Abstract: Allozyme variation at 25 genetic loci was assayed in twelve indigenous cultivars (land races) of barley from Iran. For these loci the average probability that two gametes drawn at random from one population would differ at a locus was 0.082. In the collection as a whole, this measure of genetic diversity was 0.161, so that about half the total diversity was distributed between populations. Of the total of 31 allozyme variants, about half were common (frequency >0.10) in only one or two regions. The results were compared with diversity estimates based on spike morphological polymorphisms; with allozyme polymorphism in two composite crosses (CC21 and CC34) of cultivated barley; and with previous results for allozyme polymorphism in Israel populations of wild barley. In the land race samples, the diversity of spike types was a poor index of allozyme diversity. The total allozyme diversity in this collection of land races was intermediate between the moderate levels in composite crosses and the high levels in Hordeum spontaneum from Israel. These results emphasize the role of land races as valuable genetic resources for plant breeding. They support sampling strategies which, by taking samples of moderate size from many sites, emphasize the collection of locally common alleles, as against strategies framed to capture the rare, conspicuous morphological variant by intensive or biased sampling, or strategies based on collecting the extreme ecotypes from a cline. The chromosomal location of 20 of the allozyme loci as deduced from wheat-barley addition lines, is listed in the appendix.

Abstract: Nuclear DNA amounts are determined in 16 species and the C-banding patterns for 19 species of rodents. A list of rodent DNA amounts is compiled. The fraction of heterochromatin in the genome is determined as the length of C-banded chromosome material relative to the total karyotype length. Among all rodents, heterochromatin amounts tend to be larger in the larger genomes. However, this relationship is not exact and does not hold true for individual genera. In general the notion of a basic rodent genome of defined size to which various amounts of heterochromatin have been added is untenable.

Abstract: The karyotypes of Clethrionomys rufocanus and C. glareolus are presented using G- and C-banding techniques. There is intraspecific polymorphism in Clethrionomys rufocanus for a pericentric inversion. The main difference between the karyotypes of the two species is considered to result from a reciprocal translocation.

Abstract: The morphology, G- and C-banding pattern of the Akodon mollis chromosome complement is analysed. Over a total of 14 males and 10 females studied, 8 males and 7 females had a modal chromosome number of 22, while 6 males and 3 females showed a modal number of 23 chromosomes. In the animals with 23 chromosomes the odd element was considered a B chromosome on the basis of: (a) its small size, (b) the lack of an homologous chromosome and the subsequent formation of univalents at diakinesis and metaphase I from testes, (c) the weak or null genetic action as evidenced by the lack of any obvious variation in the phenotype of carriers.

Abstract: Studies were carried out on the temperature-dependent kinetic properties (Km, Q10, Ea, thermostability) of alcohol-dehydrogenase allozymes from D. melanogaster. It was shown that there is a parallelism between the biochemical properties of the enzymes and the behaviour of the genes in natural and cage populations. Furthermore, the relationship between the temperature-dependent kinetic properties of alcohol dehydrogenase and assay temperature was examined in three tropical and two temperate Drosophila species. Km patterns were similar among species from the same habitat and different between habitats. No such parallelism was seen with respect to thermal inactivation. The Q10 values in general reflected temperature-dependent changes in Km. It is discussed that the mechanistic connection observed between the biochemical and population levels (intra-and interspecifically) strongly suggests that temperature acts as a selective factor on the structural Adh locus in the genus Drosophila.

Abstract: The genetics of one malate dehydrogenase locus and two peroxidase loci were studied in leaves of diploid and more particularly tetraploid Dactylis glomerata L. by means of starch gel electrophoresis. Seven, two and four codominant alleles at the PX1, PX2 and MDH1 loci respectively are described. Malate dehydrogenases showed dimeric structure and peroxidases behaved as monomers but with several molecular structures in the case of PX1. No linkage was found between PX1 and MDH1 nor between PX1 or MDH1 and other loci studied previously.

Abstract: A case is made for the occurrence of simultaneous multiple chromosome rearrangements as a mechanism for karyotypic change. The evidence for this type of rearrangement from population studies and rare mutant animals is reviewed and the structural prerequisites for such a mode of evolution are considered.

Abstract: A chromosomal analysis of the monitor Varanus acanthurus Boulenger has been made using G- and C-banding and silver-staining techniques. This species has two cytotypes, one of which has a pericentric-inversion polymorphism, whereas the other is chromosomally monomorphic. A ZZ/ZW sex-chromosome system is also present in both cytotypes of this species. The banding patterns of these mechanisms are described and their evolution is discussed.

Abstract: Temperature and ethanol concentration have major effects upon the longevity of adults exposed to ethanol vapour, but do not much influence ADH activity. In contrast, Adh loeus genotypes differ in ADH activity quite substantially, while the above two environmental variables have minimal effects. This laboratory result is consistent with certain field results, and emphasizes the need to select phenotypes of direct physiological and ecological importance as primary study materials of natural populations, in addition to conveniently assayable electrophoretic variants.

Abstract: To elucidate the forees maintaining protein polymorphisms, microgeographic differentiation in proteins, encoded by 30 loci, was tested in 285 individuals comprising 3 species of landsnails in Israel. Each test consisted of 2 close subpopulations: one from the drier and warmer south-facing slope and the other from the opposite wetter and cooler north-facing slope. The 5 tests involved 2 of Buliminus labrosus in Mediterranean Count Carmel; 1 of Sphincterochila zonata in the northern, and 2 of S. prophetarum in the central Negev desert. The results indicate significant allele differences between the two slopes in several loci in each of the 5 local tests, involving primarily esterases (Est), aspartate aminotransferase (Aat) and leucine amino peptidases (Lap). The differential slope patterns appear to be adaptive, and are presumably maintained by microclimatic diversifying selection.

Abstract: To determine whether geographic patterns of variation in the frequency of shell polymorphisms in the land snail Cepaea nemoralis mark regions of extensive genetic differentiation, allele frequencies at six polymorphic enzyme-encoding loci were analyzed electrophoretically in 74 samples from the central part of the Spanish Pyrenees. Within a large ‘area effect’ for unbanded shells on the southern slope of the Pyrenees, there is no enzyme locus at which allele frequencies are homogeneous. Because this morphological area effect does not mark a region of pervasive genetic change, the genetic structure of populations in the region studied does not conform to recent models of ‘area effect speciation’. Factor analysis of allele frequencies at three loci controlling shell polymorphisms and six enzyme loci separated populations on the southern slope into two groups, one of which is similar to the group of populations on the northern slope. There is therefore considerable geographic structuring of both molecular and morphological polymorphism in this species.

Abstract: Phenotypic and genetic variation was studied in two of the four European subspecies of the marine isopod Idotea baltica; the Mediterranean I. b. basteri and the Baltic I. b. baltica. Spatial and temporal patterns of colour polymorphism were analysed in northern Adriatic and western Baltic Sea populations. Pronounced differences in phenotype composition were observed between populations of both subspecies as seen in the distribution of various colour variants bilineata, lineata, flavafusca and several combined forms). Compared with Adriatic samples, western Baltic Sea populations show higher phenotypic diversity. To obtain an estimate of the degree of genetic divergence between the subspecies, 12 gene-enzyme systems were investigated electrophoretically. The results obtained indicate a relatively high level of genetic variation; I. b. basteri from the nothern Adriatic tends to be more polymorphic and more heterozygous than I. b. baltica from the western Baltic. Both subspecies share identical electrophoretic mobilities of the homologous enzyme proteins examined; however, in allelic composition they exhibit significant differences at approximately half the number of loci scored. The genetic distance (Nei's D) measured at the subspecific level was 0.04. Amounts and geographical patterns of variation, observed both in colour phenotype and electrophoretic variation, are considered.

Abstract: By means of the marker strain Va/Ba wild chromosomes O of Drosophila subobscura were extracted from eight natural populations situated on a north-south gradient from Sweden or Scotland to Tunesia. Lethal frequencies and viability effects of the wild chromosomes O were studied in homozygous and random heterozygous combinations. In accordance with results from other Drosophila species random heterozygotes were always more viable than homozygotes. The viability-determining polygene system proved, however, dominant to some degree. Geographic differences became apparent especially with respect to three different characteristics: (1) The lethal frequencies for chromosomes O from central populations are higher than for those from northern and southern marginal populations; (2) Mean viabilities of non-lethal homozygotes and random heterozygotes are lower for central than for marginal populations; (3) The increase of viability through heterozygosity is more pronounced in the northern populations than in the others. The differences are thought to be mainly due to differences in the adaptation strategy of marginal and central populations. The viability fitness components seem of more importance for the marginal populations while fertility components may be of greater weight under central conditions. The geographic variability of the viability polygene system is finally compared with that of other genetic traits in D. subobscura.

Abstract: An ultrastructural study of holocentric chromosomes during meiotic division I and, for the first time, on meiotic division II of three arachnids (the scorpion Tityus bahiensis and the spiders Dysdera crocata and Segestria florentina) is presented. While the results obtained in spiders are similar to those obtained in species previously analyzed, T. bahiensis is an exception to the rule since it shows kinetochore plates during division I. Furthermore, such plates were observed in the three species during division II.

Abstract: Four D. melanogaster strains characterized by different alcohol dehydrogenase (ADH) activities were compared for their oviposition site preferences. The comparison was made between different temperatures (15 °C, 20 °C, 25 °C, 30 °C), day and night, replicates, and different concentrations in ethanol (00%, 5%, 10%, 15%) in the medium. All these factors influence behaviour. ADH activities seem to affect the oviposition site preferences as they directly affect ethanol tolerance and the ability to use alcohol as a source of metabolic energy.

Abstract: The relative genome sizes and the proportions of X- and Y-chromosomal DNA in Drosophila hydei, D. neohydei and D. eohydei were measured by microspectrophotometry. Some implications of the results with respect to genome evolution in these species are discussed.

Abstract: Crosses between strains belonging to the Tetranychus urticae complex often reveal some degree of mortality in the eggs laid by the F4 females. Two such strains were studied. Non-Mendelian features characterize the F1 infertility: F1 females of the same cross differ considerably regarding mortality in their eggs, reciprocal crosses give different results and the degree of egg mortality changes when the F1 female gets older. Moderate changes in physical circumstances and the quality of the host plant have little or no influence on egg mortality. Haploid eggs, laid by virgin F1 females, suffer considerably more mortality than eggs fertilized by sperm from the paternal or the maternal strain. Nine generations of repeated backcrossing to males of the original paternal strain did not result in a notable reduction of egg mortality, although evidence from another study (De Boer, unpublished) makes it highly unlikely that agents with a strictly maternal inheritance are involved.

Abstract: A clone of Rhoeo spathacea var. variegata was exposed to a constant temperature of 37°C to examine the effects of high temperature on the chiasma frequency. Rhoeo was chosen for this study for its unusual meiotic chromosome configurations (rings and chains) at diakinesis and the first metaphase which permitted the calculation of terminal-chiasma frequency, and for its genetic homogeneity among plants in a clone. Plants treated for 12 h and 24 h at 37°C had similar mean terminal-chiasma frequencies to that of controls (10.93±0.11, 10.95±0.09 and 10.64±0.07 respectively), while those treated for 36 h, 48 h or 60 h had lower mean terminal-chiasma frequencies than that of controls (8.06±0.18, 4.25±0.15, 0.76±0.07 and 10.64±0.07 respectively). Analysis of variance was performed to find out whether the mean terminal-chiasma frequencies resulted from different treatments were significantly different from one another. The results of the analysis indicated that prolonged exposures to high temperature significantly reduced the chiasma frequencies.

Abstract: In Silene pratensis three loci (g, gl and fg) control the glycosylation of isovitexin. Three alleles are known for both the g-locus (g, g G and g X ) and the gl-locus (gl, gl A and gl R ); for the fg-locus there are only two alleles (fg and Fg). The distribution of these alleles over 285 European populations of S. pratensis has been investigated. It was concluded that there are three different chemical races within S. pratensis in Europe. The first race contains the populations in western and southern Europe and displays high frequencies of g G , gl and fg. The frequencies of g G and gl R are very high in the second chemical race, which can be found in the USSR, Scandinavia and eastern Poland. The third chemical race occurs in central Europe and in this race the frequencies of both g and gl R are high, Fg has low to moderate frequencies in the second and third groups. The alleles gl A and g X are seldom found in S. pratensis, but are present in the closely related S. dioica. They do occur with low frequencies in some populations of S. pratensis, possibly as a result of hybridization with S. dioica.

Abstract: Polygenic modifiers of the L4 and L5 wing veins in Drosophila simulans were used to study the degree of genetic independence of veins within the same developmental compartment. The L4 and L5 were selected for opposite changes in length. Whole-chromosome assays of heterozygous effects showed that the L4 and L5 polygenic modifiers were associated with differences both in chromosomes and in interchromosomal interactions. A comparison of selection responses confirmed that, though some modifiers had strictly vein-specific action, others acted either upon all veins within the posterior compartment or upon all veins in the wing. The results support the idea that some genes control pattern formation in the wing as a whole, others regulate structures within a single compartment, and still others are limited to a single element within a compartment.

Abstract: The cytogenetic study of two populations of Eliomys quercinus L. (Rodentia, Gliridae), whose geographic ranges are relatively near, showed that numerical and morphological differences exist between their karyotypes. The French dormouse has a diploid number 2n=50, while the Spanish one had 2n=48. The sex chromosomes and the number of autosomal arms are identical in both populations. The morphological differences are limited to the autosomal metacentric pair 12 of the Spanish dormouse, which does not appear in the French dormouse. However, the latter possesses two pairs of acrocentric chromosomes (20, 24) which are absent in the Spanish dormouse. The bands that correspond to the q and p arms of pair 12 in the Spanish dormouse are identical to pairs 20 and 24 in the French one, respectively. Consequently, we consider the Spanish Eliomys quercinus and the French Eliomys quercinus as having a common ancestor. The Spanish form has originated by means of a Robertsonian translocation, Rb (20, 24), between pairs 20 and 24 of the common ancestor.

Abstract: The number and location of nucleolus organizer regions, and G- and C-band karyotypes of Ochrotomys nuttalli were compared with those of other seemingly closely related New World peromyscine rodents. Although Ochrotomys was once considered a subgenus of Peromyscus, it shares few apparent G-band homologies with any peromyscine. The presumed homologous karyotypic elements shared between Ochrotomys and other peromyscine genera also are shared with Neotoma (the probable sister group of peromyscines) and these elements are hypothesized to be primitive for the group. The largest autosome in Ochrotomys appears to be shared with a distantly related species, Sigmodon hispidus, and this chromosome might be represented as two acrocentric autosomes (tandem fission products) in peromyscines and Neotoma. If this hypothesis is correct, the peromyscines as currently recognized likely are polyphyletic. The unusually extensive rearrangement of the Ochrotomys karyotype relative to peromyscines appears to represent a case of karyotypic megaevolution.

Abstract: In order to analyze the effect of B-chromosomes on chiasma frequency, the offspring of different females of the grasshopper Eyprepocnemis plorans have been studied. From the comparison between individuals of the different families having a given number of B's and between individuals with different numbers of B-chromosomes within the same family, it can be concluded that the effect of the genetic background on chiasma frequency is greater than that produced by the presence of B's, and that there is a between-families variation in the effect of B-chromosomes which, in addition, is negatively correlated with the chiasma frequency of related individuals without B's. This genotype-dependent effect of B-chromosomes is discussed.

Abstract: Banded chromosomes of five species of testudinid turtles (Geochelone pardalis, G. elongata, G. elephantopus, Gopherus berlandieri, and G. polyphemus) reveal little variation within either genus, although there are differences in amount and distribution of heterochromatin between Geochelone pardalis and G. elongata. The chromosomal position and size of the nucleolar-organizer region differs between species of the two genera.

Abstract: The haploid DNA content and karyotypes of eight species of Blennius are studied. Six species had 2n=48, two had 2n=46.

Abstract: Changes in allele frequencies at the esterase 6 (Est 6) and alcohol dehydrogenase (Adh) enzyme loci of Drosophila melanogaster and simulans are examined in natural populations and artificial populations maintained at two temperatures. Results from cage populations at 18 °C and 25 °C provide evidence for temperature selection at both loci. Seasonal population samples show no significant change in gene frequencies for either locus, a reasonable outcome given the small selection coefficients found in cage populations. The temperature effect for the Adh locus appears to be direct: natural selection of the fast allele in cool environs and of the slow allele in warm environs. The temperature effect for Est 6 is weaker and complicated by sex differences and deviations from Hardy-Weinberg expectation. This evidence and different Est 6 frequencies found for melanogaster and simulans, in conjunction with evidence of the male reproductive function of this enzyme, suggest that Est 6 polymorphisms are maintained in natural populations by a complex form of sexual selection.

Abstract: Non-reciprocal hybrid infertility between the strains ZI and ZII of the spider mite Tetranychus urticae Koch, probably based on an interaction between a chromosomal gene N, and a non-chromosomal factor E, is studied. A hypothesis that N-E interaction causes egg mortality indirectly through the formation of recessive lethal genes, is tested and rejected.

Abstract: Even in cases in which C-bands are intercalary in chromosomes of Allium carinatum and A. flavum. chiasmata are formed in immediately adjacent regions. This argues against considerations that there exists merely a spatial proximity between the commonly found distal chiasmata and the C-bands in corresponding regions, without any causal relation. Furthermore, a closely related species, A. sipyleum, without distinctly visible C-bands has a much less localized chiasma distribution in its bivalents.

Abstract: Bufo bufo verrucosissima has a karyotype consisting of 22 chromosomes (6 pairs of large and 5 pairs of small chromosomes which are meta- and submetacentric). By means of Ag-AS-staining nucleolar organizers were localized in the telomeric region of the long arms of the 6th pair of chromosomes. The karyotype differs from those of the other B. bufo subspecies by the form of the 4th pair, which is metacentric. A slight chromosomal polymorphism was shown also after C-banding of B. b. verrucosissima and B. b. bufo chromosomes.