Suchergebnisse

Abstract
Mute swan Cygnus olor is the most abundant breeding swan species in Rīga and Latvia. Since manmade habitats are the preferred breeding habitats of this species - Cygnus olor is of particular interest in studies of urban biodiversity. The latest records show that 30-40 pairs breed annually in Rīga, 400-700 individuals migrate through the area, and 120-150 individuals stay over winter. The goal of our study was to determine the genetic variation of the mute swan population in Rīga. Blood samples were collected from 47 individual birds found in different sites in Rīga or elsewhere in Latvia. The universal retrotransposon based iPBS markers were used to estimate diversity. Three primers (2076, 2080, and 2415) amplified 64 DNA fragments; of these 18 (28%) were polymorphic. The average diversity index based on polymorphic markers for the studied individuals was 0.425. All individuals, with the exception of two pairs of individuals, could be separated by means of these markers. The grouping of individuals was not be associated with their sampling location, gender and age. The genetic diversity indexes were compared between these groups. The breeding individuals (including their cygnets) had bands not showing variation among breeding birds as compared to the not breeding ones.

Abstract
White clover (Trifolium repens L.) is well represented in the urban environment and wide areas. The goal of this study was to compare the genetic features and to determine the genetic distances and similarities between some populations of white clover using iPBS (inter primer binding sites) technique in a retrotransposon-based method in samples from ecologically different areas in Latvia. Comparisons were made between three plant groups: urban environment (different areas in Rīga), Latvian countryside territory (four different localities), and the commercial variety 'Daile'. The Shannon diversity index was not high (0.2974 for Rīga, 0.3079 in countryside territories, and 0.3367 for the variety 'Daile'), but the polymorphic bands present in all evaluated plant sets were higher than 89%. Using principal coordinates analysis the white clover formed three clusters. One cluster included plants from the variety 'Daile'. The plants from Rīga urban area and different sites of Latvia formed two clusters.

Abstract
Spring barley breeding has been carried out for almost a century in all three Baltic countries. The efforts of breeders have resulted in many new improved varieties released. The goal of our project was to survey the effect of these efforts throughout the century on this crop. The material included in this study consisted of 64 accessions originating from Latvia, Estonia and Lithuania, representing landraces, varieties released from 1927 to 2001, and breeding lines. Six agronomic traits (days to heading, days to maturing, plant height, harvest index, volumetric weight and thousand kernel weight) were recorded during two years (2002 and 2003) at three locations - Priekuïi (Latvia), Landskrona (Sweden) and Bjørke (Norway). The differences between spring barley materials of different origin and from different breeding periods were assessed, and variation of their performance in different environments was discussed