+3+5+7 which was described as 'sex ratio' chromosome, endemic in North Africa and the Canary Islands. The mean female frequency in the total offspring of all trapped males was 61%. This percentage was stable for more than ten years. F1 females from the mating of wild Tunisian males to Küsnacht standard females were backcrossed to Küsnacht standard males. In the offspring of this back cross, A2+3+5+7-males were sterile. The fertility of A2+3+5+7-males could be restored in two ways: 1) When the Küsnacht standard autosomes were replaced by Tunisian autosomes, most of the A2+3+5+7-males were again fertile. The A2+3+5+7-chromosome seems to be incompatible with autosomes from a geographically distant region. 2) After exchanging autosomes between lines, in which A2+3+5+7-males were 100% sterile, fertility could be restored in 30% of the A2+3+5+7-males. All males carrying one specific A2+3+5+7 stayed sterile as well in combination with autosomes from different lines as with Tunisian autosomes. The Y-chromosome and the cytoplasm was the same in sterile and in fertile A2+3+5+7-males. Therefore the origin of the Y-chromosome and the cytoplasm could not play a major role in sterility. The percentage of fertile males varied for different Y-chromosomes. Thus the Y-chromosomes may have some influence on fertility in this study. The restored fertility of A2+3+5+7-males can be explained assuming complementation. Defects of autosomes, and perhaps of the Y-chromosomes, could differ from line to line. Genomic changes may have happened when the A2+3+5+7 was in the genome together with autosomes and Y-chromosomes from Swiss populations. The A-chromosome which prevented fertility in all combinations, is thought to be itself defective. In one cross the 'sex ratio' trait was modified. In the offspring of some males the male to female ratio was 1:1. The variable sex ratio in the offspring from different males may have been an effect of the autosomes. In short, the intraspecific hybrid sterility and modification of the 'sex ratio' trait in D. subobscura indicate that: a) an incompatibility possibly existed between the gene arrangement A2+3+5+7 from one population and autosomes respectively Y-chromosomes from a population isolated from the former. b) In addition unidentified genomic changes occurred, c) induced by the A2+3+5+7-chromosome. d) The sex chromosomes A and Y, and the autosomes were involved.

C-banding in the polytene chromosomes of species of the plumosus group (Diptera, Chironomidae) and their experimental hybrids

The localization and amount of heterochromatin in the plumosus group were studied, including the species Chironomus plumosus L., C. vancouveri and C. balatonicus. The appearance of C bands of Chironomus plumosus in several European populations is traced. The role of the C heterochromatin in the differentiation of this species is discussed. From the evolutionary point of view the Swiss populations, in which large centromere heterochromatin blocks have been discovered, are more varied as to the amount of heterochromatin. The importance of duplications for this process is pointed out. The chromosomes of the individuals from C. vancouveri and C. balatonicus have centromeric, telomeric and interstitial heterochromatin. The centromeric heterochromatin is represented by thin C-bands. The particularities in the appearance of C heterochromatin in C. vancouveri and C. balatonicus reflect the structural peculiarities of their chromosomes. The change in the euchromatin regions in these forms is discussed in the light of transformation of euchromatin to heterochromatin in the process of evolution.

Genfrequenzen des Coeruloplasmins in schweizerischen Populationen (Nordschweizer, Walliser und Walser)

Coeruloplasmin has been studied on 3051 individuals from Swiss populations. The C*PA frequencies of 0.0050 reported for Northern Switzerland as well as for the Upper Rhone Valley (Brig, Goms) and the Visp Valleys (Valais) are in the range of those of other European populations. In the village of Törbel and in the Lötschental (both Canton of Valais) the C*PA frequencies are somewhat lower. The individuals from the French speaking part of Valais showed only the C*PB allele. The fixation of the C*PB allele in the Walser of the Safiental (The Grisons) can be explained under the assumption of founder effect or of genetic drift. A new CP variant (C*PW) is described.

2.7. Properdin factor B (Bf) polymorphism in Sweden

The demographic research by R. M. Netting and W. Ellis in 1970 71, 1974 and 1977 about the relatively isolated population of Torbel (Canton of Wallis, Switzerland) offers a valuable source for a serogenetic study (blood groups, serum proteins, enzymes) and for a programme on the population genetics of this community. The historical data (since 1665) of the village represent fundamental information on the population changes (population dynamics), the familial structure of the population (pedigrees, gene pool) and its connections with other communities and valleys (migration). The blood research programme, undertaken with the collaboration of the Gerichtlich-Medizinisches Institut Zurich (H. Hartmann and M. Mahler) and the Zentrallaboratorium des Schweizerischen Roten Kreuzes Bern (R. Butler and R. Pflugshaupt), concerns seven blood groups, ten serum proteins and 17 enzymes of the red blood cells. Up to now, the research has led to the detection of some rare blood protein alleles (Gc’ c3) which are, respectively, rare phenotypes in the systems 6-PGD, Pi, Gc, C3 and Bf. Formal genetics of these rare phenotypes was done with the help of large families. Micro-evolutionary processes such as isolation, migration and genetic drift are considered as possible explanations for numerous statistically significant deviations in the allele frequencies of the Tijrbel population from other Swiss populations,