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Winter conditions impose dramatic constraints on temperate, boreal, and polar ecosystems, and shape the abiotic and biotic interactions underpinning these systems. At high latitudes, winter can last longer than the growing season and may have a disproportionately large impact on organisms and ecosystems. Even so, our understanding of the ecological implications of winter is often lacking. Indeed, even what exactly defines winter is currently unclear, and boundaries that delineate this season are blurred across marine, freshwater, and terrestrial realms and fields of biology. Here, we discuss the complexity of defining winter, and highlight the importance of maintaining the capacity to test hypotheses across seasons, realms, and domains of life. We then outline questions drawn from diverse fields of research that address current gaps in our understanding of winter ecology and how winter influences multiple levels of biological organization, from individuals to ecosystems. Finally, we highlight the potential consequences of changes to both the length and severity of winter due to climate change, and discuss the role winter may play in mediating ecosystem function in the future. Key words: climate change, communities, ecosystems, individuals, populations. Les conditions hivernales imposent des contraintes dramatiques aux ecosystemes temperes, boreaux et polaires, et elles faconnent les interactions abiotiques et biotiques qui soutiennent ces systemes. Aux hautes latitudes, l'hiver peut durer plus longtemps que la saison de croissance et il peut avoir un impact disproportionne sur les organismes et les ecosystemes. Malgre cela, notre comprehension des implications ecologiques de l'hiver est souvent insuffisante. En effet, meme ce qui definitexactementl'hiver n'est pas clair actuellement et les frontieres qui delimitent cette saison sont floues a travers les domaines marins, d'eau douce et terrestres et les champs de la biologie. Les auteurs discutent ici de la complexite de definir l'hiver et soulignent l'importance de maintenir la capacite de tester des hypotheses a travers les saisons, les roy-aumes et les domaines de la vie. Ils presentent ensuite des questions tirees de divers domaines de recherche qui visent a combler les lacunes actuelles dans notre comprehension de l'ecologie hivernale et de la facon dont l'hiver influence de multiples niveaux d'organisation biologique, des individus aux ecosystemes. Enfin, ils soulignent les consequences potentielles des changements de la duree et de la rigueur de l'hiver dus aux changements climatiques et discutent du role que l'hiver pourrait jouer dans la mediation de la fonction des ecosystemes dans le futur. [Traduit par la Redaction] Mots-cles: changements climatiques, communautes, ecosystemes, individus, populations., Introduction Ecologists have traditionally regarded winter as a dormant time of year; a time when most organisms actively or passively depress their metabolism or seek out warmer climates until spring [...]

Background: Immunoglobulin A (IgA) nephropathy is a disorder of the immune system affecting kidney function, and genome‐wide association studies (GWAS) have defined numerous loci with associated variation, all implicating components of innate or adaptive immunity. Among these, single nucleotide polymorphisms (SNPs) in a region including the multiallelic copy number variation (CNV) of DEFA1A3 are associated with IgA nephropathy in both European and Asian populations. At present, the precise factors underlying the observed associations at DEFA1A3 have not been defined, although the key alleles differ between Asian and European populations, and multiple independent factors may be involved even within a single population. Methods: In this study, we measured DEFA1A3 copy number in UK family trios with an offspring affected by IgA nephropathy, used the population distributions of joint SNP–CNV haplotypes to infer the likely segregation in trios, and applied transmission disequilibrium tests (TDT) to examine joint SNP–CNV haplotypes for over‐ or undertransmission into affected offspring from heterozygous parents. Results and Conclusions: We observed overtransmission of 3‐copy class 2 haplotypes (raw p = 0.029) and some evidence for under‐transmission of 3‐copy class 1 haplotypes (raw p = 0.051), although these apparent effects were not statistically significant after correction for testing of multiple haplotypes. [ABSTRACT FROM AUTHOR]

(1) The eastern spruce budworm (Choristoneura fumiferana, Clem.) is a native irruptive forest pest that defoliates spruce‐fir forests throughout North America's boreal zone. (2) Past studies suggest that successful spruce budworm population control requires high natural mortality from a variety of sources, including predators, especially from parasitoids and birds. While well represented in many different ecosystems, the role of generalist predatory spiders in these boreal systems remains largely unstudied. (3) To determine the identity and percentage of spiders preying upon spruce budworm, we hand‐collected spiders from balsam fir (Abies balsamea) in stands with relatively high spruce budworm densities from forests in insular Newfoundland and Labrador, Canada. (4) Using a spruce budworm‐specific TaqMan real‐time PCR assay, we successfully amplified spruce budworm DNA in 32% of collected spiders. After spider molecular barcoding, we found the web builders Grammonota angusta Dondale, Pityohyphantes (aff. subarcticus), Dictyna brevitarsa Emerton and Estrandia grandaeva (Keyserling) represented 58% of the spiders feeding on spruce budworm, and the wandering hunter Philodromus rufus Dondale represented 11.8%. (5) Our molecular approach was an effective means with which to identify recently consumed prey and natural enemies in this boreal system. [ABSTRACT FROM AUTHOR]

• We use a novel model to predict the drivers of severe spruce budworm defoliation. • We conduct our study at the leading edge of the outbreak, Newfoundland, Canada. • Precipitation and temperature were key predictors of forest stand defoliation. • Host tree species was not an important predictor of forest stand defoliation. • Our results reconcile uncertainty in the drivers of spatial defoliation patterns. Eastern North America is in the midst of a spruce budworm (Choristoneura fumiferana Clem., SBW) epidemic. SBW is one of the most important forest insects with regard to outbreak coverage and impacts to the forest industry in this region. Numerous bioclimatic, vegetation, and spatial–temporal variables can influence the distribution and outbreak patterns of phytophagous insects such as SBW. Published models have yet to agree on consensus drivers of SBW defoliation. Spatially-explicit, fine-scale predictive models are needed, however, to aid in our understanding of current and future SBW impacts. We used a species distribution model - MaxEnt to examine the relationships between the 1972–1981 SBW defoliation and 13 predictor variables for the island of Newfoundland, Canada the leading edge of the current SBW outbreak. The optimal model for predicting the probability of severe SBW defoliation included precipitation in May and June, precipitation in July and August, and maximum temperature in June and July. The probability of severe defoliation rapidly increased when precipitation ranged at 75.0 mm – 91.0 mm in May and June but showed a complex relationship with precipitation in July and August. Probability also increased with maximum temperature in June and July until temperature reached 18.0 °C. Defoliation probability decreased with increasing distance from major roads and river channels, suggesting possible corridor effects. Counter to research in other study areas, host tree species was not an important predictor of defoliation in our analysis. We then used this MaxEnt machine learning algorithm to predict the probability of severe defoliation for the forests of the entire island on a 2 km resolution raster. Areas with high probability (>0.80) were concentrated in the northeast part of the island where black spruce (Picea mariana (Mill.) BSP) dominates the forest landscape. The predicted severe defoliation area (probability 0.4–1.0) for black spruce was 1.4 times the area for balsam fir, which is the dominant canopy forming tree species on the island and preferred host species for SBW. The higher predicted probability of severe defoliation in black spruce stands relative to balsam fir stands may arise due to the unique combination of climatic conditions and geographical distributions of two species on the island. Species distribution models for irruptive insect impacts (i.e., defoliation) are relatively rare but may be an important tool in forecasting future insect damage. [ABSTRACT FROM AUTHOR]

Tetropium fuscum (Fabricius) (Coleoptera: Cerambycidae), a phloem-feeding and wood-boring beetle introduced from Eurasia, attacks spruce in eastern Canada alongside its native congener Tetropium cinnamopterum Kirby. We reared phloem- and wood-feeding insects (and their predators) from bolts of red and Norway spruce (Picea rubens and Picea abies) in Nova Scotia, comparing insect communities between bolts with added eggs of T. fuscum or T. cinnamopterum and bolts without added Tetropium (controls). We tested for impacts of each Tetropium on insect community structure (Simpson's diversity, richness, and evenness). We also asked whether, consistent with Darwin's Naturalization Hypothesis, Tetropium spp. would have greater impacts on emergence of its closer relatives (which might be most likely to compete and/or share natural enemies). Addition of Tetropium eggs (either species) to bolts lowered insect diversity in both host trees. Both richness and evenness components of diversity were always lower in +Tetropium treatments, although different components reached statistical significance in different Tetropium species x host combinations. Addition of Tetropium spp. significantly reduced emergence of some species: Evodinus monticola (Randall) (Coleoptera: Cerambycidae) was reduced by T. fuscum on both hosts and by T. cinnamopterum on Norway spruce; Hylobius congener Dalla Torre, Schenkling, and Marshall was reduced by T. fuscum on red spruce; and Xylophagus sp. (Diptera: Xylophagidae) was reduced by T. cinnamopterum on Norway spruce. However, there was no relationship between Tetropium's impact on a community member and their phylogenetic relatedness, and the overall impacts of Tetropium presence were not very different between T. fuscum and T. cinnamopterum. [ABSTRACT FROM AUTHOR]