Alternative metrics exist for representing variation in plant body size, but the vast majority of previous research for herbaceous plants has focused on dry mass. Dry mass provides a reasonably accurate and easily measured estimate for comparing relative capacity to convert solar energy into stored carbon. However, from a “plant's eye view”, its experience of its local biotic environment of immediate neighbors (especially when crowded) may be more accurately represented by measures of “space occupancy” (S–O) recorded in situ—rather than dry mass measured after storage in a drying oven. This study investigated relationships between dry mass and alternative metrics of S–O body size for resident plants sampled from natural populations of herbaceous species found in Eastern Ontario. Plant height, maximum lateral canopy extent, and estimated canopy area and volume were recorded in situ (in the field)—and both fresh and dry mass were recorded in the laboratory—for 138 species ranging widely in body size and for 20 plants ranging widely in body size within each of 10 focal species. Dry mass and fresh mass were highly correlated (r2 > .95) and isometric, suggesting that for some studies, between-species (or between-plant) variation in water content may be unimportant and fresh mass can therefore substitute for dry mass. However, several relationships between dry mass and other S–O body size metrics showed allometry—that is, plants with smaller S–O body size had disproportionately less dry mass. In other words, they have higher “body mass density” (BMD) — more dry mass per unit S–O body size. These results have practical importance for experimental design and methodology as well as implications for the interpretation of “reproductive economy”—the capacity to produce offspring at small body sizes—because fecundity and dry mass (produced in the same growing season) typically have a positive, isometric relationship. Accordingly, the allometry between dry mass and S–O body size reported here suggests that plants with smaller S–O body size—because of higher BMD—may produce fewer offspring, but less than proportionately so; in other words, they may produce more offspring per unit of body size space occupancy.
Background Foraging activities of wild boar (Sus scrofa) create small-scale soil disturbances in many different vegetation types. Rooting alters species composition by opening niches for less-competitive plants and as a recurrent factor becomes a part of the community disturbance regime. Vegetation responses to wild boar disturbance have mostly been studied in the boar’s non-native range or in native forest, rather than in open habitats in the native range. We investigate the response of open European semi-dry grassland vegetation dominated by (Brachypodium pinnatum) to native wild boar pressure in an abandoned agricultural landscape. Methods To describe the disturbance regime, we repeatedly mapped rooted patches during a 5-year period. Additionally, to study the vegetation response, we performed an artificial disturbance experiment by creating 30 pairs of simulated disturbances and undisturbed plots. The vegetation composition of the paired plots was repeatedly sampled five times in eight years of the study. Results Based on repeated mapping of disturbances, we predict that if the disturbance regime we observed during the 5-year period were maintained over the long term, it would yield a stable vegetation ratio consisting of 98.7 % of the grassland undisturbed, 0.4 % with fresh disturbance and 0.9 % in older successional stages. Vegetation composition on the artificially disturbed plots was continuously converging to that of undisturbed vegetation, but these disturbed plots still differed significantly in composition and had higher species number, even after eight years of succession. Synthesis Our results thus show that wild boar disturbance regime in its native range increases heterogeneity and species diversity of semi-dry grassland vegetation.
1. Many of the ‘adaptive' traits in angiosperm flowers occur only in some species within a clade. One good example of such traits is floral colour change, that is the retention of old, nonreproductive, rewardless, but fully turgid flowers in an altered colour. This trait has been viewed as a plant strategy to enhance distant pollinator attraction while minimizing visits to nonreproductive flowers. Considering that the same scenario appears true for most visually oriented flower visitors, however, it is unclear why this trait does not prevail in nature. 2. To understand such evolutionary patterns, we conducted a screening search for floral colour change in 219 angiosperm species. We quantified spectral alterations in petals or petaloid organs and translated them into colour shifts through insect eyes. Using phylogeny-based comparative methods, we further explored possibilities accounting for the infrequent occurrences of floral colour change: tendency of related species to resemble each other more than those randomly drawn from the phylogenetic tree (i.e. phylogenetic signal), constraints imposed through pigment coloration and their functions and evolutionary correlates of floral colour change. 3. Ultraviolet-sensitive insect eyes were estimated to perceive floral colour change more often than previously noticed. We detected significant phylogenetic signal in the degree of floral colour change. The evolution of floral colour change appeared constrained by pigment chemistry, because greater changes were more likely to occur in yellow or red floral parts. Postchange colours tended to retain distant visual detectability (i.e. green-receptor contrast), while reducing attractiveness in a close range (i.e. colour contrast), indicating another constraint imposed through the functions of pigment coloration. Data also suggest a possible evolutionary association between floral colour change and bee pollination. 4. Results indicate that floral colour change is scarce in nature because it primarily evolved to accommodate bees or comparable pollinators and because its occurrence was constrained by phylogenetic relatedness, pigment chemistry and ecological functions. An understanding of floral evolution thus requires considering different causalities for trait diversity in an integrative manner.
Studying patterns of species distributions along elevation gradients is frequently used to identify the primary factors that determine the distribution, diversity and assembly of species. However, despite their crucial role in ecosystem functioning, our understanding of the distribution of below-ground fungi is still limited, calling for more comprehensive studies of fungal biogeography along environmental gradients at various scales (from regional to global). Here, we investigated the richness of taxa of soil fungi and their phylogenetic diversity across a wide range of grassland types along a 2800 m elevation gradient at a large number of sites (213), stratified across a region of the western Swiss Alps (700 km2). We used 454 pyro-sequencing to obtain fungal sequences that were clustered into operational taxonomic units (OTUs). The OTU diversity-area relationship revealed uneven distribution of fungal taxa across the study area (i.e. not all taxa are everywhere) and fine-scale spatial clustering. Fungal richness and phylogenetic diversity were found to be higher in lower temperatures and higher moisture conditions. Climatic and soil characteristics as well as plant community composition were related to OTU alpha, beta and phylogenetic diversity, with distinct fungal lineages suggesting distinct ecological tolerances. Soil fungi, thus, show lineage-specific biogeographic patterns, even at a regional scale, and follow environmental determinism, mediated by interactions with other taxonomic groups, such as plants.
PLEASE NOTE, THESE DATA ARE ALSO REFERRED TO IN TWO OTHER PUBLICATIONS. PLEASE SEE DOI: 10.1111/ddi.12548 AND https://doi.org/10.1111/geb.12357 --- The popularity of species distribution models (SDMs) and the associated stacked species distribution models (S?SDMs), as tools for community ecologists, largely increased in recent years. However, while some consensus was reached about the best methods to threshold and evaluate individual SDMs, little agreement exists on how to best assemble individual SDMs into communities, that is, how to build and assess S?SDM predictions.
Here, we used published data of insects and plants collected within the same study region to test (a) if the most established thresholding methods to optimize single species prediction are also the best choice for predicting species assemblage composition, or if community?based thresholding can be a better alternative, and (b) whether the optimal thresholding method depends on taxa, prevalence distribution and/or species richness. Based on a comparison of different evaluation approaches, we provide guidelines for a robust community cross?validation framework, to use if spatial or temporal independent data are unavailable.
Our results showed that the selection of the “optimal” assembly strategy mostly depends on the evaluation approach rather than taxa, prevalence distribution, regional species pool or species richness. If evaluated with independent data or reliable cross?validation, community?based thresholding seems superior compared to single species optimisation. However, many published studies did not evaluate community projections with independent data, often leading to overoptimistic community evaluation metrics based on single species optimisation.
The fact that most of the reviewed S?SDM studies reported over?fitted community evaluation metrics highlights the importance of developing clear evaluation guidelines for community models. Here, we move a first step in this direction, providing a framework for cross?validation at the community level.
Premise of the study: The One Thousand Plant Transcriptomes Project (1KP, 1000+ assembled plant transcriptomes) provides an enormous resource for developing microsatellite loci across the plant tree of life. We developed loci from these transcriptomes and tested their utility. Methods and Results: Using software packages and custom scripts, we identified microsatellite loci in 1KP transcriptomes. We assessed the potential for cross-amplification and whether loci were biased toward exons, as compared to markers derived from genomic DNA. We characterized over 5.7 million simple sequence repeat (SSR) loci from 1334 plant transcriptomes. Eighteen percent of loci substantially overlapped with open reading frames (ORFs), and electronic PCR revealed that over half the loci would amplify successfully in conspecific taxa. Transcriptomic SSRs were approximately three times more likely to map to translated regions than genomic SSRs. Conclusions: We believe microsatellites still have a place in the genomic age—they remain effective and cost-efficient markers. The loci presented here are a valuable resource for researchers.
