Population Local Adaptation Research Articles

Does selection by resistant hosts trigger local adaptation in plant–pathogen systems?

Understanding the consequences of selection by host resistance on pathogen population structure provides useful insights into the dynamics of host-parasite co-evolution processes and is crucial for effective disease management through resistant cultivars. We tested general vs. local population adaptation to host cultivars, by characterizing a French collection of Phytophthora infestans (the causal organism of potato late blight) sampled during two consecutive years on cultivars exhibiting various levels of resistance. Local populations were structured by the host for virulence (qualitative pathogenicity) but also for aggressiveness (quantitative pathogenicity). All populations had a low genotypic diversity for amplified fragment length polymorphisms (AFLPs), and presumably consisted of a few closely related clonal lineages. No correlation was detected between pathogenicity traits and AFLP genotypes. The data support the hypothesis of general adaptation for aggressiveness, to which directional selection for virulence is superimposed when race-specific resistance is introduced.

Population structure in the Atlantic salmon: insights from 40 years of research into genetic protein variation

Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, >350 scientific papers on protein variation have been published encompassing 25 000+ salmon from over 400 locations in >200 river systems across the species’ distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine <40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub‐species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species’ modern range. However, variation at MEP‐2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time.

Mediators of Modernity: "Photo-interpreters" in Japanese Silent Cinema

Mediators of Modernity:"Photo-interpreters" in Japanese Silent Cinema Isolde Standish (bio) The film critic and theorist Kaeriyama Norimasa,1 writing in the trade journal Kinema Record in August 1915—for the benefit of foreign readers he wrote in English—, defines the role of benshi/katsuben as that of "photo-interpreters." The case of the benshi thus provides an excellent example of the processes of modification and alteration to the introduction of new technologies, and the adaptation of local populations to the accompanying introduction of new worldviews. In this article I shall explore two avenues of thought in relation to the role played by the benshi in the history of early Japanese cinema. First, following on from Kaeriyama Norimasa, I shall argue that the benshi functioned as mediators of modernity through their interpretation of foreign films for Japanese audiences. Second, I shall explore their role within the domestically produced melodramatic genres (shinpa-derived traditions of "women's weepies" and the matatabimono "men's weepies") as vehicles through which characters were given a greater sense of psychological depth, while exploring how their inclusion as a central element in the film experience impacted the development of cinematic conventions in these genres. For the discussion of narrational norms and the benshi within the melodramatic traditions of early cinema, I have drawn heavily on a set of video releases of Japanese films covering the decade from the mid-1920s to [End Page 93] the mid-1930s produced by the Matsuda Film Company (Matsuda Eiga-sha) in the early 1990s. These releases come complete with benshi narration by Matsuda Shinsui (1925-1987) and Sawato Midori. Mediators of Modernity The best criticism, and it is uncommon, is of [the] sort that dissolves considerations of content into those of form. (Sontag 1983:103) While I do not want to take an overtly technological determinist line, there are various implications that need to be considered in relation to cinema as a western technological invention, and the historicity of the juncture in time when it was invented. Cinema began in the age of Freudian psychoanalysis, which also saw the rise of nationalism and the emergence of consumerism. As Ella Shohat and Robert Stam (1996:152) remind us, the first film screenings by Lumiere and Edison in the 1890s closely followed the "scramble for Africa" that erupted in the 1870s, the Battle of "Rorke's Drift" (1879) which opposed the British to the Zulus . . ., the British occupation of Egypt in 1882, the Berlin Conference of 1884 that carved up Africa into European "spheres of influence," the massacre of the Sioux at Wounded Knee in 1890, and countless other imperial misadventures. Relatedly, Comolli2 has argued that the development of the camera obscura as a "machine" is not neutral, but comes imbued with certain ideological assumptions that underpinned its development (Bordwell, Staiger, et al. 1999:250): "[T]echnology is produced in large part by a socially derived conception of [the] world and how we know it . . . [Comolli] finds the origin of cinema not in scientific inquiry but in nineteenth-century [End Page 94] ideological pressures to represent 'life as it is' and in economic desires to exploit a new spectacle." This desire, to represent "life as we know it is," stems from the Renaissance project that attempted to reproduce "reality" through mimesis. The invention of the camera and the development of photography was a direct result of this aim, an aim compatible with a western ideological/aesthetic tradition, which, since the Renaissance and later the Enlightenment, sought to distance humanity's understanding of the natural world and civil society from a purely metaphysical and religious context, and to locate that understanding in the "real," this worldly study of the "sciences." As the landscape painter John Constable remarked, "painting is a science and should be pursued as an inquiry into the laws of nature" (quoted in Ernst Gombrich 1996:29). The development of the camera was a progression in this ideological/aesthetic tradition that pursued art as "science." This development freed artists from the need to represent "reality" and can be related to the reactionary development of expressionist and impressionist art movements of the twentieth century. The transference of the drive to...

Distribution of genetic variation in the growth hormone 1 gene in Atlantic salmon (Salmo salar) populations from Europe and North America

The level and hierarchical distribution of genetic variation in complete sequences of the Atlantic salmon (Salmo salar) growth hormone (GH1) gene were investigated in populations from Europe and North America with a view to inferring the major evolutionary forces affecting genetic variation at this locus. Seventeen polymorphic sites were identified in complete sequences from nine populations, with levels of noncoding (intron and untranslated region sequences) nucleotide diversity being similar to those observed in other species. No variation, however, was observed in exonic sequences, indicating that nucleotide diversity in the Atlantic salmon GH1 gene is three and 25 times less than that estimated for human and Drosophila coding sequences, respectively. This suggests that purifying selection is the predominant contemporary force controlling the molecular evolution of GH1 coding sequences. Comparison of haplotype relationships within and between populations indicated that differentiation between populations from Europe and North America was greater than within-continent comparisons. However, several haplotypes observed in the northernmost European populations were more similar to those observed in North American than to any other haplotypes observed in Europe. This is most likely to be a result of historical, rather than contemporary, gene flow. Neutrality test statistics, such as Tajima's D, were significantly positive in the European populations in which North American-like haplotypes were observed. Although a positive Tajima's D is commonly interpreted as the signal of balancing selection, a more likely explanation in this case is that either historical migration or ascertainment bias, rather than within population local adaptation, has given rise to an excess of intermediate frequency alleles.

Inferring seed exchange between farmers from population genetic structure of barley landrace Arabi Aswad from Northern Syria

Apart from their significance in genetic conservation, barley landraces are still favoured by local farmers in low-input farming systems. They often perform more predictably under adverse conditions than modern cultivars due to local adaptation. Increased seed exchange between farmers may put adaptation of local populations of barley landraces at risk. Isozyme markers were used to investigate differentiation and infer gene flow between local populations of barley landrace Arabi Aswad in Northern Syria. Inferred gene flow decreased exponentially with geographic distance and may imply that seed exchange between farmers is limited to a regional scale and diminishes over longer distance. Gene flow seems to be a suitable index for estimating seed exchange in highly inbreeding crop species such as barley. In the future, improved mobility of farmers and extension work may facilitate seed exchange over longer distances, and consequently jeopardise preservation of locally adapted landraces in barley.

LOCAL ADAPTATION OF AN ANURAN AMPHIBIAN TO OSMOTICALLY STRESSFUL ENVIRONMENTS

Water salinity is an intense physiological stress for amphibians. However, some species, such as Bufo calamita, breed in both brackish and freshwater environments. Because selection under environmentally stressful conditions can promote local adaptation of populations, we examined the existence of geographic variation in water salinity tolerance among B. calamita populations from either fresh or brackish water ponds in Southern Spain. Comparisons were made throughout various ontogenetic stages. A combination of field transplant and common garden experiments showed that water salinity decreased survival probability of individuals in all populations, prolonged their larval period, and reduced their mass at metamorphosis. However, significant population × salinity interactions indicated that the population native to brackish water (Saline) had a higher salinity tolerance than the freshwater populations, suggesting local adaptation. Saline individuals transplanted to freshwater environments showed similar survival probabilities, length of larval period, and mass at metamorphosis than those native to freshwater. This indicates that increased tolerance to osmotic stress does not imply a loss of performance in freshwater, at least during the larval and juvenile phases. Despite the adaptive process apparently undergone by Saline, all populations still shared the same upper limit of embryonic stress tolerance (around 10 g/l), defining a window of salinity range within which selection can act. Significant differences in embryonic and larval survival in brackish water among sibships for all populations suggest the existence of a genetic basis for the osmotic tolerance.

Hitchhiking mapping: a population-based fine-mapping strategy for adaptive mutations in Drosophilamelanogaster.

The identification of genes contributing to the adaptation of local populations is of great biological interest. In an attempt to characterize functionally important differences among African and non-African Drosophila melanogaster populations, we surveyed neutral microsatellite variation in an 850-kb genomic sequence. Three genomic regions were identified that putatively bear an adaptive mutation associated with the habitat expansion of D. melanogaster. A further inspection of two regions by sequence analysis of multiple fragments confirmed the presence of a recent beneficial mutation in the non-African populations. Our study suggests that hitchhiking mapping is a universal approach for the identification of ecologically important mutations.

Geographical and altitudinal population genetic structure of two dung fly species with contrasting mobility and temperature preference

Local adaptation of populations requires some degree of spatio-temporal isolation. Previous studies of the two dung fly species Scathophaga stercoraria and Sepsis cynipsea have revealed low levels of geographic and altitudinal genetic differentiation in quantitative life history and morphological traits, but instead high degrees of phenotypic plasticity. These patterns suggest that gene flow is extensive despite considerable geographic barriers and large spatio-temporal variation in selection on body size and related traits. In this study we addressed this hypothesis by investigating genetic differentiation of dung fly populations throughout Switzerland based on the same 10 electrophoretic loci in each species. Overall, we found no significant geographic differentiation of populations for either species. This is inconsistent with the higher rates of gene flow expected due to better flying capacity of the larger S. stercoraria. However, heterozygote deficiencies within populations indicated structuring on a finer scale, seen for several loci in S. cynipsea, and for the locus PGM (Phosphoglucomutase) in S. stercoraria. Additionally, S. cynipsea showed a tendency towards a greater gene diversity at higher altitudes, mediated primarily by the locus MDH (malate dehydrogenase), at which a second allele was only present in populations above 1000 m. This may be caused by increased environmental stress at higher altitudes in this warm-adapted species. MDH might thus be a candidate locus subject to thermal selection in this species, but this remains to be corroborated by direct evidence. In S. stercoraria, no altitudinal variation was found.

Latitudinal differentiation in the effects of the toxic dinoflagellate Alexandrium spp. on the feeding and reproduction of populations of the copepod Acartia hudsonica

Blooms of the dinoflagellate Alexandrium spp. increase in their frequency, toxicity and historical presence with increasing latitude from New Jersey (USA) to the Gaspé peninsula (Canada). Biogeographic variation in these blooms results in differential exposure of geographically separate copepod populations to toxic Alexandrium. We hypothesize that the ability of copepods to feed and reproduce on toxic Alexandrium should be higher in copepods from regions that are frequently exposed to toxic Alexandrium blooms. We tested this hypothesis with factorial common environment experiments in which female adults of the copepod Acartia hudsonica from five separate populations ranging from New Jersey to New Brunswick were fed toxic and non-toxic strains of Alexandrium, and the non-toxic flagellate Tetraselmis sp. Consistent with the hypothesis, when fed toxic Alexandrium we observed significantly higher ingestion and egg production rates in the copepods historically exposed to toxic Alexandrium blooms relative to copepods from regions in which Alexandrium is rare or absent. Such differences among copepod populations were not observed when copepods were fed non-toxic Alexandrium or Tetraselmis sp. These results were also supported by assays in which copepods from populations both historically exposed and naı̈ve to toxic Alexandrium blooms were fed mixtures of toxic Alexandrium and Tetraselmis sp. Two-week long experiments demonstrated that when copepods from populations naı̈ve to toxic Alexandrium were fed a toxic strain of Alexandrium they failed to acclimate, such that their ingestion rates remained low throughout the entire two-week period. The differences observed among populations suggest that local adaptation of populations of A. hudsonica from Massachusetts (USA) to New Brunswick (Canada) has occurred, such that some populations are resistant to toxic Alexandrium.

The Evolution of Plant Ecophysiological Traits: Recent Advances and Future Directions

functional diversity, which underlies variation in growth rates, productivity, population and community dynamics, and ecosystem function. The broad congruence of these variations with climatic and environmental conditions on local, regional, and global scales has fostered the concept that plant ecophysiological characteristics are well adapted to their local circumstances. For example, the repeated occurrence of plants with CAM (Crassulacean Acid Metabolism) photosynthesis and succulent leaves or stems in severely water-limited environments, and the independent evolution of these traits in numerous plant lineages, provides compelling evidence of the physiological evolution of these water-conserving traits under the influence of natural selection (Ehleringer and Monson 1993). Similarly, studies of the evolution of heavy metal tolerance confirm that natural selection may cause rapid ecophysiological evolution in just a few generations, leading to local adaptation in populations just a few meters apart (Antonovics et al. 1971). Many ecophysiological traits—considered here as all aspects of resource uptake and utilization, including biochemistry, metabolism, gas exchange, leaf structure and function, nutrient and biomass allocation, canopy structure, and growth—are likely to influence fitness and undergo adaptive evolution. Traits affecting the assimilation and use of resources such as carbon, water, and nutrients directly influence plant growth. Patterns of resource allocation to growth, reproduction, defense, and stress tolerance are also likely to be under strong selection. Phenotypic plasticity, the expression of different phenotypes by

Life history adaptation along a latitudinal cline in the water strider Aquarius remigis (Heteroptera: Gerridae)

AbstractWe addressed the general hypothesis that life history differences among eastern populations of the North American water strider, Aquarius remigis (Heteroptera: Gerridae), along a north‐south gradient are manifestations of genetic differentiation due to natural selection. We raised offspring of two field‐caught populations from each of three latitudes in a common laboratory environment at 20° C and two photoperiods. Nearly all Quebec (PQ) individuals (ca. 46° N) entered diapause to reproduce the following spring (univoltine life cycle), while intermediate proportions of New York (NY; ca. 43° N) and New Jersey (NJ; ca. 41° N) individuals reproduced directly, producing a second generation (bivoltine life cycle). PQ females were smaller, developed faster, and laid smaller eggs than NY and NJ individuals; NY and NJ populations differed little in these variables. NY females had longer life spans than either PQ or NJ females, but lower oviposition rates. Total reproductive output did not differ across latitudes. Photoperiod affected body length, development time, and reproductive pathway, resulting in a latitude by environmental interaction. PQ individuals reproduced directly under 15L : 9D (summer) conditions only, while the NY and NJ populations exhibited more direct reproduction under 13L : 11D (spring or fall) conditions. Some life history characters of the NY and NJ populations displayed the higher variability indicative of phenological transition zones. These results indicate local adaptation of populations to long‐term climatic patterns. Water striders appear to adapt to longer seasons by extending development, growing larger, and breeding directly. Larger body size and extended or rapid development are associated with bivoltinism and increase in egg size, but not necessarily with higher fecundity or oviposition rate. The phenological transition zone appears to be unrelated to a transition zone a little further south established by allozyme data and morphology, as all populations studied here could be electrophoretically identified as northern "type".

The genetic impact of introduced fishes on native species

The introduction of nonnative fishes or "exotics" and transplants of fishes outside their geographic range but within the same country is a contentious issue. The effects of these introductions on native fish faunas are well documented and have resulted in legislation controlling future introductions of alien species and management policies based largely on living with past mistakes. However, fish introductions also occur at two more subtle levels: transfers within the range of the species, and introduction of foreign DNA to produce "transgenics." The rationale for transfers is largely typological in that "a fish is a fish," at least as far as any given species might be concerned. Transfers disregard the concept that species are divided into genetically distinct units or "stocks" adapted to their particular environment and that introduction of nonlocal conspecifics can disrupt the genetics and adaptation of local populations. This paper raises some of the major issues and the need to synthesize the concepts, documented cases, and effects.

Środowiskowe uwarunkowania osadnictwa pradziejowego i wczesnośredniowiecznego w północnej części Borów Tucholskich

The dissimilanity of development in economy and setlement in the northern part of Tuchola Forest in relation to generally accepted scheme for Polish Lands was stated in the paper. This dissimilarity does not result from economic under-development of the discussed territories but from the perfect adaptation of local population to possibilities created by natural environment. Some "delay" in applying new ways of farming was caused by ecologic conditioning which for the whole time was determinent for forms and economic and settlement level in the northern part of Tuchola Forest.

Relationships in Taeniatherum (Poaceae)

Hybridization and cytogenetic studies of Taeniatherum caput-medusae (L.) Nevski were carried out on three diploid subspecies (2n = 14) including ssp. caput-medusae, ssp. crinitum (Schreb.) Melderis, and ssp. asperum (Simk.) Melderis. Most combinations showed high sterility. A high degree of bivalent pairing was observed in meiosis, indicating that all taxa have the same basic genome and that the differences between them are genetic rather than segregational. The occurrence of local population adaptation is assumed.

DISJUNCTIVE CLINE OF CRITICAL PHOTOPERIOD IN THE REPRODUCTIVE DIAPAUSE OF DROSOPHILA LACERTOSA.

EvolutionVolume 40, Issue 2 p. 418-421 Note and CommentFree Access DISJUNCTIVE CLINE OF CRITICAL PHOTOPERIOD IN THE REPRODUCTIVE DIAPAUSE OF DROSOPHILA LACERTOSA NOBUAKI ICHIJÔ, NOBUAKI ICHIJÔ Zoological Institute, Faculty of Science, Hokkaido University, Sapporo Hokkaido, 060 JapanSearch for more papers by this author NOBUAKI ICHIJÔ, NOBUAKI ICHIJÔ Zoological Institute, Faculty of Science, Hokkaido University, Sapporo Hokkaido, 060 JapanSearch for more papers by this author First published: March 1986 https://doi.org/10.1111/j.1558-5646.1986.tb00482.xCitations: 7AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume40, Issue2March 1986Pages 418-421 ReferencesRelatedInformation

Neighbors ameliorate local salinity stress for a rhizomatous plant in a heterogeneous environment.

The selection pressures experienced by clonal plants in heterogeneous environments may be significantly affected by physiological integration among ramets via rhizome connections. We experimentally examined how connections affected the response to saline soil conditions in Ambrosia psilostachya clones from natural saline basins in eastern Nebraska. Paired stems connected by uniform lengths of rhizome were grown in partitioned pots in 3 watering regimes: (1) both stems watered with tapwater, (2) both stems watered with salt water (1% NaCl), and (3) one stem watered with salt water and one with tapwater. All plants survived and grew in salt water, yet dry weight gain of salt-salt plants was only 34% of that for plants in uniform tapwater. Salt plants connected to tapwater plants had 2-fold higher dry weight gain than salt-salt plants. Their tapwater neighbors had significantly smaller biomass than pairs with both stems growing in tapwater. Measurements of leaf stomatal conductance, transpiration rate and water potential, together with root-shoot allocation patterns, suggest that rhizomes transported both water and photosynthate from tapwater plants to their neighbors in saline soil. These results indicate that ramets in a locally inferior environment can be helped by their neighbors, but at some cost to the contributing ramet. We discuss the consequences of this phenomenon for the evolution of local adaptation in populations of rhizomatous plants.