2024 Onward

Permanent URI for this collectionhttps://hdl.handle.net/1807/137402

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Small granivores remove the seeds of 25 plant species at similarly high rates in an old-field plant community
(Canadian Science Publishing, 2024-09-25) Frasier, Hailey; Lucenay, Joel; Gillis, Evan; Verra, Audrey J; Jones, Riley M; Schamp, Brandon S
Plant species vary in the number, size, and character of seeds produced; consequently, there is considerable reason for granivores to differentially target the seeds of some species, impacting plant species abundance and coexistence. In an old-field plant community, we set out trays of seeds for 25 plant species to test for the influence of plant species identity, seed size, native status, and time across the growing season on granivory (i.e. seed removal rates). Most seeds (83%), regardless of species identity, were removed by granivores, and removal rates were higher earlier in the growing season. Forb seeds were removed at slightly higher rates than graminoid seeds (~4% more seeds removed, on average), but seed removal rates were not influenced by seed size or plant native status. Seed removal rate differed for only 4% of plant species pairs and these differences were small (~3 out of 20 seeds). Seed removal per plant species was not associated with the field abundance of that plant species. Similarly high removal rates of differently sized seeds suggest that several granivore guilds with different size preferences are present in the community. Temporal variation in removal rates suggests a strong influence of seed availability on granivore behaviour.
Tissue-specific expression of HCN and its metabolic precursors in Trifolium repens
(Canadian Science Publishing, 2024-08-08) Bhachu, Keerath; Santangelo, James S.; Johnson, Marc T J; Emad Fadoul, Hind
Cyanogenesis, the release of hydrogen cyanide (HCN), is governed by two loci, Ac and Li, in white clover (Trifolium repens L.). Ac encodes a three gene region that regulates cyanogenic glucoside production, while Li encodes linamarase that hydrolyzes cyanogenic glucosides to produce HCN. We examined Ac and Li expression in leaf, floral, and root tissues of cyanogenic and acyanogenic plants, complemented by gene expression analysis, to understand tissue specific expression of HCN metabolism. Ac metabolic expression was present in leaves, absent in roots, and rare in flowers. Li metabolic expression in leaves perfectly correlated with that in flowers but was present in roots regardless of linamarase presence in leaves, suggesting spatial enzyme expression variation due to a homologous gene copy. Hydrogen cyanide expression in flowers was infrequently expressed at low concentrations in plants with functional Ac and Li. Gene expression analysis confirmed some tissue-specific expression patterns and also suggested more complex molecular regulation than previously described. This study provides the first detailed examination of cyanogenesis tissue-specificity in white clover, a plant of agriculture significance. The varied expression of cyanogenic secondary metabolites across tissues indicates the need for research into how white clover regulates its defenses to conserve resources.
Do linear clearings in boreal peatlands recover? Comparing taxonomic, phylogenetic, and functional plant diversity
(Canadian Science Publishing, 2024-07-14) Goud, Ellie M; Davidson, Scott J; Dabros, Anna; Kleinke, Kimberly; Schmidt, Megan A; Strack, Maria
Land-use changes and anthropogenic disturbances are major threats to biodiversity, affecting ecosystem function and recovery. In boreal Alberta, Canada, petroleum development has led to extensive landscape fragmentation, notably through linear clearings created for seismic exploration that remove surface vegetation and microtopography. Despite partial recovery on forested seismic lines, peatland recovery is often arrested, impacting wildlife and carbon dynamics. Restoration efforts employ silviculture techniques to create microtopography and foster tree growth, but the efficacy of restoration treatments in restoring peatland plant diversity remains uncertain. We compared taxonomic, phylogenetic, and functional diversity of understory plant communities across treated and untreated seismic lines, alongside reference sites in treed bogs and fens. Treated lines generally had a twofold increase in plant height, leaf dry matter content, foliar nitrogen and phosphorus contents compared to reference sites. In bogs, treated lines differed from reference conditions driven by increases in herbaceous taxa, while fens displayed disparities mainly in taxonomic and phylogenetic diversity. Differential responses of bogs and fens underline the necessity for tailored management strategies. Changes in plant diversity away from restoration targets have implications for ecosystem recovery, emphasizing the importance of long-term monitoring to evaluate the effectiveness of silviculture techniques in restoring boreal peatland plant communities.
Phenological growth stages of highbush blueberries (Vaccinium spp.): codification and description according to the BBCH scale
(Canadian Science Publishing, 2024-07-25) Wichura, Merret Anna; Koschnick, Felix; Jung, Jeanette; Bauer, Sina; Wichura, Alexandra
Highbush blueberries (Vaccinium spp.) are cultivated crop plants worldwide and they are still gaining importance. But a common uniform description of the phenological development was missing so far. In this work, a specific code is presented, based on the decimal BBCH scale. The BBCH scale comprises the macrostages 0-9, with macrostage 4 being omitted here, because it has no relevance for blueberry crops grown in the field. Each macrostage is subdivided in several microstages, each describing a notable developmental stage. The BBCH code takes special reference to the fruit development, fruit ripening and several fruit pickings, which are typical for blueberries. For each macrostage the main development as well as cultivation characteristics are explained in more detail. The new BBCH code is compared with other descriptions of phenotypical development of highbush blueberries and transformations are suggested. The BBCH code is developed for cultivated highbush blueberries and is therefore applicable to northern, southern, and rabbiteye blueberries as well.
Observations on the curvature of Physcomitrium patens (Hedw.) Mitt. and Funaria hygrometrica (Hedw.) caulonemal filaments
(Canadian Science Publishing, 2024-06-08) Antonishyn, Nick; Duckett, Jeffrey G.; Ashton, Neil William
Light-grown, whole gametophytic colonies of Physcomitrium (formerly Physcomitrella) patens (Hedw.) Mitt. exhibit a spiral morphology resulting from the strongly coordinated curvature of the population of peripheral caulonemal filaments. The direction of curvature is predominantly clockwise when cultures are illuminated from above and anticlockwise when illuminated from below. In P. patens, side branch initials (SBIs) emerge from caulonemal subapical cells on the outside of the curve. By contrast, the curvature of caulonemata of Funaria hygrometrica is predominantly anticlockwise when colonies are illuminated from above and clockwise when illuminated from below. In F. hygrometrica, SBIs emerge from caulonemal subapical cells on the inside of the curve. We have discounted a role for gravity in these phenomena and discuss several other possible mechanistic explanations. We also document for the first time thigmotropism of protonemata of P. patens.
Contributions of leaflet anatomy to the distinction of two species of Ceiba Mill. (Malvaceae - Bombacoideae): Ceiba pubiflora (A. St.-Hil.) K. Schum. and Ceiba speciosa (A. St.-Hil.) Ravenna
(Canadian Science Publishing, 2024-05-21) Bento, João Pedro Pena; Rodrigues da Silva, Jane; Belan dos Santos, Fernando; Amano, Érika; Dias, Edna Scremin
Ceiba is a genus of tree species with a predominantly neotropical distribution which, in general, are readily recognized in the landscape in the vegetative stage by their large trunk with prickles, commonly ventricose (swollen). Some Ceiba species have overlapping geographical distributions, such as C. speciosa and C. pubiflora. These species have quite uniform vegetative features, making it difficult to differentiate them when they are not in flowering. Here, we examined the leaflets anatomical features of the two species in order to distinguish them while in the vegetative phase. Fully expanded leaves were collected, fixed, embedded in paraffin and cross-sections were made from the leaflets midvein, margin and intercostal region. Ceiba speciosa has hypostomatic leaflets, with continuous biseriate epidermis along the adaxial face, rectilinear margin with a vascular bundle at the end of the margin while Ceiba pubiflora has amphistomatic leaflets, with interrupted biseriate epidermis along the adaxial face and curved margin on the abaxial face. These taxonomically important anatomical features of C. speciosa and C. pubiflora leaflets have provided additional characters good for distinguishing the species especially when they are in the vegetative phase; and therefore updates the existing accounts of the characters useful for the taxonomy of Malvaceae.
An experimental test of niche versus dispersal limitation of the distribution limit of the Ghost Antler Lichen, Pseudevernia cladonia, along a temperate-boreal elevation gradient
(Canadian Science Publishing, 2024-04-20) Rinas, Christina Lynn; Vellend, Mark
Understanding the mechanisms underlying species’ distribution limits is critical for predicting how species may respond to environmental change. For species restricted to mountain summits, there is concern that climatic changes may result in increasingly restricted distributions. Two central mechanisms govern species distribution limits: (i) niche limitations – environmental conditions beyond distribution limits that are insufficient for survival and reproduction, and (ii) dispersal limitations that prevent colonization of suitable habitat beyond distribution limits. Here, we conducted a transplant experiment to examine the effect of niche versus dispersal limitation on the altitudinal distribution limit of the Ghost Antler Lichen (Pseudevernia cladonia) that, within Québec, Canada, is restricted to high-elevation mountain summits in the southeast. Along an elevation gradient, we transplanted individuals into sites within its distribution, at the edge, and beyond its distribution. We observed that survival and performance were greatest within its distribution and decreased markedly beyond its distribution, supporting our prediction that this lichen is niche limited along the elevation gradient. We suggest that cooler and more humid conditions at the summit are important environmental factors for species’ persistence. Our findings suggest that projected climatic changes in these montane habitats may result in less suitable habitat for this species.
First evidence of nitrogen fixation associated with bryophytes from coastal Wabanaki-Acadian forests
(Canadian Science Publishing, 2024-04-22) Jean, Mélanie; Bellenger, Jean-Philippe
Associations between bryophytes and dinitrogen (N2)-fixing bacteria are a significant source of exogenous N in unmanaged boreal and possibly temperate ecosystems. However, the extent to which biological N2-fixation (BNF) applies to the boreal-temperate ecotone remains elusive. The current focus on common species limits our understanding of BNF at the community level. Our objective was to characterize the presence of cyanobacteria and BNF activity associated with bryophytes in the coastal forests of Fundy National Park (New Brunswick, Canada). In 2021, we harvested three liverwort and 11 moss species from two sites (71 samples) and measured environmental covariates (e.g., canopy composition, soil pH). We used stable isotope incubations with 15N2 gas in growth chambers to quantify potential BNF activity and used phycocyanin extractions as a cyanobacteria abundance proxy. Many species presented detectable BNF rates, which were similar to or higher than those of well-studied feather mosses. These included species that have rarely been found to contribute to BNF. While cyanobacteria were present on most samples, we found no positive association between abundance and BNF. Our findings are among the first records for bryophyte-associated BNF in the boreal-temperate ecotone of eastern Canada and offer insights into the potential role of this process in N cycling in coastal conifer-dominated forests.
Phylogenetic placement of Carex dianae Steud., a sedge endemic to the South Atlantic island of St Helena
(Canadian Science Publishing, 2024-04-14) Bradshaw, Cassandra D.V.; Percy, Diana M.; Thomas-Williams, Vanessa; Cairns-Wicks, Rebecca; Gray, Alan; Cronk, Quentin C B
Carex dianae Steud. is an endemic sedge of St Helena, an isolated island in the South Atlantic. Our study provides the first molecular sequence data for this taxon. We generated sequence data for plastid matK and trnK regions and nuclear ITS and ETS regions to determine the placement of C. dianae in the broader Carex phylogeny. The placement of C. dianae falls within Carex sect. Spirostachyae Drejer, and it is sister to a clade including Carex clavata Thunb., Carex aethiopica Schkuhr (both from the Cape region of S. Africa), and Carex gunniana Boott (southern Australia). The existence of three divergent nucleotype groups and two plastotypes is revealed from genetic variation within C. dianae. The results suggest that the ancestor of C. dianae likely originated in the Cape region of South Africa, followed by transoceanic dispersal to St Helena estimated at 4.4 - 4.9 Mya, likely by a bird vector. The most divergent population is that on an isolated hill known as “The Barn” which may represent a distinct taxon. The existence of highly structured molecular variation within an island only 16 km long is discussed.
The Arrhenia peltigerina complex—preliminary report
(Canadian Science Publishing, 2024-02-27) Voitk, Andrus; Saar, Irja; Burzynski, Michael; Corriol, Gilles
Phylogenetic study of Arrhenia peltigerina revealed a complex of seven divergent clades. Type specimens of Agaricus peltigerinus and Omphalina cupulatoides fell into separate clades; the latter was recombined as Arrhenia cupulatoides. Four clades were described as new species: Arr. baltica, Arr. fennoscandica, Arr. mohniensis, and Arr. talpoides; the fifth, with only a single specimen, was left formally undescribed. These cryptic species are uncommon—more so in North America than Scandinavia—and collections are often misidentified. Spore measurements separated Arr. baltica from the others by its narrower spores; average measurements help separate some species a bit better than ranges. So far, Arr. peltigerina was found only in North America, Arr. mohniensis and Arr. talpoides in both Europe and North America, and the remainder only in Europe. The host species of Peltigera was P. hymenina for Arr. cupulatoides, P. rufescens for Arr. baltica, and varied for the others. All but one collection came from soil over calcareous bedrock. Small sample size does not permit assigning high confidence to noted interspecific differences; these await confirmation by greater experience from future study.

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