Erhaltung und Wiederansiedlung des Kleinen Rohrkolbens ( Typha minima ) - Vegetationsaufnahmen, Monitoring und genetische Herkunftsanalysen

Abstract.: Galeuchet D. J. and Holderegger R. 2005. Conservation and re-introduction of Dwarf Bulrush (Typha minima) - vegetation surveys, monitoring and genetic analysis of origin. Bot. Helv. 115: 15-32. Typha minima was formerly widespread along fast flowing alpine rivers but is now red-listed as critically endangered. To assess its conservation perspectives, we surveyed the few remaining natural populations along the alpine part of the River Rhine from 1997 to 2002 and determined their genetic diversity using isozyme electrophoresis. Six of the populations became extinct or extremely small, probably due to shading by taller plants and trampling, while six other populations remained stable or increased, partly due to habitat restoration measures. The largest populations, with areas of more than 10'000 m2, are found in secondary habitats which are regularly disturbed due to water regime management. Of the 19 investigated isozyme loci, only six were polymorphic. Allelic diversity (1.4-1.8) was low in all populations, and the number of multilocus genotpyes (1-18) was low for 11 of 13 investigated populations. Genetic diversity was also studied for ex-situ cultivations of T. minima in Swiss botanical gardens and reintroduced stands.These artificial populations (each with 1-3 multilocus genotypes) were genetically similar to natural populations (average genetic distance 0.094). For two ex-situ cultivations with unknown origin, the likely origin could genetically be defined. Hybridisation between two ex-situ cultivations of different origin (i.e. a potential risk of genetic introgression) was detected in one botanical garden. It is concluded that the long-term conservation of T. minima requires both the restoration of regularly disturbed, sparsely vegetated river margins and the re-introduction of plants from ex-situ cultivations with appropriate origi

Adaptive vs. neutral genetic diversity: implications for landscape genetics

Genetic diversity is important for the maintenance of the viability and the evolutionary or adaptive potential of populations and species. However, there are two principal types of genetic diversity: adaptive and neutral - a fact widely neglected by non-specialists. We introduce these two types of genetic diversity and critically point to their potential uses and misuses in population or landscape genetic studies. First, most molecular-genetic laboratory techniques analyse neutral genetic variation. This means that the gene variants detected do not have any direct effect on fitness. This type of genetic variation is thus selectively neutral and tells us nothing about the adaptive or evolutionary potential of a population or a species. Nevertheless, neutral genetic markers have great potential for investigating processes such as gene flow, migration or dispersal. Hence, they allow us to empirically test the functional relevance of spatial indices such as connectivity used in landscape ecology. Second, adaptive genetic variation, i.e. genetic variation under natural selection, is analysed in quantitative genetic experiments under controlled and uniform environmental conditions. Unfortunately, the genetic variation (i.e. heritability) and population differentiation at quantitative, adaptive traits is not directly linked with neutral genetic diversity or differentiation. Thus, neutral genetic data cannot serve as a surrogate of adaptive genetic data. In summary, neutral genetic diversity is well suited for the study of processes within landscapes such as gene flow, while the evolutionary or adaptive potential of populations or species has to be assessed in quantitative genetic experiments. Landscape ecologists have to mind these differences between neutral and adaptive genetic variation when interpreting the results of landscape genetic studie

Characterization of microsatellite loci in Leucorrhinia caudalis , a rare dragonfly endangered throughout Europe

Leucorrhinia caudalis is a rare dragonfly, threatened throughout Europe. It only survived in a single population in Switzerland in the 1980s. However, it recently spread and colonized new ponds. In order to be able to study contemporary migration in this species, eight new microsatellite markers were developed and tested on 24 individuals from six Swiss ponds. We detected three to eleven alleles per polymorphic locus and found observed and expected heterozygosities of 0.250 to 0.875 and 0.215 to 0.840, respectivel

Development of microsatellite markers for the wetland grasshopper Stethophyma grossum

Stethophyma grossum is a threatened Eurosiberian grasshopper species. Since it is bound to wetlands, S. grossum is often used as indicator for extensive wet meadows. To study its movement capability and dispersal habitat in landscape genetic analyses, we developed ten polymorphic microsatellite markers, making use of next generation sequencing. Markers were tested on 75 individuals collected in five populations from Switzerland. We found four to 18 alleles per locus. Observed and expected heterozygosities varied between 0.215-0.893 and 0.397-0.831, respectively. One marker seems to be sex-chromosome X-linked and one showed high null allele frequencies, a phenomenon generally detected in microsatellite studies on grasshopper

Utility of Multilocus Genotypes for Taxon Assignment in Stands of Closely Related European White Oaks from Switzerland

Background and Aims European white oaks (Quercus petraea, Q. pubescens, Q. robur) have long puzzled plant biologists owing to disputed species differentiation. Extensive hybridization or shared ancestry have been proposed as alternative hypotheses to explain why genetic differentiation between these oak species is low. Species delimitation is usually weak and often shows gradual transitions in leaf morphology. Hence, individual identification may be difficult, but remains a critical step for both scientific work and practical management. Methods Multilocus genotype data (five nuclear microsatellites) were used from ten Swiss oak stands for taxon identification without a priori grouping of individuals or populations, using model-based Bayesian assignment tests. Key Results Three groups best structured the data, indicating that the taxonomical signal was stronger than the spatial signal. Most individuals showed high posterior probabilities for either of three genetic groups that were best circumscribed as taxonomical units. The assignment of a subset of trees, whose taxonomic status had been previously characterized in detail, supported this classification scheme. Conclusions Molecular-genetic assignment tests are useful in the identification of species status in critical taxon complexes such as the European white oaks. Such an approach is of practical importance for forest management, e.g. for stand certification or in seed trade to trace the origin of forest product

Cost-Effective, Species-Specific Microsatellite Development for the Endangered Dwarf Bulrush (Typha minima) Using Next-Generation Sequencing Technology

The dwarf bulrush (Typha minima Funck ex Hoppe) is an endangered pioneer plant species of riparian flood plains. In Switzerland, only 3 natural populations remain, but reintroductions are planned. To identify suitable source populations for reintroductions, we developed 17 polymorphic microsatellite markers with perfect repeats using the 454 pyrosequencing technique and tested them on 20 individuals with low-cost M13 labeling. We detected 2 to 7 alleles per locus and found expected and observed heterozygosities of 0.05-0.76 and 0.07-1, respectively. The whole process was finished in less than 6 weeks and cost approximately USD 5000. Due to low costs and reduced expenditure of time, the use of next-generation sequencing techniques for microsatellite development represent a powerful tool for population genetic studies in nonmodel species, as we show in this first application of the approach to a plant species of conservation importanc

Monitoring von Populationen der Helm-Azurjungfer Coenagrion mercuriale (Odonata: Coenagrionidae) : was taugen zwei Begehungen pro Saison?

Schutzmassnahmen für bedrohte Kleinlibellenarten werden für die Erfolgskontrolle oft von einem minimalen Monitoring mit zwei Begehungen pro Jahr begleitet. Dabei wird die Anzahl Imagines erfasst. Wir haben untersucht, ob ein solches Minimalmonitoring eine vertrauenswürdige Schätzung der Bestandesgrössen erlaubt. Dazu wurden zwei Datensätze, die im Jahr 2009 in denselben Populationen der Helm-Azurjungfer Coenagrion mercuriale erhoben wurden, miteinander verglichen. Der eine Datensatz umfasste ein Minimalmonitoring mit zwei Begehungen pro Jahr. Für den anderen Datensatz wurde während der Fortpflanzungsperiode jeder Tag mit guten Wetterbedingungen für Erhebungen genutzt, um so eine verlässliche Schätzung der Populationsgrössen zu erhalten. Die statistische Auswertung zeigte eine gute Übereinstimmung der beiden Methoden. Daraus folgern wir, dass auch mit einem Minimalmonitoring von zwei Begehungen pro Jahr Bestandesgrössen adäquat geschätzt werden können – ein Ergebnis, das wahrscheinlich auch auf andere Kleinlibellenarten übertragbar ist