Populations Of Different Geographic Origin Research Articles

Genetic variation within and among some broomrape populations of different geographical origin

Knowledge of the genetic variation and their evolutionary basis in Orobanche cumana Wallr. populations are essential for establishment of the risks of new physiological races emergence of this devastating sunflower parasite. In the current study, the genetic diversity of 33 broomrape populations from 6 countries (Republic of Moldova, Romania, Bulgaria, Serbia, Turkey and China) was analyzed, using two molecular marker systems (SSR and ISSR). Analysis of molecular variance (AMOVA) at different hierarchical levels (within populations, between populations and between groups of populations - countries, races) revealed a high genetic variation among populations, when no population structure was considered (i), an approximately equal partitioning of total variance among countries, populations and within populations (ii) and a low genetic variance attributed to divergence between races (iii).

Molecular genetic characteristics of broccoli (Brassica oleracea L. var. italica Plenck) from the VIR collection

Background. Broccoli is an early-ripening vegetable crop that contains many biologically active compounds and mineral elements. According to the Genesys database, the global genebank collections contain no more than 465 different broccoli accessions. Fourteen cultivars and hybrids developed in Russia are registered in the State Register of the Russian Federation. The need to improve the assortment in a number of important breeding target areas (small habitus, non-spawning, bud size, disease resistance, etc.) requires the use of new effective techniques, including marker-assisted selection methods and association mapping. In this regard, it seems relevant to evaluate the VIR collection of broccoli using molecular genetic markers, which will provide new source material for breeding.Materials and methods. A molecular genetic study involved 39 broccoli cultivars and hybrid populations of different geographical origin, with various biological characteristics, and for various uses. For the analysis, 35 markers of microsatellite sequences specific to the Brassica L. genome were selected. PCR products were separated by electrophoresis on a 3% agarose gel.Results and conclusions. As a result, 110 polymorphic fragments were identified. In the studied loci, 3 to 7 alleles were pinpointed. The discriminating power of markers ranged from 0.75 to 0.96, and averaged 0.91; the average number of fragments per marker was 4.4. Ten unique alleles and 12 rare alleles (found in less than 8% of the samples) were observed in the studied accessions. On the other hand, the 201 bp allele of the locus BC65 was found in 95% of accessions, that is, it was almost common. All used markers have a sufficiently high diagnostic value and can be recommended for DNA identification in broccoli cultivars. An analysis of the genetic similarity of the collection accessions, carried out in the DarWin program using the Unweighted Neighbor-Joining method, made it possible to establish four closely related clusters.

Показатели роста кедра сибирского разного географического происхождения на подвое сосны обыкновенной

Forests dominated by Siberian pine (Pinus sibirica Du Tour) occupy about 40 mln ha in Russia. They fulfll soil- and water-protective roles, produce oxygen, and are the source of valuable nuts, wood, and other materials. The 36-year-old grafted trees of Siberian pine growing on a hybrid seed plantation in the suburban area of Krasnoyarsk region were the study object. A comparison of growth indices of 36-year-old ramets of Siberian pine of different geographical origin was the research purpose. Graftings were made on the Scots pine young growth in 1982. Grafting stocks were cut from plants grown from seeds harvested in 1960in populations of different geographical origin. The location of the initial populations differs in latitude by 12°, longitude by 64° and altitude by 900 m above sea level. It has been found that the average height of 36-year-old grafted trees depending on geographical origin varies between 12.4 and 15.0 m; the trunk diameter – 29.7 and 40.9 cm; and the crown diameter – 6.4 and 7.6 m. Clones of Tomsk origin are characterized by the best growth. Clones of the northern populations (Komi and Sakha Republics) are characterized by the lowest height. The average diameter of scion exceeds the diameter of rootstock by 6.4–39.7 % depending on the graft geographical origin. Good graft intergrowth (the scion diameter is equal to the rootstock diameter) is observed in 10–27 % of trees. A relationship was found between the grafted trees: close, between trunk and crown diameter (r = 0.855); trunk diameter and crown volume (0.827); signifcant, between trunk diameter and crown length (0.520). It has been established that both the geographical origin and the clone belonging of scion influence on the growth intensity of the grafted trees and intergrouth of the grafted components. The obtained results can be used in creation of clonal plantations of the second generation. For citation: Matveeva R.N., Butorova о.F., Bratilova N.P., Shcherba I.E., Komarnitsky V.V. Growth Indices of Siberian Pine of Different Geographical Origin Grafted on a Scots Pine Rootstock. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 2, pp. 9–19. DOI: 10.37482/0536-1036-2020-2-9-19

Inferring phenotypic plasticity and population responses to climate across tree species ranges using forest inventory data

AbstractAimTo test whether intraspecific trait responses to climate among populations across species distribution ranges can be untangled using field observations, under the rationale that, in natural forest tree populations, long‐term climate shapes population responses while recent climate change drives phenotypic plasticity.LocationEurope.Time period1901–2014.TaxaSilver fir (Abies alba Mill.) and sessile oak [Quercus petraea (Matt.) Liebl.].MethodsWe estimated the variation of individual tree height as a function of long‐term and short‐term climates to tease apart provenance effects (variation among populations of different geographical origin), plasticity and their interaction, using mixed‐effect models calibrated with national forest inventory data (in‐situ models). To validate our approach, we tested the ability of in‐situ models to predict independently tree height observations in common gardens experiments where provenance and plastic effects can be measured and separated. In‐situ model predictions of tree height variation among provenances and among planting sites were compared to observations in common gardens and to predictions from a similar model calibrated using common garden data (ex‐situ model).ResultsIn Q. petraea, we found high correlations between in‐situ and ex‐situ model predictions of provenance and plasticity effects and their interaction for tree height (r > .80). We showed that the in‐situ models significantly predicted tree height variation among provenances and sites for A. alba and Q. petraea. Spatial predictions of phenotypic plasticity across species distribution ranges indicate decreasing tree height in populations of warmer climates in response to recent anthropogenic climate warming.Main conclusionsOur modelling approach using national forest inventory observations provides a new perspective for understanding patterns of intraspecific trait variation across species ranges. Its application is particularly interesting for species for which common garden experiments do not exist or do not cover the entire climatic range of the species.

Adaptive genetic variability and differentiation of Croatian and Austrian Quercus robur L. populations at a drought prone field trial

Provenance trials, where populations of different geographical origin are tested in a common environment (common garden test), are a tool suited to allow the study of intraspecific adaptive genetic variation. Research of pedunculate oak (Quercus robur L.) adaptive genetic variability through analyses of populations in common garden tests has a long tradition. However, pedunculated oak populations originating south-eastern from the Alps have been scarcely studied in this way. This study addresses the adaptive genetic variability and differentiation of pedunculate oak populations originating from Austria and Croatia in a provenance/progeny field trial. Studied plants were six years old and were growing at the trial for three years. After two years of unusually low precipitations height and survival were analysed. The total mean height of all plants in the trial was 137.8 cm and ranged from 123.0 cm to 151.8 cm. The overall mean survival rate was rather high (0.85). Mean population survival ranged from 0.64 to 0.94. Individual narrow-sense heritabilities (hi2), family mean heritabilities (hf2), the coefficients of additive genetic variation (CVA) and quantitative genetic differentiation coefficients (QST) were calculated. A multivariate regression tree (MRT) analysis was used to determine the pattern of genetic differentiation of the populations. Individual heritabilities for height ranged between 0.00 and 0.39. Family mean heritabilities for height were rather low in most populations as well (<0.5). Family mean heritabilities for survival were higher than for height (ranging between 0.00 and 0.77). Calculated QST coefficients (0.25 for height and 0.14 for survival) indicated between-population genetic differentiation. The populations were separated into two clusters by MRT analysis regarding a climatic variable, namely Hargreaves’ reference evapotranspiration. Populations originating from comparatively more humid habitats were grouped in the first cluster. The first cluster had a lower mean height and survival compared to the second one. The differences between these clusters were highly statistically significant. The observed quantitative genetic differentiation might have been driven by natural selection caused by differences in the relative moisture of the habitats from which the progeny populations originate. The results suggest ecotypic pattern of the quantitative genetic differentiation among studied populations.

Changes related to gender, geographic population and habitat in the antennal phenotype of Triatoma patagonica Del Ponte, 1929 (Hemiptera: Reduviidae)

Triatomines undergo morphological changes as an adaptive response to different habitats (wild, peridomestic, domestic, laboratory). The characterization of the antennal phenotype provides information on intraspecific variation caused by geographical origin and/or habitat. Triatoma patagonica Del Ponte, 1929 is known to occur in peridomiciles of rural areas in Argentina, where it also invades non-colonized dwellings. Here we describe and compare the antennal phenotype of T. patagonica in populations of different geographic origin, and explore possible modifications induced by laboratory rearing with the aim of investigating the range of phenotypic variation of the species for the first time. Sixty antennas of adult males and females of T. patagonica belonging to two peridomiciliary populations of different geographical origin were analyzed. Four types of sensilla were observed in three antennal segments, showing sexual dimorphism in the species. The multivariate analysis separated the populations of similar habitat (peridomicile) but different geographical origin, without showing differences between the peridomiciliary and laboratory populations of the same geographical origin. These results suggest phenotypic plasticity in T. patagonica, which would allow the species to adapt to a wide range of habitats without having a close association with a given host and its environment. The range of antennal phenotypic variation of T. patagonica would also be an indicator of its current stage of adaptation to the human environment.

Molecular phylogeny of the Robust clade (Faviidae, Mussidae, Merulinidae, and Pectiniidae): An Indian Ocean perspective

Recent phylogenetic analyses have demonstrated the limits of traditional coral taxonomy based solely on skeletal morphology. In this phylogenetic context, Faviidae and Mussidae are ecologically dominant families comprising one third of scleractinian reef coral genera, but their phylogenies remain partially unresolved. Many of their taxa are scattered throughout most of the clades of the Robust group, and major systematic incongruences exist. Numerous genera and species remain unstudied, and the entire biogeographic area of the Indian Ocean remains largely unsampled. In this study, we analyzed a portion of the mitochondrial cytochrome c oxidase subunit 1 gene and a portion of ribosomal DNA for 14 genera and 27 species of the Faviidae and Mussidae collected from the Indian Ocean and New Caledonia and this is the first analysis of five of these species. For some taxa, newly discovered evolutionary relationships were detected, such as the evolutionary distinctiveness of Acanthastrea maxima, the genetic overlap of Parasimplastrea omanensis and Blastomussa merleti, and the peculiar position of Favites peresi in clade XVII together with Echinopora and Montastraea salebrosa. Moreover, numerous cases of intraspecific divergences between Indian Ocean and Pacific Ocean populations were detected. The most striking cases involve the genera Favites and Favia, and in particular Favites complanata, F. halicora, Favia favus, F. pallida, F. matthaii, and F. rotumana, but divergence also is evident in Blastomussa merleti, Cyphastrea serailia, and Echinopora gemmacea. High morphological variability characterizes most of these taxa, thus traditional skeletal characteristics, such as corallite arrangement, seem to be evolutionary misleading and are plagued by convergence. Our results indicate that the systematics of the Faviidae and the Mussidae is far from being resolved and that the inclusion of conspecific populations of different geographical origin represents an unavoidable step when redescribing the taxonomy and systematics of scleractinian corals. More molecular phylogenies are needed to define the evolutionary lineages that could be corroborated by known and newly discovered micromorphological characters.

English

The acetylation polymorphism is one of the most common inherited variations in the biotransformation of drugs and chemicals and large number of studies has been done to determine the distribution of acetylator phenotypes among populations of different geographic origin. The aim of this study was to investigate the acetylator phenotypes of the Pakistani population and compare it between male and female healthy volunteers. The polymorphic acetylation of sulphamethazine has been investigated in male and female volunteers (50 each) of Pakistani population. Sulphamethazine was administered orally in Capsule form as 500 mg to each healthy male and female volunteer. Sulphamethazine and acetylsulphamethazine were determined in the six hour plasma samples by&nbsp;high-pressure liquid chromatography (HPLC). Acetylator phenotype was determined from the metabolic ratio of acetylsulphamethazine to sulphamethazine in the plasma samples. The acetylation of sulphamethazine by&nbsp;arylamine N-acetyltransferase 2 (NAT2) showed bimodal population frequency distribution. 60% of the female volunteers were found to be fast and 40% to be slow acetylators while that of male volunteers were 62% fast and 38% slow acetylators. &nbsp; Key words:&nbsp;NAT2 acetylation phenotype, sulphamethazine, male &amp; female volunteers, HPLC assay.

Thermal plasticity of wing size and shape in Drosophila melanogaster, D. simulans and their hybrids

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 43:71-79 (2010) - DOI: https://doi.org/10.3354/cr00880 Thermal plasticity of wing size and shape in Drosophila melanogaster, D. simulans and their hybrids V. Trotta1,*, C. Pertoldi2,3, A. Rudoy1, T. Manenti1, S. Cavicchi1, D. Guerra1 1Alma Mater Studiorum, Università di Bologna, Dipartimento di Biologia Evoluzionistica Sperimentale, Via Selmi 3, 40126 Bologna, Italy 2Department of Biological Sciences, Ecology and Genetics, Aarhus University, Ny Munkegade, Building 1540, 8000 Århus C, Denmark 3Mammal Research Institute, Polish Academy of Sciences, Waszkiewicza 1c, 17-230 Bialowieża, Poland *Email: v.trotta@unibo.it ABSTRACT: Populations of Drosophila melanogaster, as well as of other Drosophila species, show body size differences according to their geographic origin. Thermal selection is considered to be the most likely cause explaining these differences. We investigated wing size, wing shape and their relationship in 3 different geographic populations of D. melanogaster, 1 population of D. simulans, and their interspecific hybrids grown at 18, 21, 25 and 28°C. The aim was to explore how the past adaptive history of 2 related species, or populations of the same species, modulates the plastic response to the environment. The wing size plasticity of hybrids between the temperate D. simulans (Bologna) and the 2 tropical D. melanogaster populations (Belém and Rio de Janeiro) was higher than that of parental species, probably as a side effect of a decanalized and compromised development at higher temperatures. The wing size plasticity of Bologna hybrids was the same as the parents, suggesting that the 2 species are subjected to the same plasticity selection. Wing shape was typical of each species, population and temperature. Shape differences increased in hybrids at higher temperatures as a consequence of developmental perturbation. The allometric relationship between size and shape changed among temperatures and among species, suggesting that the wing development is differently regulated in the 2 species and can be altered by natural selection. The allometry changed between populations of different geographic origin of D. melanogaster, but was similar in the 2 species that shared the same selective environment. Two species would have been subjected to the same plasticity selection, so the breakdown of the plastic response is avoided in hybrids. As a whole, these data suggest that thermal plasticity is a trait under selection and that similar mechanisms are at work in different species. KEY WORDS: Drosophila · Hybrids · Development · Evolutionary constraints · Phenotypic plasticity Full text in pdf format PreviousNextCite this article as: Trotta V, Pertoldi C, Rudoy A, Manenti T, Cavicchi S, Guerra D (2010) Thermal plasticity of wing size and shape in Drosophila melanogaster, D. simulans and their hybrids. Clim Res 43:71-79. https://doi.org/10.3354/cr00880 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 43, No. 1-2. Online publication date: August 05, 2010 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2010 Inter-Research.

Is there any difference between acetylator phenotypes in tuberculosis patients and healthy subjects?

Many studies have been done to determine the distribution of acetylator phenotypes among populations of different geographic origin. The goal of this study was to investigate the acetylator phenotypes of the Iranian population and compare them between tubercular patients and healthy subjects. The study population consisted of two groups; the first group included 100 newly diagnosed tubercular patients and the second group consisted of 100 healthy subjects. Acetylator phenotype was determined from the metabolic ratio of acetyl-isoniazid to isoniazid in the plasma samples. Metabolic ratio was used to classify subjects as slow (= or < 0.70) or fast acetylators (>0.70). In the tubercular patients, the frequencies of slow and fast acetylator phenotypes were 62 and 38%, respectively. Of the healthy individuals, 45% were found to be slow acetylators and the remaining 55% were fast acetylators. It seems that tubercular patients metabolize isoniazid more slowly than healthy individuals.

Sexual dimorphism in winter survival rate differs little between damselbug species (Heteroptera: Nabidae)

The winter survival of three closely related univoltine heteropterans that overwinter as adults, Nabis rugosus, N. erice- torum and N. pseudoferus was investigated. After 150 days of low temperature treatment (3-5°C, 16L : 8D, r.h. 70-80%) more males than females died. The mortality rate ranged from 88.8 to 93.8% in males and from 54.2 to 60.7% in females. However, these sexual differences in mortality did not differ significantly across the three species and populations of different geographic origin. It remains a general question whether this considerable evolutionary stability in the sex-specific investment into reproduction and sur- vival phylogenetically conserved or frequently evolves anew to similar levels in separated populations and species. In Nabis rugosus, the relative loss of body mass during overwintering was up to 37.8%. This reflects dramatic somatic costs of adult overwin- tering and indirectly supports the hypothesis that food supply during overwintering is important for some heteropteran predators. However, body mass before overwintering did not significantly explain the survival pattern in N. rugosus in either sex. The similar sex-specific survival rate of overwintering adult nabids regardless of species and geographic origin can be useful for studies on population dynamics of nabids in agroecosystems and biocontrol.

Genetic diversity patterns at the human clock gene period 2 are suggestive of population-specific positive selection

Period 2 (PER2) is a key component of the mammalian circadian clock machinery. In humans, genetic variation of clock genes or chronic disturbance of circadian rhythmicity has been implied in the onset of several phenotypes, ranging from periodic insomnias to advanced or delayed sleep phases, to more severe disorders. Peculiar geographic diversity patterns in circadian genes might represent an adaptive response to different light/dark cycles or environmental changes to which different human populations are exposed. To investigate the degree and nature of PER2 gene variation in human populations of different geographic origin, and its possible correlation with different latitudes, we sequenced a 7.7 kb portion of the gene in 20 individuals worldwide. In total, 25 variable sites were identified. The geographic distribution of haplotypes defined by five polymorphic sites was analyzed in 499 individuals from 11 populations from four continents. No evidence for latitude-driven selective effects on PER2 genetic variability was found. However, a high and significant difference in the geographic distribution of PER2 polymorphisms was observed between Africans and non-Africans, suggesting a history of geographically restricted natural selection at this locus. In support of this notion, we found several signals for selection in the sequences. The putative selected haplotype showed a recent coalescent age (8.7 Kyr), and an unusually high frequency in non-African populations. Overall, these findings indicate that a human clock-relevant gene, PER2, might have been influenced by positive selection, and offer preliminary insights into the evolution of this functional class of genes.

The composition and taxonomic significance of fatty acid patterns in three white rust species: Albugo amaranthi, A. candida and A. tragopogonis (Peronosporales, Albuginaceae)

The fatty acid composition of the biotrophic white rust species A. amaranthi, A. candida and A. tragopogonis was identified by means of GC and GC/MS analysis. Besides the common saturated fatty acids of C14 to C22 chain length, several unusual monounsaturated and polyunsaturated fatty acids were present in significant amounts in the lipid profiles of the three species. Each taxon revealed its own characteristic pattern which was uniform among populations of different geographic origin and independent from the host species. Fatty acids were obtained from minute amounts of sporangia collected from the surface of desiccated host plants. Comparison of herbarium specimens revealed a decrease of polyunsaturated compounds after storage for 30 months at room temperature, but still allowed unquestionable species differentiation.

Effect of generation of inbreeding, cutting treatment and year on agronomic traits in berseem populations

The selfing effect in berseem clover (Trifolium alexandrinum L.) was analysed by comparing generation means for nine agronomic traits (dry matter yield, plant height, leaf-stem ratio, harvest index, seed yield and its components). Parents, S1, S2, S3, and S4 generations of six populations of different geographical origin (3 from Egypt and 3 from southern Italy) were investigated to estimate the relative changes with increasing homozygosity and to prove the effectiveness of selfing in a breeding program. The experiment was carried out at Foggia (Italy) under field conditions for two years (1995 and 1996) adopting two cutting treatments: at fifth internode elongation (A) and flowering (B). The mean values decreased with the advancement in selfing generations in both years and cutting treatments for the most of the traits. Treatment B yielded more biomass and seed yield than treatment A in both years. Cutting treatments did not affect the adaptability of the selfed progenies of populations with different geographical origin, in fact, the Italian populations were more productive for dry matter under both cutting treatments (856.6 g m-2 on average), whereas Egyptian populations proved superior for seed yield particularly under treatment B (62.5 g m-2 on average). Inbreeding depression was greater for forage dry matter and seed yield (−62and −79% on average, respectively), whereas the plant height and 1000-seed weight were the least susceptible traits (−26 and −19% on average, respectively). Estimates of the parameters of the stability analysis showed that not all populations responded to inbreeding level and environment variations to the same degree. Differences were evident under treatment A, only. Development of self-fertile, relatively vigorous inbred lines of berseem clover with different degrees of homozygosity appears possible. Genotypes tolerant to selfing from Egyptian and Italian groups have been obtained by inbreeding and selection for self-fertility; they could be utilised as basis for producing new breeding activities.

LACK OF NONADDITIVE GENETIC EFFECTS ON EARLY FECUNDITY IN DROSOPHILA MELANOGASTER

Fecundity is usually considered as a trait closely connected to fitness and is expected to exhibit substantial nonadditive genetic variation and inbreeding depression. However, two independent experiments, using populations of different geographical origin, indicate that early fecundity in Drosophila melanogaster behaves as a typical additive trait of low heritability. The first experiment involved artificial selection in inbred and non-inbred lines, all of them started from a common base population previously maintained in the laboratory for about 35 generations. The realized heritability estimate was 0.151 ± 0.075 and the inbreeding depression was very small and nonsignificant (0.09 ± 0.09% of the non-inbred mean per 1% increase in inbreeding coefficient). With inbreeding, the observed decrease in the within-line additive genetic variance and the corresponding increase of the between-line variance were very close to their expected values for pure additive gene action. This result is at odds with previous studies showing inbreeding depression and, therefore, directional dominance for the same trait and species. All experiments, however, used laboratory populations, and it is possible that the original genetic architecture of the trait in nature was subsequently altered by the joint action of random drift and adaptation to captivity. Thus, we carried out a second experiment, involving inbreeding without artificial selection in a population recently collected from the wild. In this case we obtained, again, a maximum-likelihood heritability estimate of 0.210 ± 0.027 and very little nonsignificant inbreeding depression (0.06 ± 0.12%). The results suggest that, for fitness-component traits, low levels of additive genetic variance are not necessarily associated with large inbreeding depression or high levels of nonadditive genetic variance.

Transposon associated markers for the parasitic nematode Haemonchus contortus

We have previously characterized a Tc1-like transposable element Hctc1, from the parasitic nematode Haemonchus contortus. Here we describe the genetic variation of Hctc1 insertion sites in H. contortus populations differing in geographical origin, resistance to chemotherapeutics and level of inbreeding. Clear differences between populations were observed on Southern blots with a Hctc1-specific probe. Sequencing the 5′- or 3′-flanks of individual Hctc1 integration sites allowed the design of PCR reactions between a Hctc1-specific primer and the flanking regions. This revealed a considerable variation of integration sites of Hctc1 both within and between populations, although several integrations were shared by populations of different geographical origin. For four of the eight markers allele frequencies were shifted during selection for resistance to chemotherapeutics and/or inbreeding. For two positions both the 5′ and 3′ regions flanking Hctc1 were isolated and PCR showed that for these two positions the variation of transposon associated markers between populations were indeed caused by variation in integration of Hctc1. For these two positions co-dominant markers were developed. These results indicate that Hctc1 insertions may serve as genetic markers for H. contortus.

Polymorphism at the tetranucleotide repeat locus DYS389 in 10 populations reveals strong geographic clustering.

Several short tandem repeat polymorphism loci at the non-recombining part of the Y chromosome have been described recently and are now widely used for the investigation of the history and the diversity of man. The tetranucleotide repeat polymorphism at the DYS389 locus consists of two repetitive stretches with different numbers of (TCTG)n (TCTA)m repeat units. To study the overall variability of this locus, 768 alleles from males from 10 human populations (two sub-Saharan African, four Caucasoid and four Asian/Amerind populations) were investigated. The alleles found in the populations of different geographic origin exhibited remarkable differences in the number and arrangement of repeats in the two repetitive stretches and up to nine different sequence variants for a single fragment length have been detected. So far 53 different alleles, i.e. haplotypes, have been observed. Analysis of molecular variance (AMOVA) indicates that at least 24.5% of the total genetic variance was found between the populations and that these differences were significant in most pairwise comparisons. We propose a model, in which both founder effects and genetic drift together with single step replication slippage mutations explain the picture of haplotype diversity observed with this single locus.

A new experimental approach to investigate migration in Pieris brassicae L.

Abstract. It is possible to correlate distinct sequences of flight behaviour in caged females of the migrant butterfly Pieris brassicae with the main flight direction of released individuals of the same stock. The attempts to escape out of the cage point to the same mean direction as the flights of the released butterflies. This provides an experimental tool to investigate some unsolved questions concerning migration behaviour. This study examines the constancy of the flight direction of a group of butterflies, the specificity of the direction in two populations of different geographical origin, and the frequently reported change in flight direction of subsequent generations. The results indicate that the main flight direction of a tested group is very constant during 2 days of observation. Different directions have been detected in populations originating from Northern Germany and Southern France, respectively. The preferred directions are discussed as an adaptation to the geographical circumstances. Subsequent generations of the population from Northern Germany also show different directions. The spring generation flies to the north, the autumn generation in the opposite direction. This result corresponds to field observations that in P.brassicae a return flight occurs in subsequent generations of a year.

Genetic variability of the interpulse interval of courtship song among some European populations of Drosophila melanogaster.

The interpulse interval of the courtship song of Drosophila melanogaster is a character which may play a significant role in mating success and reproductive isolation. Here we examine the variability of interpulse interval among replicated laboratory strains of D. melanogaster. There is no significant variation among populations of different geographical origin. This suggests that interpulse interval is subject to strong selection, as the populations are known to differ for other characters. One population, however, was sufficiently different to allow a genetic analysis. Reciprocal F1s and backcrosses implied that the variance was predominantly additive and autosomal. Possible sources of selection on interpulse interval are discussed.

Hypervariable-control-region sequences reveal global population structuring in a long-distance migrant shorebird, the Dunlin (Calidris alpina).

Hypervariable segments of the control region of mtDNA as well as part of the cytochrome b gene of Dunlins were amplified with PCR and sequenced directly. The 910 base pairs (bp) obtained for each of 73 individuals complete another of the few sequencing studies that examine the global range of a vertebrate species. A total of 35 types of mtDNA were detected, 33 of which were defined by the hypervariable-control-region segments. Thirty of the latter were specific to populations of different geographic origin in the circumpolar breeding range of the species. The remaining three types indicate dispersal between populations in southern Norway and Siberia, but female-mediated flow of mtDNA apparently is too low to overcome the effects of high mutation rates of the control-region sequences, as well as population subdivision associated with historical range disjunctions. A genealogical tree relating the types grouped them into five populations: Alaska, West Coast of North America, Gulf of Mexico, western Europe, and the Taymyr Peninsula. The Dunlin is thus highly structured geographically, with measures of mutational divergence approaching 1.0 for fixation of alternative types in different populations. High diversity of types within populations as well as moderate long-term effective population sizes argue against severe population bottlenecks in promoting this differentiation. Instead, population fragmentation in Pleistocene refuges is the most plausible mechanism of mtDNA differentiation but at a much earlier time scale than suggested previously with morphometric data.