6 research outputs found
Spatial genetic structure of the sea sandwort (<i>Honckenya peploides</i>) on Surtsey:an immigrant's journey
Sea sandwort (Honckenya peploides) was one of the first plants to successfully colonize and
reproduce on the volcanic island Surtsey, formed in 1963 off the southern
coast of Iceland. Using amplified fragment length polymorphic (AFLP) markers,
we examined levels of genetic variation and differentiation among
populations of H. peploides on Surtsey in relation to populations on the nearby island
Heimaey and from the southern coast of Iceland. Selected populations from
Denmark and Greenland were used for comparison. In addition, we tested
whether the effects of isolation by distance could be seen in the Surtsey
populations. Using two primer combinations, we obtained 173 AFLP markers
from a total of 347 plant samples. The resulting binary matrix was then
analysed statistically. The main results include the following: (i) Surtsey had
the highest proportion of polymorphic markers as well as a comparatively
high genetic diversity (55.5% proportion of polymorphic loci, PLP; 0.1974 HE) and Denmark the lowest
(31.8% PLP; 0.132 HE), indicating rapid expansion during an early
stage of population establishment on Surtsey and/or multiple origins of
immigrants; (ii) the total genetic differentiation (FST) among Surtsey
(0.0714) and Heimaey (0.055) populations was less than half of that found
among the mainland populations in Iceland (0.1747), indicating substantial
gene flow on the islands; (iii) most of the genetic variation (79%, p < 0.001) was found within localities, possibly due to the
outcrossing and subdioecious nature of the species; (iv) a significant genetic
distance was found within Surtsey, among sites, and this appeared to
correlate with the age of plant colonization; and (v) the genetic structure
analysis indicated multiple colonization episodes on Surtsey, whereby H. peploides most
likely immigrated from the nearby island of Heimaey and directly from the
southern coast of Iceland
Heavy metal and nitrogen concentrations in mosses are declining across Europe whilst some “hotspots” remain in 2010
In recent decades, naturally growing mosses have been used successfully as biomonitors of atmospheric deposition of heavy metals and nitrogen. Since 1990, the European moss survey has been repeated at five-yearly intervals. In 2010, the lowest concentrations of metals and nitrogen in mosses were generally found in northern Europe, whereas the highest concentrations were observed in (south-)eastern Europe for metals and the central belt for nitrogen. Averaged across Europe, since 1990, the median concentration in mosses has declined the most for lead (77%), followed by vanadium (55%), cadmium (51%), chromium (43%), zinc (34%), nickel (33%), iron (27%), arsenic (21%, since 1995), mercury (14%, since 1995) and copper (11%). Between 2005 and 2010, the decline ranged from 6% for copper to 36% for lead; for nitrogen the decline was 5%. Despite the Europe-wide decline, no changes or increases have been observed between 2005 and 2010 in some (regions of) countries
Country-specific correlations across Europe between modelled atmospheric cadmium and lead deposition and concentrations in mosses
Previous analyses at the European scale have shown that cadmium and lead concentrations in mosses are
primarily determined by the total deposition of these metals. Further analyses in the current study show
that Spearman rank correlations between the concentration in mosses and the deposition modelled by
the European Monitoring and Evaluation Programme (EMEP) are country and metal-specific. Significant
positive correlations were found for about two thirds or more of the participating countries in 1990,
1995, 2000 and 2005 (except for Cd in 1990). Correlations were often not significant and sometimes
negative in countries where mosses were only sampled in a relatively small number of EMEP grids.
Correlations frequently improved when only data for EMEP grids with at least three moss sampling sites
per grid were included. It was concluded that spatial patterns and temporal trends agree reasonably well
between lead and cadmium concentrations in mosses and modelled atmospheric deposition