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Questions: The latitudinal biodiversity gradient; i.e., the increase in biodiversity towards the equator, is one of the most prominent biodiversity patterns. Nevertheless, many questions remain to be answered about the influence of multiple environmental factors on the latitudinal biodiversity gradient, especially for mosses, and the functional diversity of mosses and vascular plants. This study aims at evaluating the influence of latitude, climate, environmental variables, and habitat types (bog vs fen) on taxonomic and functional diversity (α‐diversity and β‐diversity) and the composition of vascular plant and moss species. Location: 49° N to 55° N in Northwestern Quebec, Canada. Taxon: Mosses, vascular plants. Methods: We used a database containing 376 phytosociological plots (400 m2) sampled in boreal peatlands located along a 600‐km latitudinal gradient. We evaluated changes in α‐diversity and β‐diversity in response to latitude, longitude, climate, and local abiotic variables for both taxonomic groups using linear mixed effect models. We evaluated the effects of these variables on taxonomic and functional composition using variance partitioning by redundancy analysis. Results: Moss diversity increased with latitude, although the effects were masked by environmental variables, whereas vascular plant diversity decreased with latitude in fens and did not vary with latitude in bogs. We observed a decrease in taxonomic and functional uniqueness with latitude. Moss and vascular plant taxonomic and functional composition were primarily structured by contrasting local conditions in bogs and fens, whereas climatic variations along the latitudinal gradient played a secondary role. Conclusions: Our results highlight the contrasting biodiversity patterns in both peatland types and the importance of local habitat conditions in structuring vascular plant and moss diversity. These patterns varied depending on the diversity indicator used, as α‐ and β‐diversity and functional and taxonomic diversity were often decoupled. Future studies should therefore include more than one diversity indicator and consider the differences between ecosystems and taxon groups. [ABSTRACT FROM AUTHOR]

Questions: Does urbanization promote biotic differentiation or homogenization of swamp plant communities? What is the contribution of natives and exotics to swamp response to urbanization? Location: Quebec City, Canada. Methods: Plant communities of 34 swamps located in low, moderately or highly urbanized landscapes were sampled, and species classified into three exclusive groups: native wetland, native upland and exotic plants. Urbanization's influence on the richness of each plant group was assessed using mixed models. Between‐site compositional similarities were calculated to identify variations in beta diversity with urbanization level using tests for homogeneity in multivariate dispersion. Beta diversity was further partitioned into species replacement and richness difference for each plant group. Finally, the relationships of ten environmental variables representing soil water saturation and microtopography with plant assemblages were determined by redundancy analysis. Results: Although the richness of exotics increased with urbanization intensity, revealing increasing propagule pressure, it remained six to 27 times lower compared to the richness of natives, which remained stable with urbanization. On the other hand, beta diversity increased with urbanization, with higher dissimilarities in species composition between highly urbanized swamps than between low‐urbanized ones. This pattern resulted from high species replacement among natives, while richness difference mainly contributed to exotic beta diversity. Changes in plant assemblages were mostly associated with bryophyte cover and soil drainage and red mottle size, suggesting that hydrological conditions likely acted as a strong driver of swamp plant community response to urbanization. Conclusions: Swamp plant communities experienced biotic differentiation with increasing urbanization. This differentiation pattern likely was linked to the unpredictable effect of urbanization on hydrological regimes, which promoted high native turnover while limiting exotic spread. Long‐term monitoring is recommended to ensure that exotics do not outcompete natives through time. Designing sustainable cities requires a greater understanding of the multifaceted effect of urbanization on biodiversity. [ABSTRACT FROM AUTHOR]

Aims: We investigated whether biotic homogenization of plant communities occurs over three decades in a small urban protected forest, and what the possible drivers are underlying the observed changes. Location: A 96 ha temperate forest, Montréal, Canada. Methods: We surveyed vegetation and explanatory variables (ecological conditions, disturbances, spatial structure) in 62 plant communities in 1980 and 2011. We collected plant attributes to identify functional groups (FGs). We evaluated changes in beta diversity using tests for homogeneity of multivariate dispersions. We used space–time interaction models to assess changes in FGs spatial structures. We used multivariate analyses to identify relationship between spatial patterns and explanatory variables, and variation partitioning analyses to identify the drivers involved in beta diversity changes. Results: Beta diversity declined only in the herb–shrub communities. About 35% of their FGs had significantly changed their spatial distribution over time. Those that contracted their distribution were mainly composed of plants with wind‐dispersed seeds or with low to intermediate vegetative propagation capabilities, while those that expanded were plants with fleshy fruits or extensive vegetative propagation capabilities. In 1980, communities were structured into small isolated clumps, while in 2011, clumps expanded and coalesced near disturbed areas. In 1980, the spatial assembly processes relied essentially on endogenous factors while in 2011 exogenous factors, such as disturbances, became more influential. Multivariate analyses suggested that edge effect, past agricultural disturbances, and beaver activities facilitated the decrease of beta diversity (homogenization process). Conclusions: The homogenization of herb–shrub communities likely resulted from changes in their clumped spatial structure. FGs with the most adapted attributes to disperse under urban forest conditions were those that expanded spatially. Structural changes seem to have begun with an unpredictable stage governed by dispersal limitation processes, followed by a predictable stage mostly driven by land‐use legacy and disturbances. [ABSTRACT FROM AUTHOR]

Aim In urbanized areas, exotic invasions, native extinctions, and the alteration of habitats and natural processes drive homogenization, which is a form of biotic impoverishment. This study examines whether urbanization and flooding induce homogenization of herbaceous communities in riparian forests and quantifies the relationships between taxonomic and functional β-diversity. Location Montréal, Québec, Canada. Methods Inventories were conducted in 56 riparian forests. Taxonomic and functional β-diversity were calculated as between-site similarities in species or trait composition for three levels of urbanization and flooding. Differences among the disturbance levels were compared using tests for homogeneity in multivariate dispersions. We quantified the correlation between local species richness, exotic proportion, taxonomic and functional β-diversity. We also partitioned taxonomic β-diversity into species turnover and richness difference. Results Urbanization led to taxonomic and functional differentiation, while increased flooding led to taxonomic and functional homogenization. We found a significant correlation between taxonomic and functional β-diversity. Changes in β-diversity were associated with species and trait turnover among both urbanization and flood levels, and with changes in species richness. Differentiation was associated with low species richness, and homogenization with high species richness. Exotic invasions tended to favour differentiation, but only at a low urbanization level. Main Conclusions The effect of urbanization on plant diversity in riparian forests was twofold: first, it directly induced taxonomic and functional differentiation through its effect on species loss and turnover (higher β-diversity at high urbanization level); second, differentiation was indirectly favoured through the reduction in flooding (higher β-diversity at low flood level). Taxonomic and functional β-diversity followed similar patterns, likely because species invasions and extinctions are not random, but are related to species traits. Our results underline the need to move our focus from exotic species to the true underlying factors of biodiversity loss and homogenization, notably land use changes and human disturbances. [ABSTRACT FROM AUTHOR]

Questions What are the spatial processes structuring plant trait composition in urban riparian forest communities at different spatial scales? What are the relative roles of local conditions (including historical aspects), landscape context and spatial processes in the community assembly of these forests? Location Montréal, Québec, Canada. Methods Species plant composition was inventoried in 57 riparian forests located along a gradient of urbanization. To analyse plant communities in terms of their trait composition, community-weighted means were calculated using eight functional traits. Forests were characterized by local (physical features, hydrological regime and historical disturbances) and landscape (surrounding land use) variables. Spatial processes structuring communities were assessed using Moran's eigenvector maps and asymmetric eigenvector maps. The relative importance of these three subsets (local, landscape and spatial variables) on tree, shrub and herb functional composition was quantified by variation partitioning using redundancy analyses. Results Functional patterns in riparian forests resulted primarily from environmental filtering (local and landscape variables). Local conditions, especially flood intensity, exerted an overriding selection pressure on functional composition of riparian plant communities. Urbanization seemed to act indirectly on trait patterns through the alteration of hydrological disturbances caused by on-going and historical land transformation. Nevertheless, dispersal along rivers was also a significant structuring force, while overland dispersal was negligible. Conclusions Our study highlights that under severe natural disturbance regimes, the effect of natural filters outweighed the negative effects of urban filters. However, the alteration of natural flooding processes by human activities is also a major mechanism influencing plant trait composition in urban riparian communities as forests subjected to reduced flooding intensity experienced a greater effect of urbanization. The effects of urbanization and of past land uses on plant communities were greater for trees than for shrubs and herbs due to the high turnover rate of the latter. Finally, our results showed the importance of dispersal along rivers for biodiversity even in fragmented urban landscapes. [ABSTRACT FROM AUTHOR]

Egg production is a costly component of reproduction for female birds in terms of energy expenditure and maternal investment. Because resources are typically limited, clutch size and egg mass are expected to be constrained, and this putative trade-off between offspring number and size is at the core of life history theory. Nevertheless, empirical evidence for this trade-off is equivocal at best, as individual heterogeneity in resource acquisition and allocation may hamper the detection of the negative correlation between egg number and mass within populations. Here, we investigated how female body mass and landscape composition influences clutch size, egg mass, and the relationship between these two traits. To do so, we fitted linear mixed models using data from tree swallows Tachycineta bicolor breeding in a network of 400 nestboxes located along a gradient of agricultural intensity between 2004 and 2011. Our dataset comprised 1463 broods for clutch size analyses and 4371 eggs (from 847 broods laid between 2005-2008) for egg mass analyses. Our results showed that agricultural intensity negatively impacted clutch size, but not egg mass nor the relationship between these two traits. Female mass, on the other hand, modulated the trade-off between clutch size and egg mass. For heavier females, both traits increased jointly, without evidence of a trade-off. However, for lighter females, there was a clear negative relationship between clutch size and egg mass. This work shows that accounting for individual heterogeneity in body mass allows the detection of a clutch size/egg mass trade-off that would have remained undetected otherwise. Identifying habitat and individual effects on resource allocation towards reproductive traits may help bridging the gap between predictions from theory and empirical evidence on life history trade-offs. [ABSTRACT FROM AUTHOR]

In areas where peatlands are abundant, they are likely to play a significant role in the hydrological and hydrogeological dynamics of a watershed. Although individual case studies are reported in the literature, there is a large range of aquifer-peatland interactions and there is a need to understand the controls of these interactions. The objectives of this study were (1) to better understand aquifer-peatland connections and how these may be predicted by geology and geomorphic location and (2) to provide a variety of reference sites for glacial geological settings. Slope and depression peatlands were studied in the Abitibi-Témiscamingue region and in the St. Lawrence Lowlands, two contrasting regions of southern Quebec. A total of 12 transects that span a shallow aquifer-peatland interface were instrumented with piezometers. Field investigations included peatland characterization, monthly water level monitoring, and continuous hydraulic head measurements with pressure transducers. The results indicate that 7 of the 12 transects receive groundwater from the surrounding shallow aquifer. At the peatland margin, four lateral flow patterns were identified and associated with slope peatlands (parallel inflow and divergent flow) and with depression peatlands (convergent flow and parallel outflow). Vertical hydraulic gradients suggest that water flows mainly downwards, i.e. from the peatland to the underlying mineral deposits. Vertical connectivity appears to decrease as the distance from the peatland margin increases. All of these exchanges are important components in the sustainability of peatland hydrogeological functions. The regional comparison of aquifer-peatland flow dynamics performed in this study provides a new set of referenced data for the assessment of aquifer-peatland connectivity. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Questions What vegetation changes occurred over three decades on two large temperate peatlands (1115 ha) isolated in an agricultural landscape and affected by a human-ignited fire? Location Southwest Québec, Canada. Methods In 2012, we revisited 103 plots first sampled in 1984-85. Changes in species composition were evaluated using the Sørensen dissimilarity index, in species frequency with Chi-square goodness-of-fit tests, and in species cover using one-sample t-tests. Tree encroachment was evaluated using aerial photographs and satellite imagery. We used linear discriminant analyses ( LDA) and ANOVA to evaluate the impact of tree encroachment on species composition. Results We found a floristic dissimilarity of 35% between 1984 and 1985 and 2012. Most species whose frequency and mean cover increased were peatland species, while most species with lower frequency and mean cover in 2012 were non-peatland species. The total area occupied by forest increased from 26% to 51%, an overall gain of 280 ha of forest. The species composition of old and new forests as well as of open sectors was highly distinct, as shown by the LDA that correctly assigned 97% of the sampling plots to these groups. Non-peatland species were 15 and five times more abundant than peatland species in old and new forests than open habitats, respectively. Conclusions Gradual drying of the peatland margins due to drainage of the surrounding catchment, as well as post-fire succession are likely the main drivers of the changes observed. Overall, our study showed that peatlands isolated in an anthropogenic landscape are dynamic ecosystems where vegetation communities can experience substantial changes in a short time frame. The broader implication is that peatland conservation in highly modified landscapes must be linked to restoration. [ABSTRACT FROM AUTHOR]

* Premise of the study: Assessing seed quality in orchids has been hindered by stringent germination requirements. Seed quality has traditionally been assessed in orchids using in vitro or in situ germination protocols or viability staining. However, these methods are not always well suited for rapid assessment of viability in the context of ecological studies. * Methods: The potential of an ex situ protocol for seed viability assessment of orchids in ecological studies was investigated by sowing seeds of Platanthera blephariglottis on Sphagnum moss collected in the orchid's natural habitat. Ex situ germination results were compared with those obtained by viability staining using triphenyltetrazolium chloride (TTC), and the effect of seed testa color on staining and germination results was investigated. * Key results: The ex situ protocol yielded high germination rates, with 66% of the seeds germinating after 9 wk. Depending on the seed testa color class, ex situ germination rates were about 1.4 to 2.5 times higher than viability rates determined using TTC, indicating that the TTC technique underestimated viability compared with the method using ex situ germination. The TTC estimates of viability rates were higher for seeds with dark-colored testae than for pale ones, whereas seed testa color had no effect on germination. * Conclusions: Our study showed promising results for the use of ex situ germination as an alternative to previously developed protocols for seed viability assessment of orchids in ecological studies. Staining using TTC might not be well suited for this purpose, since it introduced a bias with respect to seed testa color. [ABSTRACT FROM AUTHOR]

We sequenced genes coding for components of the SNARE complex ( STX1A, VAMP2, SNAP25) and their regulatory proteins (STXBP1/Munc18-1, SYT1), which are essential for neurotransmission, in 95 patients with idiopathic mental retardation. We identified de novo mutations in STXBP1 (nonsense, p.R388X; splicing, c.169+1G>A) in two patients with severe mental retardation and nonsyndromic epilepsy. Reverse transcriptase polymerase chain reaction and sequencing showed that the splicing mutation creates a stop codon downstream of exon-3. No de novo or deleterious mutations in STXBP1 were found in 190 control subjects, or in 142 autistic patients. These results suggest that STXBP1 disruption is associated with autosomal dominant mental retardation and nonsyndromic epilepsy. Ann Neurol 2009;65:748-753 [ABSTRACT FROM AUTHOR]

Journal of Ecology (2003) 91, 1008–1021 [ABSTRACT FROM AUTHOR]