Infraspecific variation in Cerastium alpinum s. lat. (Caryophyllaceae) in Central Norway

Within Cerastium alpinum s. lat., several taxa have been circumscribed. Three infraspecific taxa are currently recognized in Nordic literature, but the opinions have varied about their taxonomic levels and relations to each other. Populations of these three taxa — alpinum, glabratum and lanatum — were investigated in Central Norway to elucidate taxonomic relationships on a regional scale. Morphometric analyses (PCA ordination) based on two data sets; one with 61 characters, and one without the 35 indumentum characters, gave different results. The former partly support the use of a higher rank for glabratum , but this analysis may put too much weight on indumentum characters. The reduced data set gave a more continuous transition between the three taxa, with no special status for glabratum. Crossing experiments between the taxa indicated full cross compatibility as far as relative seed set was concerned. Finally, vegetation analysis (DCA ordination) indicated that the three taxa have somewhat different ecological demands. This suggests that they, in spite of hybridization abilities, normally are maintained as separate entities due to habitat differences. A delimitation of three infraspecific taxa at the same level within C. alpinum s. lat. is thus supported by this study. Whether these taxa should be treated as subspecies or varieties strongly depends upon the definitions of these categories. Viewed in a wide geographical context, however, the arguments for subspecific rank are strengthened.     

The effect of triacontanol on growth, photosynthesis and photorespiration in Chlamydomonas reinhardtii and Anacystis nidulans

Chlamydomonas reinhardtii Dangerad 11–32(90) (−), which exhibits C3 properties, and Anacystis nidulans (Strain no. UTEX 625), which exhibits C4 properties, were used to study the effects of triacontanol on growth, photosynthesis and photorespiration. Photosynthetic rate was measured as CO2 uptake and the O2 inhibition of photosynthesis was used as a measure of photorespiration. Triacontanol dissolved in chloroform and dispersed in Tween-20 and triacontanol colloidally dispersed in an aqueous solution of sodium tallow alkyl sulfate were tested. Chlamydomonas cultures increased significantly in cell number after 4 days, and in chlorophyll content after 3 days of treatment with 2.3 × 10⁻⁸ M TRIA in chloroform/Tween-20. In cultures of Anacystis the chlorophyll content became significantly higher 3 days after treatment with 2.3 × 10⁻⁹ M TRIA and the cell number was noticeably higher than the controls.
CO₂ uptake by triacontanol-treated Chlamydomonas cultures was about the same in both 2 and 21% O2, and the O2 inhibition was significantly reduced as compared with the controls. Photosynthesis in Anacystis was O2-insensitive under the experimental condition used. When Anacystis was treated with triacontanol there was no change in the rate of CO2 uptake and no change in the O2 sensitivity of its CO2 uptake. It appears that triacontanol affects some process which regulated the balance between photosynthesis and photorespiration, but other processes which result in increased growth are probably also affected.     

Genetic differentiation in endemic Lobularia (Brassicaceae) in the Canary Islands

Patterns of genetic diversity were examined in five endemic subspecies of the Lobularia canariensis complex from six of the Canary Islands. The taxa are interfertile, insect-pollinated outbreeders with wind dispersal. Electrophoretic analysis revealed a high level of genetic polymorphism at ten loci coding soluble enzymes, with a mean of 2.38 alleles per locus, 73.7 % polymorphic loci, and a mean heterozygosity of 0.279. Excesses of homozygotes, indicating inbreeding, were observed in small populations. The average total diversity was high, F.,=0.518. Among-population diversity, F_ST=0.318, contributed more to the total diversity than within-population diversity, F_IS=0.222. Little geographic or taxonomic patterning of the allozyme variation was observed. The mean genetic identitity for pairwise comparisons of the 19 populations was 0.76, with a range of 0.51–0.96 and c. 17 % of the comparisons below 0.67 and c. 8 % above 0.90. The results contrast with the many cases of high genetic identities reported for populations of endemic plants on oceanic islands. High levels of allozyme divergence suggest a relatively old origin of the L. canariensis complex and a long period of isolation of some of the populations.     

Subject: Migration

Research Notes on Avian Biology 1994: Selected Contributions from the 21st International Ornithological CongressGeneral Biology: Migration

Subject: Migration     

Improved efficiency of plant regeneration from protoplasts of eggplant Solanum melongena L.

Eggplant (Solanum melongena L.) mesophyll protoplasts were obtained from in vitro growing plants of line 410 and cv. Classic. Relatively high (15%) plating efficiency was achieved using petri dishes with alternate quadrants containing reservoir medium (R medium + 1% activated charcoal) and culture medium. Shoot regeneration occurred within 6 weeks following initiation of protoplast culture.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan Israel, No. 1164-E, 1984 Series.     

Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe

Recent studies from mountainous areas of small spatial extent (<2500 km²) suggest that fine‐grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate‐change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine‐grained thermal variability across a 2500‐km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT) and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within <1000‐m² units (community‐inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1‐km² units; (2) the relationship between CiT range and topographically and geographically derived predictors at 1‐km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100‐km² units. Ellenberg temperature indicator values in combination with plant assemblages explained 46–72% of variation in LmT and 92–96% of variation in GiT during the growing season (June, July, August). Growing‐season CiT range within 1‐km² units peaked at 60–65°N and increased with terrain roughness, averaging 1.97 °C (SD = 0.84 °C) and 2.68 °C (SD = 1.26 °C) within the flattest and roughest units respectively. Complex interactions between topography‐related variables and latitude explained 35% of variation in growing‐season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing‐season CiT within 100‐km² units was, on average, 1.8 times greater (0.32 °C km^?1) than spatial turnover in growing‐season GiT (0.18 °C km^?1). We conclude that thermal variability within 1‐km² units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.