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Key messageThe response of herbivore abundance to birch genotypic diversity varies depending on the host specificity of the herbivores. Specialist, but not generalist, herbivores were affected by birch genotypic diversity.Biological control is an important ecosystem service mediated through plant diversity. Responses of herbivore abundance to plant genotypic diversity may depend on host specificity, especially the host-feeding type. We conducted a common-garden experiment by manipulating plot-level genotypic diversity (number of source populations per plot) of Erman’s birch (Betula ermanii) to understand how birch genotypic diversity affected the abundance of three herbivore feeding types (chewers, galls, and suckers). Specifically, we investigated whether the effects of plant genotypic diversity on herbivore abundance were additive or non-additive. Furthermore, we examined this mechanism as a possible change in plant phenotype (plant productivity and/or leaf traits) and/or herbivore foraging behavior (associational resistance with neighboring plant individuals). We found that genotypic diversity had a significant positive effect on condensed tannin concentration; however, it did not affect plant growth. There was no effect of increasing birch genotypic diversity on the density of chewers (generalists) and chewing herbivory, whereas the density of galls and suckers (specialists) decreased significantly. A negative non-additive effect was observed with regard to gall density and a negative additive effect on sucker density was observed. Gall density was not related to the increase in condensed tannins affected by birch genotypic diversity. This implies that associational resistance is more likely to explain the negative non-additive effects on gall density. Our study shows that the loss of birch genotypic diversity due to shrinking population sizes will strongly affect specialist herbivores in the boreal forests of Hokkaido.

Objective: This research was conducted to assess the influence of CSN2 exon 7 milk production and the additive and dominance effects. Materials and Methods: DNA was isolated from 64 goats that possessed the CSN2 gene and subjected to a polymerase chain reaction and genotyping by Sanger sequencing. Genotype effect can be assessed through analysis of variance and the generalized linear model, which can estimate additive and dominance effects. Results: Dairy traits are greatly influenced by the crucial role played by the CSN2 gene. The influence of SNP g.8946C > T on milk yield (MY) is statistically significant (p < 0.05). Nevertheless, the impact of SNP g.8956G > A on MY is not statistically significant. Furthermore, the MY of Sapera goats is affected by both Parity (p < 0.01) and days in milk (p < 0.01). Conclusion: The CC genotype demonstrates a higher MY without noticeable additive or dominance effects. Evaluating the SNP g.8946C > T necessitates many samples and phenotypes.

Several compounds, such as hormones, are released uncontrolled into the aquatic environment, and some of these pollutants have an adverse effect on endocrine systems of humans and other organisms. However, there is insufficient information about the effect of natural and synthetic hormones on non-target organisms, such as cyanobacteria. Therefore, in this study, the adverse effects of hormones, singly and in combination, on Microcystis aeruginosa were explored for the first time. Chronic toxicity was evaluated based on biomass and chlorophyll a measurements during 14 days of exposure. Growth of cyanobacteria after exposure to 0.1–100 mg L−1 of hormones was inhibited in a concentration-dependent manner. In most cases, a low concentration of hormones (0.1–1 mg L−1) did not affect the growth of cyanobacteria, but a higher concentration (> 10 mg L−1) inhibited the growth. The obtained 14-day EC50 values were 88.92–355.15 mg L−1. According to these values, the decreasing order of the toxicity of the eight hormones to tested cyanobacteria was 17-α-ethinylestradiol > progesterone > 17ß-estradiol > 5-pregnen-3β-ol-20-one > testosterone> estrone > levonorgestrel > estriol. Moreover, data show that mixed hormones were more toxic than single compounds and more than additive effect was observed. The achieved 14-day EC50 values for mixed hormones were 56.66–166.83 mg L−1. Simultaneous presence of several hormones in the aquatic environment may lead to increased toxicity (more than additive effect) and cause serious ecological effects, more harmful than expected.

1. It has long been recognized that leaf traits exert a crucial control on litter decomposition, a key process for nutrient cycling, and that invading species can greatly alter such soil processes via changes in mixed litter trait composition. Trait effects on ecosystem processes are hypothesized to operate via changes in either dominant trait values in the community (often calculated as community-weighted mean trait values; CWM) or trait functional diversity (dissimilarity between species trait values; FD). Few have studied the effects of these community trait components in tandem due to their interdependence. 2. We studied litter mixture decomposition using three exotic and six native European tree species with a range in litter decomposability, to disentangle the unique and combined roles of CWM and FD in explaining net litter mixture mass loss. 3. We showed that while CWM exerted the strongest effect on mass loss, FD modulated its effects, increasing mass loss in mixtures with low mean decomposability and decreasing mass loss in mixtures with high mean decomposability. Litter species identity and native/exotic status explained relatively little additional variation in mass loss after accounting for CWM and FD. We further showed that alterations to CWM and HD were more important than the replacement of a native species with an exotic counterpart in predicting mass loss. 4. Synthesis: Our results indicate that the effect of adding an exotic or losing a native species on litter decomposition rate can be predicted from how a species alters both CWM and FD trait values. This supports the idea that the repercussions of exotic species on ecosystem processes depends on the extent that introduced species bear novel traits or trait values and so on how functionally dissimilar a species is compared to the existing species in the community.

The current study was conducted to investigate the effect of crossbreeding between Golden Sabahia (GS) and White Leghorn (WL) strains on body weight (BW) and egg production traits and estimate crossbreeding parameters such as direct heterosis, additive effect and evaluating the growth and egg production curves. GS pure line had the significantly highest BW0, BW56, BW70 and BW84, however, it had a significantly lower BW14 than the crossbreds. Furthermore, the GS - sired crossbred was significantly heavier in BW14, BW28 and BW42 than the pure lines and the reciprocal cross. GS × WL cross showed significantly higher daily body weight gains than the reciprocal cross except for BWG8 - 12. WL purebred line had the lowest EW90 among the strain groups, meanwhile, EW10 was at its highest mean in the GS × WL crossbred. Moreover, WL × GS crossbred had the lowest performance among the groups in terms of P10. Positive direct additive effects were shown for body weights and most egg production traits, indicating GS’s superior genetic potential. The direct additive effects were positive for the egg production traits studied apart from P10. Overall, the GS - sired crossbreds displayed the best performance in terms of growth rate and egg production, making them a promising option for poultry breeding programs.

1. Both plant species diversity and genetic diversity within a plant species can affect community properties and ecosystem processes. However, the relative contribution of species diversity and genetic diversity to ecosystem functioning is poorly known. Furthermore, ecosystem processes may respond non-additively to interactions between species diversity and genetic diversity. If interactive effects exist, the impact of biodiversity loss may not be predictable from simple assessments of either species diversity or genetic diversity alone. 2. Here, we addressed how plant species diversity and genetic diversity within a dominant species independently and interactively influenced plant community biomass in a Great Lakes sand dune ecosystem. To test the independent effects of diversity, we established two experiments. In one, we manipulated genetic diversity within the dominant dune species, Ammophila breviligulata. In the other, we manipulated the number of plant species, excluding A. breviligulata. Then, to test for interactive effects, we constructed communities that varied the number of species and levels of genetic diversity within A. breviligulata. 3. Although there were no independent effects of either species diversity or genetic diversity within A. breviligulata on biomass production in this system, interactive effects of species diversity and genetic diversity significantly influenced overall above-ground biomass production of the plant communities. Specifically, as genetic diversity within the dominant species increased, the relationship between species diversity and community-level biomass shifted from negative to positive. Negative non-additive effects of diversity drove this pattern. 4. Synthesis. These results show, for the first time, that interactions between plant species diversity and genetic diversity within a dominant species can alter biomass production, highlighting the importance of incorporating interactions between levels of biodiversity into our understanding of how biodiversity influences ecosystem function.

Eutrophication is a persistent threat to aquatic ecosystems worldwide. Foundation species, namely those that play a central role in the structuring of communities and functioning of ecosystems, are likely important for the resilience of aquatic ecosystems in the face of disturbance. However, little is known about how interactions among such species influence ecosystem responses to nutrient perturbation. Here, using an array (N = 20) of outdoor experimental pond ecosystems (15,000 L), we manipulated the presence of two foundation species, the macrophyte Myriophyllum spicatum and the mussel Dreissena polymorpha, and quantified ecosystem responses to multiple nutrient disturbances, spread over two years. In the first year, we added five nutrient pulses, ramping up from 10 to 50 μg P/L over a 10-week period from mid-July to mid-October, and in the second year, we added a single large pulse of 50 μg P/L in mid-October. We used automated sondes to measure multiple ecosystems properties at high frequency (15-minute intervals), including phytoplankton and dissolved organic matter fluorescence, and to model whole-ecosystem metabolism. Overall, both foundation species strongly affected the ecosystem responses to nutrient perturbation, and, as expected, initially suppressed the increase in phytoplankton abundance following nutrient additions. However, when both species were present, phytoplankton biomass increased substantially relative to other treatment combinations: non-additivity was evident for multiple ecosystem metrics following the nutrient perturbations in both years but was diminished in the intervening months between our perturbations. Overall, these results demonstrate how interactions between foundation species can cause surprisingly strong deviations from the expected responses of aquatic ecosystems to perturbations such as nutrient additions.

Insect pollination and biological pest control simultaneously influence crop yield, but are often investigated individually. This can lead to under‐ or over‐estimation of the importance of individual services when they interact to affect yield. Recent, limited evidence from field studies showed contrasting results with both additive and non‐additive positive and negative effects. To disentangle the mechanisms underlying these responses, we conducted a greenhouse experiment and a field study. We tested the potential and realized contribution of insect pollination to cotton boll retention and yield under various pest pressures and biocontrol levels. We found both additive and interactive effects of insect pollination and biocontrol within a single crop system depending on the level of pest pressure. In the greenhouse experiment, pollination did not contribute to cotton boll retention and final yield at low pest pressure. At high pest abundances, boll retention and final yield were higher when pollinators were present. In the field study, pollination was sufficient to alter the negative effect of pests on boll retention. Thus, interactive effect between the two ecosystem services on boll retention was present at high pest pressure in the greenhouse and at natural levels of pest pressure in the field, but not at lower pest abundances in controlled conditions. Although cotton plants partly compensated for bolls shedding by increasing their weight in the greenhouse experiment, this effect was not detected in the field study, likely due to higher environmental variation. Similarly, interactive effect of pollination and biocontrol on the final yield was present only in the greenhouse study. Synthesis and applications. We conclude that the contrasting findings of additive versus non‐additive effects between ecosystem services may be due to the levels of services and disservices tested and environmental variation. Further, this study shows that even when an ecosystem service does not appear to limit crop yield, it can make a substantial contribution to yield and act as insurance when the other service is reduced. For achieving food and fibre security, it is essential that future studies test interactive effects between these ecosystem services in different systems and environmental conditions.

Population endangerment typically arises from multiple, potentially interacting anthropogenic stressors. Extensive research has investigated the consequences of multiple stressors on organisms, frequently focusing on individual life stages. Less is known about population-level consequences of exposure to multiple stressors, especially when exposure varies through life. We provide the first theoretical basis for identifying species at risk of magnified effects from multiple stressors across life history. By applying a population modeling framework, we reveal conditions under which population responses from stressors applied to distinct life stages are either magnified (synergistic) or mitigated. We find that magnification or mitigation critically depends on the shape of density dependence, but not the life stage in which it occurs. Stressors are always magnified when density dependence is linear or concave, and magnified or mitigated when it is convex. Using Bayesian numerical methods, we estimated the shape of density dependence for eight species across diverse taxa, finding support for all three shapes.

Abiotic stress tolerance in plants is pivotal to increase yield stability, but its genetic basis is still poorly understood. To gain insight into the genetic architecture of frost tolerance, this work evaluated a large mapping population of 1739 wheat (Triticum aestivum L.) lines and hybrids adapted to Central Europe in field trials in Germany and fingerprinted the lines with a 9000 single-nucleotide polymorphism array. Additive effects prevailed over dominance effects. A two-dimensional genome scan revealed the presence of epistatic effects. Genome-wide association mapping in combination with a robust cross-validation strategy identified one frost tolerance locus with a major effect located on chromosome 5B. This locus was not in linkage disequilibrium with the known frost loci Fr-B1 and Fr-B2. The use of the detected diagnostic markers on chromosome 5B, however, does not allow prediction of frost tolerance with high accuracy. Application of genome-wide selection approaches that take into account also loci with small effect sizes considerably improved prediction of the genetic variation of frost tolerance in wheat. The developed prediction model is valuable for improving frost tolerance because this trait displays a wide variation in occurrence across years and is therefore a difficult target for conventional phenotypic selection.