Genetic variation and clonal diversity in island Cephalanthera rubra populations from the Biebrza National Park, Poland

Three populations of the orchid species Cephalanthera rubra localized on neighbouring mineral islands in the Biebrza National Park (north-east Poland) were examined using 16 allozyme loci. The percentage of polymorphic loci in these C. rubra populations ranged from 25 to 31.3% and the mean number of alleles per polymorphic locus from 1.25 to 1.31. The levels of observed heterozygosity at polymorphic loci were higher than expected for all populations. The overabundance of heterozygotes was noted in every population. The values of fixation indices were highly negative. The genetic differentiation among the three populations was small ( F _ST = 0.0173), albeit statistically significant ( P  < 0.001). The level of gene flow varied from 13 to 16. Fourteen multilocus genotypes were found among the 401 ramets sampled from the populations. Only four of them were common for all populations. The frequency of genotypes was different in these three populations of C. rubra . Some of the multilocus genotypes dominated in the given populations, others were found sporadically. Genetic variation within C. rubra populations is mainly the result of small population sizes and reflects the influences of breeding system and type of reproduction. On the other hand, these properties are also connected with habitat conditions.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 99–108.     

High levels of genetic diversity in populations of Iris aphylla L. (Iridaceae), an endangered species in Poland

We used RAPDs (Random Amplified Polymorphic DNAs) to investigate genetic diversity and its partition within and between three populations of Iris aphylla in Poland. Analysis of Molecular Variance (AMOVA) of 84 distinct RAPD multiband genotypes revealed higher variation within populations (77.2%) than genetic differentiation between them (22.8%, P  < 0.002). Values of genetic diversity indices ( H ) were similar in all three sites (0.21–0.24). The differentiation of the populations corresponded to low average gene flow ( Nm  = 0.81). Our results indicated that genetic diversity was independent of population size. We concluded that although sexual reproduction and gene flow between populations of I. aphylla were very limited, they preserved high levels of genetic diversity. Relatively large number of seeds, which migrated in the past to populations, as well as patterns of reproduction and life history of I. aphylla may explain this situation.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 65–72.     

Long tree‐ring chronologies reveal 20th century increases in water‐use efficiency but no enhancement of tree growth at five Iberian pine forests

We investigated the tree growth and physiological response of five pine forest stands in relation to changes in atmospheric CO₂ concentration (c_a) and climate in the Iberian Peninsula using annually resolved width and δ¹³C tree‐ring chronologies since ad 1600. ¹³C discrimination (Δ≈c_i/c_a), leaf intercellular CO₂ concentration (c_i) and intrinsic water‐use efficiency (iWUE) were inferred from δ¹³C values. The most pronounced changes were observed during the second half of the 20th century, and differed between stands. Three sites kept a constant c_i/c_a ratio, leading to significant c_i and iWUE increases (active response to c_a); whereas a significant increase in c_i/c_a resulted in the lowest iWUE increase of all stands at a relict Pinus uncinata forest site (passive response to c_a). A significant decrease in c_i/c_a led to the greatest iWUE improvement at the northwestern site. We tested the climatic signal strength registered in the δ¹³C series after removing the low‐frequency trends due to the physiological responses to increasing c_a. We found stronger correlations with temperature during the growing season, demonstrating that the physiological response to c_a changes modulated δ¹³C and masked the climate signal. Since 1970 higher δ¹³C values revealed iWUE improvements at all the sites exceeding values expected by an active response to the c_a increase alone. These patterns were related to upward trends in temperatures, indicating that other factors are reinforcing stomatal closure in these forests. Narrower rings during the second half of the 20th century than in previous centuries were observed at four sites and after 1970 at all sites, providing no evidence for a possible CO₂‘fertilization’ effect on growth. The iWUE improvements found for all the forests, reflecting both a c_a rise and warmer conditions, seem to be insufficient to compensate for the negative effects of the increasing water limitation on growth.     

A new Aspleniutn hybrid from Valencia (Spain) related to A. majoricum Litard

PANGUA, E., PRADA, C, PAJARON, S. & SALVO, E., 1992. A new Aspleniutn hybrid from Valencia (Spain) related to A. majoricum Litard . A new diploid Asplenium hybrid, found in the Iberian Peninsula (Valencia, Benifairo de Valldigna), is described and the name Asplenium x protomajoricum proposed. The plants exhibit c. 72^I at meiosis. The cytology and morphology of the hybrid and its occurrence between the assumed parentals suggest that it originated from a cross between A. fontanum and A. petrarchae subsp. bivalens. The occurrence of A. petrarchae subsp. bivalens in eastern Spain is confirmed cytologically. The occurrence of A. majoricum on the mainland is also discussed.     

Allozyme differentiation and genetic structure of the Lady's slipper (Cypripedium calceolus) island populations in north-east Poland

The population genetic structure in the rare and endangered perennial plant, Cypripedium calceolus , from north-east Poland was investigated. A total of 11 loci were analysed, of which five were polymorphic for the species and in every population. The 11 loci resolved gave a total of 19 alleles with the mean number of 1.73 alleles per locus. The proportion of polymorphic loci (P) was the same for the species and in every population, 45.5%. The average observed and expected heterozygosities for the total Lady's slipper data set were 0.156 and 0.184, respectively. The average expected heterozygosity for the populations under study ranged from 0.176 to 0.188 and did not differ significantly among populations. Genetic diversity within C. calceolus populations from the Biebrza Valley is relatively high compared with rare taxa and taxa with similar life histories. The genetic diversity among populations of C. calceolus studied ( F _ST = 0.016) is much smaller than the genetic diversity within populations. In the species studied, there was no significant correlation between genetic and geographical distances ( r = −0.73, Mantel test). This may indicate the relatively recent origin of the populations studied, or a high level of gene flow among populations. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 433–440.     

Climate increases regional tree-growth variability in Iberian pine forests

Tree populations located at the geographical distribution limit of the species may provide valuable information about tree‐growth response to changes on climatic conditions. We established nine Pinus nigra, 12 P. sylvestris and 17 P. uncinata tree‐ring width chronologies along the eastern and northern Iberian Peninsula, where these species are found at the edge of their natural range. Tree‐growth variability was analyzed using principal component analysis (PCA) for the period 1885–1992. Despite the diversity of species, habitats and climatic regimes, a common macroclimatic signal expressed by the first principal component (PC1) was found. Moreover, considering the PC1 scores as a regional chronology, significant relations were established with Spanish meteorological data. The shared variance held by the tree chronologies, the frequency of narrow rings and the interannual growth variability (sensitivity) increased markedly during the studied period. This shows an enhancement of growth synchrony among forests indicating that climate might have become more limiting to growth. Noticeably, an upward abrupt shift in common variability at the end of the first half of the 20th century was detected. On the other hand, moving‐interval response functions showed a change in the growth–climate relationships during the same period. The relationship between growth and late summer/autumn temperatures of the year before growth (August–September, negative correlation, and November, positive correlation) became stronger. Hence, water stress increase during late summer previous to tree growth could be linked to the larger growth synchrony among sites, suggesting that climate was driving the growth pattern changes. This agrees with the upward trend in temperature observed in these months. Moreover, the higher occurrence of extreme years and the sensitivity increase in the second half of the 20th century were in agreement with an increment in precipitation variability during the growing period. Precipitation variability was positively related to tree‐growth variability, but negatively to radial growth. In conclusion, a change in tree‐growth pattern and in the climatic response of the studied forests was detected since the mid‐20th century and linked to an increase in water stress. These temporal trends were in agreement with the observed increase in warmer conditions and in precipitation variability.     

Abnormal Ultrastructural Features of a Marine Dinoflagellate Adapted to Grow Successfully in the Presence of Inhibitory Fluoride Concentration1

ABSTRACT. Amphidinium carteri was unable to grow on nutrient-enriched seawater in the presence of 200 μg/ml fluoride (F) but could be adapted to grow successfully on this F concentration when repeatedly cultured with stepwise increases in sub-inhibitory F concentration. Electron microscopic investigation of the F-adapted dinoflagellate cells showed abnormal ultrastructural features in the chloroplast (especially the pyrenoid), mitochondria, and nucleus. Simultaneous comparison with the F-inhibited dinoflagellate cells showed that thylakoid formation was extremely disorganized by fluoride and that F-adaptation conferred a prolamellar-like configuration on the thylakoids in the center of the pyrenoid. This unexpected appearance of lamellae formation in the F-adapted cells suggested that the pyrenoid may be a center for thylakoid assembly. Such cells also showed large, intensely osmiophilic inclusions in the mitochondria. Microbodies are found in close juxtaposition to the mitochondria and chloroplast, suggesting an increased metabolic dependence on photorespiration. The F-adapted nucleus showed dark and light concentric rings in the nucleolus region, accompanied by other signs of mitotic activity, which were not observed in the F-inhibited cells. It was inferred that the F-adaptation may have required some form of genetic change resulting presumably in the development of a phenotype mutant.