Irma Saloniemi

Glyphosate in northern ecosystems

Glyphosate is the main nonselective, systemic herbicide used against a wide range of weeds. Its worldwide use has expanded because of extensive use of certain agricultural practices such as no-till cropping, and widespread application of glyphosate-resistant genetically modified crops. Glyphosate has a reputation of being nontoxic to animals and rapidly inactivated in soils. However, recent evidence has cast doubts on its safety. Glyphosate may be retained and transported in soils, and there may be cascading effects on nontarget organisms. These processes may be especially detrimental in northern ecosystems because they are characterized by long biologically inactive winters and short growing seasons. In this opinion article, we discuss the potential ecological, environmental and agricultural risks of intensive glyphosate use in boreal regions.

Differences in sea migration between wild and reared Atlantic salmon (Salmo salar L.) in the Baltic Sea

The effect of origin, smolt size and year of release on the sea migration pattern of Atlantic salmon ( Salmo salar L.) in the Baltic Sea was examined by tagging experiments conducted in 1991–1993 on wild and reared smolts of the Simojoki river salmon stock. The tag recovery data analysed by log-linear models revealed significant differences in both spatial and temporal sea migrations between the wild and reared salmon; the variation was attributed to the year of release and to the origin of the fish. Grilse accounted for the majority of reared returners (76%) but for a smaller proportion (46%) of the wild fish. The effect of smolt size could be studied only in the smolt groups tagged in 1991. Wild fish were more frequently (71%) caught in the Baltic Main Basin than were reared fish (51%) during their second sea year, and the size variation between wild and reared smolts did not explain the recovery site. No such differences in spatial distribution were found during the third sea year. The tagging place (hatchery/trap) of the reared fish did not affect their later sea migration. The differences in sea migration patterns suggest that the wild salmon are more vulnerable to the intensive salmon fishery in the Baltic Main Basin than are reared fish.

Seasonally varying diet quality and the quantitative genetics of development time and body size in birch feeding insects.

Abstract Genetic variance‐covariance structures (G), describing genetic constraints on microevolutionary changes of populations, have a central role in the current theories of life‐history evolution. However, the evolution of Gs in natural environments has been poorly documented. Resource quality and quantity for many animals and plants vary seasonally, which may shape genetic architectures of their life histories. In the mountain birch‐insect herbivore community, leaf quality of birch for insect herbivores declines profoundly during both leaf growth and senescence, but remains stable during midsummer. Using six sawfly species specialized on the mountain birch foliage, we tested the ways in which the seasonal variation in foliage quality of birch is related to the genetic architectures of larval development time and body size. In the species consuming mature birch leaves of stable quality, that is, without diet‐imposed time constraints for development time, long development led to high body mass. This was revealed by the strongly positive phenotypic and genetic correlations between the traits. In the species consuming growing or senescing leaves, on the other hand, the rapidly deteriorating leaf quality prevented the larvae from gaining high body mass after long development. In these species, the phenotypic and genetic correlations between development time and final mass were negative or zero. In the early‐summer species with strong selection for rapid development, genetic variation in development time was low. These results show that the intuitively obvious positive genetic relationship between development time and final body mass is a probable outcome only when the constraints for long development are relaxed. Our study provides the first example of a modification in guild‐wide patterns in the genetic architectures brought about by seasonal variation in resource quality.

Birch family and environmental conditions affect endophytic fungi in leaves

Abstract We investigated whether variation in foliar endophyte frequency among mountain birch trees from different maternal families was due in part to genetic differences among trees. The effect of different environmental conditions on the susceptibility of these mountain birch families to foliar endophytes was tested. The 3-year study was conducted in two tree gardens (altitudinal difference 180 m) with ten families of mountain birch. The frequency of the commonest endophytic fungus in mountain birch leaves, Fusicladium sp., was significantly affected by mountain birch family, with the ranking of families relative to Fusicladium sp. frequency being consistent from environment to environment. Variation in the frequency of Melanconium sp. was difficult to interpret because of significant family × garden × year interaction. Fusicladium sp. and Melanconium sp. endophytes were most frequent in different tree individuals, families and gardens. We conclude that mountain birch trees show heritable variation in their foliar endophyte frequency, and thus one of the conditions necessary for foliar endophytes of mountain birch trees to be able to affect the evolution of their host plant is fulfilled. However, the effect of mountain birch family on the frequency of endophytic fungi varies depending on the endophytic genera in question and partially also on environmental conditions.

Leaf surface traits: overlooked determinants of birch resistance to herbivores and foliar micro-fungi?

Previous studies on the mechanisms of birch resistance to herbivores and foliar micro-fungi (both pathogenic and endophytic) have focused mainly on the role of internal leaf chemistry. In the present study, we examined genetic correlations between leaf surface traits (glandular trichome density and total concentrations of surface flavonoid aglycones) and occurrence of three species of foliar micro-fungi, one pathogenic rust (Melampsoridium betulinum) and two endophytic fungi (Fusicladium sp. and Melanconium sp.), and performance of autumnal moth larvae (Epirrita autumnata) in two birch species, Betula pubescens ssp. czerepanovii and B. pendula. The performance of autumnal moth larvae on B. pubescens ssp. czerepanovii was negatively correlated with density of glandular trichomes (RGR: r=−0.855; pupal mass: r=−0.709). In addition, rust infection was negatively correlated with trichome density in B. pendula (r=−0.675) and with epicuticular flavonoid aglycones in B. pubescens ssp. czerepanovii (r=−0.855). The frequency of the endophytic fungus Fusicladium sp., was related to epicuticular flavonoid aglycones (r=−0.782), while another endophytic fungus, Melanconium sp., showed no associations with any of the studied variables in B. pubescens ssp. czerepanovii. Our results indicate that leaf surface traits may be at least as important determinants of herbivore performance and micro-fungi abundance in birch as leaf internal chemistry.

Cell proliferation and chromosomal changes in human ameloblastoma

Cell proliferation and chromosomal imbalances, important parameters in relation to tumor progression, were studied in ameloblastoma (n=20), a benign odontogenic tumor of locally recurrent nature. Immunocytochemical staining with MIB-1 antibody and comparative genomic hybridization (CGH) were performed on formalin-fixed paraffin-embedded ameloblastomas. The mean follow-up time was 12.4 years. An MIB-1-index was formed by counting 5000 tumor-cell nuclei in 10-15 randomly chosen high-power fields and calculating percentages of positively stained cells. CGH involved hybridization of FITC-dUTP-labeled tumor DNA with Texas-red-labeled normal DNA. Images were digitally analyzed. The MIB-1-index (range 0-2.51) was low for all tumors. No statistically significant correlation between MIB-1 index and tendency to recurrence was found. Chromosomal aberrations were detected in 2 of 17 cases. The results suggest that formation of an MIB-1 index is not helpful in assessing future clinical behavior of an ameloblastoma and that chromosomal imbalances are uncommon.

Temporally stable population-specific differences in run timing of one-sea-winter Atlantic salmon returning to a large river system

The understanding of migration patterns can significantly contribute to conservation and management. The spawning migrations of Atlantic salmon (Salmo salar) cover thousands of kilometers from the feeding areas at sea to their natal rivers to reproduce. Migrating salmon are exposed to intensive harvest, but little is known of the population‐specific differences in migration behavior. In this study, timing of return migration was investigated among one‐sea‐winter Atlantic salmon within a river system. By utilizing knowledge of the genetic population structure, population of origin was reliably identified for c. 1500 fish caught in mixed stock fisheries after adopting an approach to minimize the complications arising from potential nonsampled populations. Results demonstrated significant and temporally stable differences among populations as well as between sexes. Generally, female salmon from tributary populations entered fresh water first. Run timing was not however related to in‐river migration distance. Rather, one‐sea‐winter salmon from larger populations and with a higher proportion of multi‐sea‐winter females arrived later in the season. These findings are a significant step toward a more thorough understanding of the salmon migration behavior and behavioral ecology, providing concrete tools for the management and conservation of the remaining indigenous Atlantic salmon stocks.

WITHIN-SEASON VARIABILITY OF PUPAL PERIOD IN THE AUTUMNAL MOTH: A BET-HEDGING STRATEGY?

Pupal period is highly variable in Epirrita autumnata (Lepidoptera, Geometridae) lasting from about one to over three months. We aimed to find proximate and ultimate explanations for the high variability, including the possibility that variation in eclosion time represents a diversified bet-hedging strategy. Patterns of variation in pupal period, both among and within populations, were analyzed in several common environment experiments, including one with a half-sib design. We further assessed possible selective forces on eclosion date and its variance using an empirical simulation model. Latitudinal among-population differences in pupal period were shown to have a genetic basis. Within populations, there was a considerable among-sibship variance in this trait that suggests high heritabilities of pupal period. The environmental component of the variance was unlikely to result from a deterministic reaction norm, neither adaptive nor constraint-based, and may thus represent a type of variance on which a bet-hedging strategy can be based. Importantly, there were significant among-sibship differences in the variance itself, and a significant sire effect on offspring variability in the half-sib design. This suggests a possibility for the variance in pupal period to be selected for as such, and for increased random environmental variance (a bet-hedging strategy) to evolve via natural selection. We assumed that seasonal changes in night temperatures and predation rate determine the optimal timing of adult flight period in E. autumnata. Results of modeling suggested that there are apparently flat fitness profiles in relation to eclosion date, which is the probable reason for maintenance of high genetic diversity in pupal period. Unpredictable temperature during adult flight period has a potential to select for high variance in eclosion dates, although the selective pressure appears to be weak. Genetic variance in variance of pupal period may thus be largely selectively neutral in the studied system.

High Lactose Tolerance in North Europeans: A Result of Migration, Not In Situ Milk Consumption

The main carbohydrate in milk is lactose, which must be hydrolyzed to glucose and galactose before the sugars can be digested. While 65% or more of the total human population are lactose intolerant, in some human populations lactase activity commonly persists into adulthood. Lactose tolerance is exceptionally widespread in Northern European countries such as Sweden and Finland, with tolerance levels of 74% and 82%, respectively. Theoretically, this may result either from a strong local selection pressure for lactose tolerance, or from immigration of lactose tolerant people to Northern Europe. We provide several lines of archaeological and historical evidence suggesting that the high lactose tolerance in North Europeans cannot be explained by selection from in situ milk consumption. First, fresh cow milk has not belonged to the traditional diet of Swedes or Finns until recent times. Second, not enough milk has been available for adult consumption. Cattle herding has been neither widespread nor productive enough in Northern Europe to have provided constant access to fresh milk. We suggest that the high prevalence of lactose tolerance in Finland in particular may be explained by immigration of people representing so-called Corded Ware Culture, an early culture representing agricultural development in Europe.

Leaf fluctuating asymmetry in tree-line mountain birches, Betula pubescens ssp. tortuosa : genetic or environmentally influenced?

Fluctuating asymmetry (FA), or random nondirectional deviations from anticipated symmetry, is increasingly being discussed as a potential indicator of environmental stress. However, the factors underlying FA, especially in plants, remain poorly understood. We measured leaf FA by comparing the difference in width between the right and left halves of leaves in mountain birch (Betula pubescens ssp. tortuosa) from half-sib families growing in the field at its northern/altitudinal distributional limit to determine if genetic variance existed in this trait. We also tested for a correlation between leaf fluctuating asymmetry and tree-wide shoot growth to determine if leaf FA was associated with a decline in plant performance. There was no relationship between leaf FA and shoot growth. There was also no among-family variation in leaf FA, which suggests that there is little or no genetic variance in this trait in mountain birch.