Adapting to winter in wheat: a long-term study follows parallel phenotypic and genetic changes in three experimental wheat populations

Drawing a direct connection between adaptive evolution at the phenotypic level and underlying genetic factors has long been a major goal of evolutionary biologists, but the genetic characterization of adaptive traits in natural populations is notoriously difficult. The study of evolution in experimental populations offers some help — initial conditions are known and changes can be tracked for extended periods under conditions more controlled than wild populations and more realistic than laboratory or greenhouse experiments. In this issue of Molecular Ecology , researchers studying experimental wheat populations over a 12-year period have demonstrated evolution in a major adaptive trait, flowering time, and parallel changes in underlying genetic variation ( Rhoné et al . 2008 ). Their work suggests that cis -regulatory mutations at a single gene may explain most of the flowering time variation in these populations.     

Food specialization in ruminants: the role of endosymbiosis in its formation

Peculiarities of endosymbiosis have been studied in four species of ruminant animals with different food specialization (Cervus elaphus, Moschus moschiferus, Carpa sibirica, ans Gasella subgutturosa) using the methods of macromorphology, light and electron microscopy, and histochemistry. The differences in morphology of bacteria from populations inhabiting rumen epithelium of the studied animals have been revealed. The specificity of connection of bacteria with cornified epithelium has been demonstrated. This connection is reflected on the structure of outer epithelium layers. The functional interpretation of gizzard epithelium macrolandscape peculiarities has been improved. An important part of endosymbiosis in evolutionary-morphological transformations of stomach and intestines, and in formation of food specialization in wild animal species has been underlined.     

Genetic diversity of <Emphasis Type="Italic">Bradysia difformis</Emphasis> (Sciaridae: Diptera) populations reflects movement of an invasive insect between forestry nurseries

The fungus gnat, Bradysia difformis (Sciaridae: Diptera) has recently been recorded for the first time from South Africa where it has been found in forestry nurseries. The presence of this insect in all the major forestry nurseries as the dominant and only sciarid species raises intriguing questions regarding its origin and population genetic structure. A 395 bp portion of the mitochondrial COI gene was analysed from B. difformis individuals collected from four nursery populations in South Africa and three nursery populations in Europe. Shared haplotypes between South African and European populations indicated a historical connection. South African populations showed high genetic diversity and low genetic differentiation. These patterns most likely reflect multiple and/or relatively large introductions of B. difformis into South Africa from its origin combined with subsequent and continued movement of plants between nurseries.     

Genetic structure within and among regional populations of the Eurasian badger (Meles meles) from Denmark and the Netherlands

The Eurasian badger Meles meles has a wide distribution area ranging from Japan to Ireland. In western Europe badger habitats are severely disturbed by anthropogenic factors, leading to fragmentation into subpopulations and formation of a metapopulation substructuring of once continuous panmictic populations. We have examined the genetic structure of Dutch and Danish badger populations on a relatively small scale (within countries) and a larger scale (between countries). The levels of genetic variation of populations were moderate and did not differ significantly among populations (overall H _O=0.30, overall H _E=0.34). Considerable genetic differentiation between the Dutch and Danish populations was found (overall F _ST=0.32, mean pairwise Dutch–Danish F _ST=0.42), indicating a large-scale substructuring of these western European badger populations. Further analysis showed that the Danish badger population can be substructured into three clusters [ P _{( k =3)}=0.99], but the Dutch populations cluster into one more or less panmictic population [ P _{( k =1)}=0.99] with little or no substructuring. The presence of migration barriers, such as roads, together with the peninsular geography of Denmark, may have led to this structuring of badger populations. In contrast, measures that improve migration and connection to other populations from neighboring countries may have prevented substructuring of the Dutch badger population.     

The genetics of the opioid system and specific drug addictions

Addiction to drugs is a chronic, relapsing brain disease that has major medical, social, and economic complications. It has been established that genetic factors contribute to the vulnerability to develop drug addiction and to the effectiveness of its treatment. Identification of these factors may increase our understanding of the disorders, help in the development of new treatments and advance personalized medicine. In this review, we will describe the genetics of the major genes of the opioid system (opioid receptors and their endogenous ligands) in connection to addiction to opioids, cocaine, alcohol and methamphetamines. Particular emphasis is given to association and functional studies of specific variants. We will provide information on the sample populations and the size of each study, as well as a list of the variants implicated in association with addiction-related phenotypes, and with the effectiveness of pharmacotherapy for addiction.     

A test of the relationship between cuticular melanism and immune function in wild‐caught Mormon crickets

Cuticular melanism and innate immune parameters can share common physiological pathways in insects, and this functional connection may contribute to the maintenance of insect colour polymorphisms. However, evidence linking colouration and immune function has been equivocal, particularly when tested in wild populations. The present study investigates phenotypic links between colouration and immune function in migratory Mormon crickets (Anabrus simplex, Haldeman), in which juveniles occur in conspicuous colour variants but mature to become uniformly melanic adults. Wild‐caught insects are used to evaluate the relationship between juvenile colouration and three immune parameters: encapsulation ability, lysozyme‐like activity and phenoloxidase activity. As nymphs, brown crickets are better able to encapsulate an inert implant introduced into the haemocoel than green crickets, although the difference is slight and ceases after they all become darkly‐coloured adults. By contrast, adults that develop from brown nymphs have a higher basal phenoloxidase activity than those that develop from green nymphs, regardless of the fact that all adults are brown. Intrinsic factors other than colouration exert larger effects on immunity: males show stronger encapsulation responses but lower phenoloxidase activity than females, suggesting a sex‐specific trade‐off between these two immune parameters, and adults exhibit higher immune function than nymphs. In summary, modest support is found for a correlation between cuticular melanism and increased immune function in wild Mormon crickets. Additional intrinsic factors such as developmental stage and sex appear to interact with colouration and have a more substantial connection to immune function in the wild.     

Oscillations and waves in the models of interactive neural populations

The dynamics of activity in interactive neural populations is simulated by the networks of Wilson–Cowan oscillators. Two extreme cases of connection architectures in the networks are considered: (1) 1D and 2D regular and homogeneous grids with local connections and (2) sparse random coupling. Propagating waves in the network have been found under the stationary external input and the regime of partial synchronization has been obtained for the periodic input. It has been shown that in the case of random coupling about 60% of neural populations demonstrate oscillatory activity and some of these oscillations are synchronous. The role of different types of dynamics in information processing is discussed. In particular, we discuss the regime of partial synchronization in the context of cortical microcircuits.     

Oscillations and waves in the models of interactive neural populations

The dynamics of activity in interactive neural populations is simulated by the networks of Wilson-Cowan oscillators. Two extreme cases of connection architectures in the networks are considered: (1) 1D and 2D regular and homogeneous grids with local connections and (2) sparse random coupling. Propagating waves in the network have been found under the stationary external input and the regime of partial synchronization has been obtained for the periodic input. It has been shown that in the case of random coupling about 60% of neural populations demonstrate oscillatory activity and some of these oscillations are synchronous. The role of different types of dynamics in information processing is discussed. In particular, we discuss the regime of partial synchronization in the context of cortical microcircuits.     

Medico-genetic study of the Kostroma Region population. VIII. Genetic structure of large subdivided populations and its relation with the incidence of autosomal-recessive pathology

FST was estimated for 67 communities and 6 small towns of Kostroma province. The mean FST value for rural and urban populations was (0.83 +/- 0.08).10(-3) and (0.29 +/- 0.07).10(-3), respectively. The connection between FST values and the load of autosomal-recessive disorders was established; the coefficient of correlation (by Chuprov) was 0.34 (chi 2 = 8.45; P less than 0.05). The matrices of genetic distances for two groups of districts of Kostroma province, based on surnames frequencies, were calculated. Dendrogramms were constructed using genetic distances, which reflect the degree of genetical similarity of the populations. The conclusion drawn from the analysis of these dendrogramms is that there is distinct isolation by distance in populations of Kostroma province. It is shown that genetical subdivision of populations is dependent on geographical and some other factors and on the load of autosomal-recessive pathology in the population.     

Comparative study of early-life survival variability of herring Clupea harengus, in the north-eastern Atlantic

Variation in the survival of herring between the egg stage and the age of recruitment to the spawning population has been examined for seven Atlantic herring populations in northern European waters. The sources of the variation have been partitioned between density-dependent and density-independent factors. The magnitude of the density-independent component was found to be related to the scale of the processes controlling the dispersion and distribution of larvae from the various populations. We conclude that the spawning strategies of some populations are adapted to oceanographic conditions to maximize the probability of a particular larval transport pattern, although no single model could account for all spawning strategies.     

Different shell development in Mytilus galloprovincialis in 2 different populations from the Gulf of Naples

The size frequency distribution, the shell weight, the semilogarythmic growth, the carbonic anhydrase activity has been investigated between two populations of mussels from different sampling zones. Significative differences were found in the parameters investigated between the two populations. The authors conclude that the reason of this morphological and biochemical differences may arise from different natural hydrobiological factors and/or from different pollution of their habitat.     

Natural selection. V. How to read the fundamental equations of evolutionary change in terms of information theory

The equations of evolutionary change by natural selection are commonly expressed in statistical terms. Fisher's fundamental theorem emphasizes the variance in fitness. Quantitative genetics expresses selection with covariances and regressions. Population genetic equations depend on genetic variances. How can we read those statistical expressions with respect to the meaning of natural selection? One possibility is to relate the statistical expressions to the amount of information that populations accumulate by selection. However, the connection between selection and information theory has never been compelling. Here, I show the correct relations between statistical expressions for selection and information theory expressions for selection. Those relations link selection to the fundamental concepts of entropy and information in the theories of physics, statistics and communication. We can now read the equations of selection in terms of their natural meaning. Selection causes populations to accumulate information about the environment.     

Identification of local selective sweeps in human populations since the exodus from Africa

Selection on the human genome has been studied using comparative genomics and SNP architecture in the lineage leading to modern humans. In connection with the African exodus and colonization of other continents, human populations have adapted to a range of different environmental conditions. Using a new method that jointly analyses haplotype block length and allele frequency variation (F(ST)) within and between populations, we have identified chromosomal regions that are candidates for having been affected by local selection. Based on 1.6 million SNPs typed in 71 individuals of African American, European American and Han Chinese descent, we have identified a number of genes and non-coding regions that are candidates for having been subjected to local positive selection during the last 100 000 years. Among these genes are those involved in skin pigmentation (SLC24A5) and diet adaptation (LCT). The list of genes implicated in these local selective sweeps overlap partly with those implicated in other studies of human populations using other methods, but show little overlap with those postulated to have been under selection in the 5-7 myr since the divergence of the ancestors of human and chimpanzee. Our analysis provides focal points in the genome for detailed studies of evolutionary events that have shaped human populations as they explored different regions of the world.     

Influence of the population size on the frequency of flies infected by sigma virus in populations of Drosophila melanogaster

The frequency of flies infected by the hereditary, noncontagious rhabdovirus sigma has been followed in experimental populations bred from very few adults. The average frequency of infected flies decreased. These results suggest that overwinterning might be one of the factors responsible for the discrepancy between wild and laboratory populations; in France, previous experiments have shown that about 20% of the individuals in natural populations are infected by the sigma virus, while in laboratory populations set up from samples collected in the wild, virus is detectable in almost the whole population. The effect of winter on the frequency of infected flies might be twofold: first, it has been shown previously that infected flies seem to be more sensitive to overwintering than uninfected flies; second, the reduction of population size might reduce the ability of the population to make up for the decrease during the summer generations.     

Implications of Nubian-Like Core Reduction Systems in Southern Africa for the Identification of Early Modern Human Dispersals

Lithic technologies have been used to trace dispersals of early human populations within and beyond Africa. Convergence in lithic systems has the potential to confound such interpretations, implying connections between unrelated groups. Due to their reductive nature, stone artefacts are unusually prone to this chance appearance of similar forms in unrelated populations. Here we present data from the South African Middle Stone Age sites Uitpanskraal 7 and Mertenhof suggesting that Nubian core reduction systems associated with Late Pleistocene populations in North Africa and potentially with early human migrations out of Africa in MIS 5 also occur in southern Africa during early MIS 3 and with no clear connection to the North African occurrence. The timing and spatial distribution of their appearance in southern and northern Africa implies technological convergence, rather than diffusion or dispersal. While lithic technologies can be a critical guide to human population flux, their utility in tracing early human dispersals at large spatial and temporal scales with stone artefact types remains questionable.     

Mitochondrial genetics cooperate with nuclear genetics to selectively alter immune cell development/trafficking

The nuclear genome drives differences in immune cell populations and differentiation potentials, in part regulated by changes in metabolism. Despite this connection, the role of mitochondrial DNA (mtDNA) polymorphisms (SNP) in this process has not been examined. Using mitochondrial nuclear exchange (MNX) mice, we and others have shown that mtDNA strongly influences varying aspects of cell biology and disease. Based upon an established connection between mitochondria and immune cell polarization, we hypothesized that mtDNA SNP alter immune cell development, trafficking, and/or differentiation. Innate and adaptive immune cell populations were isolated and characterizated from the peritoneum and spleen. While most differences between mouse strains are regulated by nuclear DNA (nDNA), there are selective changes that are mediated by mtDNA differences (e.g., macrophage (CD11c) differentiation), These findings highlight how nuclear-mitochondrial crosstalk may alter pathology and physiology via regulation of specific components of the immune system.     

History of methods for estimating body height by skeletal findings. Recommendations for estimating body height by skeletal findings up to the middle of the 20th century

Up to now no historical review concerning the methods to estimate body height from skeletons has been given. As well no collection of the formulae relevant to this subject, which would save laborious search in the wide-scattered literature, is available hitherto. This study tries to fill this gap. The anthropological and statistical treatment of the populations under study will not be discussed in this connection, because this has to be left to a separate study.     

The importance of genetic variability and population differentiation in the Eurasian lynx Lynx lynx for conservation,in the context of habitat and climate change

• 1 The Eurasian lynx Lynx lynx occupies a variety of environmental and climatic conditions, and the majority of present‐day European populations have either recovered from severe demographic bottlenecks, or are living in fragmented habitat. These factors may have affected the genetic variability of lynx populations. We summarize available data on genetics, population status and ecology of these felids to shed light on the pattern and mechanisms behind their genetic variability and population differentiation in Europe.
• 2 Genetic studies conducted so far, based on mtDNA and microsatellites, have shown that the Eurasian lynx has low to moderate genetic variability. Variability is lowest in the north (Scandinavian bottlenecked population), but is also low in the Carpathian region. A trend towards loss of genetic variation has been noted in fragmented and reintroduced populations. Genetically, the populations are highly differentiated from each other.
• 3 There are clear relationships between the pattern of lynx genetic variability, differentiation between the populations, and such factors as population history (demographic bottlenecks), social interactions and habitat fragmentation. The genetic divergence between lynx populations is also strongly correlated with the depth and duration of snow cover.
• 4 Our review provides evidence that the lynx is undergoing significant genetic differentiation, due to several factors. To enable better planning of conservation programmes for the Eurasian lynx, researchers should identify the Evolutionarily Significant Units among its populations, using different classes of molecular markers.

     

Flow cytometry analysis of recombinant Saccharomyces cerevisiae populations

A new fluorescent stain has been developed for detecting cloned beta-galactosidase activity in individual cells of Saccharomyces cerevisiae by flow cytometry. The staining reaction is based on enzymatic cleavage of alpha-naphthol-beta-D-galactopyranoside by intracellular beta-galactosidase and trapping of the liberated naphthol by hexazoniumpararosaniline yielding a fluorescent, insoluble end product. This stain, in connection with an appropriate host strain, has been applied for detecting plasmids encoding inducible beta-galactosidase in unstable recombinant cell populations carrying plasmids with different origins of replication. The method enables rapid determination of the fraction of plasmid-containing cells as well as quantitation of intracellular beta-galactosidase content by kinetic enzyme assay. Inducibility of the marker enzyme is important for maintaining correlation between enzyme and gene content.     

Genetic load and viability variation in korean natural populations ofDrosophila melanogaster

Summary Natural populations of Drosophila melanogaster from Anyang and Susac (suburbs of Seoul) have been analyzed with respect to viability variation on the second chromosome. Homozygotes as well as random heterozygotes for wild chromosomes were studied. The frequency of lethal factors was about 16 per cent, that of drastics 26 per cent. The average viability of homozygotes was 0.650 including lethal lines and 0.858 for quasinormals; that for random heterozygotes was 1.125. Allelism tests have been performed for the lethals. The allelism rate turned out to be as high as 0.036 and 0.0214, respectively. Using a formula by Nei, the effective population size can be estimated from these data. Korean D. melanogaster populations proved as small as 2000 to 3000 individuals. No correlation between homozygous and heterozygous viabilities could be found. According to these observations, along with the fact that partly big clusters of identic lethals could be found in the allelism tests, it is concluded that in Korean populations quite a large part of the hard genetic load is balanced. The connection between population size, population structure and associative or genuine overdominance is discussed.