Although the invasive azooxanthellate corals
and
are spreading quickly and outcompeting native species in the Atlantic Ocean, there is little information regarding the genetic structure and path of ...introduction for these species. Here we present the first data on genetic diversity and clonal structure from these two species using a new set of microsatellite markers. High proportions of clones were observed, indicating that asexual reproduction has a major role in the local population dynamics and, therefore, represents one of the main reasons for the invasion success. Although no significant population structure was found, results suggest the occurrence of multiple invasions for
and also that both species are being transported along the coast by vectors such as oil platforms and monobouys, spreading these invasive species. In addition to the description of novel microsatellite markers, this study sheds new light into the invasive process of
.
BACKGROUND AND AIMS: The dwarf eelgrass, Zostera noltii, is a predominant inhabitant of soft-bottom intertidal regions along the coasts of northern Europe. It is a monoecious, protogynous angiosperm ...in which the potential for self-fertilization and inbreeding are high, especially if clone sizes exceed pollen dispersal distances. The aim of the present study was to determine the relationship between mating system and clonal structure, examine the relative roles of geitonogamous selfing and biparental inbreeding, measure pollen availability (multiple paternities) and estimate pollen dispersal. METHODS: A 100-m² plot was established in a large, intertidal Z. noltii meadow on the island of Sylt in the German Wadden Sea. A total of 256 adult shoots was sampled: one from the centre of 100 fixed 1-m² quadrats (large scale resolution) and an additional 156 from within eight randomly selected 1-m² sub-quadrats (small-scale resolution). DNA was extracted from seeds and leaf tissue of all samples and genotyped with nine microsatellite loci. KEY RESULTS: Mating system analysis revealed high multilocus and single locus outcrossing rates. Average pollen dispersal distance was nearly the same as the average genet (clone) size. Multiple paternity was common and 20-30 % of mature seeds originated from matings within the plot. Among inbred seeds, most resulted from geitonogamy rather than biparental inbreeding. CONCLUSIONS: Moderate disturbances intrinsic to the intertidal habitat appear to facilitate seed recruitment by gap formation. Pollen dispersal distances are sufficient to maintain outcrossing and high clonal diversity.
Tall fescue (Festuca arundinacea Schreb.) plant has been often reported to reproduce by its rhizomes, although it has been generally considered as a bunch-type grass. We studied the clone structure ...of an 8-year-old pasture population of F. arundinacea cv. Hokuryo using starch gel and polyacrylamide electrophoresis to examine the extent and pattens of clonal spread. Preliminary experiment on intra-cultivar variation in zymograms of five enzyme systems (ACP, EST, GOT, 6PGD AND PGI) confirmed the usefulness of these methods for clone identification in combination with mapping of the relative positions of ramets within the sward. Two 1 x 1 centiare quadrats were sampled from the sward and determined for the phenotypes of all stands by five enzyme systems. Of 54 genets identified over two quadrats fourteen ones contained two or more ramets that were distributed closely each other. This result suggested that this F. arundinacea population may be maintained partly by rhizomes. This electrophoretic method distinguishing the clones will be useful in detecting more persistence genotypes of F. arundinacea in grazed swards
Clone structure of a perennial ryegrass (Lolium perenne L.), tetraploid cv. Friend) population was studied using starch gel electrophoresis for a 4-year-old sward. The sward consisted mosaicly of two ...patch types, one with distinct stands of L. perenne and one with dense clumps of that. In the patch with distinct stands, two 1 x 1 square meter quadrats were placed and determined for the phenotypes or genotypes of all stands by two enzyme systems (PGI and GOT). Of 54 genets detected over two quadrats, nine ones contained two or more ramets which were distributed closely each other. In the densely aggregated patch where it was hard to distinguish ramets, five 25 x 40 square-cm quadrats were excavated intact and mapped for the position of the clumps (i.e. ramet aggregation). Electrophoretic analysis showed that the genets tend to form the discrete spatial units, with high density of genet (ca. 132 genets m(-2)). Analysis of the genet composition within 10 large stands specified that six ones consisted of two or more genets. These results suggest that this L. perenne population may be maintained partly by aerial tillering, and that intermixed genets may occur frequently.
Searching for code examples on the Internet is commonly and frequently performed by software developers but wastes a lot of their time and reduces their productivity. To aid developers with this ...problem, a system is needed that can allow them to get appropriate code recommendations for reuse within the IDE. In this paper, we present our prototype tool CodeEase, developed as an Eclipse plugin, which generates method recommendations against the code of the developer. The recommendations are based on clone detection and an analysis of Method Clone Structures (MCS) - a type of structural clones- from a large repository of code.
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