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Good aerobic fitness associates positively with cognitive performance and brain health and conversely, low aerobic fitness predisposes to neurodegenerative diseases. To study how genotype together with exercise, started at older age, affects brain and behavior, we utilized rats that differ in inherited aerobic fitness. Rats bred for Low Capacity for Running (LCR) are shown to display less synaptic plasticity and more inflammation in the hippocampus and perform worse than rats bred for a High Capacity for Running (HCR) in tasks requiring flexible cognition. Here we used middle-aged (∼ 16 months) HCR and LCR rats to study how genotype and sex associate with anxiety and neural information filtering, termed sensory gating. Further, we assessed how inherited aerobic capacity associates with hippocampus-dependent learning, measured with contextual fear conditioning task. In females, we also investigated the effects of voluntary wheel running (5 weeks) on these characteristics. Our results indicate that independent of sex or voluntary running, HCR rats were more anxious in open-field tasks, exhibited lower sensory gating and learned more efficiently in contextual fear conditioning task than LCR rats. Voluntary running did not markedly affect innate behavior but slightly decreased the differences between female LCR and HCR rats in fear learning. In conclusion, inherited fitness seems to determine cognitive and behavioral traits independent of sex. Although the traits proved to be rather resistant to change at adult age, learning was slightly improved following exercise in LCR females, prone to obesity and poor fitness. peerReviewed

Active dispersal is driven by extrinsic and intrinsic factors at the three stages of departure, transfer and settlement. Most empirical studies capture only one stage of this complex process, and knowledge of how much can be generalized from one stage to another remains unknown. Here we use genetic assignment tests to reconstruct dispersal across 5 years and 232 habitat patches of a Glanville fritillary butterfly ( Melitaea cinxia ) metapopulation. We link individual dispersal events to weather, landscape structure, size and quality of habitat patches, and individual genotype to identify the factors that influence the three stages of dispersal and post-settlement survival. We found that nearly all tested factors strongly affected departure probabilities, but that the same factors explained very little variation in realized dispersal distances. Surprisingly, we found no effect of dispersal distance on post-settlement survival. Rather, survival was influenced by weather conditions, quality of the natal habitat patch, and a strong interaction between genotype and occupancy status of the settled habitat patch, with more mobile genotypes having higher survival as colonists rather than as immigrants. Our work highlights the multi-causality of dispersal and that some dispersal costs can only be understood by considering extrinsic and intrinsic factors and their interaction across the entire dispersal process.

Duck mussel, Anodonta anatina is a habitat generalist inhabiting both lentic and lotic aquatic ecosystems. Due to high morphological similarity and phenotypic plasticity, A. anatina has sometimes been misidentified as A. cygnea. Here, morphological and molecular studies were conducted on Anodonta mussels inhabiting North Iran and Finland. The individuals were collected from Anzali Wetland, Tajan River (North Iran) and Jyväsjärvi Lake (Finland). The COI sequence analysis showed the existence of A. anatina in the sampling areas. The Iranian and Finland specimens showed three and two haplotypes, respectively. The Iranian haplotypes were placed in a single clade, while the Finland haplotypes were clustered with those of Central Europe. The mean P-distance between these two clades was 2.4. The median-joining network showed that the Iranian haplotypes were lumped into a single haplogroup, while the Finland ones were in the same haplogroup as those from Central Europe. The Mediterranean haplotypes were the most divergent haplogroup from both Iranian and Central European haplogroups. In morphological characteristics, the shell pattern of all individuals from both Iranian and Finland specimens was stretched and slightly compact with light/dark brown periostracum. The mean length of the specimens from Anzali Wetland was significantly higher than those of Tajan and Jyväsjärvi. No significant difference was observed in morphometric characteristics between Tajan and Jyväsjärvi populations. The results did not indicate significant variation in shell morphology in the studied groups. In this regard, the conventional linear measurements can be supplemented using more complex geometric morphology in further studies. peerReviewed

Currently, the recently erected genus Crenubiotus (Adorybiotidae, Macrobiotoidea) includes only three species, all of which are characterised by dentate lunulae and cuticular tubercules organised in the band in the dorso-caudal part of the body. By means of integrative taxonomy, we describe a fourth species of the genus: Crenubiotus salishani sp. nov., from Salt Spring Island in British Columbia, Canada. The new species has been found in the moss growing on rock and differs from the other species in the genus due to the presence of a median anterior mucrone in the third band of the oral cavity armature (OCA) and by the presence of evident thickenings on the eggshell connecting the neighbouring processes. This finding highlights the importance of continuing to study tardigrade biodiversity, even in already explored areas, and how an integrative approach is fundamental to achieving a reliable measure of biodiversity. peerReviewed

The definition of colour polymorphism is intuitive: genetic variants express discretely coloured phenotypes. This classification is, however, elusive as humans form subjective categories or ignore differences that cannot be seen by human eyes. We demonstrate an example of a 'cryptic morph' in a polymorphic wood tiger moth (Arctia plantaginis), a phenomenon that may be common among well-studied species. We used pedigree data from nearly 20,000 individuals to infer the inheritance of hindwing colouration. The evidence supports a single Mendelian locus with two alleles in males: WW and Wy produce the white and yy the yellow hindwing colour. The inheritance could not be resolved in females as their hindwing colour varies continuously with no clear link with male genotypes. Next, we investigated if the male genotype can be predicted from their phenotype by machine learning algorithms and by human observers. Linear discriminant analysis grouped male genotypes with 97% accuracy, whereas humans could only group the yy genotype. Using vision modelling, we also tested whether the genotypes have differential discriminability to humans, moth conspecifics and their bird predators. The human perception was poor separating the genotypes, but avian and moth vision models with ultraviolet sensitivity could separate white WW and Wy males. We emphasize the importance of objective methodology when studying colour polymorphism. Our findings indicate that by-eye categorization methods may be problematic, because humans fail to see differences that can be visible for relevant receivers. Ultimately, receivers equipped with different perception than ours may impose selection to morphs hidden from human sight.

Background Microbes play a role in their host's fundamental ecological, chemical, and physiological processes. Host life-history traits from defence to growth are therefore determined not only by the abiotic environment and genotype but also by microbiota composition. However, the relative importance and interactive effects of these factors may vary between organisms. Such connections remain particularly elusive in Lepidoptera, which have been argued to lack a permanent microbiome and have microbiota primarily determined by their diet and environment. We tested the microbiome specificity and its influence on life-history traits of two colour genotypes of the wood tiger moth (Arctia plantaginis) that differ in several traits, including growth. All individuals were grown in the laboratory for several generations with standardized conditions. We analyzed the bacterial community of the genotypes before and after a reciprocal frass (i.e., larval faeces) transplantation and followed growth rate, pupal mass, and the production of defensive secretion. Results After transplantation, the fast-growing genotype grew significantly slower compared to the controls, but the slow-growing genotype did not change its growth rate. The frass transplant also increased the volume of defensive secretions in the fast-growing genotype but did not affect pupal mass. Overall, the fast-growing genotype appeared more susceptible to the transplantation than the slow-growing genotype. Microbiome differences between the genotypes strongly suggest genotype-based selective filtering of bacteria from the diet and environment. A novel cluster of insect-associated Erysipelotrichaceae was exclusive to the fast-growing genotype, and specific Enterococcaceae were characteristic to the slow-growing genotype. These Enterococcaceae became more prevalent in the fast-growing genotype after the transplant, which suggests that a slower growth rate is potentially related to their presence. Conclusions We show that reciprocal frass transplantation can reverse some genotype-specific life-history traits in a lepidopteran host. The results indicate that genotype-specific selective filtering can fine-tune the bacterial community at specific life stages and tissues like the larval frass, even against a background of a highly variable community with stochastic assembly. Altogether, our findings suggest that the host's genotype can influence its susceptibility to being colonized by microbiota, impacting key life-history traits.

Background Sympatric speciation along ecological gradients has been studied repeatedly, in particular in freshwater fishes. Rapid post-glacial ecological divergence has resulted in numerous endemic species or ecologically distinct populations in lakes of the temperate zones. Here, we focus on the Baltic cisco (Coregonus albula) complex, to study the genetic similarity among two pairs of sympatric autumn- and spring-spawning populations from post-glacial German Lakes Stechlin and Breiter Luzin. For comparison, we included a similar pair of sympatric populations from the Swedish Lake Fegen. We wanted to explore potential genetic similarities between the three sympatric cisco population pairs in the three lakes, to evaluate whether the pairs may have emerged independently in the three lakes, or whether two different species may have colonized all three lakes independently. Furthermore, we considered allopatric C. albula populations from three Polish, three Finnish, and four Swedish locations, added one Siberian population of the sister species C. sardinella and a Swedish C. maraena (whitefish) population. By genotyping nine microsatellite markers in 655 individuals from these 18 populations, we wanted to elucidate how strongly the cisco populations differ across a larger geographical area within Europe. Finally, we compared the genetic differences between the spring- and autumn-spawning populations of ciscoes in the two German lakes to infer the potentially deteriorating effect of strong anthropogenic pressure on the lakes. Results Dendrogram, Principal Coordinate Analysis and admixture analysis all indicated strong correspondence between population differentiation and geographical location for most cisco populations in Europe, including the Siberian population of C. sardinella. However, populations from some Swedish lakes deviated from this general pattern, by showing a distinct genetic structure. We found evidence for independent evolution of the three sympatric population pairs, because the populations co-occurring in the same lake were always most closely related. However, genetic differentiation was weak in the two German population pairs, but strong in the Swedish Lake Fegen, indicating that the weak differentiation in the German pairs reported earlier has eroded further. Conclusions Our results suggest that the genetic differentiation at neutral genetic markers among populations of the Baltic cisco complex has evolved (and is maintained) by random genetic drift in isolated populations. However, earlier studies on the Swedish populations combining mitochondrial DNA and microsatellite data indicate that also post-glacial immigration from separate glacial refugia has shaped the present genetic population structure. The low neutral differentiation of the German sympatric pairs in contrast to the Swedish pair suggests that recent anthropogenic effects on the lakes in Germany may put the endemic spring-spawners at risk to extinction.

Childhood fractures are common injuries, but the underlying risk factors arising from the prenatal environment or genetics are not well studied. It is not clear why certain children, without bone-affecting diseases, suffer a larger number of fractures than others. The external reasons, such as hobbies and nutritional issues, explain only part of the difference, particularly among young children. Maternal smoking and alcohol consumption during pregnancy are known to cause detrimental effects to the developing fetus. The purpose of this study is to investigate the possible association of these habits with childhood fractures. In addition, the birth weight and birth length of a child have also been shown to reflect the intrauterine conditions; therefore, the association of these parameters to the pediatric fractures was evaluated in this thesis. We also aimed to examine whether there would be genetic loci associated with fractures in children before school age by using a genome-wide association study. The study material included the Northern Finland Birth Cohort 1986, which is a comprehensive pregnancy-birth cohort that includes all women with the expected date of delivery between July 1985 and June 1986, and their live-born offspring from the two northernmost provinces of Finland. The fracture data was acquired from the National Hospital Discharge Register. We found that maternal smoking during pregnancy was associated with 1.83-fold (95% CI 1.06–3.02) increase and the prenatal alcohol consumption was associated with 2.22-fold (CI 1.09–4.12) increase in the offspring’s risk of suffering an inpatient treated bone fracture before school age. We did not find a significant association between the fracture risk and birth weight or birth length. The genome-wide association study (GWAS) revealed one genetic locus (SNP rs112635931) with significant association (p = 7.28x10-9) to fractures and six loci with suggestive association. Tiivistelmä Murtumat ovat yleisiä vammoja lapsuudessa, mutta niiden genetiikasta tai raskaudenaikaisista olosuhteista johtuvat taustatekijät ovat huonosti tunnettuja. On epäselvää, miksi osa luustoltaan terveistä lapsista murtaa luunsa useammin kuin toiset. Vaikka lapsuuden murtumariskiin vaikuttavat mm. ravitsemus ja harrastukset, eivät ulkoiset tekijät kuitenkaan täysin selitä eroa etenkään pienillä lapsilla. Äidin raskaudenaikaisen tupakoinnin ja alkoholin käytön tiedetään aiheuttavan kehittyvälle sikiölle vakavia haittoja. Tämän tutkimuksen tavoitteena oli selvittää, onko äidin raskaudenaikaisella tupakoinnilla tai alkoholin käytöllä yhteyttä lapsuusajan murtumiin. Syntymäpainon ja -pituuden on myös havaittu heijastavan kohdunsisäisiä olosuhteita, joten myös näiden parametrien yhteyttä lapsuusajan murtumiin tutkittiin. Halusimme myös selvittää genomin laajuisella assosiaatioanalyysilla, löytyykö aineistosta lapsuusajan murtumiin assosioituvia geneettisiä lokuksia. Tutkimuksen aineistona käytettiin Pohjois-Suomen syntymäkohortti 1986:sta, joka sisältää kaikki Oulun ja Lapin läänin alueella asuneet naiset, joiden laskettu aika oli heinäkuun 1985 ja kesäkuun 1986 välillä, sekä heidän elävänä syntyneet jälkeläisensä. Murtumatiedot saatiin terveydenhuollon hoitoilmoitusrekisteristä. Tutkimustemme tulosten valossa äidin raskaudenaikainen tupakointi assosioitui 1.83-kertaiseen (95% CI 1.06–3.02) murtumariskiin ja alkoholinkäyttö 2.22-kertaiseen (CI 1.09–4.12) murtumariskiin alle kouluikäisillä lapsilla. Lapsen syntymäpainolla ja -pituudella ei havaittu tilastollisesti merkitsevää yhteyttä murtumiin. Genomin assosiaatioanalyysi paljasti yhden geneettisen lokuksen (SNP rs112635931), joka assosioitui merkitsevästi (p = 7.28x10-9) lapsuuden murtumiin ja kuusi lokusta, jotka eivät yltäneet tilastolliseen merkitsevyyteen, mutta viittasivat mahdolliseen yhteyteen.

Background: Lung function is highly heritable and differs between the sexes throughout life. However, little is known about sex-differential genetic effects on lung function. We aimed to conduct the first genome-wide genotype-by-sex interaction study on lung function to identify genetic effects that differ between males and females. Methods: We tested for interactions between 7,745,864 variants and sex on spirometry-based measures of lung function in UK Biobank (N=303,612), and sought replication in 75,696 independent individuals from the SpiroMeta consortium. Results: Five independent single-nucleotide polymorphisms (SNPs) showed genome-wide significant (P

Background Diploid genome assembly is typically impeded by heterozygosity because it introduces errors when haplotypes are collapsed into a consensus sequence. Trio binning offers an innovative solution that exploits heterozygosity for assembly. Short, parental reads are used to assign parental origin to long reads from their F1 offspring before assembly, enabling complete haplotype resolution. Trio binning could therefore provide an effective strategy for assembling highly heterozygous genomes, which are traditionally problematic, such as insect genomes. This includes the wood tiger moth (Arctia plantaginis), which is an evolutionary study system for warning colour polymorphism. Findings We produced a high-quality, haplotype-resolved assembly for Arctia plantaginis through trio binning. We sequenced a same-species family (F1 heterozygosity ∼1.9%) and used parental Illumina reads to bin 99.98% of offspring Pacific Biosciences reads by parental origin, before assembling each haplotype separately and scaffolding with 10X linked reads. Both assemblies are contiguous (mean scaffold N50: 8.2 Mb) and complete (mean BUSCO completeness: 97.3%), with annotations and 31 chromosomes identified through karyotyping. We used the assembly to analyse genome-wide population structure and relationships between 40 wild resequenced individuals from 5 populations across Europe, revealing the Georgian population as the most genetically differentiated with the lowest genetic diversity. Conclusions We present the first invertebrate genome to be assembled via trio binning. This assembly is one of the highest quality genomes available for Lepidoptera, supporting trio binning as a potent strategy for assembling heterozygous genomes. Using our assembly, we provide genomic insights into the geographic population structure of A. plantaginis.

1.Trade‐offs have been shown to play an important role in the divergence of mating strategies and sexual ornamentation, but their importance in explaining warning signal diversity has received less attention. In aposematic organisms, allocation costs of producing the conspicuous warning signal pigmentation under nutritional stress could potentially trade‐off with life‐history traits and maintain variation in warning colouration. 2. We studied this with an aposematic herbivore Arctia plantaginis (Arctiidae), whose larvae and adults show extensive variation in aposematic colouration. In larvae, less melanic colouration (i.e. larger orange patterns) produces a more efficient warning signal against predators, whereas high amounts of melanism (smaller orange pattern) enhance thermoregulation, correlate with better immunity and make individuals harder to detect for naïve predators. 3. We conducted a factorial rearing experiment with larvae originating from lines selected for either small or large orange signal size, which were reared on an artificial diet that had either low or high protein content. Protein content of the diet is critical for melanin production. We measured the effects of diet on individual colouration, life‐history traits, immune defence and reproductive output. We also compared the responses to dietary conditions between the small and large larval signal genotypes. 4. Protein content of the diet did not affect warning colouration in the larval stage, but larval signal sizes differed significantly among selection lines, confirming that its variation is mainly genetically determined. In adults, signal line or diet did not affect colouration in hindwings, but males’ forewings had more melanin on the high than on low protein diet. Contrary to colouration, diet quality had a stronger impact on life‐history traits: individuals developed for longer, had smaller hindwing sizes in females and lower immune defence on the low protein content diet compared to the high. These costs were higher for more melanic larval signal genotypes in terms of development time and female hindwing size. 5. We conclude that low plasticity in warning signal characteristics makes signal expression robust under varying dietary conditions. Therefore, variation in diet quality is not likely to constrain signal expression, but can have a bigger impact on performance. peerReviewed

Striking variation in melanin coloration within natural populations is likely due to the different fitness outcomes of alternative phenotypes in varying environmental conditions. There are two types of melanin: eumelanins yield blackish hues, whereas pheomelanins yield reddish hues. The production of eumelanins requires low levels of glutathione (GSH), which is the most important intracellular antioxidant, whereas the production of pheomelanins requires high levels of GSH. We investigated the oxidative status of male pied flycatchers (Ficedula hypoleuca) with different degrees of melanin coloration under different temperatures during the nestling period. Moreover, we assessed the oxidative status of offspring in relation to their biological or foster father's melanin coloration and ambient temperature. To separate offspring genotype effects and paternal effects in different temperatures, we used a partial cross-foster design. The temperature differently affected the oxidative status of differently colored male pied flycatchers and their foster offspring. When the weather was relatively cold, black males had higher glutathione S-transferase levels compared with brown males, indicating enhanced stress in black males. Foster offspring of black males had a lower ratio between reduced and oxidized GSH followed by higher total amount of GSH than foster offspring of brown males. Thus, foster offspring of black males seem to suffer from oxidative stress under relatively cold weather compared with those of brown males, and vice versa under relatively warm weather. Although differently colored males experienced changes in their oxidative status under different temperatures, the link between paternal melanin coloration and offspring oxidative stress appears to be environmentally induced. peerReviewed

The study of polymorphic immune genes in host populations is critical for understanding genetic variation in susceptibility to pathogens. Controlled infection experiments are necessary to separate variation in the probability of exposure from genetic variation in susceptibility to infection, but such experiments are rare for wild vertebrate reservoir hosts and their zoonotic pathogens. The bank vole (Myodes glareolus) is an important reservoir host of Borrelia afzelii, a tick-borne spirochete that causes Lyme disease. Bank vole populations are polymorphic for Toll-like receptor 2 (TLR2), an innate immune receptor that recognizes bacterial lipoproteins. To test whether the TLR2 polymorphism influences variation in the susceptibility to infection with B. afzelii, we challenged pathogen-free, lab-born individuals of known TLR2 genotype with B. afzelii-infected ticks. We measured the spirochete load in tissues of the bank voles. The susceptibility to infection with B. afzelii following an infected tick bite was very high (95%) and did not differ between TLR2 genotypes. The TLR2 polymorphism also had no effect on the spirochete abundance in the tissues of the bank voles. Under the laboratory conditions of our study, we did not find that the TLR2 polymorphism in bank voles influenced variation in the susceptibility to B. afzelii infection.

A better understanding of the environmental and genetic contribution to migratory behavior and the evolution of traits linked to migration is crucial for fish conservation and fisheries management. Up to date, a few genes with unequivocal influence on the adoption of alternative migration strategies have been identified in salmonids. Here, we used a common garden set-up to measure individual migration distances of generally highly polymorphic brown trout Salmo trutta from two populations. Fish from the assumedly resident population showed clearly shorter migration distances than the fish from the assumed migratory population at the ages of 2 and 3 years. By using two alternative analytical pipelines with 22186 and 18264 SNPs obtained through RAD-sequencing, we searched for associations between individual migration distance, and both called genotypes and genotype probabilities. None of the SNPs showed statistically significant individual effects on migration after correction for multiple testing. By choosing a less stringent threshold, defined as an overlap of the top 0.1% SNPs identified by the analytical pipelines, GAPIT and Angsd, we identified eight candidate genes that are potentially linked to individual migration distance. While our results demonstrate large individual and population level differences in migration distances, the detected genetic associations were weak suggesting that migration traits likely have multigenic control.

Within‐host interactions between co‐infecting parasites can significantly influence the evolution of key parasite traits, such as virulence (pathogenicity of infection). The type of interaction is expected to predict the direction of selection, with antagonistic interactions favouring more virulent genotypes and synergistic interactions less virulent genotypes. Recently, it has been suggested that virulence can further be affected by the genetic identity of co‐infecting partners (G × G interactions), complicating predictions on disease dynamics. Here, we used a natural host–parasite system including a fish host and a trematode parasite to study the effects of G × G interactions on infection virulence. We exposed rainbow trout (Oncorhynchus mykiss) either to single genotypes or to mixtures of two genotypes of the eye fluke Diplostomum pseudospathaceum and estimated parasite infectivity (linearly related to pathogenicity of infection, measured as coverage of eye cataracts) and relative cataract coverage (controlled for infectivity). We found that both traits were associated with complex G × G interactions, including both increases and decreases from single infection to co‐infection, depending on the genotype combination. In particular, combinations where both genotypes had low average infectivity and relative cataract coverage in single infections benefited from co‐infection, while the pattern was opposite for genotypes with higher performance. Together, our results show that infection outcomes vary considerably between single and co‐infections and with the genetic identity of the co‐infecting parasites. This can result in variation in parasite fitness and consequently impact evolutionary dynamics of host–parasite interactions. peerReviewed

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.

Frontotemporal lobar degeneration (FTLD) is the second most common neurodegenerative disease leading to early-onset dementia (

Independent of genotype, increased spacing results in increased branch diameter of Scots pine (Pinus sylvestris L.), but on different levels for different genotypes. Frequency of defects like spike knots and crooked stems are under stronger genetic than silvicultural control. Simultaneous improvement of rate of growth and timber properties is feasible. Deteriorating of both factors can happen rapidly at a negative selection. This needs consideration when selecting seed trees for natural regeneration. A defect like stem cracking of Norway spruce (Picea abies (L.) Karst.) only manifests itself under drought stress when certain genetic and environmental prerequisites are present, like high fertility and wide spacing. This emphasize the fact that new silvicultural methods may reveal genetic weaknesses.

The paper discusses the theoretical basis of quantitative analysis of the effect of genotype and environment in forest trees. Perhaps the main problem in the understanding of the laws of intrapopulation variability of the species of woody forest plants is the study of the structure of their populations. It may be characterized by a number of parameters. The intrapopulation variability of quantitative characteristics appears as a result of environmental and genetic factors, but to determine the relative weight of these factors in a concrete case is not easy. The study of the structure of a population by its quantitative characteristics has a wider task: to establish the relevance of the hereditary differences of the individuals of a population. Also, the differences caused by diverse growth conditions and how they are reflected in the level of general phenotypic variability of the quantitative characteristics in a given population has to be identified. The author gives examples of assessment of heritability in forest trees. The PDF includes a summary in Finnish.

Background In nature, organisms are commonly coinfected by two or more parasite strains, which has been shown to influence disease virulence. Yet, the effects of coinfections of environmental opportunistic pathogens on disease outcome are still poorly known, although as host-generalists they are highly likely to participate in coinfections. We asked whether coinfection with conspecific opportunistic strains leads to changes in virulence, and if these changes are associated with bacterial growth or interference competition. We infected zebra fish (Danio rerio) with three geographically and/or temporally distant environmental opportunist Flavobacterium columnare strains in single and in coinfection. Growth of the strains was studied in single and in co-cultures in liquid medium, and interference competition (growth-inhibiting ability) on agar. Results The individual strains differed in their virulence, growth and ability for interference competition. Number of coinfecting strains significantly influenced the virulence of infection, with three-strain coinfection differing from the two-strain and single infections. Differences in virulence seemed to associate with the identity of the coinfecting bacterial strains, and their pairwise interactions. This indicates that benefits of competitive ability (production of growth-inhibiting compounds) for virulence are highest when multiple strains co-occur, whereas the high virulence in coinfection may be independent from in vitro bacterial growth. Conclusions Intraspecific competition can lead to plastic increase in virulence, likely caused by faster utilization of host resources stimulated by the competitive interactions between the strains. However, disease outcome depends both on the characteristics of individual strains and their interactions. Our results highlight the importance of strain interactions in disease dynamics in environments where various pathogen genotypes co-occur. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-0922-2) contains supplementary material, which is available to authorized users.