Climatic shifts within recent decades created favorable conditions for invasive species flourishing in more Northern parts of Europe. Our study was aimed at evaluation of genetic variability and habitat features of Impatiens parviflora populations growing in Lithuania. Twenty one populations were selected and analysed using simple sequence repeat (SSR) and randomly amplified polymorphic DNA (RAPD) assays. Evaluated by SSRs, 315 individuals were all monomorphic and homozygous at 4 loci and heterozygous at 1 locus. RAPD analyses revealed that the percentage of polymorphic DNA loci (% P) per population ranged from 7 to 39% and genetic differentiation between populations was ΦPT=0.790 (P<0.01). Genetic distances among populations (0.135–0.426) correlated significantly with geographical distances (r=0.183; P<0.008). Populations in overmoistured soil contained higher % P (28.3) when compared to drier soil (18.7; P<0.05). All recorded populations were close to roads; their % P did not depend on proximity to buildings, light intensity or population size. Our RAPD analyses indicate multiple introductions of this species in Lithuania. Analyses of I. parviflora at SSR and RAPD loci show that the invasion process is reflected in genetic structure.

Currently, there is an increasing focus on understanding the interactions between genetic features of the invader and environmental factors that ensure the success of invasion. The objective of our study was to evaluate the genetic diversity of Lithuanian populations of highly invasive small balsam (Impatiens parviflora) by amplified fragment length polymorphism (AFLP) markers and to relate molecular data to biotope features defined by employing neighboring species of herbaceous plants. Low polymorphism of I. parviflora populations was observed at AFLP loci. Hierarchical analysis of molecular variance did not reveal differentiation of populations depending on biotope, geography, or road types. Bayesian analyses of AFLP data demonstrated many genetic clusters. Our results suggest multiple introductions of I. parviflora into Lithuania. The polymorphism of AFLP loci of populations significantly correlated with the total coverage by herbaceous plants in the sites. Defined by principal component analysis, the variability of study sites was most related to the coverage of herbaceous plants and least related to the molecular features of I. parviflora populations. The sites with I. parviflora were classified into agricultural scrubland, riparian forest, and urban forest biotopes. Of them, urban forest was distinguished by the highest coverage of I. parviflora and the lowest Ellenberg indicatory values for light, soil acidity, and richness in nutrients.

Data on alien species show that plant invasions are caused by a complex combination of characteristics of invasive species (invasiveness) and characteristics of invaded environment (invasibility). Impatiens parviflora is one of Europe’s top invasive species. The present study aimed to evaluate molecular diversity of populations of highly invasive in Lithuania I. parviflora by applying several DNA markers and relating genetic parameters to abiotic and biotic environment. For sampling, urban forests, riparian forests, and agrarian shrublands were selected. Three different DNA-based techniques, Simple Sequence Repeats (SSR), Inter Simple Sequence Repeat (ISSR) markers, and Random Amplified Polymorphic DNA (RAPD), were used for detecting genetic variation between 21 populations. All population individuals were monomorphic and homozygotic for four loci and heterozygotic for one locus by SSR analysis. Hierarchical analyses of molecular variance at ISSR and RAPD loci revealed significant differentiation of populations depending on geographic zones of the country. Bayesian Structure analyses of molecular data demonstrated existence of many genetic clusters and this finding is in support to multiple introduction of the species. The polymorphism extent at ISSR loci was positively correlated with the total coverage of herbaceous plant species. The coverage by I. parviflora was negatively correlated with the total number of herbaceous species and light in the sites. Our results indicate that Lithuanian sites with I. parviflora might be distinguished by high soil nutrient levels. According to the principal component analysis, the coverage by I. parviflora was a more important variable of populations compared to molecular data or parameters of abiotic environment. In conclusion, complexity of invasibility and invasiveness factors determine the variability of I. parviflora sites, including genetic traits, coverage of invasive species and conditions of environment that were significant and interrelated.

Surprisingly little information is available about adaptations of invasive species in the Baltic countries. Since 1934 Impatiens parviflora DC. was recorded in the suburbs of Vilnius, supposedly it escaped from the VU Botanical Garden. Presently I. parviflora belongs to naturalized species of active distribution. In Lithuania, I. parviflora occurs abundantly in man-disturbed localities -urban sites, roadsides or farmyards. Permanently overmoistured gleyic forest sites are also common habitats of I. parviflora. Our study aimed at selection of RAPD primers for evaluation of genetic variability among geographically contrasting four populations of I. parviflora. Populations growing near the western, southern, northern and eastern borders of Lithuania (Karklė, Ratnyčia, Žagarė, Švenčionys) were selected. Randomly Amplified Polymorphic DNA (RAPD) as the most ubiquitous for plant analysis molecular markers type was selected for evaluation of genetic diversity of I. parviflora populations. Among thirty RAPD primers tested, 222, 250, 269, 340, 474, 516,, OPQ-11 generated the largest amount of DNA bands and were selected for the analyses. For each population, the percentage of polymorphic bands with ten primers was 21-27 (the lowest for Karklė and the highest for Žagarė population), and the number of polymorphic bands ranged in the interval 40-50. Molecular variance among populations was much higher (82%) than within populations. Varying geographically, populations of I. parviflora were sufficiently distinct according to RAPD based principal component analyses, also by UPGMA dendrograms. Pair-wise genetic distance among these populations ranged from 0.349 to 0.583. The obtained data show that distribution of invasive species might bring changes in genetic diversity.Key words: small balsam, Balsaminaceae, polymorphism, invasion, alien species INTRODUCTIONGlobalisation provides vastly expanded opportunities for plant species to be transported to new locations through a wide range of pathways [1]. Alien species might have serious implications for the environment and communities. Urgent problems of Europe include pathways of invasion and elucidation of species traits in determining invasiveness [2]. After introduction of I. parviflora to European botanical gardens at the beginning of the 19th century (e. g. 1837, in Dresden), its intervention to the natural communities was soon observed [3]. It is supposed that in Lithuania I. parviflora escaped from the VU Botanical Garden and in 1934 it was recorded in the suburbs of Vilnius for the first time [4]. Within the last decades in many European countries great attention has been paid to Impatiens glandulifera [5,6]. Investigations of behaviour of sister species, small balsam, are surprisingly scarce despite the fact that it belongs to naturalized species of active distribution [7], presently being very common for cities and intervening deciduous forest communities [8,9]. There is lack of information regarding local differentiation of both alien Impatiens 131Selection of RAPD pri...