| 1. |
- Andersson, Anna-Carin, et al.
(författare)
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Genetisk variation hos vildaväxter och djur i Sverige : En kunskapsöversikt om svenska arter och populationer, teori och undersökningsmetoder Genetic variation in natural populations of animals and plants in Sweden – a review of case studies, theory and some methods
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige har genom Konventionen om biologisk mångfald förbundit sig att bevarasin biologiska mångfald (biodiversitet) på ekosystem-, art- och gennivån. Ettvanligt synsätt är att bevarandet av ekosystem och naturtyper också bevarararter och att bevarandet av arter också bevarar genetisk variation inom arterna.Det finns en ökande insikt om att bevarandet av arter inte nödvändigtvis bevarar den genetiska mångfalden inom arterna. Bevarandet av genetisk variationhar hittills fått relativt liten uppmärksamhet inom den praktiska naturvården.På senare år har en del forskare argumenterat för att bevarandearbetetkanske borde fokuseras på att försöka förhindra utdöenden av genetisktdistinkta populationer snarare än att förhindra att arter dör ut. Förespråkarnamenar att man genom att satsa på att bevara genetiskt distinkta populationerbättre bevarar en arts evolutionära potential och anpassningsförmåga. På såsätt minskar risken att arten dör ut även i ett längre tidsperspektiv.Naturvårdsverket fick ett regeringsuppdrag 2006 att ”i samråd med Statensjordbruksverk, Skogsstyrelsen, Fiskeriverket och Sveriges lantbruksuniversitet,ta fram ett nationellt handlingsprogram för bevarande av genetisk variation hosvilda växter och djur.” Den här kunskapsöversikten är en del av underlagetinom uppdraget och har två huvudmålsättningar.Den första målsättningen med kunskapsöversikten är att beskriva den genetiska variationen i svenska populationer utifrån ett antal teman. Dessa teman ärvalda för att belysa vilka generella frågeställningar och problem som i dagslägetidentifieras som betydelsefulla inom den bevarandegenetiska forskningen. Varjetemaavsnitt redovisar det internationella forskningsläget, med exempel på relevanta genetiska studier av svenska organismer.Kunskapsöversiktens andra målsättning är att göra ämnesområdet genetikmer lättillgängligt för personer som inte har arbetat med genetiska frågeställningar tidigare eller de som vill repetera den teoretiska bakgrunden. Den somhar kunskap i populationsgenetiska och evolutionära processer behöver inteläsa detta för att kunna tillgodogöra sig resten av kunskapsöversikten. Kunskapsöversiktens syfte är inte att ge en heltäckande redogörelse för allagenetiska studier som är gjorda i Sverige. Studier före 1997 finns sammanställdai två tidigare rapporter (Laikre & Ryman 1997; Lönn m.fl. 1998). Dessa rapporter är fortfarande mycket aktuella. Eftersom det sker mycket genetiskforskning i Sverige och andra länder, gör den här kunskapsöversikten inteanspråk på att samla all nyvunnen genetisk kunskap om vilda växter och djursedan 1997, utan fokus ligger på de processer som kan antas förändra dengenetiska variationen i vilda populationer utifrån ett svenskt perspektiv.Nyttan av genetisk mångfald. Genetiska skillnader mellan individer, dengenetiska variationen, utgör grunden för all evolution och anpassning. Om allaindivider av en art är genetiskt identiska sätts evolutionen ur spel, med följd attarten inte kan anpassa sig till nya situationer t.ex. de klimatförändringar somförväntas ske till följd av mänskliga utsläpp av växthusgaser. Att mäta dengenetiska variationen och sätta den i samband med evolutionär förändring och ekologisk funktion i vilda populationer är forskningsmässigt mycket krävande.Dock visar en sammanfattande studie av ett stort antal växtstudier ett tydligtsamband mellan populationsstorlek, genetisk variation och olika mått på fertilitetoch livsduglighet, och en annan att ålgräsängar bestående av flera genotypervar mindre känsliga för miljöförändringar, växte tätare och hyste fler smådjur,än genetiskt enhetliga ålgräsängar.Mänskliga aktiviteter kan ha negativa konsekvenser för den genetiskamångfalden och därmed för anpassningsförmågan. Oavsett om variationen ärtill nytta för dagens populationer vet vi inte säkert vilka egenskaper som blirnödvändiga för överlevnaden i en ny miljösituation.Genetisk utarmning av små populationer. Minskad populationsstorlek ärett problem för många djur och växter i människopåverkade områden. Små,isolerade populationer förlorar genetisk variation p.g.a. slumpmässiga, lokalaprocesser (genetisk drift), och på sikt kan även anpassningsförmågan påverkas.Undersökningar visar att många populationer är tillräckligt små och isoleradeför att påverkas av genetisk utarmning, och att utarmade populationer ofta harlägre fertilitet och överlevnadsförmåga som en följd av ökad inavel eller att värdefulla alleler gått förlorade. Enligt flera studier kan det dock räcka med ettfåtal immigranter för att motverka negativa effekter av inavel. Däremot är detsvårt att dra generella slutsatser om hur genetisk utarmning påverkar populationers långsiktiga anpassningsförmåga utifrån de få studier som hittills utförts.Genetisk mångfald efter genflöde och hybridisering. Mänskliga aktiviteterhar i många fall medfört ett ökat genutbyte mellan naturliga djur- och växtpopulationer. Ett stort eller långväga genflöde kan påverka de populationersom tar emot genflödet. Det finns flera fall där mänskliga aktiviteter ökat genflödet genom att skapa gränszoner eller ”hybridmiljöer” där genetiskt olikapopulationer eller närbesläktade arter kunnat mötas och utbyta gener medvarandra. Hos flera arter, t.ex. skogshare respektive växten gulluzern vet manatt gener från införda eller domesticerade släktingar (fälthare resp. blåluzern)spridits ut i den svenska naturen. Däremot saknar vi fortfarande kunskap omdet genflöde som sker när nyanlagda vägslänter besås med utländskt gräsfröeller när utplanterade skogsträd, fåglar och fiskar med främmande bakgrundkommer i kontakt med inhemska bestånd i Sverige. Studier av bl.a. lax visar att genflöde kan vara skadligt genom att ge upphovtill hybrider med låg fertilitet eller livskraft (utavelsdepression). I andra fall hargenflödet gått så långt att arters särprägel hotas, som i fallet med de individfattiga öländska bestånden av silverviol som lätt bildar hybrider med andraarter. Ibland har det uppstått populationer med förmåga att invadera naturligaekosystem efter det att människan underlättat hybridisering mellan närbesläktade arter. Negativa effekter av genflöde måste också beaktas när naturvårdsprojekt avser förstärka populationer genom att tillföra uppfödda individer ellerindivider från andra, avlägsna populationer.Genetiska effekter av beskattning. Många djur- och växtarter utsätts för enregelbunden beskattning i form av fiske, jakt eller skogsbruk. Beskattning förväntas bl.a. öka risken för genetisk utarmning genom att minska den genetiskteffektiva populationsstorleken. I en studie av torsk ledde lokal beskattning tillett ökat inflöde av individer (och gener) från andra populationer, med följd att även det storskaliga variationsmönstret också påverkades. Det finns flera exempel på beskattade djurpopulationer som genomgått en riktad evolutionär förändring, som ett resultat av att beskattningen varit selektiv. I flera fall har dennaförändring minskat populationens förmåga att återhämta sig. Genetisk mångfald och pågående habitat- och klimatförändringar. Lokalanpassning innebär att populationer av en art är genetiskt anpassade till olikamiljötyper. Förmågan att anpassa sig utgör populationers evolutionära potentialoch denna är generellt sett större ju mer genetisk variation som finns i en population. Det finns många exempel på svenska arter som utvecklat lokalt anpassadepopulationer i vissa miljöer, t.ex. strandsnäcka, blåmussla, sill, storspigg, spåtistel, tall, och vitklöver. Förekomsten av lokala anpassningar betyder attindivider från olika populationer inte är direkt utbytbara – lokalt anpassadepopulationer har ett bevarandevärde i sig. Lokal anpassning är därigenom enviktig aspekt vid restaurering, stödutsättning och utnyttjande av populationer.För varje typ av anpassning behövs specifik genetisk variation och hur dennavariation är fördelad inom och mellan populationer samt i hur hög grad variationen kan spridas genom genflöde är i huvudsak okänt och ett område där viktig kunskap saknas. Genetisk särprägel hos svenska populationer. Sverige har få endemiska arteroch de som finns har uppkommit i sen tid som resultat av lokala processer(hybridisering, polyploidisering). Samtidigt finns det många genetiskt särprägladepopulationer. Populationerna är olika för att de har olika ursprung och invandringsvägar eller för att de är anpassade till sin lokala miljö. Taxonomiska enheter som arter, varieteter och former, liksom indelningar i evolutionärt signifikanta enheter och skötselenheter avspeglar en genetisk differentieringsom skett inom eller utanför landet. Genetiskt skilda grupper kan vara svåra atturskilja morfologiskt (de är kryptiska) och det finns flera studier där man medhjälp av molekylära markörer kunnat upptäcka tidigare okända genetiskstruktur hos svenska arter.Lönn m.fl. (1998) framhöll att populationer med en huvudsaklig utbredning i Sverige inte är marginella ur ett genetiskt perspektiv, medan arter som harhuvudsaklig sydlig utbredning och randpopulationer i Sverige är mindre genetiskt variabla här. I många fall är svenska populationer minst lika variabla sompopulationer i områden som inte varit nedisade under den senaste istiden. Dessamönster har bekräftats av senare undersökningar. Likaså styrker senare studieratt populationer från Öland och Gotland, Östersjön med dess stränder,fjällvärlden och det gamla odlingslandskapet är genetiskt särpräglade. Varjeförlorad population innebär en risk att värdefull genetisk variation – och därmed anpassningsförmåga – också går förlorad. Eftersom den genetiska mångfalden återfinns i enskilda popul
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| 2. |
- Berry, Max, 1969, et al.
(författare)
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Endovascular training with animals versus virtual reality systems: an economic analysis
- 2008
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Ingår i: J Vasc Interv Radiol. - : Elsevier BV. - 1051-0443. ; 19:2 Pt 1, s. 233-8
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To assess the relative costs of a virtual reality (VR) laboratory and an animal laboratory for endovascular skills training. MATERIALS AND METHODS: Cost data extracted from a previous experiment was used to perform a financial analysis according to the guidelines published by the National Institutes of Health. The analysis compared the purchase or rental of a Procedicus Vascular Interventional System Trainer to the rental of an animal laboratory. RESULTS: The VR laboratory course cost $3,434 per trainee versus $4,634 in the animal laboratory according to the purchase-versus-rental analysis. The cost ratio was 0.74 in favor of the VR laboratory. Cost ratio sensitivity analysis ranged from 0.25 in favor of the VR laboratory to 2.22 in favor of the animal laboratory. The first-year potential savings were $62,410 assuming exclusive use of the VR laboratory. The 5-year training savings totaled $390,376, excluding the $60,000 residual value of the simulator. Simulator rental reduced the course price to $1,076 per trainee and lowered the cost ratio to 0.23 in favor of the VR laboratory. Findings of sensitivity analysis ranged from 0.08 to 0.70 in favor of the VR laboratory. The first-year and 5-year potential national savings increased to $185,026 and $1,013,238, respectively. CONCLUSIONS: Although evidence remains sparse that the training of interventional skills in artificial environments translates to better performance in human procedures, there are good pedagogic grounds on which to believe that such training will become increasingly important. The present comparison of the direct costs of two such models suggests that VR training is less expensive than live animal training.
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| 3. |
- Chen, DeJiu, et al.
(författare)
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Model integration in the development of embedded control systems - A characterization of current research efforts
- 2006
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Ingår i: 2006 IEEE Conference on Computer-Aided Control System Design, Vols 1 and 2. - : IEEE conference proceedings. - 9780780397972 ; , s. 283-289
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Konferensbidrag (refereegranskat)abstract
- The design of advanced embedded control systems requires a systematic approach in handling their increasing complexity and in particular integration of the different aspects and parts of a product worked on by different experts. Several variants of model-based approaches are today advocated to facilitate systems integration. This paper describes a number of representative efforts that address multiple concerns or views including modeling languages such as AADL and EAST-ADL as well as model integration environments such as GeneralStore, ToolNet, and Fujaba. We present a characterization of the approaches and thereby highlight their commonalities and differences regarding basic integration mechanisms and engineering support. We conclude with a prospect for future work.
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| 4. |
- Gunnarsson, Urban, et al.
(författare)
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Local-scale genetic structure in the peatmoss Sphagnum fuscum
- 2007
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 16:2, s. 305-312
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Tidskriftsartikel (refereegranskat)abstract
- Sphagnum (peatmoss) dominates huge areas of the Northern Hemisphere and acts as a significant carbon sink on a global scale, yet little is known about the genetic structure of Sphagnum populations. We investigated genetic structure within a population of the common peatmoss Sphagnum fuscum, to assess local patterns of genetic diversity and the spatial extent of clones. One hundred seventeen shoots were sampled from five transects in Fuglmyra, central Norway, and sequenced for three anonymous DNA regions. Five neighbourhood patches were marked along each transect, and from each patch, five stems were sampled for molecular analyses. Seventeen haplotypes could be distinguished and two major groups of haplotypes differed by 12 mutational steps. The two major haplotype groups differed significantly in microhabitat association along the distance to groundwater table and the pH gradients, indicating microhabitat differentiation. The haplotypes within these groups were all genetically similar, differing by one or two mutations. The most common haplotype occurred in four transects separated by 250-m distance. Most of the molecular variation in the population was found among transects, and within patches. Large dominating clones within each transect resulted in low variation explained by the among-patch-within-transect component of spatial structure. Mutation appears to account for a larger proportion of the population variation than recombination. Within the population, vegetative growth and asexual reproduction from gametophyte fragments dominate as the main reproductive mode.
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| 5. |
- J:son Lönn, Eva, 1960-
(författare)
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Jobb(iga) nyheter : om dagstidningars bevakning av arbetsmiljöfrågor
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the beginning of this millennium the increasing level of work related illness was de-scribed, in the public debate, as one of the most serious and costly social problems of our times. An important question in the present study is whether or not the newspapers contributed to make their readers, the politicians and other social actors aware of this vast and growing problem.Thus, the main purpose was to find out the extent of the news media coverage on occupational health/ill-health in Swedish newspapers in the end of the 1990s, and the ways in which the topic was framed. Furthermore the intent was to produce a better and deeper understanding of the factors influencing the coverage.Theoretically the study draws on framing theory. Framing here refers to the process through which complex issues are reduced to journalistically manageable dimensions in the construction of news stories, resulting in a text, a news story that presents and high-lights some aspects and perspectives of the perceived reality but not others.A combination of research methods was used - A content and frame analysis of six months of occupational health coverage in seven newspapers; an interview study with journalists and their scientific sources about the news production; a one week’s news-room study aimed at observing the everyday production of news; and finally, a short email survey directed to the editorial staff at the examined news papers, with the purpose to get some indication on how the coverage of occupational health was organised and prioritized at the different newspapers.In the empirical analysis the newspapers´ picturing of occupational health/ill-health was compared with picture emerging from official statistics on occupational sickness and injury. In many respects a deviation was found between the two. Furthermore, simi-larities and differences in content between different newspapers, between different news sections and between news stories written by journalists of different sex, were examined.A key finding is that the Swedish newspapers did not draw their readers’ attention to the extensive and growing problem at the places of work. A majority of the stories related to occupational health/ill-health were episodic, and treated the issues as isolated and random events rather than predictable and preventable problems, although there were also more thematic articles written during special circumstances. The results indicate that a primary cause of the topics low priority in the newspapers was that the coverage of occupational health/ill-health had not been integrated into the journalistic routines.
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| 6. |
- Jonsson, Magnus, et al.
(författare)
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Genetic divergence of climatically marginal populations of Vicia pisiformis on the Scandinavian Peninsula
- 2008
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 145:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Vicia pisiformis L. is a perennial leguminous plant with a main distribution in broadleaved forest-steppes of eastern Europe. The species is classified as endangered (EN) according to the IUCN red-lists in both Norway and Sweden, due to severe fragmentation, small population sizes and continuing population decline. The populations on the Scandinavian Peninsula constitute the northern limit of the species distribution and are mostly restricted to warm stony slopes with predominantly southern aspects. In this study we used the AFLP method, which is a high-resolution genetic fingerprint method. Samples were collected from 22 Scandinavian populations. The overall genetic structure was analysed in an AMOVA, in a Mantel test and through constrained correspondence analysis (CCA). The ordination scores representing non-geographic genetic divergence were extracted from the CCA and analysed in a linear model using habitat variables and population size as explanatory variables. We found (i) a strong geographic structure, (ii) significant genetic divergence between populations, (iii) that this genetic divergence remained significant even after removing the effect of geography in a partial CCA and (iv) that the remaining non-geographic part of genetic divergence (distance from the ordination centre) was associated with aspect, populations with a northern aspect were more genetically divergent. Aspect explains more variation than population size and is the only variable retained in the minimal adequate model. We suggest that local adaptation has caused this divergence from an expected geographical pattern of genetic variation. This explanation is further supported by the association between aspect and specific AFLP fragments. Many plant populations are relics of a different climate (Aguirre-Planter et al. 2000; Despres et al. 2002; Pico and Riba 2002). In response to long-term climate change, populations can either migrate towards a more favourable climate or adapt to the new conditions (delaVega 1996; Jump et al. 2006). Species with limited dispersal ability are at risk of reaching isolated dead-ends of decreasingly suitable habitat, without any suitable habitat within dispersal distance (Colas et al. 1997). Isolated populations have to use their inherent evolutionary potential and adapt to changes in environmental conditions, or they will go extinct. As population fragments go extinct, those that remain will become increasingly isolated from each other both spatially and also genetically as the level of gene flow declines with increasing distance. Such correlation between genetic dissimilarities and geographic distances, known as isolation by distance (Slatkin 1993; Wright 1943), when found, suggests a history of geographically limited gene flow (Kimura and Weiss 1964). On top of an isolation by distance pattern there might be other genetic structures to be found. Occasional long-distance dispersal events for example may disturb geographic patterns with puzzling allele distributions as a result (Nichols and Hewitt 1994). Genetic drift is a process that will affect any pattern of genetic variation in a random fashion. Local adaptation through natural selection is a process that, if sufficiently strong in comparison with gene flow and genetic drift, will create patterns where genetic differentiation is associated with certain environmental conditions (Wright 1951). Several studies have shown the importance of local adaptation of populations (reviewed by Kawecki and Ebert 2004) (see also Bonin et al. 2006; Knight and Miller 2004; Kolseth and Lönn 2005; Lönn et al. 1998). Local adaptation can be strong also at small spatial scales (Snaydon and Davies 1976; Lönn 1993) even though it is sometimes very limited in terms of the number of genes involved (Kärkkainen et al. 2004) Environmental variability provides a base for biological variation by imposing differentiated selection pressures resulting in local adaptation. Topography provides large environmental variation within a relatively small area and thereby provides a basis for small-scale local adaptations. Depending on the local topographic possibilities populations can either migrate up and down slopes or along the same altitude to a different aspect to find a suitable microclimate. The dispersal distance will be much shorter per degree of temperature change during altitudinal migration (Hewitt 1996), than during simple latitudinal migration across a flat landscape. Slope and aspect are two important topographic parameters that determine the influx level of solar radiation, especially towards the poles where the total global radiation decreases (Larcher 2003). Vicia pisiformis is an endangered poorly-dispersed long-lived forest herb with its main distribution across the semi-open broadleaved forest steppes of eastern Europe. The Scandinavian populations are believed to be climate relict populations from warmer times. Earlier genetic studies of V. pisiformis using allozymes, RAPD:s and morhology, have found low to very low levels of genetic variation (Gustafsson and Gustafsson 1994; Black-Samuelsson et al. 1997; Black-Samuelsson and Lascoux 1999). Therefore we used AFLP (amplified fragment length polymorphism) markers, which detect even very small genetic differences between individuals. AFLP mainly analyse neutral variation, as the major fraction of most genomes is assumed to be neutral. However, since the AFLP-fragments are distributed randomly throughout the whole genome some fragments may be situated so close to regions under selection that they become more or less linked to them. This linkage disequilibrium between molecular markers and regions under selection, often referred to as quantitative trait loci (QTL), forms the basis for both QTL-mapping and marker assisted selection (MAS), reviewed by Dekkers and Hospital (2002). Gardner and Latta (2006) for example, found QTL under selection in both natural environments and in the greenhouse. Markers have been found to be connected to biomass production (Cavagnaro et al. 2006) and environmental variation (Bonin et al. 2006; Jump et al. 2006; Porcher et al. 2006). In this study we examine 22 Swedish and Norwegian populations of Vicia pisiformis and ask (i) if there is genetic differentiation between these populations, (ii) if there is can it be explained in its entirety by geographic location or (iii) can it partly be explained by habitat characteristics, suggesting local adaptation, or population size, suggesting genetic drift. We show that populations are differentiated geographically and that genetic variation in addition to the geographical pattern is associated with habitat.
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| 7. |
- Kolseth, Anna-Karin, 1976-
(författare)
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Evolutionary Processes and Spatial Genetic Variation in Euphrasia stricta on the Baltic Island of Gotland
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The identification of processes governing genetic structure at different spatial scales remains a major challenge in evolutionary biology and is of considerable applied interest in conservation biology. In Euphrasia stricta five varieties have been identified (brevipila, gotlandica, stricta, suecica and tenuis) based on differences in habitat, phenology and morphology. In this thesis, I examined genetic variation at AFLP and microsatellite marker loci in relation to variation in habitat and morphology within and among varieties of E. stricta on the island Gotland in the Baltic Sea. The results are discussed in relation to evolutionary processes acting within this species complex.In a study conducted at the regional scale, the two early-flowering varieties suecica and tenuis each formed a genetically distinct group, while the three late-flowering varieties brevipila, gotlandica and stricta formed a third group. The results suggest that suecica and tenuis have ancient origins since they are genetically different both from the brevipila/gotlandica/stricta group and from each other despite their similar habitat preferences. This pattern was obtained using both marker systems. Discrepancies between AFLP and microsatellites were found in patterns of isolation by distance and in estimates of expected heterozygosity, He.Focusing on the mixed genetic group brevipila/gotlandica/stricta and the causes behind their clustering together despite differences in morphology and habitat preferences, I performed a study at a smaller geographic scale. Studying a population of E. stricta I found that, although gene flow within the population was strong, it had not prevented the formation of genetic groups associated with micro-habitat properties.An important result for conservation of the rare variety suecica is its distinct genetic separation from variety tenuis. If the aim of conservation is to preserve the uniqueness of suecica, the two varieties should be treated as separated entities.
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| 8. |
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| 9. |
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| 10. |
- Kolseth, Anna-Karin, et al.
(författare)
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Genetic structure of Euphrasia stricta on the Baltic island of Gotland, Sweden
- 2005
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 28:4, s. 443-452
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Tidskriftsartikel (refereegranskat)abstract
- Genetic differentiation between and within five varieties of Euphrasia stricta (var. brevipila, var. gotlandica, var. stricta, var. suecica and var. tenuis) on Gotland was investigated, using amplified fragment length polymorphism, AFLP. The varieties are described in the literature by morphology and association to habitat type. We wanted to investigate whether the varieties are locally adapted populations to the typical habitat type for each variety or if they are preadapted to certain habitat types and have colonized Gotland in their present form. A constrained principal coordinate analysis revealed three genetically differentiated subunits within the species. The two early-flowering varieties suecica and tenuis each formed a distinct group, while the three late-flowering varieties brevipila, gotlandica and stricta together formed the third group. A phylogenetic tree confirms the partitioning into three groups. Within the group containing the late-flowering varieties there are populations that pair as each other's closest relatives, but belong to different varieties. These pairs are also geographically adjacent. The phylogenetic tree had a “star-like” appearance indicating a stronger divergence between populations than between varieties. The same pattern was seen in the partitioning of genetic diversity, with a lower amount of genetic variation occurring between varieties, FST=0.14, than between populations within the varieties, FST ranging from 0.26 to 0.60. In Euphrasia stricta the varieties suecica and tenuis and the group containing the varieties stricta/gotlandica/brevipila are likely to have a phylogeographical history outside Gotland, or an ancient and concealed local origin on the island. Within the group stricta/gotlandica/brevipila local evolutionary events seem to determine the variety identity, probably through local adaptation. Natural selection, genetic drift and mutations create genetic differentiation between populations. Gene flow, on the other hand, may counteract these processes (Slatkin 1987). Local adaptation is affected by the stability and strength of the natural selection and the amount of gene flow (Rice and Mack 1991, van Tienderen 1992, Miller and Fowler 1994), but also by the amount of genetic variability for the character that selection works on (Dudley 1996). Many studies have been done in the area of local adaptation (Lönn 1993, Prentice et al. 1995, Lönn et al. 1996, Liviero et al. 2002), and some studies have identified selective agents causing the adaptations. The selective agents are for example small differences in ecological niches and frequency dependent selection caused by pathogens (Parker 1994) or differences in selection regimes in different habitats (Kittelson and Maron 2001). Recent findings on ecological speciation emphasizes the importance of niche-shifting in local populations or groups of populations (Levin 2003) and rapid accumulation of beneficial mutations in isolated small populations (Rieseberg et al. 2003). Evolution works on different spatial and temporal scales, which makes it important to consider these different scales when studying evolutionary processes. Looking at the local phylogeny, geographic and temporal aspects are important when they link evolutionary processes to the extant landscape and the properties of the genetic structure. Linking evolutionary processes to the extant landscape is an important tool in evaluating evolutionary potential and predicting effects of landscape changes. Regional dynamics within species, using varieties/ecotypes, may also give information on initiation of speciation events. Manel et al. (2003) introduce and define landscape genetics as the combination of molecular population genetics and landscape ecology. The advantage of landscape genetics is the combination of the broad geographical span of scales (landscape to microclimate) and the high genetic resolution (individuals) compared to biogeography and phylogeography, which focuses more on species level at a broad spatial and temporal scale. Escudero et al. (2003), like Manel et al. (2003), put an emphasis on the spatial analysis of genetic diversity where a second step is to find ecological or demographic processes that could have shaped the genetic structure. A more direct approach is to measure habitat and genetic properties at many geographic locations and then model the biological processes shaping the spatial genetic structure (Lönn 1993, Prentice et al. 1995), which is the approach we intend to follow here. Molecular markers will be able to trace stochastic processes like drift and gene-flow (Page and Holmes 1998) as well as selective events through hitch-hiking (Hedrick 1980) and linkage events: AFLP has been used to identify quantitative trait loci by Via and Hawthorne (2002) and to explore the role of directional selection in whitefish ecotypes by Campbell and Bernatchez (2004). Yeo (1954, 1956, 1961, 1962, 1964, 1966, 1968) has done an extensive study of the cytology, hybridisation, cultivation, germination and relationship between species of British and European Euphrasia species. Yeo (1968) concludes that differences in chromosome number, habitat preferences and spatial distribution drives the speciation of Euphrasia in Europe and limits the hybridisation between species. The hybridisation may however result in new gene combinations for selection to work on (Yeo 1968). Yeo (1968) suggests that Euphrasia has gone through a fast and quite recent evolution in Europe after the last glaciation since Euphrasia has interfertile species of which many are endemic to small areas. Today, species differentiation within Euphrasia may be due to vegetation history, hybridisation and the parallel selection of well-adapted biotypes in similar or identical habitats (Karlsson 1976). Both Karlsson (1986) and Yeo (1968) put emphasis on the habitat specialization as an important factor in speciation referring to high morphological variability and hybridisation creating possibilities to evolve habitat specializations in Euphrasia.Zopfi (1998) showed in cultivation experiments that there is a genetic basis for different ecotypic variants of Euphrasiarostkoviana defined by grassland management, concerning onset of flowering, seed size and flowering period, life-history characters that are important adaptations to grazing and mowing. Euphrasia stricta is a tetraploid annual hemiparasite belonging to the Scrophulariaceae family (Yeo 1968, Krok and Almquist 2001). The species occurs all over Europe, except on the British Isles and in Spain and Portugal (Hultén and Fries 1986). In Sweden five varieties are found, which are subdivided based on morphology, phenology and habitat preference (Krok and Almquist 2001). They all grow on the Baltic island of Gotland, which is situated east of Sweden consisting of Silurian limestone (Fredén 1994). Euphrasia stricta var. suecica and E. stricta var. tenuis grow in traditionally managed wooded hay meadows and both are early flowering (Karlsson 1984). The variety suecica is red-listed according to the Swedish Red List (Gärdenfors 2000) and exists only in meadows on Gotland. The variety tenuis exists not only on Gotland but also on the Swedish mainland although it is declining throughout its distribution range. The populations of suecica and tenuis on Gotland are well known (Karlsson 1984, Petersson 1999). Euphrasia stricta var. stricta and E. stricta var. brevipila occur in pastures, along paths and on cultivated land. They flower later in the summer than var. suecica and var. tenuis. The variety stricta is common on the calcareous ground on Gotland with short grass turf, but rare on the mainland in contrast to the variety brevipila, which is common in whole of Sweden except on Gotland. The variety brevipila prefers soils that contain more sand compared to stricta. The late-flowering variety gotlandica is only found on Gotland and Öland, the second Baltic island on the Swedish east coast, were it is restricted to temporary pools on limestone ground (alvar) (Karlsson 1986). All Euphrasia species seems to lack a persistent seed bank (Karlsson 1984), but seeds have survived for up to three years in pots in cultivation experiments of other Euphrasia species (Yeo 1961). Artificial selfing and crosses within and between populations of Euphrasia stricta var. stricta yield high fertility in progeny pollen, 70–100% in between population crosses and 90–100% in selfing or within population crosses (Karlsson 1986). Flowering time for Euphrasia is not only dependent on habitat, but also to some extent on temperature and host attachment (Wilkins 1963, Yeo 1964, Molau 1993, Svensson et al. 2001, Svensson and Carlsson 2004). Euphrasia stricta probably have a mixed mating system (von Wettstein 1896). Based on these factors, which separates the varieties spatially and temporal, the aim of this study was to examine whether the varieties are locally adapted ecotypes that have evolved more than one time on the studied geographical scale or if they are distinct units over the region, implying colonization from outside or a single evolutionary event
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