Inversion polymorphism in malarial mosquito <Emphasis Type="Italic">Anopheles messeae</Emphasis> natural populations from the north-eastern region of the range

A cytogenetic study of eight natural populations of Anopheles messeae from the north-eastern part of the species areal was conducted. Complete predominance of homozygotes XL₁₁ and 3R₁₁ in the northern populations was observed. Change in the chromosome 2 inversion frequencies from south northwards was shown. The 2R₁₁ variant, which was not observed in the southern region, was found in the northern populations. These results indicate the maintenance of chromosome frequency of the distribution of inversions XL₁ and 3R₁ (in longitude) and 2R₁ (in latitude). The inversion frequency distribution in the examined part of the areal have been preserved for a long time.     

Cytogenetic analysis of the species composition and inversion structure of populations of malarial mosquitoes in the Astrakhan region

A cytogenetic analysis of Anopheles mosquitoes in the Astrakhan region was carried out. Three species of Anopheles were identified. An. messeae lives everywhere and prevails in all of the areas of research, An. hyrcanus is found in the southwest of the region, and An. maculipennis in the northern part of the region. The populations of An. messeae show a high level of inversion polymorphism for the sex chromosome and the third autosome. A clear clinal trend of an increase in chromosomal rearrangements XL1, 3R1, and 3L1 and a decrease in the frequency of evolutionary source alternatives was revealed in laraval hemipopulations of the species from south to north.     

Inversion polymorphism of the malarial mosquito Anopheles messeae. V. The interaction of different chromosomal inversions in the spatial area

The relations between inversions of chromosome XL, 2R, 3R, 3L from 8 populations of the central part and periphery of the species area were studied. 2-, 3- and 4-factor analysis was carried out. Interaction of inversions XL1, 2R1, 3R1 in central populations (Riga, Moscow, Tomsk) was observed. The nonrandom association of definite inversional genotypes was stationary in spatial - temporary. The phylogenetic initial sequences XL0, 2R0, 3R0 display "+" interaction. The 3-factor analysis of populations of Tomsk shows: 1) interaction of inversions is more essential in males than in females; 2) the statistically significant interaction of 3-4 inversions is not always determined by the effect of 2-factor analysis; 3) the chromosome 3R has a dominance influence on the pattern of association of the multiinversional complex. These data support the hypothesis that differential selection for chromosomes with certain combinations of arrangements is mainly responsible for this phenomenon. In peripheral area populations (Syctyvkar, Irkutsk, Chita), no associations were observed (2R and 3R). When they do take place, their character is changed (Kiev - XL and 3R). This phenomenon may be explained by the influence of frequency-dependent selection.     

Inversion polymorphism in malaria mosquito Anopheles messeae. Part X. Resistance of larvae with different genotypes to toxins of crystal-forming bacteria Bacillus thuringiensis subsp. israelensis (serovar H14)

Insensibility of larvae with different chromosomal inversions to the toxins of Bacillus thuringiensis subsp. israelensis (Bti) was examined. It has been shown that larvae with inversion combinations XL0(XL1)2R0-3R0-3L0 had greater variability after treatment with Bti than larvae with inversions XL1(XL2)2R1-3R1-3L1(3L0). The former inversion combinations were previously shown to dominate in the south of the species area and to be supported by K-selection. The latter inversion combinations form "northest" karyotypes and are supported by r-selection. It is obvious that genetic effects of treatments with Bti depend on the population's structure and the directions of natural selection. The decrease in the level of heterozygotes after treatment of larvae with Bti reflects destruction of the system of genetic homeostasis in the natural populations of A. messeae.     

Inversion polymorphism of the malarial mosquito Anopheles messeae. IV. The stability of the frequency distribution of the inversions by species area

Distribution of the frequencies of inversions XL1, 2R1, 3R1, 3L1, from geographically widely separated 8 populations had been studied during a long period of time. The geographical inclines of distribution of inversions XL1, 3R1 (a longitudinal) and 2R1 (a latitudinal) are stable in time. Stationarity of inversional polymorphism is not connected with superdominance of heterozygotes. It is supposed that the stable equilibrium of the frequencies of inversions is supported by variable selection.     

Geographic variability of the polytene chromosome banding sequence of non-biting midge <Emphasis Type="Italic">Chironomus pseudothummi</Emphasis> Str. (Diptera,Chironomidae)

The karyotypes and chromosomal polymorphism of Chironomus pseudothummi were investigated in different parts of its areal. It was established that chromosomal variability in the natural populations of this species was represented mainly by the inversion polymorphism of arm G. Only rare and unique inversions were found to be heterozygous in arms C, D, and E. In total, 14 banding sequences of polytene chromosomes form the banding sequence pool of C. pseudothummi. Geographic differences in the distribution of chromosomal banding sequences throughout the areal were established. The presence of banding sequences pstG1 and pstG2 is characteristic of European populations. The banding sequence pstG1 disappeared completely with a simultaneous increase in the frequency of pstG2 and with the appearance of a new inversion banding sequence pstG3 in Siberian populations. Differences in the set of rare and unique inversions in arms C, D, and E between the West-European and West-Siberian populations have been revealed.     

Gene pool structure of Russian populations from the European part of Russia inferred from the data on Y chromosome haplogroups distribution

Population structure of Russian population from the European part of Russia was investigated by analyzing the distribution of 23 SNP makers of Y chromosome in Russian populations from Kaluga oblast, Yaroslavl' oblast, Vladimir oblast, Nizhny Novgorod oblast, Pskov oblast, Tula oblast, Belgorod oblast, and Novgorod oblast. In the populations studied a total of 14 Y-chromosome haplogroups (E, F*, I, J, K*, N3a, N2, P*, R1*, R1a1, C3, H, and A) were discovered, of which haplogroups R1a1, I, and N3a were the prevailing. Analysis of Phi statistics in the populations grouped in accordance to the dialect subdivision of the Russian language, showed the absence of statistically significant differences between Russian population groups. Analysis of the Y-chromosome markers distribution patterns among Russian population (10 population groups) in comparison with the population of Germany (11 population groups) revealed statistically significant differences between the gene pools of Slavs (Russians and Poles) and Teutons (Germans).     

Gene pool structure of Russian populations from the European part of Russia inferred from the data on Y chromosome haplogroups distribution

Population structure of Russian population from the European part of Russia was investigated by analyzing the distribution of 23 SNP makers of Y chromosome in Russian populations from Kaluga, Yaroslavl’, Vladimir, Nizhni Novgorod, Pskov, Tula, Belgorod, and Novgorod oblasts. In the populations studied a total of 14 Y-chromosome haplogroups (E, F*, I, J, K*, N3a, N2, P*, R1*, R1a1, C3, G, H, and A) were discovered, of which haplogroups R1a1, I, and N3a were the prevailing. Analysis of Φ statistics in the populations grouped in accordance to the dialect subdivision of the Russian language, showed the absence of statistically significant differences between Russian population groups. Analysis of the Y-chromosome markers distribution patterns among Russian population (10 population groups) in comparison with the population of Germany (11 population groups) and Poland (8 population groups) revealed statistically significant differences between the gene pools of Slavs (Russians and Poles) and Teutons (Germans).     

Chromosomal polymorphism in the populations of malaria mosquito <Emphasis Type="Italic">Anopheles messeae</Emphasis> (Diptera,Culicidae) in the Volga region

We studied the species composition and chromosomal variability of malaria mosquitoes in the Volga Basin (Upper, Middle, and Lower Volga regions). We investigated larvae karyotypes of sibling species of the Anopheles maculipennis group. We calculated the frequencies of chromosomal inversions in the local populations of the dominant species An. messeae. We discovered that karyotypic structure of An. messeae populations depends on landscape-climatic zones. Populations of the Upper, Middle and Lower Volga differ in frequency of chromosome inversions XL, 2R, 3R, and 3L.     

Chromosome polymorphism in the ant,Pheidole nodus

A survey of chromosome polymorphism was made in populations of Pheidole nodus (Hymenoptera, Formicidae). A total of 1,666 males were collected from 11 localities in Japn. Four polymorphic karyotypes were observed: (1) n = 17 with 4 metacentrics (abbreviated as 4M), (2) n = 18(3M), (3) n = 19(2M) and (4) n = 20(1M). These differences are due to the Robertsonian type rearrangement. The karyotype 18(3M) is found in all the populations examined, but the others are more or less localized in their distribution. The 17(4M) appears mainly in Shikoku and the northern Kyushu populations, 19(2M) along the Pacific coast of Honshu, Shikoku and Kyushu, and 20(1M) in the eastern part of Honshu and Shikoku. This distribution pattern indicates that 18(3M) is the oldest, 19(2M) and 20(1M) are derived from 18(3M) by centric fission, and 17(4M) by centric fusion. The most probable mechanism of karyotype evolution in this species is considered to be the centric fission.     

Chromosomal inversion polymorphism in Afrotropical populations of Drosophila melanogaster

When 41 populations from Africa (south of the Sahara) and Indian Ocean islands were analysed for their chromosomal inversion polymorphism, 34 rearrangements were found, including the four common cosmopolitans (In(2L)t, In(2R)NS, In(3L)P and In(3R)P), four rare cosmopolitans (In(2L)NS, In(3R)C, In(3R)Mo and In(3R)K) and six African polymorphic ('recurrent') endemics. Mean inversion frequencies per major autosome arm were positively and, generally, highly correlated to each other. There was no altitudinal nor latitudinal cline of inversion frequency, except for one African polymorphic endemic. Significant longitudinal clines were detected for In(2L)t, In(3L)P and In(3R)K; in all cases, inversion frequencies decreased eastward. Principal components analysis and ANOVA made it possible to distinguish three groups of populations. A high level of polymorphism was found in populations from west tropical Africa. The other low altitude populations from the mainland were moderately polymorphic, whereas the lowest levels of polymorphism were those of high altitude populations and of Indian Ocean islands. Moreover, some regional and local differentiation was also found. The frequency of unique autosomal inversions was not different from those found in Asia, Australia and America, but was significantly higher than that in Europe and North Africa. A West-East differentiation was also observed for the African polymorphic endemics. The present geographic pattern suggests a long, patchy evolution with restricted gene flow, followed by the modern period with numerous recent migrations linked to human transportation.     

Genetics of plumage color in the Gyrfalcon (Falco rusticolus): analysis of the melanocortin-1 receptor gene

Genetic variation at the melanocortin-1 receptor (MC1R) gene is correlated with melanin color variation in a few reported vertebrates. In Gyrfalcon (Falco rusticolus), plumage color variation exists throughout their arctic and subarctic circumpolar distribution, from white to gray and almost black. Multiple color variants do exist within the majority of populations; however, a few areas (e.g., northern Greenland and Iceland) possess a single color variant. Here, we show that the white/melanic color pattern observed in Gyrfalcons is explained by allelic variation at MC1R. Six nucleotide substitutions in MC1R resulted in 9 alleles that differed in geographic frequency with at least 2 MC1R alleles observed in almost all sampled populations in Greenland, Iceland, Canada, and Alaska. In north Greenland, where white Gyrfalcons predominate, a single MC1R allele was observed at high frequency (>98%), whereas in Iceland, where only gray Gyrfalcons are known to breed, 7 alleles were observed. Of the 6 nucleotide substitutions, 3 resulted in amino acid substitutions, one of which (Val(128)Ile) was perfectly associated with the white/melanic polymorphism. Furthermore, the degree of melanism was correlated with number of MC1R variant alleles, with silver Gyrfalcons all heterozygous and the majority of dark gray individuals homozygous (Ile(128)). These results provide strong support that MC1R is associated with plumage color in this species.     

The Levant versus the Horn of Africa: evidence for bidirectional corridors of human migrations

Paleoanthropological evidence indicates that both the Levantine corridor and the Horn of Africa served, repeatedly, as migratory corridors between Africa and Eurasia. We have begun investigating the roles of these passageways in bidirectional migrations of anatomically modern humans, by analyzing 45 informative biallelic markers as well as 10 microsatellite loci on the nonrecombining region of the Y chromosome (NRY) in 121 and 147 extant males from Oman and northern Egypt, respectively. The present study uncovers three important points concerning these demic movements: (1) The E3b1-M78 and E3b3-M123 lineages, as well as the R1*-M173 lineages, mark gene flow between Egypt and the Levant during the Upper Paleolithic and Mesolithic. (2) In contrast, the Horn of Africa appears to be of minor importance in the human migratory movements between Africa and Eurasia represented by these chromosomes, an observation based on the frequency distributions of E3b*-M35 (no known downstream mutations) and M173. (3) The areal diffusion patterns of G-M201, J-12f2, the derivative M173 haplogroups, and M2 suggest more recent genetic associations between the Middle East and Africa, involving the Levantine corridor and/or Arab slave routes. Affinities to African groups were also evaluated by determining the NRY haplogroup composition in 434 samples from seven sub-Saharan African populations. Oman and Egypt's NRY frequency distributions appear to be much more similar to those of the Middle East than to any sub-Saharan African population, suggesting a much larger Eurasian genetic component. Finally, the overall phylogeographic profile reveals several clinal patterns and genetic partitions that may indicate source, direction, and relative timing of different waves of dispersals and expansions involving these nine populations.     

Unique TCR β-subunit variable gene haplotypes in Africans

This study investigated polymorphisms of genes in two regions of the T-cell antigen receptor beta-subunit (TCRB) locus, including BV9S2P, and BV6S7 in a 5' linkage group, and BV8S3, BV24S1, BV25S1, BV18S1, BV2S1, BV15S1 and BV3S1 in a 3' linkage group. These loci have been genotyped in individuals from five regions in Africa, including The Gambia, Nigeria, Cameroon, Tanzania, and Zambia, and in individuals from northern Britain, northern India, and Papua New Guinea (PNG). In the 3' linkage group, 11 unique haplotypes were identified in the combined African populations; two equally frequent haplotypes represent the majority of African chromosomes. One haplotype was found in all four regions studied. This is the most frequent haplotype in the northern British, northern Indian and PNG populations. Although present, it is infrequent in the African populations. A North-South gradient in the frequency of a common African haplotype was observed. The distribution did not represent that of a known disease. Evidence suggests that malaria is not responsible for selection of these haplotypes. Overall, this study highlights large differences in the genetic constitution of the TCRB locus between Africans and other populations.     

Inversion polymorphism in the malaria mosquito Anopheles messeae. VI. Local selection and 3-dimensional differentiation of the inversion gene complexes for fertility

A field experiment was carried on with the view of compulsory change of the frequency of chromosomal inversion (2R1) in the population of Anopheles messeae from the centre of the area. Quick return of the population to the original structure was observed. This confirmed that the local differentiation of chromosomal polymorphism is supported by natural selection. The fertility of the females was shown to be connected with the inversion polymorphism. The females with inversion complexes of genes of the "northern" type (with homozygotes 2R1) had higher fertility and lower dispersion of the fertility, in comparison with those having gene complexes which prevailed in the south part of the area.     

The potential role of climate in the distribution and zonation of the introduced seagrass Zostera japonica in North America

The current distribution of the introduced seagrass Zostera japonica is restricted to the mid- to upper intertidal zone in the coastal Pacific Northwest region of North America. The climate in this region is cool and wet, becoming hotter and dryer with increasing distance southward. Since temperature is likely to be an important factor affecting distribution of this species, growth of two populations located near the northern and southern limits of its established range along the Pacific Coast of North America were measured in an experimental setting across a range of temperatures typical of those in the field during the growing season (10, 20, and 30 °C). The effects of temperature and population were both significant. Leaf elongation, growth, and areal productivity rates of the northern population were consistently lower than those of the southern population. Across the range of temperatures, mean leaf elongation rates ranged from 0.47 to 1.40 cm² shoot⁻¹ d⁻¹; mean growth rates ranged from 0.19 to 0.52 mg dry wt shoot⁻¹ d⁻¹. Mean areal productivity ranged from 0.54 to 1.92 g dry wt m⁻² d⁻¹. Maximum rates of leaf elongation, growth, and areal productivity for both populations were observed at 20 °C. However, leaf elongation, growth, and areal productivity of the northern population declined markedly at 30 °C, whereas no comparable declines were observed for the southern population. This suggests that Z. japonica populations near the southern limits of its established range may be better adapted to warmer temperatures than populations near the northern range limits and further range extensions southward along the California coast may be likely. These differences could be important in predicting the outcome of competitive interactions between native and introduced seagrass species, and in determining future patterns of distribution and zonation of Pacific Coast seagrasses.     

Karyology and distribution of Sesleria tenuifolia complex (Poaceae) in the Italian Peninsula

Karyological analyses of wild populations of Sesleria tenuifolia complex collected from throughout the Italian peninsula was performed to check the stability of the chromosome number along both geographical and ecological gradients. The chromosome counts showed that the Italian populations of the Sesleria tenuifolia complex consist of octoploid plants (2n=8x=56) and dodecaploid plants (2n=12x=84). The discovery of a dodecaploid chromosome number is the first for the genus Sesleria. The distribution of octoploid and dodecaploid populations follows strictly geographical boundaries and seems to be uninfluenced by synecological or physical factors. No overlapping between octoploid and dodecaploid populations was found; in fact, octoploid populations occupy northern, central and part of Peninsular Italy, whereas dodecaploid ones are restricted to the Pollino massif and the Orsomarso range, which together form the southernmost limit of the distribution area of the Sesleria tenuifolia complex.     

Chromosome inversion polymorphisms in Drosophila melanogaster II. Geographic clines and climatic associations in Australasia,North America and Asia

The four paracentric autosomal chromosome inversions In(2L)t, In(2R)NS, In(3L)P and In(3R)R are commonly polymorphic in natural populations of D. melanogaster in Australasia, North America and Asia, with latitudinal clines in the frequencies of each inversion in each region. In each region inversion frequency decreases with increasing distance from the equator, although the precise relationship between frequency and latitude varies between inversions and, for In(2L)t and In(2R)NS, among regions. Each inversion also shows a longitudinal cline in at least one region but none show such a cline in all three. Although no inversion's frequency is associated with the same climatic variable in all three regions, inversion frequencies are generally positively related to annual maximum temperature and, more particularly, minimum temperature and minimum rainfall. The directions of the latitudinal clines and the climatic associations are consonant with evidence from D. melanogaster that inversion frequencies decline in winter. They are also consonant with evidence from some other Drosophila species that inversion heterozygosities are lower at the geographic margins than at the centre of the species' ranges.     

Changes in Relative Fitness with Temperature among Second Chromosome Arrangements in Drosophila Melanogaster

Development time and body weight of In(2L)t, R (a putative short inversion on the left arm of the second chromosome) and ST (standard) karyotypes of Drosophila melanogaster were measured at different temperatures. Frequency changes were followed in populations polymorphic for In(2L)t and ST and kept under different environmental conditions. These experiments were carried out in order to explain the worldwide latitudinal clines for In(2L)t and other inversions. To avoid interactions with the Adh and alpha Gpdh loci, which also have latitudinal clines, all karyotypes were homozygous AdhS alpha GpdhF. In(2L)t homokaryotypes had a longer development time and a lower weight than the other karyotypes at all temperatures. R/ST heterokaryotypes had the shortest development time and ST/ST had the smallest weight decrease with increasing temperature. The differences among the In(2L)t and ST karyotypes in development time were further analyzed in an experiment where the age at which 50% of the larvae were able to become adults, without further food ingestion, was determined. In polymorphic populations at 20 degrees and 25 degrees a significant decline of In(2L)t frequencies was observed. At 29.5 degrees and 33 degrees there was no change in In(2L)t frequencies but a significant excess of heterokaryotypes occurred. On ethanol-supplemented food the most drastic decline in In(2L)t frequency was observed. Populations transferred at 2- and 3-week intervals at 25 degrees exhibited large differences in final In(2L)t frequencies. The frequency changes could in part be attributed to the differences in development time and to previously observed differences in high temperature resistance. The experiments prove that the karyotypes are under selection. The results are discussed in relation to the geographic distribution of In(2L)t.     

Sperm chromosome analysis in a man heterozygous for a paracentric inversion of chromosome 7 (q11q22)

Summary Human sperm chromosomes were studied in a man heterozygous for a paracentric inversion of chromosome 7 (q11q22). The pronuclear chromosomes were analysed after in vitro penetration of golden hamster (Mesocricetus auratus) eggs. Ninety-four sperm chromosome spreads were examined, of which 34 contained the normal number 7 chromosome and 59 the inverted 6. This segregation was significantly different from the expected 1:1 ratio. The number of X- to Y-bearing sperm was 48 and 46 respectively. No sperm contained a recombinant chromosome caused by a crossover within the inversion. The frequency of chromosomal abnormalities in other chromosomes was 9.6%, which is not significantly different from the frequency observed in normal donors (8.9%) in our laboratory. These result suggest that the risk of chromosomally unbalanced sperm is not high for this paracentric inversion.