No abstract

We studied genetic diversity within and among populations of warty cabbage (Bunias orientalis L.), which is an alien species in Lithuania and other Baltic countries. In Lithuania, this weed colonises two main types of habitats: railway/roadsides and meadows on riversides. The aim of this study was to assess the genetic structure of invasive populations of B. orientalis in Lithuania and consider the impact of diverse habitats on the partitioning of genetic diversity using inter-simple sequence repeat (ISSR) markers. An analysis of molecular variance (AMOVA) carried out on the basis of ISSR showed that there is high genetic differentiation (46%) among populations of B. orientalis, which is probably caused by the founder effect and limited gene flow. However, we observed no impact of habitat on the genetic difference among populations. Similar levels of ISSR polymorphic loci were observed in riverside (P = 31.67%) and railway/roadsides (P = 30.51%) populations. UPGMA cluster analysis and principal coordinate analysis (PCoA) also did not show grouping of studied populations according to habitat type. High genetic differentiation among populations, as indicated by ISSR markers, confirm multiple independent introductions of this species in Lithuania.

Erigeron annuus (L.) Pers. (Asteraceae) is native species to eastern North America, but has been introduced to Europe and many other temperate regions of the world. In order to assess the impact of spreading history and settlement time on the genetic diversity of invasive populations of E. annuus, individual plants were sampled from 16 populations located in Switzerland, Poland, Lithuania and Latvia along the south-northern expansion direction of this species in Europe. One population was collected in native range (New Brunswick, Canada). The analysis of ISSR polymorphism in 253 plants revealed 161 polymorphic bands. The highest genotype variation and genetic diversity parameters were revealed in the populations from Switzerland and Poland, the least – in Latvian populations. All 37 plants from Latvia were clones of the same genotype. The comparison of genetic diversity parameters of populations from different countries showed the decrease of genetic diversity on the south-north direction.

The alien species Erigeron annuus (L.) Pers. is in an intensive spreading phase in Lithuania. Random amplified polymorphic DNA (RAPDs) and inter-simple sequence repeats (ISSRs) assays were used to study the genetic structure of old and new invasive populations and to determine the most spread genotypes of this species in Lithuania. Pairwise genetic distances between populations established using RAPD and ISSR markers significantly correlated (r=0.91, P<0.05). Our study indicates that there are two genetically different types of E. annuus populations. The first type is represented by a widely spread main clone and related monomorphic populations. The second type is represented by polymorphic populations, some of them present at sites where E. annuus has not been previously observed. Main clone predominates in nine populations and is from the region where this species was first described in natural ecosystems of Lithuania. UPGMA cluster analysis revealed genetic relationships between the main clone and accessions from old cemeteries where E. annuus has been grown as an ornamental plant. We found high genetic differentiation among populations (G ST=0.58 for RAPDs, G ST=0.64 for ISSRs). Taken together, our results will contribute to the monitoring of E. annuus spread in Lithuania.

No abstract