No abstract

The chloroplast genome of the chromophytic alga Vaucheria bursata has been characterized by restriction site and gene mapping analysis. It is represented by a circular molecule 124.6 kb in size. An inverted sequence duplication (IR) not larger than 5.85 kb carries the rRNA genes and separates two single-copy regions of 64.6 kb and 48.3 kb from one another. The Vaucheria plastid genome exists in two equimolar isomers which is due to intramolecular flip-flop recombination within the IR sequences. The coding sites for 21 structural and soluble proteins have been mapped on both single-copy regions using heterologous gene sequences as probes. Although the overall gene order is found to be rearranged when compared with other chromophytic algal and land plant chloroplast genomes, most of the transcriptional units of cyanobacteria and land plant chloroplast genomes appear to be conserved. The phylogenetic implications of these findings are further discussed.

No abstract

1. The challenges to which plants are exposed in urban environments represent, in miniature, the challenges plants face as a result of global environmental change. Hence, urban habitats provide a unique opportunity to assess whether processes of local adaptation are taking place despite the short temporal and geographical scales that characterize the anthropocene . 2. We quantified the ecological diversity of spontaneously occurring urban habitat patches of A. thaliana. Using plant community indicators, we show that these patches differ in their levels of soil nutrient content and disturbance. Accordingly, plants in each patch displayed significantly different flowering time, size, and fitness. 3. Using a deep sampling approach coupled with reduced genome-sequencing, we demonstrate that most individuals can be assigned to a limited set of clonal lineages; the genetic diversity of these lineages represents the diversity observed in western European populations of the species, indicating that established urban populations originate from a broad regional pool of lineages. 4. We assessed the genetic and phenotypic diversity of these lineages in a set of common garden experiments. We report marked genetic differences in life-history traits, including time of primary and secondary dormancy as well as of flowering. These genetic differences in life-history traits are not randomly distributed but sorted out by ecological differences among sites of origin. 5. Synthesis: Our study shows that the genetically diverse phenology of a regional A. thaliana gene pool is not randomly distributed but filtered by urban environmental heterogeneity. This report is the first to show a pattern of local genetic adaptation within urban environments. We conclude that environmental filtering helps maintain functional diversity within species.

No abstract