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Gene expression is highly plastic, which can help organisms to both acclimate and adapt to changing environments. Possible variation in gene expression among individuals with the same genotype (among clones) is not widely considered, even though it could impact the results of studies that focus on gene expression phenotypes, for example studies using clonal lines. We examined the extent of within and between clone variation in gene expression in the earthworm Dendrobaena octaedra, which reproduces through apomictic parthenogenesis. Five microsatellite markers were developed and used to confirm that offspring are genetic clones of their parent. After that, expression of 12 genes was measured from five individuals each from six clonal lines after exposure to copper contaminated soil. Variation in gene expression was higher over all genotypes than within genotypes, as initially assumed. A subset of the genes was also examined in the offspring of exposed individuals in two of the clonal lines. In this case, variation in gene expression within genotypes was as high as that observed over all genotypes. One gene in particular (chymotrypsin inhibitor) also showed significant differences in the expression levels among genetically identical individuals. Gene expression can vary considerably, and the extent of variation may depend on the genotypes and genes studied. Ensuring a large sample, with many different genotypes, is critical in studies comparing gene expression phenotypes. Researchers should be especially cautious inferring gene expression phenotypes when using only a single clonal or inbred line, since the results might be specific to only certain genotypes. peerReviewed

Biodiversity affects ecosystem functioning positively. Metal-contamination diminishes species diversity and ecosystem function depends on the remaining species, and the genotypes within them. I studied how the clonally reproducing earthworm Dendrobaena octaedra responds to soil metal contamination and how its genetic diversity affects decomposition. Expression of the gene for the metal tolerance protein metallothionein was compared between populations with or without metal exposure history: with exposure history expression was high and stable and without there was a slow response. Adaptation to metal contamination likely explains the differences. Clonality of D. octaedra was verified with microsatellite markers. However, there was considerable gene expression variation both between and within genotypes, highlighting the need to consider such variation in comparative gene expression studies. The main study question focused on if genetic diversity is important for ecosystem functioning in metalcontaminated soil. I manipulated genetic diversity of a key decomposer, D. octaedra in a microcosm experiment. Indications of positive effects of higher genetic diversity on decomposition were found, especially in the contaminated conditions. However, the differences between the treatments often depended on which genotype was in the low diversity treatment, suggesting that traits of the genotypes might be more important than the level of genetic diversity for ecosystem functioning. An alternative technique to the real-time quantitative PCR, droplet digital PCR, was tested for gene expression measurements, and found to be a promising technique.

Growth and nutrition of 20 clones representing different species and interspecific hybrids of willows growing on an abandoned field were studied. There were highly significant differences between the clones as regards the survival, number of sprouts/stool, sprout mean height and diameter and stem biomass production/stool. The differences between the clones in the concentrations of all nutrients in both the leaves and stems were highly significant.

Micropropagated and seed-born plants of silver birch (Betula pendula Roth) were compared for survival and growth in a field trial at the age of six years. Three clones for micropropagation were selected from open-pollinated progenies of selected southern Finnish plus trees at the age of 17 and 20. The three seed-born lots were of southern Finnish stand origin. The best two lots of the experiment as regards the height and diameter growth at the age of six were the clones. The best of these differed significantly from the best growing seed-born lot. The weakest lot of the experiment was also a clone, which was clearly slow-growing with a dense and bushy-like crown. Survival of the material was high (mean = 94%), and there was no damage caused by voles and elks for example. The results clearly show, that the selection of material for clonal propagation should be done carefully. The clones should also be tested for performance in the field before propagation on a large-scale.

For biomass forestry in the inland parts of southern and central Finland, the obvious choice of willow species is Salix myrsinifolia. However, selection of clones of indigenous species has not yet been completed and more research and selection is needed. In the Piipsanneva old peatland trial, indigenous species of willow, mostly clones of S. myrsinifolia and S. phylicifolia, were compared in terms of biomass production, coppicing, height growth and diameter distributions. In this trial, the mean annual biomass production was not particularly high; more important results were attained in the ranking of clones. This trial strengthens the hypothesis that, over the long term, the biomass production of S. myrsinifolia is higher than that of S. phylicifolia. It was supposed that behind the highest yield there was a clone with uniform quality, one whose diameter distribution would be narrow and positively skewed. Comparisons of parameters of Weibull functions showed that the distributions of the best clones were wide, indicating that those clones use the whole growth space better than these with narrow distribution.

Possibilities of developing suitable willow ( spp.) clones for short-rotation forestry on mined peatlands in the north-western area of Finland were studied in a field experiment in which 300 willow clones were tested during 1985â87. Most of the tested clones started to grow from cuttings on limed and fertilized peat soil. L. clones of southern origin had a higher leafless above ground biomass production than the well adapted control clone and the local Finnish willows, but their winter hardiness was not satisfactory. The growth habit of some southern willows was also better than that of the control clone. It was also possible to select clones with good sprouting capacity. There were few Calisb. clones of Finnish origin, which had better cold tolerance than all other willows tested and higher biomass production than that of the control clone. The most critical factor to be selected for this is the optimal combination of winter hardiness and biomass production. This is attempted by selecting clones on the basis of this experiment for a breeding program.SalixSalix viminalisSalix myrsinifolia

In a greenhouse experiment that lasted for two years, nitrogenase activity, height growth and biomass production was compared in six clones of alder of which four were clones of and two x hybrids. In addition, the effect of a fertilizer nitrogen gradient was tested on one of the clones.Alnus incanaA. incanaA. glutinos